การพัฒนาวงจรขยายสัญญาณพัลส์นิวเคลียร์เพื่อการใช้งานสำหรับเครื่องมือวัดรังสี

Abstract

The objective of this study was to develop a pulse amplifier for radiation instrumentation by using small and economical devices which could be found in local with low price. The developed pulse amplifier had stable working and low noises. It could be integrated with any nuclear instruments such as Nuclear Instrumentation Module (NIM). The developed amplifier was tested to examine the output shape, gain level, non-linearity and noise level.  The results showed that the output signal had a semi-Gaussian shape, which has pulse width about 6 ms. Its gain level could be adjusted from 200 to 1,000 with a very good linearity and the noise level was about 35 mV_rms at the maximum gain level. The developed amplifier was integrated with a 2”x2” NaI(Tl) detector and a multichannel analyzer (MCA) in order to determine the energy resolution of energy spectrum of Cs-137 and Co-60 radioactive sources compared with a commercial amplifier (Canberra 816). The results showed that the energy resolution at energies of 662, 1,173 and 1,332 keV was 9.7%, 5.19% and 5.51% respectively. The different energy resolutions between the developed amplifier and the commercial amplifier at the energy of 662 keV were only 1.5% which was very small. Based on its specifications and test results, the developed amplifier could be applied with a nuclear measuring system.