Cherenkov Photon Background for Low-Noise Silicon Detectors in Space

TL;DR

This paper models Cherenkov radiation from cosmic rays in silicon detectors, revealing it as a significant background source for space-based ultra-low-noise photon detection.

Contribution

It introduces a calibrated model of Cherenkov photon background in silicon detectors, crucial for designing low-noise space observatories.

Findings

Cherenkov background rate is comparable to other astrophysical backgrounds.

The model is calibrated with laboratory data.

Cherenkov radiation impacts detector sensitivity in space.

Abstract

Future space observatories dedicated to direct imaging and spectroscopy of extra-solar planets will require ultra-low-noise detectors that are sensitive over a broad range of wavelengths. Silicon charge-coupled devices (CCDs), such as EMCCDs, Skipper CCDs, and Multi-Amplifier Sensing CCDs, have demonstrated the ability to detect and measure single photons from ultra-violet to near-infrared wavelengths, making them candidate technologies for this application. In this context, we study a relatively unexplored source of low-energy background coming from Cherenkov radiation produced by energetic charged particles traversing a silicon detector. In the intense radiation environment of space, energetic cosmic rays produce high-energy tracks and more extended halos of low-energy Cherenkov photons, which are detectable with ultra-low-noise detectors. We present a model of this effect that is calibrated to laboratory data, and we use this model to characterize the residual background rate for ultra-low noise silicon detectors in space. We find that the rate of cosmic-ray-induced Cherenkov photon production is comparable to other detector and astrophysical backgrounds that have previously been considered.