Estimating the Imaging Capabilities of the Gamma-Ray Polarimeter Experiment (GRAPE)

The Gamma-Ray Polarimeter Experiment (GRAPE) is a high-altitude balloon experiment designed to study the polarization of gamma-rays from GRBs over the energy range of 50-500 keV. The balloon campaign is set to launch in late summer of 2023. Currently under development, a new detector module, designed to capture photon interactions in three dimensions and provide modest imaging capabilities, is described. The module is a 3-dimensional array of high-Z (GAGG) and low-Z (P-terphenyl) scintillators read out by SiPMs. Here we present instrument capabilities, analysis methods under consideration, and a brief overview of results from lab calibrations of a prototype module. GEANT4 simulations provide the expected instrument response. Plans for the balloon flight are described.