出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We have studied the performance of a readout system with ASIC chips for our gamma camera
based on 64 channels multi-anode PSPMT(Hamamatsu flat-panel H8500) coupled to a GSO(Ce)
scintillator array. The GSO array consists of 88 pixels of 6613mm3 with the same pixel pitch
as the anode of H8500. This camera is intended for an absorber of an Electron Tracking Compton
gamma-ray camera which measures up to about 1 MeV gamma-ray. We need a readout system
with low power consumption in order to make a camera which has 64108 readout channels for
a balloon-borne experiment. We adopted the ASIC chip, IDEAS VA32_HDR11, with low power
consumption of 1.3 W/64 ch and dynamic range of -35 pC, which is one of chips with widest
range among commercial ones. However, we have to operate the H8500with the low gain of about
105 because it only measures up to about 100 keV gamma-ray with the typical gain of about 106,
and we developed an attenuator board in order to operate the H8500 with the typical gain. The
attenuator board has 64 singular resistors adjusted to the anode gain and uniforms variation of the
anode gain of the H8500, min:max1:2.3, before inputs to ASIC chips. Using the board, The
H8500 was able to operate with the gain of about 106 and the output signals from that board had
a good uniformity of min:max1:1.2. The system with the new attenuator board has the incident
energy dynamic range of 30 to 900keV, the position resolution of less than 6mm, and a typical
energy resolution of about 11.7%(FWHM) at 662keV.
