Beam Data Analysis for the Compton Pair Instrument

The Compton Pair (ComPair) telescope is a balloon-borne prototype instrument that is being built to advance the hardware and software tools necessary for future medium energy gamma-ray (MeV) missions. Astrophysical observations in the MeV range are challenging as two processes compete for photon interaction in matter. Compton scattering is dominant at lower energies and pair production is dominant at higher energies, with crossover ~ 10MeV. ComPair is designed to use both Compton scattering and pair production events to provide sensitivity over the crossover region. It achieves this goal using four subsystems: a Silicon tracker to measure the position and energy of photon interactions, a Cadmium Zinc Telluride (CZT) calorimeter to detect the Compton scattered photons, a Cesium Iodide (CsI) calorimeter for measuring the high energy pair events, and a plastic Anti-Coincidence Detector (ACD) to reject cosmic ray events. ComPair had a successful beam test at the High Intensity Gamma-ray Source at Duke University in April 2022, where the instrument was tested with gamma-ray beams ranging from 2 to 25 MeV. In this presentation, we outline our data analysis pipeline and present the current results from the beam test.