SH048-0015
The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS): proposed reflight during the next solar maximum
The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS): proposed reflight during the next solar maximum
Wednesday, 16 December 2020
Poster
Abstract:
The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) high altitude
balloon payload was successfully flown in January 2016 from Antarctica.
GRIPS provides 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’s goal is to address questions
raised by recent solar flare observations regarding particle
acceleration and energy release, such as: DO Do flare ions and electrons
share a common acceleration process? What causes the spatial separation
between energetic electrons producing hard X-rays and energetic ions
producing gamma-ray lines? Is there significant high-energy particle
acceleration at flare footpoints? How anisotropic are the relativistic
electrons, and why can they dominate in the corona? Where do flare
accelerated ions deposit their energy over the course of a flare? How do
the compositions of accelerated and ambient material vary with space and
time, and why? The spectrometer/polarimeter consists of 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 ~0.1 mm3. Imaging is accomplished by a
multi-pitch rotating modulator (MPRM), a single 2.5-cm thick tungsten
alloy 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, with
an estimated minimum detectable polarization of a few percent at 150-650
keV in an X-class flare. We describe our proposed second flight with
modifications to the instrument, targeting the anticipated next maximum
of solar activity around 2025.
balloon payload was successfully flown in January 2016 from Antarctica.
GRIPS provides 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’s goal is to address questions
raised by recent solar flare observations regarding particle
acceleration and energy release, such as: DO Do flare ions and electrons
share a common acceleration process? What causes the spatial separation
between energetic electrons producing hard X-rays and energetic ions
producing gamma-ray lines? Is there significant high-energy particle
acceleration at flare footpoints? How anisotropic are the relativistic
electrons, and why can they dominate in the corona? Where do flare
accelerated ions deposit their energy over the course of a flare? How do
the compositions of accelerated and ambient material vary with space and
time, and why? The spectrometer/polarimeter consists of 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 ~0.1 mm3. Imaging is accomplished by a
multi-pitch rotating modulator (MPRM), a single 2.5-cm thick tungsten
alloy 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, with
an estimated minimum detectable polarization of a few percent at 150-650
keV in an X-class flare. We describe our proposed second flight with
modifications to the instrument, targeting the anticipated next maximum
of solar activity around 2025.