Proton Radiation Damage and Annealing of COSI p-type Cross-strip HPGe Detectors

Abstract

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 150 MeV protons resulting in a net fluence of $4.95\times 10^8$ 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 4.08 keV, within 37% of its preradiation value (2.98 keV 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.

25 pages, 9 figures, 1 table, accepted to NIM A