Results from the CsI calorimeter onboard the ComPair balloon flight

The ComPair gamma-ray telescope is a technology demonstrator for a future gamma-ray telescope called the All-sky Medium Energy Gamma-ray Observatory (AMEGO). The instrument is composed of four subsystems, a double-sided silicon strip detector, virtual Frisch grid CdZnTe calorimeter, a CsI:Tl based calorimeter, and an anti-coincidence detector (ACD). ComPair is designed to maintain continuous coverage from the Compton and pair-production regime. The CsI calorimeter’s main goal is to measure the position and energy deposited from the highest energy events. This design has a dynamic energy of 0.25-30 MeV. To demonstrate the instrument’s maturity, ComPair was flown on a balloon flight in August 2023. This paper will present the results of the CsI during the balloon flight where we observed background rates and gamma-ray lines from activation.