Imaging with SiPMs in noble-gas detectors

Abstract

Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free β β 0ν experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250-500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250-350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250-315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.

Design and characterization of the SiPM tracking system of NEXT-DEMO, a demonstrator prototype of the NEXT-100 experiment

“…The recovery time of the APD pixels in this case is typically 50 ns. The typical PDE values indicated by Hamamatsu are measured using the photocurrent method in which the contribution of optical cross-talk and after-pulses cannot be subtracted [18,26]. The true PDE values of the considered MPPCs free of after-pulsing and crosstalk contributions reported in references [25,26] are about 30% lower than those indicated by the manufacturer.…”

The Mu2e crystal calorimeter and improvements in the $\mu^-\mbox{N} \to e^-\mbox{N}$ search sensitivity

“…For the CsI crystals, the proposed photosensor is a TSV-SPL MPPC from Hamamatsu [43]. Blue markers in Figure 3.5 show its photo-detection efficiency (PDE) compared to other similar devices [43,44]. In the UV range 250-350 nm, where the CsI emission spectrum peaks, the PDE of this UV-enhanced MPPC ranges between 30 − 40%, which is a factor of about 6 better than a standard MPPC from Hamamatsu [44].…”

“…Blue markers in Figure 3.5 show its photo-detection efficiency (PDE) compared to other similar devices [43,44]. In the UV range 250-350 nm, where the CsI emission spectrum peaks, the PDE of this UV-enhanced MPPC ranges between 30 − 40%, which is a factor of about 6 better than a standard MPPC from Hamamatsu [44]. Signals from the anodes of the MPPC are serialized, and the resulting signal is passed to a custom board that performs the shaping and the amplification of the signal.…”

Vacuum ultra-violet and ultra-violet scintillation light detection by means of silicon photomultipliers at cryogenic temperature

“…Their main drawback, however, is their nonsensitivity in the VUV light region, where emission spectrum of the noble gases scintillation is peaked. Usually a wavelength shifter is used to overcome this problem [1]; however, SiPMs dedicated to UV light detection have been recently developed, with PDE peaked around 200-300 nm, and sensible, with lower PDE, till 130-140 nm.…”