New Approaches to Low-Energy Calibration of Cryogenic Detectors
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New Approaches to Low‑Energy Calibration of Cryogenic Detectors M. Ghaith1 · W. Rau2 · M. Peterson‑Galema1 · P. Di Stefano1 · E. Fascione1,2 · R. Germond1,2 · R. Underwood1,2 Received: 27 August 2019 / Accepted: 29 April 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Searches for dark matter with cryogenic detectors are pushing to lower energy thresholds at each development stage. Consequently, new approaches for detector calibration at the proposed energy scales are necessary. In the case of SuperCDMS SNOLAB, energy thresholds in the range of a few eV are expected. In this paper, we are reporting R&D work for new ideas to calibrate cryogenic detectors in the eV range utilizing LEDs of various wavelengths operated at cryogenic temperatures. Keywords SuperCDMS · Cryogenic detectors · IR photon · Calibration · Dark matter
1 Introduction The Super Cryogenic Dark Matter Search (SuperCDMS) experiment uses Ge and Si detectors operated at temperatures between 30 and 50 mK to search for signatures of dark matter [1]. The new generation of SuperCDMS at SNOLAB pushes toward very low-energy thresholds, in the range of few eV, where calibration with external radioactive sources is difficult [2]. Therefore, we are developing new methods based on the use of LEDs operated at cryogenic temperatures to calibrate detectors down to the eV range and to monitor their stability. In some of our early measurements [3], a pulsed LED with a nominal wavelength of 1650 nm [4], operated at ~ 40 mK, produced particle-like events in a 2.5-cm-thick SuperCDMS Ge detector, as depicted in the right panel of Fig. 1 [5]. The specific electrode configuration [6] allowed us to estimate the penetration depth to be less than a centimeter. Initially, this seemed to disagree with the 17 cm penetration depth
* M. Ghaith [email protected] 1
Department of Physics, Queen’s University, Kingston, ON K7L 3N6, Canada
2
TRIUMF, Vancouver, BC V6T 2A3, Canada
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Vol.:(0123456789)
Journal of Low Temperature Physics
Fig. 1 Left: A sketch for the 2.54-cm-thick SuperCDMS iZIP detector, showing the layout of phonon and charge sensors on each side. Right: The electrode configuration of SuperCDMS detectors [6] separates events within a couple of mm from the surface from bulk interactions. The signal distribution between charge sensors for the collimated LED events (red dots inside black oval) on the two sides of the detector (~ 2:1) indicates a penetration depth of
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