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- Front Matter: Volume 7732
- UV Missions and Technologies
- X-Ray Observatories and Optics
- X-Ray Polarimetry
- Gamma-Ray Observatories
- Astrophysical Science Drivers for New Observatories
- Solar Missions and Technologies
- Medium X-Ray Observatories I
- Medium X-Ray Observatories II
- Medium X-Ray Observatories III
- Medium X-Ray Observatories IV
- Large X-Ray Observatories I
- Large X-Ray Observatories II
- Low-Temperature Detectors
- New X-Ray/Gamma-Ray Missions I
- New X-Ray/Gamma-Ray Missions II
- New X-Ray/Gamma-Ray Missions III
- Poster Session: UV Missions and Technology
- Poster Session: X-Ray Observatories and Optics
- Poster Session: X-Ray Polarimetry
- Poster Session: Gamma-Ray Observatories
- Poster Session: Solar Missions and Technologies
- Poster Session: Medium X-Ray Observatories
- Poster Session: Large X-Ray Observatories
- Poster Session: New X-ray/Gamma-ray Missions
- Poster Session: Technology for Future Observatories
Front Matter: Volume 7732
Front Matter: Volume 7732
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This PDF file contains the front matter associated with SPIE Proceedings Volume 7732, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
UV Missions and Technologies
Fabrication of FORTIS
Show abstract
The Johns Hopkins University sounding rocket group is building the Far-ultraviolet Off Rowland-circle Telescope for
Imaging and Spectroscopy (FORTIS), which is a Gregorian telescope with rulings on the secondary mirror. FORTIS will
be launched on a sounding rocket from White Sand Missile Range to study the relationship between Lyman alpha escape
and the local gas-to-dust ratio in star forming galaxies with non-zero redshifts. It is designed to acquire images of a 30'
x 30' field and provide fully redundant "on-the-fly" spectral acquisition of 43 separate targets in the field with a bandpass
of 900 - 1800 Angstroms. FORTIS is an enabling scientific and technical activity for future cutting edge far- and near-uv
survey missions seeking to: search for Lyman continuum radiation leaking from star forming galaxies, determine the
epoch of He II reionization and characterize baryon acoustic oscillations using the Lyman forest. In addition to the high
efficiency "two bounce" dual-order spectro-telescope design, FORTIS incorporates a number of innovative technologies
including: an image dissecting microshutter array developed by GSFC; a large area (~ 45 mm x 170 mm) microchannel
plate detector with central imaging and "outrigger" spectral channels provided by Sensor Sciences; and an autonomous
targeting microprocessor incorporating commercially available field programable gate arrays. We discuss progress to date
in developing our pathfinder instrument.
Large-format high-spatial resolution cross-strip readout MCP detectors for UV astronomy
Show abstract
We have implemented cross strip readout microchannel plate detectors in a 40mm diameter active area format, open
face (UV/particle) configuration. These have been tested with a field programmable gate array based parallel channel
electronics for event encoding which can process high input event rates (> 5 MHz) with high spatial resolution. Using
small pore MCPs (6μm) operated in a pair, we achieved spatial resolution of < 20μm FHWM at MCP gain of 1x106 e- per event. Future large aperture UV missions require detectors to have large formats (> 100 mm) with high event rate
throughput (~ MHz) while retaining high spatial resolution. We will discuss our plans to scale our 47 mm square anodes
to 100 mm and our ideas for the next front end ASIC that combines a state-of-the-art, fast charge sensitive amplifier
with fast sampling analog storage and built in ADCs.
FIREBALL: the Faint Intergalactic medium Redshifted Emission Balloon: overview and first science flight results
Show abstract
FIREBALL (the Faint Intergalactic Redshifted Emission Balloon) is a balloon-borne 1m telescope coupled to an
ultraviolet fiber-fed spectrograph. FIREBALL is designed to study the faint and diffuse emission of the intergalactic
medium, until now detected primarily in absorption. FIREBALL is a path finding mission to test new technology
and make new constraints on the temperature and density of this gas. We report on the first successful science flight
of FIREBALL, in June 2009, which proved every aspect of the complex instrument performance, and provided the
strongest measurements and constraints on IGM emission available from any instrument.
Colorado High-resolution Echelle Stellar Spectrograph (CHESS)
Show abstract
We discuss the design of a new high-efficiency, high-resolution far ultraviolet echelle spectrograph. Our project
concentrates on utilizing new technologies for gratings and detectors to reduce the impact of scattered light and
maximize quantum efficiency over a large bandpass. This program will enable advances in a vast number of
astrophysical subjects. Topics ranging from protoplanetary disks to the intergalactic medium can be addressed by
incorporating such a spectrograph into a future, long-duration mission.
The Diffuse Interstellar Cloud Experiment (DICE): integration and first-look data
Show abstract
We have assembled and launched the Diffuse Interstellar Cloud Experiment (DICE), an instrument capable of
recording high resolution (λ/δλ = 30,000) spectra in the Far Ultraviolet (FUV). Absorption measurements toward nearby
bright stars can provide new insight into the processes governing warm-hot gas in the Local Interstellar Medium. It flew
on May 21st, 2010. An anomaly in the Black Brant motor subjected the payload to abnormally high vibration. As a
result, the optics were misaligned and no spectral data fell on the detector. Here we present the details of mechanical and
electrical integration with NASA launch systems, as well as optical alignment of the telescope and spectrograph. In
addition, we summarize the flight results.
X-Ray Observatories and Optics
X-ray telescope design and technology: what the future holds
Show abstract
The great X-ray observatories of the 20th century relied exclusively on the Wolter Type I optics design to provided true imaging in the energy band 0.1-10 keV. What are the prospects for continued development of the W-I geometry in the 21st Century and what alternative designs, technologies and bright ideas maybe poised to make an impact in X-ray astronomy in the future?
Foil x-ray mirrors for astronomical observations: still an evolving technology
Show abstract
Foil X-ray mirrors, introduced by the Goddard X-ray Group in the late 1970s, were envisioned as an interim
and complementary approach toward increased sensitivity for small inexpensive astronomical instruments. The
extreme light weight nature of these mirrors dovetailed beautifully with Japan's small payload missions, leading
to several collaborative, earth orbiting observatories, designed primarily for spectroscopy, of which SUZAKU is
still in earth orbit. ASTRO-H is the latest joint instrument with Japan, presently in the implementation phase.
At Goddard, some 30 years after we introduced them, we are involved with four separate flight instruments utilizing
foil X-ray mirrors, a good indication that this technology is here to stay. Nevertheless, an improved spatial
resolution will be the most welcomed development by all. The task of preparing upwards of 1000 reflectors, then
assembling them into a single mirror with arcmin resolution remains a formidable one. Many, performance limiting
approximations become necessary when converting commercial aluminum sheets into 8 quadrant segments,
each with ~200 nested conical, ~4Å surface reflectors, which are then assembled into a single mirror. In this
paper we will dscribe the mirror we are presently involved with, slated for the Goddard high resolution imaging
X-ray spectrometer (SXS) onboard ASTRO-H. Improved spatial resolution will be an important enhancement to
the science objectives from this instrument. We are accordingly pursuing and will briefly describe in this paper
several design and reflector assembly modifications, aimed toward that goal.
Light weight optics made by glass thermal forming for future x-ray telescopes
Show abstract
Future X-ray observatory missions, such as IXO or Gen-X, require grazing incidence optics of large collecting area in
combination with a very good angular resolution. Wolter type I X-ray telescopes made of slumped glass segments could
be a possible alternative to silicon pore optics. To achieve these requirements we develop slumping methods for high
accuracy segments by experimental means. In particular, we follow the approach of indirect slumping and aim to
produce parabola and hyperbola in one piece. In order to avoid internal stress in the glass segments the thermal
expansion coefficient of the glass should closely match the thermal expansion of the mould material. Currently we focus
on a combination of the alloy KOVAR for the mould and D263 for the glass; additionally a platinum-coated silica as
mould material is studied. We investigate the behaviour of both materials during slumping in order to obtain the ideal
environment for the slumping process. Additionally we report on the design of different metrology methods to measure
the figure and thickness variations of the glass segments in visual light, e.g. interference, and on bearings used for shape
measurements and integration.
Hot slumping glass technology for the grazing incidence optics of future missions with particular reference to IXO
Show abstract
The mirrors of the International X-ray Observatory (IXO) consist of a large number of high quality segments delivering
a spatial resolution better than 5 arcsec. A study concerning the slumping of thin glass foils for the IXO mirrors is under
development in Europe, funded by ESA and led by the Brera Observatory. We are investigating two approaches, the
"Direct" and "Indirect" slumping technologies, being respectively based on the use of convex and concave moulds. In
the first case during the thermal cycle the optical surface of the glass is in direct contact with the mould surface, while in
the second case it is the rear side of the foil which touches the master. Both approaches present pros and cons and aim of
this study is also to make an assessment of both processes and to perform a trade-off between the two. The thin plates are
made of D263glass produced by Schott. Each plate is 0.4 mm thick, with a reflecting area of 200 mm x 200 mm; the
mould are made of Fused Silica. After the thermal cycle the slumped MPs are characterized to define their optical
quality and microroughness. The adopted integration process foresees the bonding of the slumped foils to a rigid
backplane by means of reinforcing ribs. During the bonding process the plates are constrained to stay in close contact to
the surface of the master (i.e. the same mould used for the hot slumping process) by the application of a vacuum pump
suction. In this way spring-back deformations and low frequency errors still present on the foil profile after slumping can
be corrected. In this paper we present the preliminary results concerning achieved during the first part of the project.
Design and development of thin quartz glass WFXT polynomial mirror shells by direct polishing
Show abstract
The Wide Field X-ray Telescope (WFXT) is a medium class mission for X-ray surveys of the sky with an unprecedented
area and sensitivity. In order to meet the effective area requirement, the design of the optical system is based on very thin
mirror shells, with thicknesses in the 1-2 mm range. In order to get the desired angular resolution (10 arcsec requirement,
5 arcsec goal) across the entire 1x1 degree FOV (Field Of View), the design of the optical system is based on nested
modified grazing incidence Wolter-I mirrors realized with polynomial profiles, focal plane curvature and plate scale
corrections. This design guarantees an increased angular resolution at large off-axis angle with respect to the normally
used Wolter I configuration, making WFXT ideal for survey purposes. The WFXT X-ray Telescope Assembly is
composed by three identical mirror modules of 78 nested shells each, with diameter up to 1.1 m. The epoxy replication
process with SiC shells has already been proved to be a valuable technology to meet the angular resolution requirement
of 10 arcsec. To further mature the telescope manufacturing technology and to achieve the goal of 5 arcsec, a
deterministic direct polishing method is under investigation. The direct polishing method has already been used for past
missions (as Einstein, Rosat, Chandra): the technological challenge now is to apply it for almost ten times thinner shells.
Under investigation is quartz glass (fused silica), a well-known material with good thermo-mechanical and polishability
characteristics that could meet our goal in terms of mass and stiffness, with significant cost and time saving with respect
to SiC. Our approach is based on two main steps: first quartz glass tubes available on the market are grinded to conical
profiles, and second the obtained shells are polished to the required polynomial profiles by CNC (Computer Numerical
Control) polishing machine. In this paper, the first results of the direct grinding and polishing of prototypes shells made
by quartz glass with low thickness, representative of the WFXT optical design, are presented.
X-Ray Polarimetry
On understanding the figures of merit for detection and measurement of x-ray polarization
Show abstract
The prospects for accomplishing X-ray polarization measurements appear to have grown in recent years after a more
than 35-year hiatus. Unfortunately, this long hiatus has brought with it some confusion over the statistical uncertainties
associated with polarization measurements of astronomical sources. The heart of this confusion stems from a
misunderstanding (or potential misunderstanding) of a standard figure of merit-the minimum detectable polarization
(MDP)-that one of us introduced many years ago. We review the relevant statistics, and quantify the differences
between the MDP and the uncertainty of an actual polarization measurement. We discuss the implications for future
missions.
Broadband soft x-ray polarimetry
Show abstract
We developed an instrument design capable of measuring linear X-ray polarization over a broad-band using
conventional spectroscopic optics, using a method previously described by Marshall (2008) involving laterally
graded, multilayer-coated flat mirrors. We present possible science investigations with such an instrument and
two possible configurations. This instrument could be used in a small orbiting mission or scaled up for the
International X-ray Observatory. Laboratory work has begun that would demonstrate the capabilities of key
components.
Hard x-ray polarimetry with HX-POL
Show abstract
X-ray polarimetry offers a unique vantage to investigate particle acceleration from compact objects and relativistic
outflows. The HX-POL concept uses a combination of Si and Cadmium Zinc Telluride (CZT) detectors to measure
the polarization of 50 keV - 500 keV X-rays from cosmic sources through the azimuthal distribution of Compton
scattered events. HX-POL would allow us to measure the polarization degrees of Crab-like sources well below
10% for a one day balloon flight. A longer (15-30 day) flight would improve the polarization degree sensitivity
to a few percent. In this contribution, we discuss the sensitivity of a space-borne HX-POL payload, and present
new results from laboratory tests of the HX-POL Si and CZT detectors.
Gamma-Ray Observatories
The building of Fermi-LAT
W. Neil Johnson
Show abstract
The Large Area Telescope (LAT) instrument on the Fermi Gamma ray Space Telescope mission was inspired by the
breadth of discoveries in high energy gamma ray sky by the EGRET instrument on the Compton Gamma Ray
Observatory. Founded in the new technologies and capabilities in high energy particle physics detectors, the first studies
for the LAT concept were begun in 1992 and the foundations of the LAT international collaboration, bringing together
the high energy particle physics community and astrophysics community, were established shortly thereafter. This paper
reviews the evolution of the LAT design from concept to launch and attempts to highlight the successes, problems and
lessons learned along the way.
The tracker of the Fermi Large Area Telescope
Show abstract
The Large Area Telescope (LAT) is the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi),
an orbital astronomical observatory that was launched on 11 June 2008. Its tracker is a solid-state instrument
that converts the gamma rays into electron-positron pairs which it then tracks in order to measure the incoming
gamma-ray direction. The tracker comprises 36 planes of single-sided silicon strip detectors, for a total of 73
square meters of silicon, read out by nearly 900,000 amplifier-discriminator channels. The system operates on
only 160 W of conditioned power while achieving > 99% single-plane efficiency within its active area and better
than 1 channel per million noise occupancy. We describe the tracker's design and performance, and discuss in
particular the excellent stability of the hardware response during the first two years of operation on orbit.
The calorimeter of the Fermi Large Area Telescope
J. Eric Grove,
W. Neil Johnson
Show abstract
The Large Area Telescope (LAT), the primary instrument on the Fermi Gamma-ray Space Telescope, has been making
revolutionary observations of the high-energy (20 MeV - 300 GeV) gamma-ray sky since its launch in June 2008. The
LAT calorimeter is a modular array of 1536 CsI(Tl) crystals supported within 16 carbon fiber structures and read out at
each crystal end with silicon PIN photodiodes to provide both energy and position information. The hodoscopic crystal
stack allows imaging of electromagnetic showers and cosmic rays for improved energy measurement and background
rejection. Signals from the array of photodiodes are processed by custom ASICs and commercial ADCs. We describe the
calorimeter design and the primary factors that led those design choices.
Astrophysical Science Drivers for New Observatories
The origin of the elements as seen through supernova remnants
Anne Decourchelle
Show abstract
Supernovae are the main sites of heavy element production in galaxies. Observing their remnants at a relatively early
stage of a few hundred years after the explosion provides a direct view of the main synthesized elements produced by
various supernova types. While the current observations offer a number of diagnostics and relevant information of the
ejected material, further progresses are hampered by the performances of current instruments. I will discuss the main
science drivers in the field of supernova remnants and their scientific requirements for future instruments.
Solar Missions and Technologies
First light of SWAP on-board PROBA2
Show abstract
The SWAP telescope (Sun Watcher using Active Pixel System detector and Image Processing) is an instrument launched
on 2nd November 2009 on-board the ESA PROBA2 technological mission.
SWAP is a space weather sentinel from a low Earth orbit, providing images at 174 nm of the solar corona. The
instrument concept has been adapted to the PROBA2 mini-satellite requirements (compactness, low power electronics
and a-thermal opto-mechanical system). It also takes advantage of the platform pointing agility, on-board processor,
Packetwire interface and autonomous operations.
The key component of SWAP is a radiation resistant CMOS-APS detector combined with onboard compression and data
prioritization. SWAP has been developed and qualified at the Centre Spatial de Liège (CSL) and calibrated at the PTBBessy
facility. After launch, SWAP has provided its first images on 14th November 2009 and started its nominal,
scientific phase in February 2010, after 3 months of platform and payload commissioning.
This paper summarizes the latest SWAP developments and qualifications, and presents the first light results.
Development of double-sided silicon strip detectors for solar hard x-ray observation
Show abstract
The Focusing Optics X-ray Solar Imager (FOXSI) is a rocket experiment scheduled for January 2011 launch.
FOXSI observes 5 - 15 keV hard X-ray emission from quiet-region solar flares in order to study the acceleration
process of electrons and the mechanism of coronal heating. For observing faint hard X-ray emission, FOXSI uses
focusing optics for the first time in solar hard X-ray observation, and attains 100 times higher sensitivity than
RHESSI, which is the present solar hard X-ray observing satellite. Now our group is working on developments
of both Double-sided Silicon Strip Detector (DSSD) and read-out analog ASIC "VATA451" used for FOXSI.
Our DSSD has a very fine strip pitch of 75 μm, which has sufficient position resolution for FOXSI mirrors
with angular resolution (FWHM) of 12 arcseconds. DSSD also has high spectral resolution and efficiency in
the FOXSI's energy range of 5 - 15 keV, when it is read out by our 64-channel analog ASIC. In advance of the
FOXSI launch, we have established and tested a setup of 75 μm pitch DSSD bonded with "VATA451" ASICs.
We successfully read out from almost all the channels of the detector, and proved ability to make a shadow
image of tungsten plate. We also confirmed that our DSSD has energy resolution (FWHM) of 0.5 keV, lower
threshold of 5 keV, and position resolution less than 63 μm. These performance satisfy FOXSI's requirements.
The technical challenges of the Solar-Orbiter EUI instrument
Show abstract
The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI)
and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the solar atmospheric layers
above the photosphere.
The EUI instrument is based on a set of challenging new technologies allowing to reach the scientific objectives and to
cope with the hard space environment of the Solar Orbiter mission.
