The Digital Silicon Photomultiplier - A Novel Sensor for the Detection of Scintillation Light

We developed a fully digital Silicon Photomultiplier (dSiPM) of 3.8 mm x 3.3 mm in size containing 8188 individual Geiger-mode cells. Each detected photon is directly converted into a digital signal in each of the Geiger-mode cells of the sensor. In addition, the complete trigger logic and a time-to-digital converter are integrated into the sensor. To show the performance of the sensor, LYSO crystals of different sizes were coupled to the sensor. The coincidence timing resolution for 3 mm x 3 mm x 5 mm LYSO crystals using a Na-22 source amounts to 153 Ps FWHM. The energy resolution at 511 keV was determined to be 10.7 % for 4 mm x 4 mm x 22 mm crystals. It is shown that saturation correction can be done without prior need for sensor calibration. The temperature dependence of the photon detection efficiency was found to be -0.6 %/degrees C including the temperature variation of the light output of LYSO.