  Thick, fully depleted p-channel charge-coupled devices (CCDs) have been
developed at the Lawrence Berkeley National Laboratory (LBNL). These CCDs have
several advantages over conventional thin, n-channel CCDs, including enhanced
quantum efficiency and reduced fringing at near-infrared wavelengths and
improved radiation tolerance. Here we report results from the irradiation of
CCDs with 12.5 and 55 MeV protons at the LBNL 88-Inch Cyclotron and with 0.1-1
MeV electrons at the LBNL Co60 source. These studies indicate that the LBNL
CCDs perform well after irradiation, even in the parameters in which
significant degradation is observed in other CCDs: charge transfer efficiency,
dark current, and isolated hot pixels. Modeling the radiation exposure over a
six-year mission lifetime with no annealing, we expect an increase in dark
current of 20 e/pixel/hr, and a degradation of charge transfer efficiency in
the parallel direction of 3e-6 and 1e-6 in the serial direction. The dark
current is observed to improve with an annealing cycle, while the parallel CTE
is relatively unaffected and the serial CTE is somewhat degraded. As expected,
the radiation tolerance of the p-channel LBNL CCDs is significantly improved
over the conventional n-channel CCDs that are currently employed in space-based
telescopes such as the Hubble Space Telescope.