The mechanical concept of the EUI instrument is based on a common structure supporting the HRI and FSI channels,
and a separated electronic box. A heat rejection baffle system is used to reduce the Sun heat load and provide a first
protection level against the solar disk straylight. The spectral bands are selected by thin filters and multilayer mirror
coatings. The detectors are 10μm pitch back illuminated CMOS Active Pixel Sensors (APS), best suited for the EUI
science requirements and radiation hardness.
This paper presents the EUI instrument concept and its major sub-systems. The current developments of the instrument
technologies are also summarized.
Medium X-Ray Observatories I
The Nuclear Spectroscopic Telescope Array (NuSTAR)
Show abstract
The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (6 - 80 keV) telescope to orbit. NuSTAR will offer a factor 50 - 100 sensitivity improvement compared to previous collimated or coded mask imagers that have operated in this energy band. In addition, NuSTAR provides sub-arcminute imaging with good spectral resolution over a 12-arcminute eld of view. After
launch, NuSTAR will carry out a two-year primary science mission that focuses on four key programs: studying the evolution of massive black holes through surveys carried out in fields with excellent multiwavelength coverage, understanding the population of compact objects and the nature of the massive black hole in the center of the Milky Way, constraining the explosion dynamics and nucleosynthesis in supernovae, and probing the nature of particle acceleration in relativistic jets in active galactic nuclei. A number of additional observations will be included in the primary mission, and a guest observer program will be proposed for an extended mission to expand the range of scientic targets. The payload consists of two co-aligned depth-graded multilayer coated grazing incidence optics focused onto a solid state CdZnTe pixel detectors. To be launched in early 2012 on a Pegasus rocket into a low-inclination Earth orbit, NuSTAR largely avoids SAA passage, and will therefore have low and
stable detector backgrounds. The telescope achieves a 10.14-meter focal length through on-orbit deployment of an extendable mast. An aspect and alignment metrology system enable reconstruction of the absolute aspect and variations in the telescope alignment resulting from mast exure during ground data processing. Data will
be publicly available at GSFC's High Energy Archive Research Center (HEASARC) following validation at the science operations center located at Caltech.
The Nuclear Spectroscopic Telescope Array (NuSTAR): optics overview and current status
Show abstract
The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission scheduled for launch in
February 2012. NuSTAR will deploy two imaging CdZnTe spectrometers in the 6-79 keV energy band. The two
NuSTAR optics utilize multilayer-coated, thermally-slumped glass integrated into a titanium-glass-epoxy-graphite
composite structure, along with an extendable mast, to obtain 10.15 meter focal length. Using this approach, the
NuSTAR optics will obtain subarcminute imaging with large effective area over its entire energy band. NuSTAR's
conic-approximation Wolter-I optics are the first true hard X-ray focusing optics to be deployed on a satellite
experiment. We report on the design of the NuSTAR optics, present the status of the two flight optics under
construction, and report preliminary measurements that can be used to predict performance.
eROSITA on SRG
Show abstract
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society. The instrument development is in phase C/D since fall 2009. The design driving science is the detection 100.000 Clusters of Galaxies up to redshift z ~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed observations. eROSITA consists of seven Wolter-I telescope modules, each equipped with 54 Wolter-I shells having an outer diameter of 360 mm. This would provide an effective area of ~1500 cm2 at 1.5 keV and an on axis PSF HEW of 15 arcsec resulting in an effective angular resolution of 28 - 30 arcsec, averaged over the field of view. In the focus of each mirror module, a fast frame-store pn-CCD provides a field of view of 1° in diameter.
The Gravity and Extreme Magnetism Small Explorer
Keith Jahoda
Show abstract
The Gravity and Extreme Magnetism Small Explorer (GEMS), currently in Phase B, will be the 13th in NASA's Small
Explorer series and is being developed for an April 2014 launch readiness date. Sensitive X-ray polarization
measurements are enabled by advances in photoelectric polarimetry. This paper summarizes the scientific objectives
and mission characteristics which exploit this advance.
The GEMS photoelectric x-ray polarimeters
Show abstract
The Gravity and Extreme Magnetism Small Explorer (GEMS) is an astrophysical observatory dedicated to X-ray
polarimetry (2-10 keV) and is being developed for launch in 2014. To maximize the polarization sensitivity of the
observatory, GEMS uses polarimeters based on the photoelectric effect with a gas micropattern time projection chamber
(TPC). We describe the TPC polarimeter concept and the details of the GEMS implementation, including factors that
affect the ultimate polarization sensitivity, including quantum efficiency, modulation factor, systematic errors, and
background.
Medium X-Ray Observatories II
Early results of MAXI (Monitor of All-sky X-ray Image) on ISS
Show abstract
MAXI, the first astronomical payload on JEM-EF of ISS, began operation on August 3, 2009 for monitoring all-sky
X-ray images every ISS orbit (92 min). All instruments as well as two main X-ray slit cameras, the GSC and SSC,
worked well as expected for one month test operation. The MAXI has been operated since August, 2009 and monitored
more than 300 X-ray sources, which include Galactic black holes and black hole candidates (BH/BHC), transient X-ray
pulsars, X-ray novae, X-ray bursts, CVns, a considerable number of AGNs and so on. Automatic nova-alert and rapid
report system is starting up, while we have published more than 30 results publicly on GCN and ATel with manual
analysis. We are also releasing daily data more than 200 targets publicly.
Now MAXI has continued steady operation since the beginning of 2010 although capability of a part of X-ray
detectors is going down from initial ability. We have obtained some remarkable results concerning BH/BHC, X-ray
pulsars and AGNs. As one of the results XTE J1752-223, an X-ray nova accompanying a black hole candidate, has
revealed an evolution of accretion disc and high energy plasma from the data for seven-month observations.
In this paper we report the operation status of MAXI on the ISS as well as early several astronomical results.
The ASTRO-H Mission
Show abstract
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
pursued.
Soft x-ray imager (SXI) onboard ASTRO-H
Show abstract
We are designing an X-ray CCD camera (SXI) for ASTRO-H, including many new items. We have developed
the CCD, CCD-NeXT4, that is a P-channel type CCD. It has a thick depletion layer of 200μm with an imaging
area of 30mm square. Since it is back-illuminated, it has a good low energy response and is robust against the
impact of micro-meteorites. We will employ 4 chips to cover the area of 60mm square. A mechanical rather
than peltier cooler will be employed so that we can cool the CCD to -120°C. We will also introduce an analog
ASIC that is placed very close to the CCD. It performs well, having a similar noise level to that assembled by
using individual parts used on SUZAKU. We also employ a modulated X-ray source (MXS), that improves the
accuracy of the calibration. The SXI will have one of the largest SΩ among various satellites.
Medium X-Ray Observatories III
The high-resolution x-ray microcalorimeter spectrometer system for the SXS on ASTRO-H
Show abstract
We present the science and an overview of the Soft X-ray Spectrometer onboard the ASTRO-H mission with
emphasis on the detector system. The SXS consists of X-ray focusing mirrors and a microcalorimeter array and
is developed by international collaboration lead by JAXA and NASA with European participation. The detector
is a 6×6 format microcalorimeter array operated at a cryogenic temperature of 50 mK and covers a 3' ×3' field
of view of the X-ray telescope of 5.6 m focal length. We expect an energy resolution better than 7 eV (FWHM,
requirement) with a goal of 4 eV. The effective area of the instrument will be 225 cm2 at 7 keV; by a factor of
about two larger than that of the X-ray microcalorimeter on board Suzaku. One of the main scientific objectives
of the SXS is to investigate turbulent and/or macroscopic motions of hot gas in clusters of galaxies.
Design of a 3-stage ADR for the soft x-ray spectrometer instrument on the ASTRO-H mission
Peter J. Shirron,
Mark O. Kimball,
Donald C. Wegel,
et al.
Show abstract
The Japanese Astro-H mission will include the Soft X-ray Spectrometer (SXS) instrument, whose 36-pixel detector array
of ultra-sensitive x-ray microcalorimeters requires cooling to 50 mK. This will be accomplished using a 3-stage
adiabatic demagnetization refrigerator (ADR). The design is dictated by the need to operate with full redundancy with
both a superfluid helium dewar at 1.3 K or below, and with a 4.5 K Joule-Thomson (JT) cooler. The ADR is configured
as a 2-stage unit that is located in a well in the helium tank, and a third stage that is mounted to the top of the helium
tank. The third stage is directly connected through two heat switches to the JT cooler and the helium tank, and manages
heat flow between the two. When liquid helium is present, the 2-stage ADR operates in a single-shot manner using the
superfluid helium as a heat sink. The third stage may be used independently to reduce the time-average heat load on the
liquid to extend its lifetime. When the liquid is depleted, the 2nd and 3rd stages operate as a continuous ADR to
maintain the helium tank at as low a temperature as possible - expected to be 1.2 K - and the 1st stage cools from that
temperature as a single-stage, single-shot ADR. The ADR's design and operating modes are discussed, along with test
results of the prototype 3-stage ADR.
Filters and calibration sources for the soft x-ray spectrometer (SXS) instrument on ASTRO-H
Show abstract
The SXS instrument is the Soft X-ray micro-calorimeter Spectrometer planned for the Japanese ASTRO-H
satellite, scheduled to be launched in 2014. In this paper, the trade off and modelling for the X-ray absorption
and optical blocking filters will be described. The X-ray absorption filter will optimize the efficiency for high
spectral resolution observations for bright sources at higher energies (notably around the Fe-K line at 6.4 KeV),
given the characteristics of the instrument while the optical blocking filter allows X-ray observations of optically
bright sources. For this mission a novel type of on-off-switchable X-ray calibration source, using light sensitive
photo-cathodes, is being developed, which will be used for gain calibration and contamination monitoring. These
sources will be used by both the SXS and SXI (Soft X-ray Imager) instruments and have the capability to be
pulsed at millisecond intervals. Details of these sources will also be discussed.
Hard x-ray telescope to be onboard ASTRO-H
Show abstract
The new Japanese X-ray Astronomy satellite, ASTRO-H will carry two identical hard X-ray telescopes (HXTs),
which cover 5 to 80 keV. The HXT mirrors employ tightly-nested, conically-approximated thin-foil Wolter-I
optics, and the mirror surfaces are coated with Pt/C depth-graded multilayers to enhance hard X-ray effective
area by means of Bragg reflection. The HXT comprises foils 450 mm in diamter and 200 mm in length, with
a focal length of 12 m. To obtain a large effective area, 213 aluminum foils 0.2 mm in thickness are tightly
nested confocally. The effective area is expected to be ~ 310 cm2 at 30 keV and the image quality to be ~1.′7
in half-power diameter.
Hard x-ray imager (HXI) for the ASTRO-H Mission
Show abstract
The Hard X-ray Imager (HXI) is one of four detectors on board the ASTRO-H mission (6th Japanese X-ray
satellite), which is scheduled to be launched in 2014. Using the hybrid structure composed of double-sided silicon
strip detectors and a cadmium telluride double-sided strip detector, the instrument fully covers the energy range
of photons collected with the hard X-ray telescope up to 80 keV with a high quantum efficiency. High spatial
resolution of 250 μm and an energy resolution of 1-2 keV (FWHM) are both achieved with low noise front-end
ASICs. In addition, the thick BGO active shields surrounding the main detector package is a heritage of the
successful performance of the Hard X-ray Detector on board the Suzaku satellite. This feature enables the
instrument to achieve an extremely high background reduction caused by cosmic-ray particles, cosmic X-ray
background, and in-orbit radiation activation. In this paper, we present the detector concept, design, latest
results of the detector development, and the current status of the hardware.
Soft gamma-ray detector for the ASTRO-H Mission
Show abstract
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage
and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will
feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on
orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The
SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield
where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as
a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good
energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due
to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive
to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes.
The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected
launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed
description of the instrument and expected performance.
Medium X-Ray Observatories IV
NHXM: a New Hard X-ray imaging and polarimetric Mission
Show abstract
The New Hard X-ray Mission (NHXM) has been designed to provide a real breakthrough on a number of hot
astrophysical issues that includes: black holes census, the physics of accretion, the particle acceleration mechanisms, the
effects of radiative transfer in highly magnetized plasmas and strong gravitational fields. NHXM combines fine imaging
capability up to 80 keV, today available only at E<10 keV, with sensitive photoelectric imaging polarimetry. It consists
of four identical mirrors, with a 10 m focal length, achieved after launch by means of a deployable structure. Three of the
four telescopes will have at their focus identical spectral-imaging cameras, while a X-ray imaging polarimeter will be
placed at the focus of the fourth. In order to ensure a low and stable background, NHXM will be placed in a low Earth
equatorial orbit. Here we will provide an overall description of this mission and of the developments that are currently
occurring in Italy. In the meanwhile we are forming an international collaboration, with the goal to have a consortium
of leading Institutes and people that are at the forefront of the scientific and technological developments that are
relevant for this mission.
The optics system of the New Hard X-ray Mission: design and development
Show abstract
The New Hard X-ray Mission (NHXM) project will be operated by 2016 and is currently undergoing the Phase B study.
It is based on 4 hard X-ray optics modules, each formed by 60 evenly spaced multilayer coated Wolter I mirror shells.
An extensible bench is used to reach the 10 m focal length. The Wolter I monolithic substrates with multilayer coating
are produced in NiCo by electroforming replication. Three of the mirror modules will host in the focal plane a hybrid a
detector system (a soft X-ray Si DEPFET array plus a high energy CdTe detector). The detector of the fourth telescope
will be a photoelectric polarimeter with imaging capabilities, operating from 2 up to 35 keV. The total on axis effective
area of the three telescopes at 1 keV and 30 kev is of 1500 cm2 and 350 cm2 respectively, with an angular resolution of
20 arcsec HEW at 30 keV. In this paper we report on the design and development of the multilayer optics of the mission,
based on thin replicated Ni mirror shells.
The NHXM spectral-imaging cameras
Show abstract
The New Hard X-ray Mission (NHXM) is conceived to extend the grazing-angle reflection imaging capability up to
energy of 80 keV. The NHXM payload consists of four telescopes. Three of them have at their focal plane identical
spectral-imaging camera operating between 0.2 and beyond 80 keV, while the fourth has a X-ray imaging polarimeter.
The spectral-imaging cameras are constituted by two detection layers: a Low Energy Detector (LED) and a High Energy
Detector (HED) surrounded by an Anti Coincidence (AC) system. Here we will present the preliminary design and the
solutions that we are currently studying to meet the top level system requirements of these cameras.
A set of x-ray polarimeters for the New Hard X-ray Imaging and Polarimetric Mission
Show abstract
The New Hard X-Ray Imaging and Polarimetric Mission makes a synergic use of Hard X-Ray Imaging, Spectroscopy
and Polarimetry, as independent diagnostic of the same physical systems. It exploits the technology of
multi-layer optics that, with a focal length of 10 m, allow for spectroscopic and imaging, with a resolution from
15 to 20 arcseconds, on the band 0.2 - 80 keV. One of the four telescopes is devoted to polarimetry. Since the
band of a photoelectric polarimeter is not that wide, we foresee two of them, one tuned on the lower energy band
(2-10 keV) and another one tuned on higher energies (6 - 35 keV). The blurring due to the inclined penetration
of photons in the gas , thanks to the long focal length is practically negligible. In practice the polarimeters fully
exploit the resolution the telescope and NHXM can perform angular resolved simultaneous spectroscopy and
polarimetry on the band 2 - 35 keV. We are also studying the possibility to extend the band up to 80 keV by
means of a focal plane scattering polarimeter.
Large X-Ray Observatories I
An overview of the IXO Observatory
Show abstract
The International X-ray Observatory (IXO) project is the result of a merger between the NASA Con-X and ESA/JAXA
XEUS mission concepts. A facility-class mission, IXO will address the leading astrophysical questions in the "hot
universe" through its breakthrough optics with 20 times more collecting area at 1 keV than any previous X-ray
observatory, its 3 m2 collecting area with 5 arcsec angular resolution will be achieved using a 20m focal length
deployable optical bench. To reduce risk, two independent optics technologies are currently under development in the
U.S. and in Europe. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution
spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond
spectroscopic timing, and high count rate capability. IXO covers the 0.1-40 keV energy range, complementing the
capabilities of the next generation observatories, such as ALMA, LSST, JWST, and 30-m ground-based telescopes.
These capabilities will enable studies of a broad range of scientific questions such as what happens close to a black hole,
how supermassive black holes grow, how large scale structure forms, and what are the connections between these
processes?
This paper presents an overview of the IXO mission science drivers, its optics and instrumental capabilities, the status of
its technology development programs, and the mission implementation approach.
ESA assessment study activities on the International X-ray Observatory
Show abstract
The International X-ray Observatory (IXO) is an L class mission candidate within the science programme Cosmic Vision
2015-2025 of the European Space Agency, with a planned launch by 2020. IXO is an international cooperative project,
pursued by ESA, JAXA and NASA. By allowing astrophysical observations between 100 eV and 40 keV, IXO would
represent the new generation X-ray observatory, following the XMM-Newton, Astro-H and Chandra heritage. The IXO
mission concept is based on a single aperture telescope with an external diameter of about 3.5 m, a focal length of 20 m
and a number of focal plane instruments, positioned at the focal point via a movable platform. A grating spectrometer,
enabling parallel measurements, is also included in the model payload. Two parallel competitive industrial assessment
studies are being carried out by ESA on the overall IXO mission, while the instruments are being studied by dedicated
instrument consortia. The main results achieved during this study are summarised.
Payload study activities on the International X-ray Observatory
Show abstract
The International X-ray Observatory (IXO) is an L class mission candidate within the science programme Cosmic Vision
2015-2025 of the European Space Agency, with a planned launch by 2020. IXO is an international cooperative project,
pursued by ESA, JAXA and NASA. By allowing astrophysical observations between 100 eV and 40 keV using a very
large effective collecting area mirror and state-of-the art instruments, IXO would represent the new generation X-ray
observatory, following the XMM-Newton, Astro-H and Chandra heritage.
The IXO mission concept is based on a single aperture telescope with an external diameter of about 3.5 m and a focal
length of 20 m. The focal plane consists of a fixed and a moveable instrument platform (FIP and MIP respectively). The
model payload consists of a suite of five instruments which can each be located at the telescope's focus by the MIP,
these are:
1. a wide field imager (WFI) based on a silicon DEPFET array;
2. a Hard-X-ray Imager (HXI), which will be integrated together with the WFI;
3. an X-ray microcalorimeter spectrometer (XMS);
4. an X-ray Polarimeter camera (X-POL) based on a gas cell with integrated anode array;
5. a High-Time Resolution Spectrometer (HTRS) based on a silicon drift detector array.
