The performance of RHESSI's germanium detectors over a 16-year science mission

The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) was a solar X-ray mission that observed the Sun at X-ray and gamma-ray wavelengths for 16 years, with an energy range covering 3 keV – 17 MeV. RHESSI instrumentation consisted of nine cryocooled, segmented, germanium detectors. We report on the performance of these detectors over the course of 16 years of science operations in a mid-latitude, low-Earth orbit environment. We assess the evolution of the energy gain and energy calibration for each detector, the segmentation status of the detectors over time, and the effectiveness of detector annealing in restoring performance. We highlight some of the challenges associated with determining the calibration over such a long on-orbit time period. These results provide valuable context for future X-ray and gamma-ray space missions.