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Proceedings Paper

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)
Author(s): Albert Y. Shih; Robert P. Lin; Gordon J. Hurford; Nicole A. Duncan; Pascal Saint-Hilaire; Hazel M. Bain; Steven E. Boggs; Andreas C. Zoglauer; David M. Smith; Hiroyasu Tajima; Mark S. Amman; Tadayuki Takahashi
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Paper Abstract

The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: 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? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungstenalloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150–650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica.

Paper Details

Date Published: 17 September 2012
PDF: 15 pages
Proc. SPIE 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 84434H (17 September 2012); doi: 10.1117/12.926450
Show Author Affiliations
Albert Y. Shih, NASA Goddard Space Flight Ctr. (United States)
Robert P. Lin, Space Sciences Lab. and Univ. of California, Berkeley (United States)
Kyung Hee Univ. (Korea, Republic of)
Gordon J. Hurford, Univ. of California, Berkeley (United States)
Nicole A. Duncan, Univ. of California, Berkeley (United States)
Pascal Saint-Hilaire, Univ. of California, Berkeley (United States)
Hazel M. Bain, Univ. of California, Berkeley (United States)
Steven E. Boggs, Univ. of California, Berkeley (United States)
Andreas C. Zoglauer, Univ. of California, Berkeley (United States)
David M. Smith, Univ. of California, Santa Cruz (United States)
Hiroyasu Tajima, Solar Terrestrial Environment Lab., Stanford Univ. (United States)
Mark S. Amman, Lawrence Berkeley National Lab. (United States)
Tadayuki Takahashi, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)

Published in SPIE Proceedings Vol. 8443:
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Stephen S. Murray; Jan-Willem A. den Herder, Editor(s)

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