In addition, the FIP will carry a grating spectrometer (XGS) mounted in a fixed position and which will allow
simultaneous observations with the on-axis instrument.
This paper provides a summary of the preliminary results achieved during the assessment activities presently ongoing at
ESA. Whereas we will provide a brief overview on the overall spacecraft design, we will focus on the payload
description, characteristics, the technology used and the accommodation on the instrument platform.
ESA optics technology preparation for IXO
Show abstract
The International X-ray Observatory (IXO) is a candidate mission in the ESA Space Science Programme Cosmic Visions
1525. IXO is being studied as a joint mission with NASA and JAXA.
The mission is building on novel optics technologies to achieve the required performance for this demanding
astrophysics observatory. The European X-ray optics technology baseline is the Silicon Pore optics (SPO), which is
being developed by an industrial consortium. In a phased approach the performance, environmental compatibility and
industrial production aspects are being addressed. As a back-up technology ESA is also investigating slumped glass
optics, which forms the baseline for the NASA approach.
The paper presents a summary of the ESA led optics technology preparation activities and the associated roadmap.
Silicon pore x-ray optics for IXO
Show abstract
Silicon pore optics is a technology developed to enable future large area X-ray telescopes, such as the
International X-ray Observatory (IXO), a candidate mission in the ESA Space Science Programme 'Cosmic
Visions 2015-2025'. IXO uses nested mirrors in Wolter-I configuration to focus grazing incidence X-ray photons
on a detector plane. The IXO optics will have to meet stringent performance requirements including an effective
area of >2.5 m2 at 1.25 keV and >0.65 m2 at 6 keV and angular resolution better than 5 arc seconds. To achieve
the collecting area requires a total polished mirror surface area of ~1300 m2 with a surface roughness better than
0.5 nm rms. By using commercial high-quality 12" silicon wafers which are diced, structured, wedged, coated,
bent and stacked, the stringent performance requirements of IXO can be attained without any costly polishing
steps. Two of these stacks are then assembled into a co-aligned mirror module, which is a complete X-ray
imaging system. Included in the mirror module are the isostatic mounting points, providing a reliable interface to
the telescope. Hundreds of such mirror modules are finally integrated into petals, and mounted onto the
spacecraft to form an X-ray optic of approximately 4 m in diameter.
In this paper we will present the silicon pore optics mass manufacturing process and latest X-ray test results of
mirror modules mounted in flight configuration.
Large X-Ray Observatories II
Mirror technology development for the International X-ray Observatory mission (IXO)
Show abstract
The International X-ray Observatory (IXO) is designed to conduct spectroscopic, imaging, and timing studies
of astrophysical phenomena that take place as near as in the solar system and as far as in the early universe. It
is a collaborative effort of ESA, JAXA, and NASA. It requires a large X-ray mirror assembly with an
unprecedented X-ray collection area and a suite of focal plane detectors that measure every property of each
photon. This paper reports on our effort to develop the necessary technology to enable the construction of the
mirror assembly required by IXO.
The x-ray microcalorimeter spectrometer onboard of IXO
Show abstract
One of the instruments on the International X-ray Observatory (IXO), under study with NASA, ESA and JAXA, is the
X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high spectral resolution images, is
based on X-ray micro-calorimeters with Transition Edge Sensor thermometers. The pixels have metallic X-ray absorbers
and are read-out by multiplexed SQUID electronics. The requirements for this instrument are demanding. In the central
array (40 x 40 pixels) an energy resolution of < 2.5 eV is required, whereas the energy resolution of the outer array is
more relaxed (≈ 10 eV) but the detection elements have to be a factor 16 larger in order to keep the number of read-out
channels acceptable for a cryogenic instrument. Due to the large collection area of the IXO optics, the XMS instrument
must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In
addition, an anti-coincidence detector is required to suppress the particle-induced background.
In this paper we will summarize the instrument status and performance. We will describe the results of design studies for
the focal plane assembly and the cooling systems. Also the system and its required spacecraft resources will be given.
The wide-field imager for IXO: status and future activities
Show abstract
The Wide Field Imager (WFI) of the International X-ray Observatory (IXO) is an X-ray imaging spectrometer based on a
large monolithic DePFET (Depleted P-channel Field Effect Transistor) Active Pixel Sensor. Filling an area of
10 x 10 cm2 with a format of 1024 x 1024 pixels it will cover a field of view of 18 arcmin. The pixel size of
100 x 100 μm2 corresponds to a fivefold oversampling of the telescope's expected 5 arcsec point spread function. The
WFI's basic DePFET structure combines the functionalities of sensor and integrated amplifier with nearly Fano-limited
energy resolution and high efficiency from 100 eV to 15 keV. The development of dedicated control and amplifier
ASICs allows for high frame rates up to 1 kHz and flexible readout modes. Results obtained with representative
prototypes with a format of 256 x 256 pixels are presented.
Critical-angle transmission grating spectrometer for high-resolution soft x-ray spectroscopy on the International X-ray Observatory
Show abstract
High-resolution spectroscopy at energies below 1 keV covers the lines of C, N, O, Ne and Fe ions, and is central
to studies of the Interstellar Medium, the Warm Hot Intergalactic Medium, warm absorption and outflows
in Active Galactic Nuclei, coronal emission from stars, etc. The large collecting area, long focal length, and 5
arcsecond half power diameter telescope point-spread function of the International X-ray Observatory will present
unprecedented opportunity for a grating spectrometer to address these areas at the forefront of astronomy and
astrophysics. We present the current status of a transmission grating spectrometer based on recently developed
high-efficiency critical-angle transmission (CAT) gratings that combine the traditional advantages of blazed
reflection and transmission gratings. The optical design places light-weight grating arrays close to the telescope
mirrors, which maximizes dispersion distance and thus spectral resolution and minimizes demands on mirror
performance. It merges features from the Chandra High Energy Transmission Grating Spectrometer and the
XMM-Newton Reflection Grating Spectrometer, and provides resolving power R = E/ΔE = 3000 - 5000 (full
width half max) and effective area >1000 cm2 in the soft x-ray band. We discuss recent results on ray-tracing
and optimization of the optical design, instrument configuration studies, and grating fabrication.
Developments of the off-plane x-ray grating spectrometer for IXO
Show abstract
The International X-ray Observatory (IXO) is a collaborative effort between NASA, ESA, and JAXA. The IXO science
goals are heavily based on obtaining high quality X-ray spectra. In order to achieve this goal the science payload will
incorporate an array of gratings for high resolution, high throughput spectroscopy at the lowest X-ray energies, 0.3 - 1.0
keV. The spectrometer will address a number of important astrophysical goals such as studying the dynamics of clusters
of galaxies, determining how elements are created in the explosions of massive stars, and revealing most of the "normal"
matter in the universe which is currently thought to be hidden in hot filaments of gas stretching between galaxies. We
present here a mature design concept for an Off-Plane X-ray Grating Spectrometer (OP-XGS). This XGS concept has
seen recent significant advancements in optical and mechanical design. We present here an analysis of how the baseline
OP-XGS design fulfills the IXO science requirements for the XGS and the optical and mechanical details of this design.
The hard x-ray imager onboard IXO
Show abstract
The Hard X-ray Imager (HXI) is one of the instruments onboard International X-ray Observatory (IXO), to be
launched into orbit in 2020s. It covers the energy band of 10-40 keV, providing imaging-spectroscopy with a
field of view of 8 x 8 arcmin2. The HXI is attached beneath the Wide Field Imager (WFI) covering 0.1-15 keV.
Combined with the super-mirror coating on the mirror assembly, this configuration provides observation of X-ray
source in wide energy band (0.1-40.0 keV) simultaneously, which is especially important for varying sources. The
HXI sensor part consists of the semiconductor imaging spectrometer, using Si in the medium energy detector and
CdTe in the high energy detector as its material, and an active shield covering its back to reduce background in
orbit. The HXI technology is based on those of the Japanese-lead new generation X-ray observatory ASTRO-H,
and partly from those developed for Simbol-X. Therefore, the technological development is in good progress. In
the IXO mission, HXI will provide a major assets to identify the nature of the object by penetrating into thick
absorbing materials and determined the inherent spectral shape in the energy band well above the structure
around Fe-K lines and edges.
The High Time Resolution Spectrometer (HTRS) aboard the International X-ray Observatory (IXO)
Show abstract
The High Time Resolution Spectrometer (HTRS) is one of the five focal plane instruments of the International
X-ray Observatory (IXO). The HTRS is the only instrument matching the top level mission requirement of
handling a one Crab X-ray source with an efficiency greater than 10%. It will provide IXO with the capability
of observing the brightest X-ray sources of the sky, with sub-millisecond time resolution, low deadtime, low
pile-up (less than 2% at 1 Crab), and CCD type energy resolution (goal of 150 eV FWHM at 6 keV). The HTRS
is a non-imaging instrument, based on a monolithic array of Silicon Drift Detectors (SDDs) with 31 cells in a
circular envelope and a X-ray sensitive volume of 4.5 cm2 x 450 μm. As part of the assessment study carried
out by ESA on IXO, the HTRS is currently undergoing a phase A study, led by CNES and CESR. In this
paper, we present the current mechanical, thermal and electrical design of the HTRS, and describe the expected
performance assessed through Monte Carlo simulations.
Low-Temperature Detectors
MIS micro-calorimeters arrays: an alternative to IXO/XMS TES/Squids baseline
Show abstract
The IXO/XMS instrument baseline is an array of TES sensors. Alternatively, we are now developing a μ-
calorimeter array based on Silicon doped sensors. Our strength stands in a very low power consumption at 50
mK, allowing more than 4000 readout channels in the limited power budget of the IXO/XMS cryostat, for a
Field of View as large as 6'x6' square while keeping the same spectral resolution. In parallel, we develop the
cold (2-4K) frontend electronics based on High Electron Mobility Transistors (GaAlAs/GaAs) and SiGe ASIC
electronics to readout, amplify and multiplex the signals. We present the status of our development and our
current design study.
Progress on the Micro-X sounding rocket x-ray telescope: completion of flight hardware
Show abstract
Micro-X is a rocket-borne X-ray telescope which will use an array of Transition Edge Sensor (TES) microcalorimeters
to obtain high resolution soft X-ray spectra of extended astronomical sources. The microcalorimeter array consists of
128 pixels with a size of 590 μm × 590 μm each. The TESs are read out with a time-division Superconducting Quantum
Interference Device (SQUID) multiplexing system. The instrument's front end assembly, which contains the
microcalorimeter array and two SQUID amplification stages, is located at the focal point of a conically approximated
Wolter mirror with a focal length of 2100 mm and a point spread function of 2.4 arcmin half-power diameter. The
telescope's effective area amounts to ~ 300 cm2 at 1 keV. The TES array is cooled with an Adiabatic Demagnetization
Refrigerator. The first flight of Micro-X is scheduled for 2011, and will likely target a Si knot in the Puppis A supernova
remnant. The time available for the observation above an altitude of 160 km will be in excess of 300 seconds. The
design, manufacturing and assembly of the flight hardware has recently been completed, and system testing is underway.
We describe the final design of the Micro-X instrument, and report on the overall status of the project.
New X-Ray/Gamma-Ray Missions I
Results from the Extended X-ray Off-plane Spectrometer (EXOS) sounding rocket payload
Show abstract
We present results from the Extended X-ray Off-Plane Spectrometer (EXOS) sounding rocket payload. The
payload was launched on November 13, 2009 and successfully obtained a spectrum of the Cygnus Loop Supernova
Remnant. The instrument observed in the ~20 - 110 Angstrom bandpass with high resolution (~50) by utilizing an offplane
reflection grating array. This payload is also the 2nd flight for a relatively new type of detector, the Gaseous
Electron Multiplier (GEM) detector. We discuss the performance of these technologies in flight, as well as an overview
of our plans for the next flight of this design.
DIOS: the diffuse intergalactic oxygen surveyor: status and prospects
Show abstract
DIOS (Diffuse Intergalactic Oxygen Surveyor) is a small scientific satellite with a main aim for the search of warm-hot intergalactic medium using redshifted OVII and OVIII lines. The instrument will consist of a 4-stage X-ray telescope and an array of TES microcalorimeters with 256 pixels, cooled with mechanical coolers.
Hardware development of DIOS and the expected results are described. Survey observations over about 5° x 5° area will reveal new filamentary structures. DIOS will be proposed to the 3rd mission in JAXA's small satellite series in 2011, aiming for launch around 2016 if it will be selected.
Xenia: cosmo-chemical evolution of the Universe
Show abstract
Xenia is a medium-sized mission optimized to study cosmic reionization, cluster formation and evolution, and
the WHIM, following cosmo-chemical evolution from the very earliest times to the present. Reconstructing
the cosmic history of metals, from the first population of stars to the processes involved in the formation of
galaxies and clusters of galaxies, is a key observational challenge. Most baryons reside in diffuse structures, in
(proto)-galaxies and clusters of galaxies, and are predicted to trace the vast filamentary structures created by
the ubiquitous Dark Matter. X-ray spectroscopy of diffuse matter has the unique capability of simultaneously
probing a broad range of elements (C through Fe) in all their ionization stages and all binding states (atomic,
molecular, and solid), and thus provides a model-independent survey of the metals. Xenia - proposed to the
Astro2010 Decadal Survey - will combine cryogenic imaging spectrometers and wide field X-ray optics with
fast repointing to collect essential information from three major tracers of metals: Gamma Ray Bursts (GRBs),
Galaxy Clusters, and the Warm-Hot Intergalactic Medium (WHIM). We give an overview of the mission and
discuss the instruments designed to carry out these observations.
JANUS: exploring the high redshift universe
Show abstract
Gamma-ray bursts (GRBs) provide extremely luminous background light sources that can be used to study the
high redshift universe out to z ~ 12. Identification of high-z GRBs has been difficult to date because no good
high-z indicators have been found in the prompt or afterglow emission of GRBs, so ground-based spectroscopic
observations are required. JANUS is an Explorer mission that incorporates a GRB locator and a near-IR
telescope with low resolution spectroscopic capability so that it can measure the redshifts of GRBs immediately
after their discovery. It is expected to discover 50 GRBs with z > 5 as well as hundreds of high redshift quasars.
JANUS will facilitate study of the reionization phase, star formation, and galaxy formation in the very early
universe. Here we discuss the mission design and status.
LOFT: a large observatory for x-ray timing
Show abstract
The X-ray sky in high time resolution holds the key to a number of observables related to fundamental physics,
inaccessible to other types of investigations, such as imaging, spectroscopy and polarimetry. Strong gravity effects, the
measurement of the mass of black holes and neutron stars, the equation of state of ultradense matter are among the
objectives of such observations. The prospects for future, non-focused X-ray timing experiments after the exciting age of
RXTE/PCA are very uncertain, mostly due to the technological limitations that need to be faced to realize experiments
with effective areas in the range of several square meters, meeting the scientific requirements. We are developing large-area
monolithic Silicon drift detectors offering high time and energy resolution at room temperature, with modest
resources and operation complexity (e.g., read-out) per unit area. Based on the properties of the detector and read-out
electronics we measured in laboratory, we built a concept for a realistic unprecedented large mission devoted to X-ray
timing in the energy range 2-30 keV. We show that effective areas in the range of 10-15 square meters are within reach,
by using a conventional spacecraft platform and launcher.
Wide Field X-ray Telescope: a moderate class mission
Show abstract
Sensitive surveys of the X-ray universe have been limited to small areas of the sky due to the intrinsically
small field of view of Wolter-I X-ray optics, whose angular resolution degrades with the square of the off axis
angle. High angular resolution is needed to achieve a low background per source, minimize source confusion, and
distinguish point from extended objects. WFXT consists of three co-aligned wide field X-ray telescopes with a
1° field of view and a≲ 10" (goal of 5") angular resolution (HEW) over the full field. Total effective area at 1 keV
will be > 5000 cm2. WFXT will perform three surveys that will cover most of the extragalactic sky to 100-1000
times the sensitivity of the ROSAT All Sky Survey, ≳ 2000 deg2 to deep Chandra or XMM-Newton sensitivity,
and ≳ 100 deg2 to the deepest Chandra sensitivity. WFXT will generate a legacy X-ray data set of ≳ 5 x 105
clusters and groups of galaxies to z ~ 2, also characterizing the physics of the intracluster gas for a significant
fraction of them, thus providing an unprecedented data set for cosmological applications; it will detect > 107
AGN to z > 6, again obtaining spectra for a substantial fraction; it will detect > 105 normal/starburst galaxies;
and it will detect and characterize star formation regions across the Galaxy. WFXT is the only X-ray survey
mission that will match, in area and sensitivity, the next generation of wide-area optical, IR and radio surveys.
http://wfxt.pha.jhu.edu
New X-Ray/Gamma-Ray Missions II
Overview of EXIST mission science and implementation
Show abstract
The Energetic X-ray Imaging Survey Telescope (EXIST) is designed to i) use the birth of stellar mass black holes, as
revealed by cosmic Gamma-Ray Bursts (GRBs), as probes of the very first stars and galaxies to exist in the Universe.
Both their extreme luminosity (~104 times larger than the most luminous quasars) and their hard X-ray detectability over
the full sky with wide-field imaging make them ideal "back-lights" to measure cosmic structure with X-ray, optical and
near-IR (nIR) spectra over many sight lines to high redshift. The full-sky imaging detection and rapid followup narrowfield
imaging and spectroscopy allow two additional primary science objectives: ii) novel surveys of supermassive black
holes (SMBHs) accreting as very luminous but rare quasars, which can trace the birth and growth of the first SMBHs as
well as quiescent SMBHs (non-accreting) which reveal their presence by X-ray flares from the tidal disruption of
passing field stars; and iii) a multiwavelength Time Domain Astrophysics (TDA) survey to measure the temporal
variability and physics of a wide range of objects, from birth to death of stars and from the thermal to non-thermal
Universe. These science objectives are achieved with the telescopes and mission as proposed for EXIST described here.
