UC San Diego

In order to understand the effects of a space radiation environment on cross-strip germanium detectors, we investigated the effects of high-energy proton damage on a COSI detector and the capabilities of high-temperature annealing in repairing detector spectral resolution. We irradiated a COSI-balloon cross-strip high-purity germanium (HPGe) detector with 150MeV protons resulting in a net fluence of 4 . 95 × 1 0 8 p + /cm 2 and corresponding to ∼ 10 years in COSI’s space radiation environment. We repaired the resulting degradation in spectral resolution through a series of high-temperature anneals to obtain a final FWHM of 4.08keV, within 37 % of its preradiation value (2.98keV FWHM). We characterized the repair of charge traps with time spent under high-temperature anneal to inform an annealing procedure for long-term maintenance of COSI’s spectral resolution.