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arXiv · 2601.00127

Light-tight skipper-CCDs for X-ray detection in space

Ana M. Botti·Yikai Wu·Brenda Cervantes·Claudio Chavez·Juan Estrada·Stephen E. Holland·Nathan Saffold·Javier Tiffenberg·Sho Uemura
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Abstract

Skipper Charge-Coupled Devices (skipper-CCDs) are pixelated silicon detectors with deep sub-electron resolution. Their radiation hardness and capability to reconstruct energy deposits with unprecedented precision make them a promising technology for space-based X-ray astronomy. In this scenario, optical and near-infrared photons may saturate the sensor, distorting the reconstructed signal. We present a light-tight shield for skipper-CCDs to suppress optical backgrounds while preserving X-ray detection efficiency. We deposited thin aluminum layers on the CCD surface using an e-beam evaporator and evaluated their blinding performance across wavelengths from 650 to 1000 nm using a monochromator, as well as the X-ray transmission using an $^{55}$Fe source. We find that 50 and 100 nm layers provide >99.6% light suppression, with no efficiency loss for 5.9 and 6.4 keV X-rays. In addition, we used Geant4 simulations to extend these results to a broader energy range and quantify the efficiency loss for different aluminum thicknesses. Results show that thin aluminum coatings are an effective, low-cost solution for optical suppression in skipper-CCDs intended for X-ray detection and space instrumentation.

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Ana M. Botti, Yikai Wu, Brenda Cervantes, Claudio Chavez, Juan Estrada, Stephen E. Holland, Nathan Saffold, Javier Tiffenberg, Sho Uemura. 2025-12-31. Light-tight skipper-CCDs for X-ray detection in space. https://doi.org/10.1088/1538-3873%2Fae60ce

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