The proposed high-energy telescope (HET) for EXIST
Show abstract
The hard X-ray sky now being studied by INTEGRAL and Swift and soon by NuSTAR is rich with energetic phenomena
and highly variable non-thermal phenomena on a broad range of timescales. The High Energy Telescope (HET) on the
proposed Energetic X-ray Imaging Survey Telescope (EXIST) mission will repeatedly survey the full sky for rare and
luminous hard X-ray phenomena at unprecedented sensitivities. It will detect and localize (<20", at 5σ threshold) X-ray
sources quickly for immediate followup identification by two other onboard telescopes - the Soft X-ray imager (SXI)
and Optical/Infrared Telescope (IRT). The large array (4.5 m2) of imaging (0.6 mm pixel) CZT detectors in the HET, a
coded-aperture telescope, will provide unprecedented high sensitivity (~0.06 mCrab Full Sky in a 2 year continuous
scanning survey) in the 5 - 600 keV band. The large field of view (90° × 70°) and zenith scanning with alternating-orbital
nodding motion planned for the first 2 years of the mission will enable nearly continuous monitoring of the full
sky. A 3y followup pointed mission phase provides deep UV-Optical-IR-Soft X-ray and Hard X-ray imaging and
spectroscopy for thousands of sources discovered in the Survey. We review the HET design concept and report the
recent progress of the CZT detector development, which is underway through a series of balloon-borne wide-field hard
X-ray telescope experiments, ProtoEXIST. We carried out a successful flight of the first generation of fine pixel large
area CZT detectors (ProtoEXIST1) on Oct 9, 2009. We also summarize our future plan (ProtoEXIST2 & 3) for the
technology development needed for the HET.
Design and scientific performance of the soft x-ray imager on board EXIST
Show abstract
The EXIST mission has been recently re-designed prior to being proposed to the ASTRO2010 Decadal Survey. One of
the most recent improvements has been the addition of a third instrument consisting of a powerful Soft X-ray Imager
(SXI) that will study in detail and help characterizing the high energy sources detected by the High Energy Telescope
(HET). The EXIST concept fully exploits the heritage of Swift in the fast follow-up of transients and in particular GRBs,
with 10 to 20 times more sensitivity in the high energy band (from 0.2 to 600 keV) and exceptional performance in the
near-IR/optical provided by the Infrared Telescope (IRT). SXI has an important role in extending by more than one
decade in energy, down to the soft X-rays the coverage of HET. Such combination will be fully exploited when
performing pointed observations. Within the EXIST follow-up program, foreseen during the second part of the mission,
SXI and HET will be able to collect high quality spectra for thousands of sources covering the energy range 0.1-
hundreds keV. Furthermore, while working in survey mode SXI will cover about half the sky in 2 years and will be able
to improve the location accuracy of many faint HET sources (reducing the positional uncertainty from 20 arcsec to ~ 1-2
arcsec). In this paper we will address the performance and the main scientific contributions expected from SXI.
EXIST deep observations of the Galactic Center region
Show abstract
The EXIST observatory planned for launch in the next decade will carry outstanding contributions in both Galactic and
Extragalactic science with a sensitivity about 10-20 better respect to the flown hard X-ray missions and full sky survey
capability. Designed mainly for the survey of SMBH and transients, thanks to the wide field of view (~70x90deg) and
large effective area of the High Energy Telescope (HET), the study of spectra and variability at all timescales of all types
of Galactic sources will be made possible. EXIST will be also capable to study in detail the Galactic Center (GC) in the
hard X-rays. This crowded region as observed recently by Chandra, Integral and Swift has been found to possibly host a
high number of high energy sources. In this work we report on the capabilities of EXIST to image the GC region and to
detect and characterize the different classes of sources on the basis of their known spectral and variability properties.
EXIST will perform the crucial observation tests to study the emission from Sgr A*, using the simultaneous observations
of IR and X-ray flares, searching for periodicity to study the Keplerian flow with NIR and/or X QPO, confirm or not the
high energy counterpart of SgrA* detected by INTEGRAL and define the spectral shape of the high energy tail. Finally,
EXIST can effectively and continuously monitor spectra from Sgr B2 to confirm the correlation of the iron line emission
with the hard X-ray continuum and establish its origin.
New X-Ray/Gamma-Ray Missions III
Development of the Advance Energetic Pair Telescope (AdEPT) for medium-energy gamma-ray astronomy
Show abstract
Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI.
These instruments, however, are not optimized for observations in the medium-energy (~0.3< Eγ < ~200 MeV) regime
where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We
outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a
combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements
in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope
(AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, mediumenergy
sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution
3-D electron tracking. We describe the performance of a 30×30×30 cm3 prototype of the AdEPT instrument.
A fast scintillator Compton telescope for medium-energy gamma-ray astronomy
Show abstract
The field of medium-energy gamma-ray astronomy urgently needs a new mission to build on the success of the
COMPTEL instrument on the Compton Gamma Ray Observatory. This mission must achieve sensitivity significantly
greater than that of COMPTEL in order to advance the science of relativistic particle accelerators, nuclear astrophysics,
and diffuse backgrounds, and bridge the gap between current and future hard X-ray missions and the high-energy Fermi
mission. Such an increase in sensitivity can only come about via a dramatic decrease in the instrumental background.
We are currently developing a concept for a low-background Compton telescope that employs modern scintillator
technology to achieve this increase in sensitivity. Specifically, by employing LaBr3 scintillators for the calorimeter, one
can take advantage of the unique speed and resolving power of this material to improve the instrument sensitivity while
simultaneously enhancing its spectroscopic and imaging performance. Also, using deuterated organic scintillator in the
scattering detector will reduce internal background from neutron capture. We present calibration results from a
laboratory prototype of such an instrument, including time-of-flight, energy, and angular resolution, and compare them
to simulation results using a detailed Monte Carlo model. We also describe the balloon payload we have built for a test
flight of the instrument in the fall of 2010.
Balloon-borne sub-MeV/MeV gamma-ray observation using a Compton camera with a gaseous TPC and scintillation camera
Shunsuke Kurosawa,
Hidetoshi Kubo,
Kaori Hattori,
et al.
Show abstract
We have developed a sub-MeV and MeV gamma-ray imaging Compton camera for use in gamma-ray astronomy; it
consists of a gaseous time-projection chamber (TPC) to convert the Compton scattering events and a scintillator array to
absorb photons. The TPC measures the energy and three-dimensional tracks of Compton-recoil electrons, while the pixel
scintillator arrays measure the energy and positions of scattered gamma rays. Therefore, our camera can reconstruct the
incident gamma rays, event by event, over a wide field of view of approximately 3 str. We are now developing a
Compton camera for a balloon-borne experiment.
The 2010 balloon campaign of the Nuclear Compton Telescope
Show abstract
The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray telescope. Its compact design uses
cross-strip germanium detectors, allowing for wide-field imaging with excellent efficiency from 0.2-10 MeV. Additionally,
the Compton imaging principle employed by NCT provides polarimetric sensitivity to several MeV.
NCT is optimized for the study of astrophysical sources of nuclear line emission. A ten-detector instrument
participated in the 2010 balloon campaign in Alice Springs, Australia, in order to conduct observations of the
Galactic Center Region. Unfortunately, a launch accident caused major damage to the payload, and no flight
was possible. We discuss the design, calibration, and performance of the instrument as well as prospects for its
future.
The scientific and technical drivers of ECLAIRs: the x- and gamma-ray telescope onboard the GRB mission SVOM
Show abstract
ECLAIRs is an X and gamma-rays wide-field coded mask camera onboard the Chinese-French
mission SVOM (Space-based multi-wavelength Variable Objects Monitor) that is dedicated to
study Gamma-ray bursts (GRBs). SVOM is due to be launched in 2015 in a low Earth orbit (630
km circular orbit with 30° inclination) for a three years duration. SVOM is designed to operate
"a la SWIFT" in order to provide fast and accurate GRB positions to ground-based and space
facilities, thanks to the combined use of ECLAIRs and 2 narrow-field instruments covering the Xrays
and the optical.
Within this strategy, ECLAIRs will play a key role since it is the instrument responsible for the
detection and the first localization of GRBs in near real time.
One of the primary goals of the mission is to study high redshift (z>6) GRBs that may appear as
very soft events in Gamma-rays. For this reason, ECLAIRs is designed to have an increased
sensitivity in the X-rays, when compared to previous equivalent instruments, thanks to a low
energy threshold of 4 keV.
In this talk we present the latest developments of the ECLAIRs design along with the expected
scientific performances.
Development of efficient Laue lenses: experimental results and projects
Show abstract
Laue lenses are an emerging technology allowing the concentration of soft gamma rays in the ~ 100 keV -
1.5 MeV energy range. Two lens designs based on recently measured crystals are presented in this paper. A
lens dedicated to the understanding of the progenitors and explosion physics of Type Ia supernovae through
the observation of the 847 keV line produced by the decay chain of the radionuclide 56Co. With a Compton
camera at the focus (as proposed for the DUAL mission), we find that a space-borne telescope could reach a 3-σ
sensitivity of 1.5×10-6 ph/s/cm2 for a 3% broadened line in 105 s, enabling the detection of several events per
year with enough significance to strongly constrain the models. On the other hand, a second generation prototype
is proposed. Made to realize a balloon-borne telescope focusing around the electron-positron annihilation line
(511 keV), this lens would primarily be a technological demonstrator. However with an estimated sensitivity of
5×10-6 ph/s/cm2 in 104 s observation time, this Laue lens telescope could bring new hints in the search of the
origin of the Galactic positrons. To build this prototype, a dedicated X-ray beamline has been built at the Space
Sciences Laboratory.
Poster Session: UV Missions and Technology
FIREBALL: the first ultraviolet fiber fed spectrograph
Show abstract
FIREBall (the Faint Intergalactic Redshifted Emission Balloon) is a balloon-borne 1m telescope coupled to an
ultraviolet fiber-fed spectrograph. FIREBall is designed to study the faint and diffuse emission of the warm hot
intergalactic medium, until now detected primarily in absorption. FIREBall is a pathfinding mission to test new
technology and make new constraints on the temperature and density of this gas. FIREBall has flown twice,
the most recent flight (June 2009) a fully functioning science flight. Here we describe the spectrograph design,
current setup, and calibration measurements from the campaign.
FIREBALL: detector, data acquisition and reduction
Show abstract
The Faint Intergalactic Redshifted Emission Balloon (FIREBALL) had its first scientific flight in June 2009.
The instrument combines microchannel plate detector technology with fiber-fed integral field spectroscopy on an
unstable stratospheric balloon gondola platform. This unique combination poses a series of calibration and data
reduction challenges that must be addressed and resolved to allow for accurate data analysis. We discuss our
approach and some of the methods we are employing to accomplish this task.
FIREBALL: instrument pointing and aspect reconstruction
Show abstract
The Faint Intergalactic Redshifted Emission Balloon (FIREBALL) had its first scientific flight in June 2009.
The instrument is a 1 meter class balloon-borne telescope equipped with a vacuum-ultraviolet integral field
spectrograph intended to detect emission from the inter-galactic medium at redshifts 0.3 < z < 1.0. The
scientific goals and the challenging environment place strict constraints on the pointing and tracking systems of
the gondola. In this manuscript we briefly review our pointing requirements, discuss the methods and solutions
used to meet those requirements, and present the aspect reconstruction results from the first successful scientific
flight.
Earth-orbiting extreme ultraviolet spectroscopic imaging mission for planetary space science
Kouichi Sakai,
Go Murakami,
Gentaro Ogawa,
et al.
Show abstract
EXtreme ultraviolet spectrosCope for ExosphEric Dynamics (EXCEED) is the earth-orbiting Extreme
Ultraviolet (EUV) spectroscope mission which dedicates to the planetary space science. Our mission will carry out the
EUV spectroscopic imaging which clarifies the plasma distributions and compositions around the planets and examines
the interaction with the solar wind. Orbital altitude should be enough high so that the earth's atmospheric absorption is
free. The spectral range of the mission is from 60 to 145 nm and the resolution is 0.2 to 0.5 nm FWHM. The mission is
planned to be launched in 2013, beginning of the next period of solar maximum. In this paper, we will introduce the
general mission overview, its instrument and its scientific targets.
Efficient EUV transmission gratings for plasma diagnostics
Show abstract
We report on a theoretical study of binary phase transmission gratings for high-resolution EUV and soft X-ray
spectroscopy and investigate their optical properties. Designed for wavelengths between about 2 and 40 nm, the
devices may provide a first order diffraction efficiency beyond 30%. We use RCWA methods in order to optimize
the grating design parameters and discuss special features of segmented grating arrays. Several elemental as
well as compound materials like Be, Mo, LiF and PMMA are considered with respect to their potential and
practical limitations in terms of feasibility and sensitivity to radiation damage. Simulations are performed for
several samples on the radiation produced by a table-top EUV plasma source and applications to astrophysical
problems are considered.
Description and ray-tracing simulations of HYPE: a far-ultraviolet polarimetric spatial-heterodyne spectrometer
Show abstract
Temperature and velocity-distribution remote-sensing of faint diffuse sources such as the interplanetary medium (IPM),
comets and planetary atmospheres, is an instrumental challenge that becomes more pronounced in the ultraviolet. All-reflective
Spatial-Heterodyne Spectrometers (SHS), an emerging new class of instruments that combines both high
étendue and high resolving power (greater than 105), are ideally suited to these types of observations. Their all-reflective
configuration and their self-compensating monolithic design enable them to operate under the tight tolerances of the
ultraviolet and to survive the rigors of space launch. An in-development sounding-rocket experiment, the Hydrogen
Polarimetric Explorer (HYPE), will merge an all-reflective SHS with a half-wave Brewster reflection polarimeter to
obtain the first interferometric polarimetry of an ultraviolet emission line source. Its initial flight will target the IPM at
the hydrogen Lyman-alpha transition (121.6nm). HYPE's novel optical configuration also combines several
improvements in reflective SHS design, including true zero-path interferometry, no aliasing, and one-dimensional
imaging. The optical layout and performance of the HYPE prototype will be described along with simulation results
from ray-tracing computations.
Fresnel diffractive imager: instrument for space mission in the visible and UV
Show abstract
We propose a new concept of diffractive optics: Fresnel arrays, for a 4 m aperture space telescope in the UV
domain.
Fresnel arrays focus light by diffraction through a very thin binary mask. They form images optically and
deliver very high quality wavefronts, specially in the UV. Up to 8% of the incident light is focussed, providing
high angular resolution and high contrast images of compact objects.
Due to their focal lengths of a few kilometers in the UV, large Fresnel arrays will require two spacecraft
in formation flying, but with relatively tolerant positioning. Diffraction focusing is also very chromatic; this
chromatism is corrected, allowing relatively broad (30 to 100 nm) spectral channels in the 120-350 nm range.
A 4 m aperture Fresnel imager providing 7 to 10 milli arc seconds resolution is very competitive for imaging
compact and high contrast objects such as protoplanetary disks and young planetary systems, AGNs, and deep
sky objects.
We have developed prototypes to validate the optical concept and related technologies : first a laboratory
setup, then a 20 cm aperture ground-based prototype, which provides high contrast and diffraction limited images
of sky objects in the visible and close IR. A new laboratory prototype is also being prepared for validation in
the 250 - 350 nm wavelength range.
It's time for a new EUV orbital mission
Show abstract
The EUV waveband includes critical spectral features containing diagnostic information often not available at other
wavelengths, and the bulk of radiation from million degree plasmas is emitted in the EUV. Such plasmas are ubiquitous,
and examples include white dwarf photospheres; accretion phenomena in young stars, CVs and AGN; stellar coronae;
and the ISM of our galaxy and of others. However, sensitive high-resolution spectroscopy is required to resolve and
identify source and ISM spectral features unambiguously, and to measure line profiles and Doppler shifts. This allows
exploitation of the full range of plasma diagnostic techniques developed in laboratory and solar physics. The J-PEX
high-resolution EUV spectrometer has made a breakthrough in capability with an effective area of 7 cm2 (220-250 Å)
and resolving power of 4000, which exceed EUVE by factors of 7 and 20 respectively, and cover a range beyond the
170-Å cutoff of the Chandra LETG. J-PEX has flown successfully twice on NASA sounding rockets, but NASA has
approved no new orbital EUV mission. It is time for one. Here we describe the scientific case for high-resolution EUV
spectroscopy, summarize the technology that makes practical such measurements, and present concepts for a ~3-month
orbital mission and for larger missions.
FIRE: Far-ultraviolet Imaging Rocket Experiment: a sounding rocket telescope
Show abstract
FIRE (Far-ultraviolet Imaging Rocket Experiment) is a sounding rocket payload telescope designed to image
between 900-1100Å. It is scheduled to launch on January 29th, 2011 from the Poker Flats complex in northern Alaska.
For its first flight, it will target G191B2B, a white dwarf calibration source, and M51 (the Whirlpool Galaxy), the
science target, to help determine the number of hot, young O stars, as well as the intervening dust attenuation. FIRE
primary consists of a single primary mirror coated in silicon carbide, a 2000Å thick indium filter and a micro-channel
plate detector coated with rubidium bromide. Combined, these create a passband of 900-1100Å for the system and reject
the hydrogen Lyman-α to approximately a factor of 10-4. To ensure that the filter survives the launch, a small vacuum
chamber has been built around it to keep the pressure at 10-8 torr or lower.
Improved EUV filter transmission with plasma cleaning
Show abstract
As-fabricated free-standing indium foils were found to have transmission in the 90nm to 120nm
band ranging from 10% to 70% of modeled values based on pure indium. Auger depth profiling of
the as-deposited indium showed little surface contamination and high purity. However, final freestanding
filters were found to have heavy contamination, particularly on the surface. An
argon/hydrogen plasma bombardment was developed which improved EUV transmission by 50% to
500% in the finished filters without causing significant pinholes to develop in the foils or
appreciably affecting blocking characteristics.
Hubble Space Telescope: Cosmic Origins Spectrograph FUV detector initial on-orbit performance
Show abstract
The Cosmic Origins Spectrograph (COS) was installed on the Hubble Space Telescope (HST) in May 2009 during
Servicing Mission 4 (SM4). This paper discusses the initial on-orbit performance of the HST-COS far ultraviolet (FUV)
detector designed and built by the Experimental Astrophysics Group at the Univ. of California, Berkeley. The HST-COS
FUV detector is an open face, photon counting, microchannel plate (MCP) based device employing a cross delay
line (XDL) readout. The detector consists of two separate, end-to-end segments (2x 85mm x 10mm - 179mm x 10mm
total with a gap between segments), each digitized within a 16384x1024 space. The input surface is curved to match the
Rowland circle of HST-COS. The CsI photocathode and open face nature result in sensitivity from <900Å to ~1750Å.
Spatial resolution is approximately 25-30μm. Comparisons of on-orbit behavior relative to expectations from ground
testing are performed. Areas of discussion include background (rate and morphology), sensitivity (system throughput
and short wavelength response), and imaging performance (apparent spatial resolution and flat field fixed pattern). A
measured increase in the MCP gain relative to ground testing is also discussed.
