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R. P. Lin (Physics Dept. and Space Sciences Laboratory, University of California, Berkeley), RHESSI Team
Solar flares are the most energetic explosions in the solar system, releasing up to 1032-1033 ergs in 10-1000s. They are also the most powerful particle accelerators, producing ions up to tens of GeV and electrons up to tens of MeV. The accelerated ~10-100 keV electrons (and sometimes ~1 MeV ions) appear to contain ~10-50% of this energy, indicating that the particle acceleration and energy release processes are intimately linked. The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer mission designed to provide imaging and spectroscopy of hard X-ray/gamma-ray continua emitted by energetic electrons, and of gamma-ray lines produced by energetic ions. The single instrument consists of an imager, made up of nine bi-grid rotating modulation collimators (RMCs), in front of a spectrometer with nine cryogenically-cooled germanium detectors, one behind each RMC. The spatial resolution is as fine as ~2.3 arcsec with a full-Sun (~1 deg) field of view, and the spectral resolution is ~1-10 keV FWHM over the energy range from soft X-rays (3 keV) to gamma-rays (17 MeV). RHESSI was launched on February 5, 2002, into a nearly circular, 38 deg inclination, 600-km altitude orbit and began continous observations a week later. Among the many new results are the first hard X-ray imaging spectroscopy of solar flares, and the first high resolution spectroscopy and imaging of flare gamma-ray lines. RHESSI is funded by NASA through contract NAG5-98033 to the University of California at Berkeley.
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.