Radiation hardness of a p-channel notch CCD developed for the X-ray CCD camera onboard the XRISM satellite

Abstract

We report the radiation hardness of a p-channel CCD developed for the X-ray CCD camera onboard the XRISM satellite. This CCD has basically the same characteristics as the one used in the previous Hitomi satellite, but newly employs a notch structure of potential for signal charges by increasing the implant concentration in the channel. The new device was exposed up to approximately $7.9\times 10^{10}\mathrm{protons}\mathrm{c}{\mathrm{m}}^{-2}$ at 100 MeV. The charge transfer inefficiency was estimated as a function of proton fluence with an ${}^{55}\mathrm{Fe}$ source. A device without the notch structure was also examined for comparison. The result shows that the notch device has a significantly higher radiation hardness than those without the notch structure including the device adopted for Hitomi. This proves that the new CCD is radiation tolerant for space applications with a sufficient margin.

10 pages, 6 figures, published in Journal of Instrumentation (JINST)