A novel measurement method for SiPM external crosstalk probability at low temperature

TL;DR

This paper introduces a new method to measure external crosstalk probability in SiPMs at low temperatures using a simple two-SiPM setup, revealing a linear relationship with overvoltage and enabling PDE measurement.

Contribution

A novel measurement technique for external crosstalk probability in SiPMs at low temperature that does not require complex optical setups.

Findings

External crosstalk probability increases linearly with overvoltage.

The method enables simultaneous measurement of photon detection efficiency at low temperature.

The setup is simple, enclosed, and effective for low-temperature SiPM characterization.

Abstract

Silicon photomultipliers (SiPMs) are being considered as potential replacements for conventional photomultiplier tubes (PMTs). However, a significant disadvantage of SiPMs is crosstalk (CT), wherein photons propagate through other pixels, resulting in secondary avalanches. CT can be categorized into internal crosstalk and external crosstalk based on whether the secondary avalanche occurs within the same SiPM or a different one. Numerous methods exist for quantitatively estimating the percentage of internal crosstalk (iCT). However, external crosstalk (eCT) has not been extensively studied. This article presents a novel measurement method for the probability of emitting an external crosstalk photon during a single pixel avalanche, using a setup involving two identical SiPMs facing each other, and without the need for complex optical designs. The entire apparatus is enclosed within a stainless steel chamber, functioning as a light-tight enclosure, and maintained at liquid nitrogen temperature. The experimental setup incorporates two Sensl J-60035 SiPM chips along with two 0.5-inch Hamamatsu Photonics (HPK) VUV4 S13370-6050CN SiPM arrays. The findings show a linear relationship between the probability of emitting an external crosstalk photon and the SiPM overvoltage for both SiPM samples. Surprisingly, this novel measurement method also rovides measurements of the SiPM photon detection efficiency (PDE) for eCT photons at low temperature.