GRAPE - A Balloon-Borne Gamma-Ray Polarimeter Experiment
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 (>π 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.
Chinese Journal of Astronomy and Astrophysics
Digital Object Identifier (DOI)
Bloser, Peter F.; Legere, Jason S.; Macri, John R.; McConnell, Mark L.; Narita, T; and Ryan, James M., "GRAPE - A Balloon-Borne Gamma-Ray Polarimeter Experiment" (2006). Chinese Journal of Astronomy and Astrophysics. 10.