Poster Session: X-Ray Observatories and Optics
Using ACIS on the Chandra X-ray Observatory as a particle radiation monitor
Show abstract
The Advanced CCD Imaging Spectrometer (ACIS) is one of two focal-plane instruments on the Chandra X-ray
Observatory. During initial radiation-belt passes, the exposed ACIS suffered significant radiation damage from
trapped soft protons scattering off the x-ray telescope's mirrors. The primary effect of this damage was to increase
the charge-transfer inefficiency (CTI) of the ACIS 8 front-illuminated CCDs. Subsequently, the Chandra team
implemented procedures to remove the ACIS from the telescope's focus during high-radiation events: planned
protection during radiation-belt transits; autonomous protection triggered by an on-board radiation monitor;
and manual intervention based upon assessment of space-weather conditions. However, as Chandra's multilayer
insulation ages, elevated temperatures have reduced the effectiveness of the on-board radiation monitor for
autonomous protection. Here we investigate using the ACIS CCDs themselves as a radiation monitor. We
explore the 10-year database to evaluate the CCDs' response to particle radiation and to compare this response
with other radiation data and environment models.
On-orbit calibration status of the hard x-ray detector (HXD) onboard Suzaku
Show abstract
Hard X-ray Detector (HXD) onboard Suzaku, the Japanese 5th X-ray observatory, consists of 64 PIN photo
diodes with 2 mm thickness (10-70 keV) and 16 phoswich detectors using 5 mm-thick GSO scintillators and
BGO active collimators (40-600 keV), and these are surrounded by 20 units of BGO Active shields. All the
detector units have been working well with no significant troubles in four and a half years since the launch
on July 2005, and given many important scientific results. In this paper, we report the recent status of on-orbit
calibrations for PIN/GSO detectors. For the PIN, analog/digital threshold levels of both in-orbit and
on-ground are raised up to avoid the increasing noise events due to in-orbit radiation damage. For the GSO,
the accuracy of the energy scale and modeling of gain variations are improved, and newly calibrated data set
including background files and response matrices are released on April 2010.
Computation of the off-axis effective area of the New Hard X-ray Mission modules by means of an analytical approach
Show abstract
One of the most important parameters determining the sensitivity of X-ray telescopes is their effective area as a function
of the X-ray energy. The computation of the effective area of a Wolter-I mirror, with either a single layer or multilayer
coating, is a very simple task for a source on-axis at astronomical distance. Indeed, when the source moves off-axis the
calculation is more complicated, in particular for new hard X-ray imaging telescopes (NuSTAR, ASTRO-H, NHXM,
IXO) beyond 10 keV, that will make use of multilayer coatings to extend the reflectivity band in grazing incidence.
Unlike traditional single-layer coatings (in Ir or Au), graded multilayer coatings exhibit an oscillating reflectivity as a
function of the incidence angle, which makes the effective area not immediately predictable for a source placed off-axis
within the field of view. For this reason, the computation of the off-axis effective area has been so far demanded to raytracing
codes, able to sample the incidence of photons onto the mirror assembly. Even if this approach should not be
disdained, it would be interesting to approach the same problem from an analytical viewpoint. This would speed up and
simplify the computation of the effective area as a function of the off-axis angle, a considerable advantage especially
whenever the mirror parameters are still to be optimized. In this work we present the application of a novel, analytical
formalism to the computation of the off-axis effective area and the grasp of the NHXM optical modules, requiring only
the standard routines for the multilayer reflectivity computation.
Methods of optimizing x-ray optical prescriptions for wide-field applications
Show abstract
We are working on the development of a method for optimizing wide-field X-ray telescope mirror prescriptions,
including polynomial coefficients, mirror shell relative displacements, and (assuming 4 focal plane detectors)
detector placement along the optical axis and detector tilt. With our methods, we hope to reduce number
of Monte-Carlo ray traces required to search the multi-dimensional design parameter space, and to lessen the
complexity of finding the optimum design parameters in that space. Regarding higher order polynomial terms
as small perturbations of an underlying Wolter I optic design, we begin by using the results of Monte-Carlo ray
traces to devise trial analytic functions, for an individual Wolter I mirror shell, that can be used to represent
the spatial resolution on an arbitrary focal surface. We then introduce a notation and tools for Monte-Carlo ray
tracing of a polynomial mirror shell prescription which permits the polynomial coefficients to remain symbolic.
In principle, given a set of parameters defining the underlying Wolter I optics, a single set of Monte-Carlo ray
traces are then sufficient to determine the polymonial coefficients through the solution of a large set of linear
equations in the symbolic coefficients. We describe the present status of this development effort.
Multiband imaging with Fresnel x-ray telescopes
Show abstract
We present a diffractive-refractive X-ray telescope for simultaneous imaging in multiple energy bands. Based on
segmented dispersion corrected hybrid lenses, the system yields an angular resolution around 1 mas for photon
energies between 5 and 10 keV. The total sensitivity, measured in terms of effective area times spectral bandwidth,
reaches several 103 cm2 keV. The suggested arrangement exploits Fresnel lenses used in higher diffraction orders
for orderly protection from scattered radiation as well as reduced refractive profiles for an enhanced throughput.
With a focal distance of a few 102 km, the telescope having its focal plane detector on a separated spacecraft,
may be re-oriented to new astrophysical targets on short timescales. Scientific applications are briefly discussed
for active galactic nuclei (AGN).
Fresnel lens arrays for x-ray imaging spectroscopy
Show abstract
Arrays of achromatic Fresnel lenses are investigated for future high-resolution X-ray imaging missions. Unlike
single-focus instruments, parallel arrangements of numerous tiny telescopes provide an easy and natural approach
to spectroscopic observations in several energy bands, at an unprecedented short focal length of few 103 m. We
suggest an optimized design with an angular resolution around 1 mas between 5 and 10 keV and analyze its
optical capabilities as well as issues like the background problem which affects the achievable signal-to-noise
ratio. An astronomical simulation is performed on the sun-like star Capella.
High-energy astrophysics at the diffraction limit
Show abstract
We discuss various astrophysical science drivers for upcoming high-resolution X-ray instruments on the mas
scale. Even more than current missions like Chandra and XMM-Newton, planned diffraction-limited telescopes
would provide unprecedented insights into hottest-ever physical processes in the universe. We apply an efficient
and simple Fresnel lens design to samples of well-known targets like stellar coronae, X-ray binaries, AGN, ultraluminous
X-ray sources and supernova remnants. The cosmological impact of deep observations is discussed as
well as potential applications to low-mass gravitational lenses.
Effects of the coating optimization on the field of view for a Wolter x-ray telescope
Show abstract
Multilayer coatings can be used as broad-band reflecting layer in X-ray focusing optics. The effective area over
the field of view is determined by the energetic and angular dependence of the coating reflectivity, with a different
behavior in dependence of the coating structure, that can be designed in order to enhance the effective area.
Often the best design is selected to maximize the on-axis effective area, but this does not ensure the performances
off-axis, where the most of the detector area is allocated.
We demonstrate the possibility of optimizing the coating over the whole field of view by means of a new
method, that does not require the use of ray-tracing procedures, being based on the computation of a simple
analytical expression computed over a limited number of points.
Our method is used to optimize a multilayer structure over the field of view. The effectiveness of the method
is tested by comparison with ray-tracing results. The performances of the multilayer structure resulting from the
optimization are then compared with a not optimized broad-band multilayer and with a multilayer optimized
for on-axis effective area.
Self-consistent computation of x-ray mirror point spread functions from surface profile and roughness
Show abstract
The angular resolution degradation of an X-ray mirror, represented by its Point Spread Function (PSF), is usually
simulated accounting for geometrical deformations and microroughness of its surface. When the surface profile is
analyzed in terms of Fourier components, figure errors comprise the spectral regime of long spatial wavelengths,
whilst microroughness falls in the regime of high spatial frequencies. The first effect is in general simulated along
with geometrical optics, while the second contribution - that heavily depends on the energy of X-rays - is derived
from the first order scattering theory. A drawback of this method, indeed, is that the separation between the
geometrical and physical optics regime is not abrupt. Moreover, it is not clear how one should merge the PSFs
derived from the two computations to retrieve an affordable reconstruction of the PSF of the mirror. In this
paper we suggest a method to compute the mirror PSF from longitudinal profiles of a grazing incidence mirror,
based uniquely on physical optics. The treatment makes use of Fresnel diffraction from measured/simulated
profiles, accounting for the surface roughness in terms of its PSD (Power-Spectral-Density). Even though this
approach was already adopted in the past to simulate the sole X-ray scattering, in this work we show, along a
series of simulations, that it can be applied to reproduce the effect of scattering, aperture diffraction and figure
errors as well. The computation returns the PSF at any X-ray energy, it is self-consistent and does not require
setting any boundary between figure errors and roughness.
Thin gold layer in NiCo and Ni electroforming process: optical surface characterization
Show abstract
Mandrel replication by NiCo electroforming is an upgrade of the well-suited X-ray mirrors manufacturing process with
pure Nickel. In this process, a Gold layer deposited on the mandrel acts as release agent and, at the same time, as
reflective coating. To increase the optical performances of X-ray mirrors, the replicated optical surface is meant to
reproduce the smooth topography of the mandrel: a surface degradation is commonly observed, indeed. A factor leading
to surface smoothness worsening can be the spontaneous roughness growth of the Gold layer itself; therefore, the optical
quality of the reflecting surface might be improved by optimizing the Gold layer thickness. A preliminary study, aimed
at investigating the effects of Gold thickness reduction (< 100 nm Vs. the usual 200 nm), had already been dealt in the
spectral range 0.02-1000 μm: measurements performed on flat electroformed samples showed that the Gold thickness
reduction chiefly affects the roughness around 1 μm. Here we presents a study of the effectiveness of a Gold layer with
reduced (< 100 nm) thickness in the NiCo X-ray mirrors electroforming, aimed at surface micro-roughness mitigation.
The characterization, in the spectral range 0.02-1000 μm, of 3 X-ray mirrors manufactured utilizing Gold layers with
different thickness values from a flight mandrel is reported. The performed investigation is organized as follows: (a)
characterization of the flight mandrel; (b) dependence of the micro-roughness from different Gold layers thicknesses
supported by XRD study; (c) comparison of the micro-roughness of mirrors manufactured in NiCo in Ni, with the same
Gold layer thickness. As a conclusive remark the effects of the Gold layer thinning on the angular degradation at high
energy are reported.
Wavefront sensing of x-ray telescopes
Show abstract
Phase Retrieval analysis of off-axis or defocused focal-plane data from telescope optics has been proven effective in
understanding misalignments and optical aberrations in normal incidence telescopes. The approach is used, e.g., in
commissioning of the James Webb Space Telescope (JWST) segmented primary mirror. There is a similar need for
evaluating low-order figure errors of grazing incidence mirrors and nested telescope assemblies. When implemented in
these systems, phase retrieval does not depend on normal incidence access to each mirror (shell) surface and, therefore,
provides an effective means for evaluating nested x-ray telescopes during integration and test.
We have applied a well-known phase retrieval algorithm to grazing incidence telescopes. The algorithm uses the
Levenberg-Marquardt optimization procedure to perform a non-linear least-squares fit of the telescope Point Spread
Function (PSF). The algorithm can also retrieve low order figure errors at visible wavelengths where optical diffraction
is the dominant defect in the PSF.
In this paper we will present the analytical approach and its implementation for grazing incidence mirrors of the
International X-Ray Observatory (IXO). We analyze the effects of low order axial surface errors individually, and in
combination on the system PSF at 633 nanometers. We demonstrate via modeling that the wavefront sensing algorithm
can recover axial errors (of the grazing incidence mirrors) to a small fraction of the known axial figure errors using
simulated PSFs as input data to the algorithm.
Improving the ruggedness of silicon pore optics
Show abstract
In this paper we present the latest developments on the ruggedisation of the Silicon Pore Optics (SPO) mirror
modules. SPO is one of the candidate technologies for producing the X-ray optics for the future space based Xray
telescope, the International X-ray Observatory (IXO). To produce SPO mirror modules, Si mirrors are first
bonded together using direct Si bonding to form a stack. These stacks are the glued into brackets, which then
connect to the supporting optical bench by invar pins. The combination of brackets and invar pins now forms a
full isostatic mount, and is rugged enough to allow the mirror module to survive the high loads of a launch. The
mounting system furthermore allows for a certain level of manufacturing tolerances for the support structure, and
ensures interchangeability of the mirror modules within one single ring of the optical bench. To prove this, a test
interface has been designed and manufactured, on which a single, full fledged mirror module will be mounted to
be exposed to environmental tests.
Lunar liquid mirror telescope: structural concepts
Show abstract
The potential of a return of human presence to the Moon, raises the possibility of significant lunar
infrastructure and with it the possibility of astronomical installations which can make use of the lunar
surface as a stable platform and take advantage of the lack of atmosphere. Studies have been done in the
US and Canada on the feasibility of such installations, and in particular studies of large lunar liquid mirror
telescopes have been performed. We report here on the structural design concepts undertaken for one of
these studies.
Effects of contamination upon the performance of x-ray telescopes
Show abstract
Particulate and molecular contamination can each impact the performance of x-ray telescope systems. Furthermore, any
changes in the level of contamination between on-ground calibration and in-space operation can compromise the
validity of the calibration. Thus, it is important to understand the sensitivity of telescope performance---especially the
net effective area and the wings of the point spread function---to contamination. Here, we quantify this sensitivity and
discuss the flow-down of science requirements to contamination-control requirements. As an example, we apply this
methodology to the International X-ray Observatory (IXO), currently under joint study by ESA, JAXA, and NASA.
Poster Session: X-Ray Polarimetry
Soft x-ray polarimeter laboratory tests
Show abstract
Multilayer-coated optics can strongly polarize X-rays and are central to a new design of a broad-band, soft X-ray
polarimeter. We have begun laboratory work to verify the performance of components that could be used in
future soft X-ray polarimetric instrumentation. We have reconfigured a 17 meter beamline facility, originally
developed for testing transmission gratings for Chandra, to include a polarized X-ray source, an X-ray-dispersing
transmission grating, and a multilayer-coated optic that illuminates a CCD detector. The X-rays produced from
a Manson Model 5, multi-anode source are polarized by a multilayer-coated flat mirror. The current configuration
allows for a 180 degree rotation of the source in order to rotate the direction of polarization. We will present
progress in source characterization and system modulation measurements as well as null and robustness tests.
A negative ion time projection chamber x-ray polarimeter for transient sources
Show abstract
A gamma-ray burst polarimeter (GRBP) is being developed at NASA Goddard Space Flight Center for measuring the Xray
polarization of energetic transients in the 2 - 10 keV energy range. The primary goal is to measure the polarization
of the prompt X-ray emission from gamma-ray bursts (GRBs) in order to distinguish between the possible emission
mechanisms. The instrument could also be capable of measuring polarization from other X-ray transients, such as soft
gamma repeaters (SGRs) or black hole transients. An instrument with a wide field of view is required to detect transient
events and a large collecting area is required to have sufficient sensitivity. The GRBP is a time projection chamber
(TPC) that uses negative ions as a charge carrier enabling a large volume, high spatial resolution detector. We describe a
GRBP prototype that is suitable for a sounding rocket measurement of the Crab Nebula or for measurements of bright
transient sources from a small satellite.
Poster Session: Gamma-Ray Observatories
Rolling and tumbling: status of the SuperAGILE experiment
Show abstract
The SuperAGILE experiment is the hard X-ray monitor of the AGILE mission. It is a 2 x one-dimensional imager, with
6-arcmin angular resolution in the energy range 18 - 60 keV and a field of view in excess of 1 steradian. SuperAGILE is
successfully operating in orbit since Summer 2007, providing long-term monitoring of bright sources and prompt
detection and localization of gamma-ray bursts. Starting on October 2009 the AGILE mission lost its reaction wheel and
the satellite attitude is no longer stabilized. The current mode of operation of the AGILE satellite is a Spinning Mode,
around the Sun-pointing direction, with an angular velocity of about 0.8 degree/s (corresponding to 8 times the
SuperAGILE point spread function every second). In these new conditions, SuperAGILE continuously scans a much
larger fraction of the sky, with much smaller exposure to each region. In this paper we review some of the results of the
first 2.5 years of "standard" operation of SuperAGILE, and show how new implementations in the data analysis software
allows to continue the hard X-ray sky monitoring by SuperAGILE also in the new attitude conditions.
SIDERALE and BIT: a small stratospheric balloon experiment for polar gamma background
Show abstract
The paper describes the SIDERALE experiment that was hosted as a piggy back payload on SoRa LDB (Sounding Radar
Long Distance Balloon) mission by the Italian Space Agency (ASI). SIDERALE was aimed at testing a detector for high
energy astrophysics applications based on a 4x4 pixel CZT solid state sensor. An onboard data handling computer, a
mass memory and a power supply units were integrated in SIDERALE. Furthermore an innovative telemetry system BIT
(Bi-directional Iridium Telemetry) was used in order for SIDERALE to be autonomous and independent from the
hosting payload. In the paper a preliminary analysis of flight and scientific data is discussed.
Poster Session: Solar Missions and Technologies
Stigmatic grazing-incidence x-ray spectrograph for solar coronal observations
Show abstract
We present the design for a stigmatic grazing incidence X-ray spectrograph designed for solar coronal observations. The
spectrograph is composed of a slit, a pair of paraboloid mirrors and a plano varied-line-space grating. All reflective surfaces
of the spectrograph operate at an angle of incidence of 88 degrees, and covers a wavelength range of 0.6 to 2.4nm (0.5 to
2.0keV). The design achieves 1.5pm spectral resolution and 15 μm spatial resolution over a 2.5mmlong slit. The current
spectrograph design is intended for a sounding rocket experiment, and designed to fit inside a NASA sounding rocket
payload behind a 1.1m focal length Wolter Type-1 telescope. This combination will have a 2.5arcsec spatial resolution
and a 8 arcminute slit length. We are currently fabricating a laboratory prototype of the spectrograph to demonstrate the
performance and establish the alignment procedures for a flight model.
Definition of an imaging spectrometer meeting the needs of UV solar physics
Show abstract
The study of the outer solar atmosphere requires combining imaging and spectroscopy in the UV lines formed
in the high chromosphere, the transition region and the corona. We start from the science requirements and we
define the instrumental specifications in terms of field-of-view (FOV), spatial, temporal and spectral resolution
and bandpass. We propose two different all-reflection optical architectures based on interferometric techniques:
Spatial Heterodyne Spectroscopy (SHS); and Imaging Transform Spectrometer (IFTS). We describe the different
set-ups and compare the potential performances of the two types of solutions, and discuss their feasibility. We
conclude that IFTS appears to be the best solution, meeting the needs of UV solar physics. However, we point
out the many difficulties to be encountered, especially as far as metrology is concerned.
