Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector Beyond 7OD

We present design, implementation, and characterization of a single photon detector based on 32-channel photomultiplier tube (PMT) sensor (model H7260-20, Hamamatsu). The developed high-speed electronics enables the photon counting with linear dynamic range (LDR) up to $10^{8}$ count/s per detector's channel. The experimental characterization and Monte Carlo simulations showed that in the single-photon counting mode the LDR of the PMT sensor is limited by photon pulsewidth (current pulse) of 900 ps and a substantial decrease of amplitudes of current pulses for count rates exceeding $10^{8}$ count/s. The multi-channel architecture of the detector and the developed firm/software allow further expansion of the dynamic range of the device by 32-fold using appropriate beam shaping. The developed single-photon counting detector was tested for the detection of fluorescence labeled microbeads in capillary flow.