Scintillation detectors with silicon photomultiplier readout in a dilution refrigerator at temperatures down to 0.2 K

Abstract

We are developing a novel high-brightness atomic beam, comprised of a two-body exotic atom called muonium (M = μ + + e -), for next-generation atomic physics and gravitational interaction measurements. This M source originates from a thin sheet of superfluid helium (SFHe), hence diagnostics and later measurements require a detection system which is operational in a dilution cryostat at temperatures below 1 K. In this paper, we describe the operation and characterization of silicon photomultipliers (SiPMs) at ultra-low temperatures in SFHe targets. We show the temperature dependence of the signal shape, breakdown voltage, and single photon detection efficiency, concluding that single photon detection with SiPMs below 0.85 K is feasible. Furthermore, we show the development of segmented scintillation detectors, where 16 channels at 1.7 K and one channel at 170 mK were commissioned using a muon beam.

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

“…The PDE of the FBK VUVHD3 SiPMs and HPK MPPCs was measured by TRIUMF and IHEP in normal incidence, in the wavelength range nm at temperatures of 163 K and 300 K, respectively. 10 The temperature dependence of the SiPM PDE is however expected to be weak, as shown from recently published results [38,39]. The procedure involves measurement of the PDE of the devices under test at a fixed wavelength (175 nm) and as a function of the applied over voltage.…”