Effects of Proton Irradiation on the Performance of Skipper CCDs

TL;DR

This study investigates how proton irradiation affects the performance of p-channel skipper CCDs, crucial for space telescopes, demonstrating their resilience and outlining future testing directions.

Contribution

First experimental assessment of proton radiation effects on skipper CCDs, showing their robustness and providing a basis for future space-based detector evaluations.

Findings

Skipper CCDs maintain functionality after high-dose proton irradiation.

Low readout noise enables sensitive characterization of radiation-induced defects.

Proton irradiation effects can be monitored via charge transfer inefficiency and dark current measurements.

Abstract

Skipper CCDs are a mature detector technology that has been suggested for future space telescope instruments requiring sub-electron readout noise in the near-ultraviolet to the near-infrared. While modern skipper CCDs inherit from the radiation-tolerant p-channel detectors developed by LBNL, the effects of high doses of ionizing radiation on skipper CCDs (such as those expected in space) remains largely unmeasured. We report preliminary results on the performance of p-channel skipper CCDs following irradiation with 217-MeV protons at the Northwestern Medicine Proton Center. The total nonionizing energy loss (NIEL) experienced by the detectors exceeds 6 years at the Sun-Earth Lagrange Point 2 (L2). We demonstrate that the skipper amplifier continues to function as expected following this irradiation. Owing to the low readout noise of these detectors, controlled irradiation tests can be used to sensitively characterize the charge transfer inefficiency, dark current, and the density and time constants of charge traps as a function of proton fluence. We conclude with a brief outlook toward future tests of these detectors at other proton and gamma-ray facilities.