The paper stresses the issue of strong temperature influence on the gain of a Silicon Photomultiplier (SiPM). High sensitivity of the detector to light (single photons) requires stable parameters during measurement, including gain. The paper presents a method of compensating the change of gain caused by temperature variations, by adjusting a suitable voltage bias provided by a precise power module. The methodology of the research takes in account applications with a large number of SiPMs (20 thousand), explains the challenges and presents the results of the gain stabilization algorithm.
This work shows a time-domain method for the discrimination and digitization of parameters of voltage pulses coming from optical detectors, taking into account the presence of electronic noise and afterpulsing. Our scheme is based on an FPGA-based time-to-digital converter as well as an adjustable-threshold comparator complemented with commercial elements. Here, the design, implementation and optimization of a multiphase TDC using delay lines shorter than a single clock period is also described. The performance of this signal processing system is discussed through the results from the statistical code density test, statistical distributions of measurements and information gathered from an optical detector. Unlike dual voltage threshold discriminators or constant-fraction discriminators, the proposed method uses amplitude and time information to define an adjustable discrimination window that enables the acquisition of spectra.