Low-power wide-dynamic-range readout system for a 64-channel multi-anode PMT of a scintillation gamma camera

We have developed a low-power wide-dynamic-range readout system for a 64-channel multi-anode photomultiplier (PMT) of a scintillation gamma camera. Each anode is individually read with the system that contains discrete devices of amplifiers, comparators, sample-hold ADCs, and FPGAs. The size of the system which is designed for a two-dimensional array of Hamamatsu flat panel PMT H8500 is 5×5×14 cm
³
. The input dynamic range is variable by replacing the feedback capacitor of the preamplifier (e.g., 700 pC and 4000 pC for GSO(Ce) and LaBr
3
(Ce) crystals, respectively). The serialized ADC data are sent to a VME sequence module. The total power consumption is 1.6 W per 64 channels. With this system we have developed a gamma camera using an 8×8 array of GSO(Ce) pixels with a pixel size of 6×6×13 mm
³
coupled to an H8500, and obtained flood-field irradiation images at energies from 30 keV to 1.3 MeV. The energy resolution was 10.8±0.4% (FWHM) at 662 keV. In addition, we used the readout system for an 8×8 array of LaBr
3
(Ce) pixels with a pixel size of 6×6×15 mm
³
and obtained a flood-field irradiation image at 662 keV.