Development of a “resistive” readout for SiPM arrays

We are developing the charge division (“resistive”) readout for several arrangements of Silicon Photomultiplier (SiPM) arrays, based on devices from Hamamatsu and SensL. The challenge with the SiPM arrays, as opposed to position sensitive photomultipliers (PSPMTs), is that the noise level is known to be high, and signal to noise ratio (S/N) is lower than in PMTs. In addition, the S/N decreases quickly with the increasing size of the module and with increasing temperatures. Key parameters to optimize are: size and coverage of the SiPM arrays, operational temperature (potential necessity of introducing system cooling), and bias voltage. All these parameters have impact on the S/N, and in consequence on the spatial resolution and the energy resolution of the detector modules. Our somewhat arbitrary but practical goal is to achieve operation similar to the one offered by H8500/H9500 flat panel PSPMTs when using LYSO scintillation arrays in applications to small PET imaging modules. Ultimately we would like to use the reduced channel number readout in the depth-of interaction (DOI) modules. Our first application is to construct ∼5cm×5cm compact PET modules for the HelmetPET brain imager prototype under construction at WVU.