Monte Carlo simulation and influencing factors of detection efficiency of PIPS-α spectrometer

In the process of -source spectrum measurement, influence factors of the detector efficiency of the PIPS- spectrometer are the geometric factor, air layer absorption, dead layer absorption, the intrinsic detection efficiency, and so on. In order to calculate the activity of sources more accurately, to analyse the type and concentration of the parent nuclide, it is of great significance to explore the influence of these factors on the detection efficiency. Monte Carlo software was used to simulate the energy spectrum measurement of different source-detector distance and vacuum degree, SRIM was used to simulate the range and distribution of alpha particles in the air and dead layer with 5 MeV alpha particles, and PIPS- spectrometer was used to measure the actual spectra of three standard radioactive sources 241Am, 238Pu，239Pu. According to the results of experiments and simulation, the influence of various factors on the detection efficiency was analyzed, the intrinsic detection efficiency of spectrum of different -sources was calculated. The results show that: in the PIPS- spectrometer measurement process, the main factors affecting the detection efficiency of the spectrometer is geometric factor and intrinsic detection efficiency; the absorption of alpha particles by air and dead layer is negligible; the intrinsic detection efficiencies of the spectrometer for 241Am, 238Pu, 239Pu standard sources are 64.84%, 49.95%, 51.55% respectively.