A novel forward-model technique for estimating EUV imaging performance: design and analysis of the SUVI telescope
Show abstract
The Solar Ultraviolet Imager (SUVI) is one of several instruments being fabricated for use on board the upcoming
Geostationary Operational Environmental Satellites, GOES-R and -S platforms, as part of NOAA's space weather
monitoring fleet. SUVI is a Generalized Cassegrain telescope that employs multilayer coatings optimized to operate in
six extreme ultraviolet (EUV) narrow bandpasses centered at 93.9, 131.2, 171.1, 195.1, 284.2 and 303.8 Å. Over the
course of its operational lifetime SUVI will image and record full disk, EUV spectroheliograms approximately every few
minutes, and telemeter the data to the ground for digital processing. This data will be useful to scientists and engineers
wanting to better understand the effects of solar produced EUV radiation with the near-Earth environment. At the focus
of the SUVI telescope is a thin, back-illuminated CCD sensor with 21 μm (2.5 arc sec) pixels. At the shortest EUV
wavelengths, image degradation from mirror surface scatter effects due to residual optical fabrication errors dominate the
effects of both diffraction and geometrical aberrations. Discussed herein, we present a novel forward model that
incorporates: (i) application of a new unified surface scatter theory valid for moderately rough surfaces to predict the bidirectional
reflectance distribution function (BRDF) produced by each mirror (which uses optical surface metrology to
determine the power spectral density, PSD, that characterizes the "smoothness" of an optical surface); (ii) use of the
BRDF for each mirror at each EUV wavelength, in tandem with the optical design, to calculate the in-band point spread
function (PSF); (iii) use of the PSF to calculate the fractional ensquared energy in the focal plane of SUVI; (iv)
comparison of BRDF measurements taken at 93.9 Å with the forward model predictions and (v) final prediction of the
in-band, total system responsivity.
High-spectral resolution high-cadence imaging x-ray microcalorimeters for solar physics
Show abstract
High spectral resolution, high cadence, imaging x-ray spectroscopy has the potential to revolutionize the study of
the solar corona. To that end we have been developing transition-edge-sensor (TES) based x-ray microcalorimeter
arrays for future solar physics missions where imaging and high energy resolution spectroscopy will enable
previously impossible studies of the dynamics and energetics of the solar corona. The characteristics of these xray
microcalorimeters are significantly different from conventional microcalorimeters developed for astrophysics
because they need to accommodate much higher count rates (300-1000 cps) while maintaining high energy
resolution of less than 4 eV FWHM in the X-ray energy band of 0.2-10 keV. The other main difference is a
smaller pixel size (less than 75 x 75 square microns) than is typical for x-ray microcalorimeters in order to
provide angular resolution less than 1 arcsecond. We have achieved at energy resolution of 2.15 eV at 6 keV in a
pixel with a 12 x 12 square micron TES sensor and 34 x 34 x 9.1 micron gold absorber, and a resolution of 2.30
eV at 6 keV in a pixel with a 35 x 35 micron TES and a 57 x 57 x 9.1 micron gold absorber. This performance
has been achieved in pixels that are fabricated directly onto solid substrates, ie. they are not supported by silicon
nitride membranes. We present the results from these detectors, the expected performance at high count-rates,
and prospects for the use of this technology for future Solar missions.
Poster Session: Medium X-Ray Observatories
The Monte Carlo simulation framework of the ASTRO-H X-ray Observatory
Show abstract
We are developing an ASTRO-H data analysis framework with the Geant4-based Monte Carlo simulation core,
and numerical models of the on-orbit environmental radiation and full-satellite mass structure. In addition,
the framework also includes a mechanism to connect and control data processing modules that are developed
independently and data communication channels among them, which has been technically proven by simulations
and analysis of the Suzaku HXD, many other detectors and astrophysical issues.
The thermal analysis of the Hard X-ray Telescope (HXT) and the investigation of the deformation of the mirror foil due to temperature change
Show abstract
The thin film technology called "depth-graded multi-layer" is used to manufacture reflector foils, which are inserted
in a hard X-ray telescope. When the temperature of the foil changes from the temperature at which the foil was
produced; thermal deformation is induced due to difference of linear coefficient of expansion of its constituents. The
deformation causes performance of X-ray image formation to deteriorate. Therefore, it is absolutely imperative to
estimate the amount of deformation quantitatively and to establish a method of temperature control for the foil under the
thermal environment on orbit. We used the hard X-ray telescope, which is part of the currently-projected the ASTRO-H
X-ray satellite, as an example for investigation. The effective method of the HXT thermal control was examined with the
thermal analytical software, "Thermal Desktop". The deformation of the foil when the temperature was changed by 1
degree C was predicted by a finite element analysis (FEA). The thermal desktop analysis shows that the overall foil
temperature in orbit can be close to the temperature at which the foils were produced (~22degree C) by the newly
developed thermal control method. The FEM analysis shows that the prediction of the foil deformation due to a
temperature change of 1 degree C is about 8 μm.
Development of BGO active shield for the ASTRO-H soft gamma-ray detector
Show abstract
Soft Gamma-ray Detector (SGD:40-600 keV) will be mounted on the 6th Japanese X-ray observatory ASTROH
to be launched in 2014. The main part of the SGD is a Compton camera with a narrow field of view and
surrounded by BGO active shields (SGD-BGO). Via this combination, the SGD can achieve sensitivity more than
ten times superior to the Suzaku/HXD. The BGO active shield will also function as a gamma-ray burst monitor
as proven by the wide-band all-sky monitor (WAM) of the Suzaku/HXD. Avalanche Photodiodes (APDs) are
used to read out scintillation lights from the BGO. The size of the former also means we need to focus on
collecting light from large, complex-shaped BGO blocks. The significant leakage current of the APD means a
lower temperature is preferred to minimize the noise while a higher temperature is preferred to simplify the
cooling system. To optimize the BGO shape and the operating temperature, we tested the performance of the
BGO readout system with various BGO shapes under different operating temperatures. We also apply waveform
sampling by flash-ADC and digital filter instead of a conventional analog filter and ADC scheme to reduce the
space and power of the circuit with increased flexibilities. As an active shield, we need to achieve a threshold
level of 50-100 keV. Here, we report on the studies of threshold energy of active shield under various conditions
and signal processings.
Monte Carlo simulation study of in-orbit background for the soft gamma-ray detector on-board ASTRO-H
Show abstract
The Soft Gamma-ray Detector onboard the ASTRO-H satellite, scheduled for launch in 2014, is a Si/CdTe
Compton telescope surrounded by a thick BGO active shield. The SGD covers the energy range from 40 to
600 keV and studies non-thermal phenomena in the universe with high sensitivity. For the success of the
SGD mission, careful examination of the expected performance, particularly the instrumental background in
orbit, and optimization of the detector configuration are essential. We are developing a Geant4-based Monte
Carlo simulation framework on the ANL++ platform, employing the MGGPOD software suite to predict the
radioactivation in orbit. A detailed validation of the simulator through the comparison with literature and the
beam test data is summarized. Our system will be integrated into the ASTRO-H simulation framework.
Measuring the EUV and optical transmission of optical blocking layer for x-ray CCD camera
Show abstract
We have developed a new back-illuminated (BI) CCD which has an Optical Blocking Layer (OBL) directly coating
its X-ray illumination surface with Aluminum-Polyimide-Aluminum instead of Optical Blocking Filter (OBF).
OBL is composed of a thin polyimide layer sandwiched by two Al layers. Polyimide and Al has a capability to
cut EUV and optical light, respectively. The X-ray CCD is affected by large doses of extreme ultraviolet (EUV)
radiation from Earth sun-lit atmosphere (airglow) in orbit as well as the optical light.
In order to evaluate the performance of the EUV-attenuating polyimide of the OBL, we measured the EUV
transmission of both the OBL and the OBF at energies between 15-72 eV by utilizing a beam line located
at the Photon Factory in High Energy Accelerator Research Organization (KEK-PF). We obtained the EUV
transmission to be 3% at 41 eV which is the same as the expected transmission from the designed thickness of
the polyimide layer. We also found no significant change of the EUV transmission of polyimide over the nine
month interval spanned by out two experiments.
We also measured the optical transmission of the OBL at wavelengths between 500-900Å to evaluate the
performance of the Al that attenuates optical light, and found the optical transmission to be less than 4×10-5.
Current status of the pre-collimator development for the ASTRO-H x-ray telescopes
Show abstract
We present the current status of the pre-collimator for the stray-light reduction, mounted on the ASTRO-H
X-Ray Telescopes (XRT). Since the ASTRO-H XRTs adopt the conical approximation of the Wolter-I type
grazing incident optics, X-rays from a source located far from the telescope boresight create a ghost image in the
detector field of view (FOV) as a stray light, and then reduce the signal-to-noise ratio even in the hard X-ray
band. We thus plan to mount the pre-collimator, which is comprised of cylindrical blades aligned with each
primary mirror, onto the XRTs to remove the stray light. While the pre-collimator for the Soft X-ray Telescopes
is designed by the similar principle adopted for the Suzaku pre-collimator, that for the Hard X-ray Telescopes
requires some trade-off studies to select an appropriate blade material. The HXT pre-collimator currently utilizes
the aluminum blade with the 50 mm height and 150 μm thickness. We examined the observational effects by the
hard X-ray (> 10 keV) stray light and the expected performance of the pre-collimator in some scientific cases,
using a ray-tracing simulator. We found that the Galactic center may be mostly covered with the stray light
from the well-known bright X-ray sources. In addition, the flux estimation of the extended X-ray emission such
as the Cosmic X-ray Background is also found to have large (~ 30%) uncertainty due to the stray light from
the outside of the XRT FOV. The pre-collimator improves the situations; the stray light covering the source-free
region in the Galactic center can be reduced by half and the uncertainty of the flux determination for the diffuse
source decreases down to < 10%.
The current status of the reflector production for ASTRO-H/HXT
Akihiro Furuzawa,
Takuya Miyazawa,
Kanou Yasufumi,
et al.
Show abstract
Japan's 6th X-ray satellite mission ASTRO-H, which is planed to be launched in the fiscal year 2013, will carry
two hard X-ray telescopes (HXT) using depth-graded multilayer reflectors which provide us the capability of hard
X-ray imaging observation up to 80 keV. ASTRO-H/HXT is the light-weight hard X-ray telescope using Pt/C
depth-graded multilayer and high-throughput thin-foil optics. The basic technology for fabricating ASTROH
/HXT has been established through the balloon borne experiments, InFOCμS and SUMIT mission. The HXT
consists of about 1300 foil reflectors of which a size of the 200 mm mirror length and the diameter range of
120-450 mm which is much larger that those for the balloon borne experiments. To clear the requirements of
the angular resolution and the effective photon collecting area for ASTRO-H/HXT, we should produce twice
the total number of reflectors and select them. Therefore we need to produce more than 5000 foil reflectors for
the two flight telescopes. The installation of the production line and optical evaluation system dedicated to the
ASTRO-H/HXT has been almost done. We are testing and improving the production line through productions
of several sizes of reflectors. The mass production of the reflectors for the flight model is scheduled to start from
July 2010.
Vibration properties of hard x-ray telescope on board satellite
Show abstract
ASTRO-H is the new Japanese X-ray astronomy satellite for launch in 2013. HXT on board the satellite has a mirror
housing which is a cylindrical case and contains reflection mirror foils, which are constrained by alignment bars. In order
to investigate vibration properties of HXT on board the satellite, vibration tests and FEM analyses were conducted. From
the results of x-vibration test, it was found that there were no resonant frequencies at frequency less than 120 Hz. It also
appeared that foils move along grooves of alignment bars when the housing was vibrated because kinetic connection
between foils and alignment bars is only friction force. From the simulated results, this loose connection used in the
actual HXT housing is useful to suppress a strong resonance at 51Hz predicted by supposing tight connections such as
adhesiveness. As for z-vibration properties, vibration property of the housing was complicated since foils leap when zacceleration
becomes larger than 1G. However it could be confirmed that the distinct resonant peaks did not appear at
frequency less than 200 Hz. From these results, it was found that HXT housing had not any resonant frequencies less
than 120 Hz, which is the maximum frequency of sinusoidal vibrations applied when launched.
Cooling system for the soft x-ray spectrometer (SXS) onboard ASTRO-H
Show abstract
The Soft X-ray Spectrometer (SXS) is a cryogenic high resolution X-ray spectrometer onboard the X-ray astronomy
satellite ASTRO-H. The detector array is cooled down to 50 mK using a 3-stage adiabatic demagnetization
refrigerator (ADR). The cooling chain from room temperature to the ADR heat-sink is composed of superfluid
liquid He, a 4He Joule-Thomson cryocooler, and 2-stage Stirling cryocoolers. It is designed to keep 30 L of liquid
He for more than 3 years in the nominal case. It is also designed with redundant subsystems throughout from
room temperature to the ADR heat-sink, to alleviate failure of a single cryocooler or loss of liquid He.
Current status of hard x-ray characterization of ASTRO-H HXT at SPring-8
Takuya Miyazawa,
Akihiro Furuzawa,
Yasufumi Kanou,
et al.
Show abstract
We present the current status of hard X-ray telescope developments of ASTRO-H. ASTRO-H is Japan's 6th Xray
satellite mission following to Suzaku. It will be launched in 2014. The HXT onboard ASTRO-H is thin-foil,
multi-nested conical optics as well as Suzaku XRT. To reflect hard X-rays efficiently, reflector surfaces are coated
with depth-graded Pt/C multilayer. Reflectors are fabricated by the epoxy-replication method. Currently, we
have finished the preparation of mirror production facility at Nagoya University, and started test production
of reflectors for HXT. The selected 22 pairs of multilayer reflectors have been characterized at the SPring-8
beamline BL20B2.
The detector subsystem for the SXS instrument on the ASTRO-H Observatory
Show abstract
The Soft X-ray Spectrometer (SXS) instrument on the Astro-H observatory is based on a 36 pixel x-ray calorimeter array
cooled to 50 mK in a sophisticated spaceflight cryostat. The SXS is a true spatial-spectral instrument, where each
spatially discrete pixel functions as a high-resolution spectrometer. Here we discuss the SXS detector subsystem that
includes the detector array, the anticoincidence detector, the first stage amplifiers, the thermal and mechanical staging of
the detector, and the cryogenic bias electronics. The design of the SXS detector subsystem has significant heritage from
the Suzaku/XRS instrument but has some important modifications that increase performance margins and simplify the
focal plane assembly. Notable improvements include x-ray absorbers with significantly lower heat capacity, improved
load resistors, improved thermometry, and a decreased sensitivity to thermal radiation. These modifications have yielded
an energy resolution of 3.5-4.0 eV FWHM at 6 keV for representative devices in the laboratory, giving considerable
margin against the 7 eV instrument requirement. We expect similar performance in flight.
Operation of the x-ray telescope eROSITA
Show abstract
The X-ray telescope eROSITA is the core instrument besides the Russian ART-XC on the Russian Spektrum-Roentgen-
Gamma satellite which will be launched in 2012 to an orbit around the L2 point of the Earth-Sun-system.
During both survey and pointing phase the solar panels and the antenna constrain the possible mission scenario. The scan
axis is supposed to point constantly towards the earth in the survey phase. In combination with the orbit, the points of
largest exposure - the scan poles - then would be areas of a few hundred deg² instead of small singularities.
The background as a permanent interference factor is limiting the performance as well as transient disruptions like solar
flares. Constraints on the instrument's side are amongst others vignetting, effectivity and aligning of the different
components.
The mission objectives and related performance imply very stringent requirements. Extremely challenging mechanical
requirements in terms of mirror accuracy, alignment and dimensional stability have to be ensured by design and realized
during manufacturing and integration. Although the Wolter telescope design is quite similar to those of XMM, the
manufacturing of the mirrors is even more challenging due to the more unfavorable geometry of the mirrors.
Mirrors, CCD-cameras and camera electronics all have their own, partly narrow working temperature ranges. Therefore
accurate thermal control has to be implemented to ensure that the telescopes are performing within specification.
Objectives of this work are to find the optimum mission scenario as well as certain operating parameters, taking into
account all environmental boundary conditions.
Solid state slit camera (SSC) onboard MAXI
Show abstract
We report the in orbit status of the MAXI/SSC onboard the international space station (ISS). It was commissioned
in August 2009. This is the first all sky survey mission employing X-ray CCDs. It is a slit camera with a
field of view of 1.5° × 90° and it scans the sky as the ISS rotates around the earth.
The CCD's are cooled down to about -60°C by peltier device and a loop heat pipe. The observation efficiency
of the SSC is about 30% due to edge glow, but all of the 32 CCDs in the SSC are cooled down as we expected
and functioning property. The performance of the CCD is continuously monitored both by the Mn-K X-rays
and by the Cu-K X-rays.
There are many sources detected not only point sources but extended sources. But further work in data
screening and more observation time is needed to obtain the clear structure of the extended emission.
VELA: a fast DEPFET readout circuit for the NHXM Mission
Show abstract
NHXM, under study by ASI (Agenzia Spaziale Italiana), is an X-ray observatory in the energy band between 0.5 and
80 keV and will have 3 telescopes dedicated to X-ray imaging with a field of view diameter of 12 arcmin and a focal
length of 10 m. We report on the development of high-speed and low-noise readout of a monolithic array of DEPFET
detector. The DEPFET based detectors, thanks to an intrinsic low anode capacitance, are suitable as low-energy
detectors (from 0.5 to 10 keV) of the new NHXM telescope.
The challenging requirements of the NHXM cameras regard the necessity to obtain images and spectra with
nearly Fano-limited energy resolution with an absolute time resolution of about 100 μs. In order to exploit the speed
capability of the DEPFET array, it has been developed a readout architecture based on the VELA circuit: a drain
current readout configuration to implement an extremely fast readout (2 μs/row) and preserve the excellent noise
performance of the detector.
In the paper the foreseen maximum achievable frame-rate and the best energy resolution will be presented in
order to assert the VELA suitability for X-ray imaging and spectroscopy.
The high-energy detector of the New Hard X-ray Mission (NHXM): design concept
Show abstract
The New Hard X-ray Mission (NHXM) is conceived to extend the grazing-angle reflection imaging capability up to 80
keV energy. The payload of the mission consists of four telescopes: three of the them having at their focal plane an
identical spectral-imaging camera operating between 0.2 and 80 keV, while the fourth one is equipped with a X-ray
imaging polarimeter. The three cameras consist of two detection layers: a Low Energy Detector (LED) and a High
Energy Detector (HED) surrounded by an Anti Coincidence (AC) system. Here we present the preliminary design and
the solutions that we are currently studying to meet the requirements for the high energy detectors. These detectors will
be based on Cadmium Telluride (CdTe) pixel sensors coupled to pixel read-out electronics using custom CMOS ASICs.
