Radiation damage from cobalt-60 gamma rays is investigated for TSL235 Light to Frequency Converters. No dose rate effects were observed. the TSL235 is found suitable for use in Low Earth Orbit up to a total dose of 1.5 Krad(Si). Sudden failure of the device is observed at approximately 5 Krad(Si), exhibited by a rapid degradation in performance and a quick rise in device supply current leading to permanent damage (burnout). Annealing at room temperature for 24 hours showed no rebound.
Joel M. Hatch,
"Radiation damage to TSL235 light-to-frequency converters", Proc. SPIE 3440, Photonics for Space Environments VI, (13 October 1998); doi: 10.1117/12.326685; https://doi.org/10.1117/12.326685