Development of Low-Energy Calibration Techniques for SuperCDMS using LEDs Operated at Cryogenic Temperatures

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Ghaith, Muad
SuperCDMS , Dark Matter , Particle Physics , Cryogenics , Calibration techniques , Cryogenic detectors , IR photon
The desire to unveil the mystery of dark matter which, according to compelling astrophysical and cosmological evidence, constitutes about 85% of the matter in the Universe, drives physicists to continuously develop their tools and search methodologies. There are several proposed candidates for new particles among which the Weakly Interacting Massive particle (WIMP) is considered the most propitious. The SuperCDMS SNOLAB experiment is a direct dark matter (DM) detection experiment. It is expected to start taking science data by the beginning of the year 2023. The plan is to start the operations with a total payload of ~30 kg of Ge and Si detectors, situated in a well-shielded cryostat with ~15 mK at the coldest thermal stage. The experiment aims to probe DM with masses down to 0.3 GeV (0.5 MeV) through nuclear (electron) scattering. To accomplish this, detectors have to have energy thresholds of a few eV. The Cryogenic Underground TEst facility (CUTE) is currently the underground facility equipped to operate the future SuperCDMS detectors. Since summer 2019, the facility has operated a variety of detectors to identify, quantify, and mitigate its noise sources and investigate its potential for dark matter search while waiting for SuperCDMS to be completed. In this thesis, I discuss key contributions to setting up and commissioning the facility in a timely manner. I also summarize the major tests and findings. The low energy reach of the new SuperCDMS detectors brings the need for new calibration methods. We propose two different methods that use LEDs operated next to the detectors. This has initiated the study of LED properties at low temperatures. One of the suggested methods has been shown to be viable, and preliminary tests for the other method have shown promising results. Finally, I show the possibility of operating LEDs in the proximity of an eV-sensitive detector without impacting its performance.
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