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GRAPE - A Balloon-Borne Gamma-Ray Polarimeter Experiment

P. F. Bloser·J. S. Legere·J. R. Macri·M. L. McConnell·T. Narita·J. M. Ryan
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Abstract

This paper reviews the development status of GRAPE (the Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs), although GRAPE could also be employed in the study of other astrophysical sources. Accurately measuring the polarization of the emitted radiation will lead to a better understating of both emission mechanisms and source geometries. The GRAPE design consists of an array of plastic scintillators surrounding a central high-Z crystal scintillator. The azimuthal distribution of photon scatters from the plastic array into the central calorimeter provides a measure of the polarization fraction and polarization angle of the incident radiation. The design of the detector provides sensitivity over a large field-of-view (>pi steradian). The design facilitates the fabrication of large area arrays with minimal deadspace. This paper presents the latest design concept and the most recent results from laboratory tests of a GRAPE science model.

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P. F. Bloser, J. S. Legere, J. R. Macri, M. L. McConnell, T. Narita, J. M. Ryan. 2005-08-14. GRAPE - A Balloon-Borne Gamma-Ray Polarimeter Experiment. https://doi.org/10.1088/1009-9271%2F6%2Fs1%2F54

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