Effects of temperature and bias voltage on the properties of a PET detector module based on the individual readout of 1 × 1 mm²LYSO crystals by monolithic arrays of SiPMs

Abstract

The aim of this work was the development and evaluation of a detector based on SiPMs and fast scintillation crystals feasible for combined PET and MR imaging. Properties of two different 4 × 4 arrays of SiPMs by Hamamatsu -breakdown voltage, pulse height, energy resolution, dark counts and optical crosstalk -were investigated in terms of temperature and voltage dependence. Each channel in such an array consists of either 400 or 1600 cells and has a surface area of 1 × 1 mm 2 . For the alignment and coupling of individual scintillation crystals (1 × 1 × 20 mm 3 ) to these channels a special holder was designed. The breakdown voltages were at about 70 V for both models. Energy resolutions better than 23 % were observed. A temperature coefficient of the signal amplitude of (-2.7 ± 0.2) %/K and a voltage coefficient of (63 ± 2) %/V were determined for the model with 400 cells, whereas optical crosstalk was found to be an issue that needs further improvement. The dark count rate was below 1 MHz.

A comprehensive study of temperature stability of Silicon PhotoMultiplier

“…Average gain variations between −2.7 and −0.7%/ • C have been reported with Hamamatsu MPPCs with different cell sizes [1]. Using a pulsed LED illumination, pulse height shifts of −2.5 and −2.7%/ • C have been measured with two MPPC models [2]. In the paper the authors also present a model that takes into account the gain term and the breakdown voltage thermal coefficient.…”

“…In this paper we show a detailed analysis of the SiPM parameters that determine the device temperature dependence extending the model in [2] with the inclusion of the effects of PDE, correlated noise and quenching resistance. An experimental validation is also provided to check the theoretical analysis with both the delivered charge and the signal amplitude.…”