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M. L. McConnell, J. Ledoux, J. R. Macri, J. M. Ryan (UNH)
We have developed a modular design for a hard X-ray and soft gamma-ray polarimeter that we call GRAPE (Gamma RAy Polarimeter Experiment). Optimized for the energy range of 50-300 keV, the GRAPE design is a Compton polarimeter based on the use of an array of plastic scintillator scattering elements in conjunction with a centrally positioned high-Z calorimeter detector. An array of GRAPE modules could be used as the basis for a dedicated science mission, either on a long duration balloon or on an orbital mission. Various imaging methods could also be employed to provide a capability for imaging polarimetry. Here we shall review the results from a laboratory model of the baseline GRAPE design and compare those results with our latest Monte Carlo simulations. The baseline design uses a 5-inch diameter position sensitive PMT (PSPMT) for readout of the plastic scintillator array and a small array of CsI detectors for measurement of the scattered photon. Possible modifications to the baseline design are discussed, along with possible designs for a dedicated polarimetry mission. With a large effective FoV, a non-imaging GRAPE mission would be ideal for studying polarization in transient sources (gamma ray bursts and solar flares). It may also prove useful for studying periodically varying sources, such as pulsars. An imaging system based on this detector design would improve the sensitivity of the polarization measurements for transient and periodic sources and may also permit the measurement of polarization in steady-state sources.
The author(s) of this abstract have provided an email address for comments about the abstract: Mark.McConnell@unh.edu
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.