Technologies for manufacturing of high angular resolution multilayer coated optics for the New Hard X-ray Mission: a status report II
Show abstract
Focusing mirrors manufactured via galvanic replication process from negative shape mandrels is the candidate solution
for some of next future X-ray missions. Media Lario Technologies (MLT) is the industrial enabler developing, in
collaboration with Brera Astronomical Observatory (INAF/OAB) and Italian Space Agency, the Optical Payload for the
New Hard X-ray Mission (NHXM) Italian project. The current and ongoing development activities in Media Lario
Technologies complement the electroforming technology with a suite of critical manufacturing and assembly of the
Mirror Module Unit. In this paper, the progress on mandrels manufacturing, mirror shell replication, multilayer coating
deposition and mirror module integration, leading to the manufacturing and testing of some astronomical Hard X-ray
Engineering Models, is reported. Mandrel production is a key point in terms of performances and schedule; the results
from mandrels fabricated using a proprietary multistep surface finishing process are reported. The progress in the
replication of ultrathin Nickel and Nickel-Cobalt substrates gold coated mirror shells is reported together with the results
of MLT Magnetron Sputtering multilayer coating technology for the hard x-ray waveband and its application to Pt/C.
Poster Session: Large X-Ray Observatories
Mounting and alignment of IXO mirror segments
Show abstract
A suspension-mounting scheme is developed for the IXO (International X-ray Observatory) mirror segments in which
the figure of the mirror segment is preserved in each stage of mounting. The mirror, first fixed on a thermally compatible
strongback, is subsequently transported, aligned and transferred onto its mirror housing. In this paper, we shall outline
the requirement, approaches, and recent progress of the suspension mount processes.
Platinum as a release layer for thermally formed optics for IXO
Show abstract
Platinum is being explored as an alternative to the sprayed boron nitride mandrel release coating under study at GSFC
for the International X-ray Observatory (IXO). Two and three inch diameter, polished (PFS) and superpolished (SPFS)
fused silica flat mandrels, were used for these tests. Pt was applied to the mandrels by DC magnetron sputtering. The
substrate material was 400 micron thick D263 glass, the material which has been proposed for the IXO segmented
optics. These substrates were placed on the mandrels and thermally cycled with the same thermal profile being used at
GSFC in the development of the BN slumping for IXO. After the thermal cycle was complete, the D263 substrates were
removed; new D263 substrates were placed on the mandrels and the process was repeated. Four thermal cycles have
been completed to date. After initially coating the mandrels with Pt, no further conditioning was applied to the mandrels
before or during the thermal cycles. The microroughness of the mandrels and of the D263 substrates was measured
before and after thermal cycling. Atomic force microscopy (AFM) and 8 keV X-ray reflectivity data are presented.
Performance of multilayer coated silicon pore optics
Show abstract
The requirements for the IXO (International X-ray Observatory) telescope are very challenging in respect of angular
resolution and effective area. Within a clear aperture with 1.7 m > R > 0.25 m that is dictated by the spacecraft envelope,
the optics technology must be developed to satisfy simultaneously requirements for effective area of 2.5 m2 at 1.25 keV,
0.65 m2 at 6 keV and 150 cm2 at 30 keV. The reflectivity of the bare mirror substrate materials does not allow these
requirements to be met. As such the IXO baseline design contains a coating layout that varies as a function of mirror
radius and in accordance with the variation in grazing incidence angle. The higher energy photon response is enhanced
through the use of depth-graded multilayer coatings on the inner radii mirror modules. In this paper we report on the first
reflectivity measurements of wedged ribbed silicon pore optics mirror plates coated with a depth graded W/Si multilayer.
The measurements demonstrate that the deposition and performance of the multilayer coatings is compatible with the
SPO production process.
Enhancing the International X-ray Observatory
Show abstract
Over the last two years, we have studied system concepts for the International X-ray Observatory (IXO) with the goal of
increasing the science return of the mission and to reduce technical and cost risk. We have developed an optical bench
concept that has the potential to increase the focal length from 20 to 25 m within the current mass and stability
requirements. Our deployable bench is a tensegrity structure formed by two telescoping booms (compression) and a
hexapod cable (tension) truss. This arrangement achieves the required stiffness for the optical bench at minimal mass
while employing only high TRL components and flight proven elements. The concept is based on existing elements, can
be fully tested on the ground and does not require new technology.
Our design further features hinged, articulating solar panels, an optical bench fully enclosed in MLI and an instrument
module with radially facing radiator panels. We find that our design can be used over a wide range of sun angles, thereby
greatly increasing IXO's field of regard, without distorting the optical bench. This makes a much larger fraction of the
sky instantaneously accessible to IXO.
A tower concept for the off-plane x-ray grating spectrometer for the International X-ray Observatory
Show abstract
An Off-Plane X-ray Grating Spectrometer (OP-XGS) concept is being developed to meet the needs of the International
X-ray Observatory (IXO). The OP-XGS will provide the required spectral resolution of R >3000 over the 0.3 - 1 keV
band with >1000 cm2 effective collecting area, using experience gained with the current generation of reflection gratings
already flown on rocket experiments. We have developed several potential configurations that meet or exceed these
requirements. This paper will focus on the mechanical design and requirements for one of these configurations, the
"tower" concept. This configuration mounts the grating modules to the instrument platform via a tower, allowing direct
alignment with the camera module. This reduces the complexity of the alignment problem while also minimizing the
overall mass of the XGS. We have developed an initial interface concept and resource requirements for this option to be
reviewed by the mission teams for design drivers. We contrast the resource requirements for this concept with those
required for other concepts which have been reviewed by the OP-XGS team. Further, we have identified those portions
of the tower design concept that will require potential technology demonstration to reach TRL 6 prior to the Preliminary
Design Review.
Estimate of the background for the x-ray microcalorimeter Spectrometer onboard of IXO
Show abstract
We present a study of the background for the array of microcalorimeters onboard of the International X-ray
Observatory space mission. We investigated through simulations the rates at the focal plane of soft and hard
particles in L2 orbit. Assuming the presence of an anticoincidence instrument, we derived an estimate of the
residual background. The preliminary results reported in this paper are based on a number of simplifications of
the actual picture. Efforts to improve the model are on-going.
The TES-based cryogenic anticoincidence detector for IXO: first results from large area prototypes
Show abstract
The technique which combines high resolution spectroscopy with imaging capability is a powerful tool to extract
fundamental information in X-ray Astrophysics and Cosmology. TES (Transition Edge Sensors)-based
microcalorimeters match at best the requirements for doing fine spectroscopy and imaging of both bright (high count
rate) and faint (poor signal-to-noise ratio) sources. For this reason they are considered among the most promising
detectors for the next high energy space missions and are being developed for use on the focal plane of the IXO
(International X-ray Observatory) mission. In order to achieve the required signal-to-noise ratio for faint or diffuse
sources it is necessary to reduce the particle-induced background by almost two orders of magnitude. This reduction can
only be achieved by adopting an active anticoincidence technique. In this paper, we will present a novel anticoincidence
detector based on a TES sensor developed for the IXO mission. The pulse duration and the large area of the IXO TESarray
(XMS X-ray Microcalorimeter Spectrometer) require a proper design of the anticoincidence detector. It has to
cover the full XMS area, yet delivering a fast response. We have therefore chosen to develop it in a four-pixel design.
Experimental results from the large-area pixel prototypes will be discussed, also including design considerations.
Arc-second alignment and bonding of International X-Ray Observatory mirror segments
Show abstract
The optics for the International X-Ray Observatory (IXO) require alignment and integration of about fourteen thousand
thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular
resolution of five arc-seconds. These mirror segments are 0.4 mm thick, and 200 to 400 mm in size, which makes it hard
not to impart distortion at the sub-arc-second level. This paper outlines the precise alignment, verification testing, and
permanent bonding techniques developed at NASA's Goddard Space Flight Center (GSFC). These techniques are used
to overcome the challenge of aligning thin mirror segments and bonding them with arc-second alignment and minimal
figure distortion. Recent advances in technology development in the area of permanent bonding have produced
significant results. This paper will highlight the recent advances in alignment, testing, and permanent bonding techniques
as well as the results they have produced.
An assessment of the problem of stray light in the optics of the International X-ray Observatory (IXO)
Show abstract
Different optical designs are under consideration for the International X-ray Observatory (IXO). In this paper we show
results of simulations of the segmented shell Wolter-I design, of the Silicon Pore Optics (SPO) conical Wolter-I
approximation and of the Silicon based Kirkpatrick-Baez design. We focus particularly on the issue of stray light. When
a source is off axis, such that it is not imaged on the detector, some of its light may still be directed by the optics onto the
detector plane. Sources close to the pointing direction can thereby introduce an extra background radiation level in the
detectors. This phenomenon is investigated by numerical ray tracing of the three designs, yielding detector images of the
stray light, and an indication of which part of the mirror that light originates. Results show the similarities and
differences of the designs with respect to stray light, and give a quantitative indication of the level of background
radiation in different cases. Furthermore, for the Silicon Pore Optics design, two different ways of partially blocking the
stray light have been modelled, indicating that a reduction of the stray light can be achieved. In general, the results that
have been found indicate that for the simulated set-ups the stray light levels are compliant with the design specifications
of the International X-ray Observatory.
Improving the angular resolution of the conical Wolter-I silicon pore optics (SPO) mirror design for the International X-ray Observatory (IXO)
Show abstract
The mirror design for the International X-ray Observatory (IXO) is currently following two paths: a segmented
slumped glass shell Wolter-I design, and a Silicon Pore Optics (SPO) conical approximation to the Wolter-I
design. The conical approximation used for the SPO imposes a lower limit to the angular resolution which puts
this option at a potential disadvantage. In this paper we describe ways in which this can be circumvented.
We analyse the surface profile modifications that can be made to lift this limitation and show that a much
closer approximation to the Wolter I ideal is possible. We describe several ways in which a much tighter
angular resolution limit could be achieved in practice and discuss ways in which this can be implemented in the
manufacture of the SPO.
IXO x-ray mirrors based on slumped glass segments with reinforcing ribs: optical and mechanical design, image error budget, and optics unit integration process
Show abstract
The International X-ray Observatory (IXO) is being studied as a joint mission by the NASA, ESA and JAXA space
agencies. The main goals of the mission are large effective area (>3m2 at 1 keV) and a good angular resolution (<5 arcsec HEW at 1 keV). This paper reports on an activity ongoing in Europe, supported by ESA and led by the Brera
Astronomical Observatory (Italy), aiming at providing an alternative method for the realization of the mirror unit
assembly. This is based on the use of thin glass segments and an innovative assembly concept making use of glass
reinforcing ribs that connect the facets to each-other. A fundamental challenge is the achievement with a hot slumping
technique of the required surface accuracy on the glass segments. A key point of the approach is represented by the
alignment of the mirror segments and co-alignment of the mirror pairs assembled together. In this paper we present the
mirror assembly conceptual design, starting from the design of the optical unit, the error budgets contributing to the
image degradation and the performance analysis to assess error sensitivities. Furthermore the related integration concept
and the preliminary results obtained are presented.
Advances in the active alignment system for the IXO optics
Show abstract
The next large x-ray astrophysics mission launched will likely include soft x-ray spectroscopy as a primary capability. A
requirement to fulfill the science goals of such a mission is a large-area x-ray telescope focusing sufficient x-ray flux to
perform high-resolution spectroscopy with reasonable observing times. The IXO soft x-ray telescope effort in the US is
focused on a tightly nested, thin glass, segmented mirror design. Fabrication of the glass segments with the required
surface accuracy is a fundamental challenge; equally challenging will be the alignment of the ~7000 secondary mirror
segments with their corresponding primary mirrors, and co-alignment of the mirror pairs. We have developed a system
to perform this alignment using a combination of a coordinate measuring machine (CMM) and a double-pass Hartmann
test alignment system. We discuss the technique, its ability to correct low-order mirror errors, and results of a recent pair
alignment including progress toward the required alignment accuracy of < 2 arcseconds, and discuss the influence of the
alignment process on mirror figure. We then look forward toward its scalability to the task of building the IXO
telescope.
Impacts on the IXO observing efficiency
Show abstract
The International X-ray Observatory (IXO) has a top level requirement that the observing efficiency be 85%. This is a
challenging requirement, given that the observing efficiencies for CXO and XMM-Newton are between 60% and 70%.
However, the L2 orbit for IXO means that it will not be subject to the earth block/radiation zone effects that are seen for
CXO and XMM-Newton. Outside of these effects the efficiencies for CXO and XMM-Newton do approach 85%, so
this requirement appears achievable for IXO. In this paper we itemize the effects which impact the observing efficiency,
in order to guide the design of the observatory. Meeting the 85% requirement should be possible but will require careful
attention to detail.
X-ray resolution tests of an off-plane reflection grating for IXO
Show abstract
We describe the experimental apparatus in use to test an off-plane reflection grating for the
soft x-ray (0.3-1.0 keV) bandpass. The grating is a prototype for the X-ray Grating
Spectrometer on the International X-ray Observatory (IXO). It has holographically-ruled
radial grooves to match the converging beam of a 6.5 m focal length telescope. Laboratory
tests are ongoing, with ray tracing indicating that a resolution (ΔE/E) >3,000 is achievable
across the 0.3-1.0 keV bandpass- the requirement to achieve IXO science goals.
Predicted x-ray backgrounds for the International X-ray Observatory
Show abstract
The background that will be observed by IXO's X-ray detectors naturally separates into two components: (1) a Cosmic X-ray Background (CXB), primarily due to unresolved point sources at high energies (E>2 keV), along with Galactic component(s) at lower energies that are generated in the disk and halo as well as the Local Bubble and charge exchange in the heliosphere, and (2) a Non-X-ray Background (NXB) created by unvetoed particle interactions in the detector itself. These may originate as relativistic particles from the Sun or Galactic Cosmic Rays (GCR), creating background events due to both primary and secondary interactions in the spacecraft itself. Stray light and optical transmission from bright sources may also impact the background, depending upon the design of the baffles and filters.
These two components have distinct effects on observations. The CXB is a sum of power-law, thermal, and charge exchange components that will be focused and vignetted by the IXO mirrors. The NXB, in contrast, is due to particle, not photon, interactions (although there will be some fluorescence features induced by particle interactions), and so will not show the same effects of vignetting or trace the effective area response of the satellite. We present the overall background rates expected from each of these processes and show how they will impact observations. We also list the expected rates for each CXB process using both mirror technologies under consideration and the predicted NXB for each detector.
Design and analysis of the International X-Ray Observatory mirror modules
Show abstract
The Soft X-Ray Telescope (SXT) modules are the fundamental focusing assemblies on NASA's next major X-ray
telescope mission, the International X-Ray Observatory (IXO). The preliminary design and analysis of these assemblies
has been completed, addressing the major engineering challenges and leading to an understanding of the factors effecting
module performance. Each of the 60 modules in the Flight Mirror Assembly (FMA) supports 200-300 densely packed
0.4 mm thick glass mirror segments in order to meet the unprecedented effective area required to achieve the scientific
objectives of the mission. Detailed Finite Element Analysis (FEA), materials testing, and environmental testing have
been completed to ensure the modules can be successfully launched. Resulting stress margins are positive based on
detailed FEA, a large factor of safety, and a design strength determined by robust characterization of the glass properties.
FEA correlates well with the results of the successful modal, vibration, and acoustic environmental tests. Deformation of
the module due to on-orbit thermal conditions is also a major design driver. A preliminary thermal control system has
been designed and the sensitivity of module optical performance to various thermal loads has been determined using
optomechanical analysis methods developed for this unique assembly. This design and analysis furthers the goal of
building a module that demonstrates the ability to meet IXO requirements, which is the current focus of the IXO FMA
technology development team.
Poster Session: New X-ray/Gamma-ray Missions
AXTAR: mission design concept
Show abstract
The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that
combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling,
and an ability to respond promptly to time-critical targets of opportunity. It is optimized for submillisecond
timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star
surfaces and black hole event horizons, thus probing the physics of ultradense matter, strongly curved spacetimes,
and intense magnetic fields. AXTAR's main instrument, the Large Area Timing Array (LATA) is a collimated
instrument with 2-50 keV coverage and over 3 square meters effective area. The LATA is made up of an array
of supermodules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement
in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also
carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition
to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for
AXTAR and present results from a preliminary mission design study.
The development of DIOS FXT (Four-stage X-ray Telescope)
Show abstract
A small satellite mission DIOS (Diffuse Intergalactic Oxygen Surveyor ) is planned to observe the warm-hot
intergalactic medium ( WHIM ) of a few millions of degree, by mapping the redshifted emission lines of oxygen.
FXT( Four Stage X-ray Telescope) has been developed as the best fit optics for DIOS. The X-ray measurement
of the first demonstration model showed a few time larger angular resolution than designed value and compact
optical measurement systems for each stage single mirror were made to clarify the reason of worse performance.
We will report on the present status of the development of FXT including compact optical measurement system
and reexamination of the process of replica foil mirror fabrication.
The x-ray camera of the EXIST/SXI telescope
Show abstract
The Energetic X-ray Imaging Survey Telescope (EXIST) mission, submitted to the Decadal Survey, is a
multiwavelength observatory mainly devoted to the study of Super Massive Black Holes, Gamma Ray Bursts and other
transient sources. The set of instruments foreseen for EXIST includes a soft x-ray telescope (SXI), proposed as a
contribution of the Italian Space Agency (ASI).
We present the baseline design of the X-Ray camera for SXI telescope, that we have finalized under ASI contract. The
camera is based on a focal plane detector consisting of a 450 μm thick silicon pixel sensor sensitive, with high QE, in the
full SXI range (0.1-10 KeV), and capable of high energy resolution when operated in photon counting mode (E/dE ~ 47
at 6 keV), frame rate ~ 100-200 frames/s (enabling timing in the ms range), and spatial resolution matching the optical
characteristics of the mirror module. We provide an overview of the mechanical, thermal and electrical concept of the
camera.
