Investigation of timing resolution and energy resolution for SiPM/PET detectors using the silicon flexible optical material

Silicon photomultipliers (SiPMs) attract extensive attentions for detecting optical photons in high energy physics and medical imaging due to its high gain, high photon detection efficiency (PDE), low operation voltage and fast timing response. We use a binary optical element (BOE) made of the silicon flexible optical material to transform the incident light intensity expressed as Gaussian distribution into uniform in space, making the incident photons be detected by the SiPM evenly. In this way, we can make full use of all cells of the SiPM, and more cells operating means more photons being detected for a certain pulse, which can increase the count rate of the incident photons and therefore improve the detection efficiency of the SiPM. Also, by comparing the outputs of the SiPM in different light intensity inputs, we can obtain the best light intensity fit for the SiPM along with the suitable scintillator and surface treatment for the positron emission tomography (PET) imaging based on the SiPM. In our experiments, we use the laser pulse as the SiPM input, whose light intensity can be expressed as Gaussian distribution in space, and then compare the readouts of the SiPM with and without the BOE. As expected, by using the BOE, the timing resolution and energy resolution of the SiPM are better than those without using it for some certain light intensity.