SiPM cross-talk in liquid argon detectors

Abstract

SiPM-based readouts are becoming the standard for light detection in particle detectors given their superior resolution and ease of use with respect to vacuum tube photo-multipliers. However, the contributions of noise detection such as the dark rate, cross-talk, and after-pulsing (AP) may significantly impact their performance. In this work, we present the development of highly reflective single-phase argon chambers capable of displaying light yields up to 32 photo-electrons per keV, with approximately 12 being primary photo-electrons generated by the argon scintillation, while the rest are accounted by optical cross-talk. Furthermore, the presence of compound processes results in a generalized Fano factor larger than 2 already at an over-voltage of 5 V. Finally, we present a parametrization of the optical cross-talk for the FBK NUV-HD-Cryo SiPMs at 87 K that can be extended to future detectors with tailored optical simulations.

Study of Silicon Photomultiplier external cross-talk

“…Although the number of emitted photons per electron in the avalanche has been estimated to be around 10 −5 , considerable variations exist among different studies. In recent work [10], external OCT was estimated using highly reflective single-phase liquid argon chambers with cubic and cylindrical shapes. However, these results heavily rely on the specific detector configurations and the modeling of light propagation inside the detectors, and caution must be exercised when extrapolating these findings to other detector setups.…”

Why would you put a flashlight in a dark matter detector?

“…This side effect is generic to silicon avalanche devices [8]. These secondary photons can themselves be detected by different pixels in the SiPM and therefore create excess, spurious signal, an effect referred to as optical crosstalk.1 Thus, a disadvantage of SiPMs is the intrinsic production of excess signal, in the form of crosstalk, upon photon detection, an effect that scales non-linearly with device gain [10,11].…”

“…Indeed, calibration of external crosstalk is not possible at the single-device level, and can only be measured by other devices within the particle detector system. While numerous groups have studied internal crosstalk [9,10,12,13], limited attention [11,14,15] has been given to studies of external crosstalk between devices within a larger detector.…”