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Proceedings Paper • Open Access

First flight of the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument
Author(s): Nicole Duncan; P. Saint-Hilaire; A. Y. Shih; G. J. Hurford; H. M. Bain; M. Amman; B. A. Mochizuki; J. Hoberman; J. Olson; B. A. Maruca; N. M. Godbole; D. M. Smith; J. Sample; N. A. Kelley; A. Zoglauer; A. Caspi; P. Kaufmann; S. Boggs; R. P. Lin

Paper Abstract

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument is a balloon-borne telescope designed to study solar- are particle acceleration and transport. We describe GRIPS's first Antarctic long-duration flight in January 2016 and report preliminary calibration and science results. Electron and ion dynamics, particle abundances and the ambient plasma conditions in solar flares can be understood by examining hard X-ray (HXR) and gamma-ray emission (20 keV to 10 MeV). Enhanced imaging, spectroscopy and polarimetry of are emissions in this energy range are needed to study particle acceleration and transport questions. The GRIPS instrument is specifically designed to answer questions including: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? GRIPS's key technological improvements over the current solar state of the art at HXR/gamma-ray energies, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), include 3D position-sensitive germanium detectors (3D-GeDs) and a single-grid modulation collimator, the multi-pitch rotating modulator (MPRM). The 3D-GeDs have spectral FWHM resolution of a few hundred keV and spatial resolution <1 mm3. For photons that Compton scatter, usually ⪆150 keV, the energy deposition sites can be tracked, providing polarization measurements as well as enhanced background reduction through Compton imaging. Each of GRIPS's detectors has 298 electrode strips read out with ASIC/FPGA electronics. In GRIPS's energy range, indirect imaging methods provide higher resolution than focusing optics or Compton imaging techniques. The MPRM gridimaging system has a single-grid design which provides twice the throughput of a bi-grid imaging system like RHESSI. The grid is composed of 2.5 cm deep tungsten-copper slats, and quasi-continuous FWHM angular coverage from 12.5-162 arcsecs are achieved by varying the slit pitch between 1-13 mm. This angular resolution is capable of imaging the separate magnetic loop footpoint emissions in a variety of are sizes. In comparison, RHESSI's 35-arcsec resolution at similar energies makes the footpoints resolvable in only the largest ares.

Paper Details

Date Published: 18 July 2016
PDF: 17 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99052Q (18 July 2016); doi: 10.1117/12.2233859
Show Author Affiliations
Nicole Duncan, Univ. of California, Berkeley (United States)
Space Sciences Lab. (United States)
P. Saint-Hilaire, Space Sciences Lab. (United States)
A. Y. Shih, NASA Goddard Space Flight Ctr. (United States)
G. J. Hurford, Space Sciences Lab. (United States)
H. M. Bain, Space Sciences Lab. (United States)
M. Amman, Lawrence Berkeley National Lab. (United States)
B. A. Mochizuki, Space Sciences Lab. (United States)
J. Hoberman, Space Sciences Lab. (United States)
J. Olson, Space Sciences Lab. (United States)
B. A. Maruca, Univ. of Delaware (United States)
Space Sciences Lab. (United States)
N. M. Godbole, Space Sciences Lab. (United States)
D. M. Smith, Univ. of California, Santa Cruz (United States)
J. Sample, Montana State Univ. (United States)
N. A. Kelley, Space Sciences Lab. (United States)
A. Zoglauer, Space Sciences Lab. (United States)
A. Caspi, Southwest Research Institute (United States)
P. Kaufmann, Univ. Presbiteriana Mackenzie (Brazil)
S. Boggs, Space Sciences Lab. (United States)
R. P. Lin, Space Sciences Lab. (United States)

Published in SPIE Proceedings Vol. 9905:
Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Jan-Willem A. den Herder; Tadayuki Takahashi; Marshall Bautz, Editor(s)

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