The x-ray mirrors for the EXIST/SXI telescope
Show abstract
The Energetic X-ray Imaging Survey Telescope (EXIST) will continuously survey the full sky in scanning mode for 2-
years followed by a 3-years pointing phase. The mission includes three instruments: a High Energy coded mask
Telescope; a 1.1m aperture optical-IR Telescope; and a Soft X-ray Imager (SXI), sensitive in the 0.1-10 keV band. SXI
is proposed as a contribution of ASI-Italy, fully developed by Italian institutes. Here we will present the optical and
mechanical design of the SXI mirror module, that includes also a pre-collimator and a magnetic diverter to ensure a low
background on the detector. In particular we will describe the mirror module characteristics in term of effective area,
imaging capability, thermal requirement and mechanical properties. The current optical design foresees 26 shells
providing an effective area comparable to one XMM-Newton mirror module up to 3 keV. The realization of these shells
is based on the well-proven Nickel replication-process technology.
ProtoEXIST: advanced prototype CZT coded aperture telescopes for EXIST
Show abstract
ProtoEXIST1 is a pathfinder for the EXIST-HET, a coded aperture hard X-ray telescope with a 4.5 m2 CZT
detector plane a 90x70 degree field of view to be flown as the primary instrument on the EXIST mission and
is intended to monitor the full sky every 3 h in an effort to locate GRBs and other high energy transients.
ProtoEXIST1 consists of a 256 cm2 tiled CZT detector plane containing 4096 pixels composed of an 8x8 array
of individual 1.95 cm x 1.95 cm x 0.5 cm CZT detector modules each with a 8 x 8 pixilated anode configured
as a coded aperture telescope with a fully coded 10° x 10° field of view employing passive side shielding and
an active CsI anti-coincidence rear shield, recently completed its maiden flight out of Ft. Sumner, NM on the
9th of October 2009. During the duration of its 6 hour flight on-board calibration of the detector plane was
carried out utilizing a single tagged 198.8 nCi Am-241 source along with the simultaneous measurement of the
background spectrum and an observation of Cygnus X-1. Here we recount the events of the flight and report
on the detector performance in a near space environment. We also briefly discuss ProtoEXIST2: the next
stage of detector development which employs the NuSTAR ASIC enabling finer (32×32) anode pixilation. When
completed ProtoEXIST2 will consist of a 256 cm2 tiled array and be flown simultaneously with the ProtoEXIST1
telescope.
Plans for the first balloon flight of the gamma-ray polarimeter experiment (GRAPE)
Show abstract
We have developed a design for a hard X-ray polarimeter operating in the energy range from 50 to 500 keV. This
modular design, known as GRAPE (Gamma-Ray Polarimeter Experiment), has been successfully demonstrated in the
lab using partially polarized gamma-ray sources and using fully polarized photon beams at Argonne National Laboratory.
In June of 2007, a GRAPE engineering model, consisting of a single detector module, was flown on a high altitude
balloon flight to further demonstrate the design and to collect background data. We are currently preparing a much larger
balloon payload for a flight in the fall of 2011. Using a large (16-element) array of detector modules, this payload is
being designed to search for polarization from known point sources of radiation, namely the Crab and Cygnus X-1. This
first flight will not only provide a scientific demonstration of the GRAPE design (by measuring polarization from the
Crab nebula), it will also lay the foundation for subsequent long duration balloon flights that will be designed for
studying polarization from gamma-ray bursts and solar flares. Here we shall present data from calibration of the first
flight module detectors, review the latest payload design and update the predicted polarization sensitivity for both the
initial continental US balloon flight and the subsequent long-duration balloon flights.
XCAT: the JANUS x-ray coded aperture telescope
Show abstract
The JANUS mission concept is designed to study the high redshift universe using a small, agile Explorer class
observatory. The primary science goals of JANUS are to use high redshift (6<z<12) gamma ray bursts and quasars to
explore the formation history of the first stars in the early universe and to study contributions to reionization. The X-Ray
Coded Aperture Telescope (XCAT) and the Near-IR Telescope (NIRT) are the two primary instruments on JANUS.
XCAT has been designed to detect bright X-ray flashes (XRFs) and gamma ray bursts (GRBs) in the 1-20 keV energy
band over a wide field of view (4 steradians), thus facilitating the detection of z>6 XRFs/GRBs, which can be further
studied by other instruments. XCAT would use a coded mask aperture design with hybrid CMOS Si detectors. It would
be sensitive to XRFs and GRBs with flux in excess of approximately 240 mCrab. In order to obtain redshift
measurements and accurate positions from the NIRT, the spacecraft is designed to rapidly slew to source positions
following a GRB trigger from XCAT. XCAT instrument design parameters and science goals are presented in this paper.
Focal plane instrumentation for the Wide-Field X-ray Telescope
Show abstract
The three X-ray imaging focal planes of the Wide-Field X-ray Telescope (WFXT) Mission will each have a field of
view up to 1 degree square, pixel pitch smaller than 1 arcsec, excellent X-ray detection efficiency and spectral resolving
power near the theoretical limit for silicon over the 0.2 - 6 keV spectral band. We describe the baseline concept for the
WFXT focal planes. The detectors are derived from MIT Lincoln Laboratory CCDs currently operating in orbit on
Chandra and Suzaku. Here we describe the baseline WFXT focal plane instrumentation and briefly consider options for
alternative detector technologies.
Ground calibrations of Nuclear Compton Telescope
Jeng-Lun Chiu,
Zhong-Kai Liu,
Mark S. Bandstra,
et al.
Show abstract
The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma ray (0.2-10 MeV) telescope designed to study
astrophysical sources of nuclear line emission and polarization. The heart of NCT is an array of 12 cross-strip
germanium detectors, designed to provide 3D positions for each photon interaction with full 3D position resolution to <
2 mm^3. Tracking individual interactions enables Compton imaging, effectively reduces background, and enables the
measurement of polarization. The keys to Compton imaging with NCT's detectors are determining the energy deposited
in the detector at each strip and tracking the gamma-ray photon interaction within the detector. The 3D positions are
provided by the orthogonal X and Y strips, and by determining the interaction depth using the charge collection time
difference (CTD) between the anode and cathode. Calibrations of the energy as well as the 3D position of interactions
have been completed, and extensive calibration campaigns for the whole system were also conducted using radioactive
sources prior to our flights from Ft. Sumner, New Mexico, USA in Spring 2009, and from Alice Springs, Australia in
Spring 2010. Here we will present the techniques and results of our ground calibrations so far, and then compare the
calibration results of the effective area throughout NCT's field of view with Monte Carlo simulations using a detailed
mass model.
Poster Session: Technology for Future Observatories
A cryo-amplifier working in a double loop-flux locked loop scheme for SQUID readout of TES detectors
Show abstract
In this paper we report on a novel SQUID readout scheme, called Double Loop-Flux Locked loop (DL-FLL), that we are
investigating in the frame of ASI and ESA technological development contracts. This scheme is based on the realization
of a cryogenic amplifier which is used in order to readout TES detectors in the Frequency Division Multiplexing
technique, where high loop-gain is required up to few MHz. Loop-gain in feedback systems is, usually, limited by the
propagation delay of the signals traveling in the loop because of the distance between the feedback loop elements. This
problem is particularly evident in the case of SQUID systems, where the elements of the feedback loop are placed both at
cryogenic and room temperature. To solve this issue we propose a low power dissipation cryo-amplifier capable to work
at cryogenic temperatures so that it can be placed close to the SQUID realizing a local cryogenic loop. The adoption of
the DL-FLL scheme allows to simplify considerably the cryo-amplifier which, being AC-coupled, don't require the
features of a precision DC-coupled amplifier and can be made with a limited number of electronic components and with
a consequent reduction of power dissipation.
The TET-1 HSRS camera structure: the second flight heritage of Cesic
Show abstract
One of the core payload elements of the Technologie-Erprobungs-Träger-1 (TET-1, Technology Experiment Carrier)
satellite, a mission of the German Aerospace Center (DLR), is the Hot Spot Recognition System (HSRS). Based on the
flight experience with the HSRS instrument, which was launched in 2001 on board of the Bi-Spectral Infrared Detection
microsatellite (BIRD), the instrument will be re-used on TET-1 after a comprehensive design update. The objectives of
the update are a significant reduction of the overall mass budget and an integrated design approach for the co-registration
of two cooled infrared and one visible camera systems. To reach a co-aligned assembly with high accuracy, a minimized
camera structure for all lenses and detectors has been designed.
In close collaboration with the DLR, ECM manufactured the new camera structure of the HSRS using its ceramic
composite material, Cesic®, in order to achieve the required low coefficient of thermal expansion, high stiffness, and
low mass.
In this paper, we describe the ESA-space-qualified process of manufacturing such high-precision space structures and
Cesic®'s advantages compared to competing materials, especially with respect to material properties and versatility of
manufacturing.
We also present the results of testing the HSRS Cesic® camera structure under launch and space environmental
conditions, including vibration, shock, and thermal vacuum exposures.
The HSRS camera structure described here is the second flight heritage of Cesic®. The first was two all-Cesic®
telescopes ECM manufactured for the SPIRALE mission (Système Préparatoire Infra-Rouge pour l'Alerte), a French
space-based early warning demonstration system consisting of two satellites. The SPIRALE satellites were launched in
February 2009 and are performing successfully. The prime contractor was THALES ALENIA SPACE.
The results presented here and the flight experience with the SPIRALE telescopes demonstrate that ECM's Cesic®
composite is a superior material for the manufacture of light-weighted, stiff, and low-CTE space structures, with
improved performance compared to aluminum and other traditional metal materials.
Concept for an innovative wide-field camera for x-ray astronomy
Show abstract
The use of large-area, fine-pitch Silicon detectors has demonstrated the feasibility of wide field imaging experiments
requesting very low resources in terms of weight, volume, power and costs. The flying SuperAGILE instrument
is the first such experiment, adopting large-area Silicon microstrip detectors coupled to one-dimensional
coded masks. With less than 10 kg, 12 watt and 0.04 m3 it provides 6-arcmin angular resolution over >1 sr field
of view. Due to odd operational conditions, SuperAGILE works in the unfavourable energy range 18-60 keV. In
this paper we show that the use of innovative large-area Silicon Drift Detectors allows to design experiments with
arcmin-imaging performance over steradian-wide fields of view, in the energy range 2-50 keV, with spectroscopic
resolution in the range of 300-570 eV (FWHM) at room temperature. We will show the concept, design and
readiness of such an experiment, supported by laboratory tests on large-area prototypes. We will quantify the
expected performance in potential applications on X-ray astronomy missions for the observation and long-term
monitoring of Galactic and extragalactic transient and persistent sources, as well as localization and fine study
of the prompt emission of Gamma-Ray Bursts in soft X-rays.
X-ray imaging and spectroscopy performance of a large area silicon drift chamber for wide-field x-ray astronomy applications
Show abstract
In the context of the design of wide-field of view experiments for X-ray astronomy, we studied the response to X-rays in
the range between 2 and 60 keV of a large area Silicon Drift Chamber originally designed for particle tracking in high
energy physics. We demonstrated excellent imaging and spectroscopy performance of monolithic 53 cm2 detectors, with
position resolution as good as 30 μm and energy resolution in the range 300-570 eV FWHM obtainable at room
temperature (20 °C). In this paper we show the results of test campaigns at the X-ray facility at INAF/IASF Rome, aimed
at characterizing the detector performance by scanning the detector area with highly collimated spots of monochromatic
X-rays. In these tests we used a detector prototype equipped with discrete read-out front-end electronics.
EUV spectroscopy of high-redshift x-ray objects
Show abstract
As astronomical observations are pushed to cosmological distances (z>3) the spectral energy distributions of X-ray
objects, AGN for example, will be redshifted into the EUV waveband. Consequently, a wealth of critical spectral
diagnostics, provided by, for example, the Fe L-shell complex and the O VII/VIII lines, will be lost to future planned X-ray
missions (e.g., IXO, Gen-X) if operated at traditional X-ray energies. This opens up a critical gap in performance
located at short EUV wavelengths, where critical X-ray spectral transitions occur in high-z objects. However, normal-incidence
multilayer-grating technology, which performs best precisely at such wavelengths, together with advanced
nanolaminate replication techniques have been developed and are now mature to the point where advanced EUV
instrument designs with performance complementary to IXO and Gen-X are practical. Such EUV instruments could be
flown either independently or as secondary instruments on these X-ray missions. We present here a critical examination
of the limits placed on extragalactic EUV measurements by ISM absorption, the range where high-z measurements are
practical, and the requirements this imposes on next-generation instrument designs. We conclude with a discussion of a
breakthrough technology, nanolaminate replication, which enables such instruments.
X-ray pencil beam facility for optics characterization
Show abstract
The Physikalisch-Technische Bundesanstalt (PTB) has used synchrotron radiation for the characterization of optics and
detectors for astrophysical X-ray telescopes for more than 20 years. At a dedicated beamline at BESSY II, a
monochromatic pencil beam is used by ESA and cosine Research since the end of 2005 for the characterization of novel
silicon pore optics, currently under development for the International X-ray Observatory (IXO). At this beamline, a
photon energy of 2.8 keV is selected by a Si channel-cut monochromator. Two apertures at distances of 12.2 m and
30.5 m from the dipole source form a pencil beam with a typical diameter of 100 μm and a divergence below 1". The
optics to be investigated is placed in a vacuum chamber on a hexapod, the angular positioning is controlled by means of
autocollimators to below 1". The reflected beam is registered at 5 m distance from the optics with a CCD-based camera
system.
This contribution presents design and performance of the upgrade of this beamline to cope with the updated design for
IXO. The distance between optics and detector can now be 20 m. For double reflection from an X-ray Optical Unit
(XOU) and incidence angles up to 1.4°, this corresponds to a vertical translation of the camera by 2 m. To achieve high
reflectance at this angle even with uncoated silicon, a lower photon energy of 1 keV is available from a pair of W/B4C
multilayers. For coated optics, a high energy option can provide a pencil beam of 7.6 keV radiation.
Research and development of a gamma-ray imaging spectrometer in the MeV range in Barcelona
Show abstract
Gamma-ray astrophysics in the MeV energy range plays an important role for the understanding of cosmic explosions
and acceleration mechanisms in a variety of galactic and extragalactic sources, e.g., Supernovae, Classical Novae,
Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN).
Through the development of focusing telescopes in the MeV energy range, it will be possible to reach unprecedented
sensitivities, compared with those of the currently operating gamma ray telescopes. In order to achieve the needed
performance, a detector with mm spatial resolution and very high peak efficiency is required. It will be also desirable
that the detector could detect polarization of the source.
Our research and development activities in Barcelona aim to study a gamma-ray imaging spectrometer in the MeV range
suited for the focal plane of a gamma-ray telescope mission, based on CdTe pixel detectors arranged in multiple layers
with increasing thicknesses, to enhance gamma-ray absorption in the Compton regime. We have developed an initial
prototype based on several CdTe module detectors, with 11x11 pixels, a pixel pitch of 1mm and a thickness of 2mm.
Each pixel is stud-bump bonded to a fanout board and routed to a readout ASIC to measure pixel position, pulse height
and rise time information for each incident gamma-ray photon.
We will report on the results of an optimization study based on simulations, to select the optimal thickness of each CdTe
detector within the module to get the best energy resolution of the spectrometer.
A brief overview of the Fusion and Astrophysics Data and Diagnostic Calibration Facility
G. V. Brown,
P. Beiersdorfer,
J. Clementson,
et al.
Show abstract
The Fusion and Astrophysics (FAST) Data and Diagnostic Calibration Facility located at the Lawrence Livermore
National Laboratory is a state-of-the-art facility used to calibrate radiation based diagnostics and study
atomic processes for investigating fusion and astrophysical plasmas. FAST has at its disposal a full suite of radiation
generation and detection devices, including two electron beam ion traps: EBIT-I and SuperEBIT and an
absolutely calibrated x-ray calorimeter spectrometer. FAST covers the energy range between 0.01 and 100 keV,
and can thus be used to calibrate a variety of plasma diagnostics. Instrument parameters that can be calibrated
include line profiles, transmission and reflection efficiencies, and the quantum efficiency of grating and crystal
spectrometers and solid state detectors. FAST can be used to test fully integrated instrumentation, and is ideal
for spectrometers and detectors to be flown on orbiting observatories, sounding rockets, used as ground support
equipment to verify flight instrumentation, in laboratory astrophysics experiments, and to diagnose magnetic and
inertial confinement fusion plasmas. Here we present an overview of the calibration capabilities of this facility
including some results.
Reflectivity and polarization sensitivity of a bent crystal with DLC deposition
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We report a development of a bent crystal for use of X-ray polarimeter. A Si(100) crystal sheet was deposited
with DLC (Diamond-Like Carbon) and bent by the difference in the internal stress between the DLC and Si. An
angular reflectivity of the crystal was measured at 8 keV (Cu-Kα). The center of the reflection peak appeared
at the Bragg angle expected for the (400) plane of Si(100). With the bending of the crystal, the angular width
of the peak is broadened. A sample indicated the angular width of 2 degree, which is equivalent to the energy
width of 0.5 keV. The modulation factor was measured to be more than 0.9 for 8 keV energy emission. If the
energy of the X-ray emission is at Fe-K lines (~7 keV), which are very important for X-ray astronomy, the Bragg
angle becomes more close to 45 degree. It means that higher sensitivity for the polarization would be expected
for these lines. The sensitivity in wide energy band with the high modulation factor indicates that the bent
crystal can be a new tool for the X-ray polarimeter. A preliminary design of the polarimetric optics composed
by the Si(100) crystal and a small-size detector (e.g. X-ray CCD camera) is proposed. For celestial objects with
large spatial extent with large emitting energy band, our optics could collect X-rays much more efficiently than
existing optics with high signal to noise ratio. Any kind of crystals can be bent with our method, and then a
combination of different crystals will further improve the performance of the polarimetric optics.
Gallium nitride photocathodes for imaging photon counters
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Gallium nitride opaque and semitransparent photocathodes provide high ultraviolet quantum efficiencies from 100 nm
to a long wavelength cutoff at ~380 nm. P (Mg) doped GaN photocathode layers ~100 nm thick with a barrier layer of
AlN (22 nm) on sapphire substrates also have low out of band response, and are highly robust. Opaque GaN photocathodes
are relatively easy to optimize, and consistently provide high quantum efficiency (70% at 120 nm) provided the
surface cleaning and activation (Cs) processes are well established. We have used two dimensional photon counting
imaging microchannel plate detectors, with an active area of 25 mm diameter, to investigate the imaging characteristics
of semitransparent GaN photocathodes. These can be produced with high (20%) efficiency, but the thickness and conductivity
of the GaN must be carefully optimized. High spatial resolution of ~50 μm with low intrinsic background (~7
events sec-1 cm-2) and good image uniformity have been achieved. Selectively patterned deposited GaN photocathodes
have also been used to allow quick diagnostics of optimization parameters. GaN photocathodes of both types show great
promise for future detector applications in ultraviolet Astrophysical instruments.