Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography

Using 5 cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1 cm×1 cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for both Co-60 and Cs-137 gamma sources. The first detector showed energy resolutions (FWHM) of 6.4% and 5.5% for 1.17 and 1.33 MeV, which were similar to energy resolutions of the second detector for Co-60, but the second detector showed 6.6% better resolution than the first detectorʹs 11.8% for Cs-137. For 10 h exposure of Co-60 (14.5 μCi), noise equivalent quanta (NEQ) and spectroscopy for both detectors have been investigated in detail. The NEQ of 25% increased after the exposure and degradations of the FWHMs of 26% and 11% have been found for 1.17 and 1.33 MeV, respectively.