Comparison of Three Pulse Processing Systems for Microdosimetry

Three different pulse processing systems coupled to a tissue-equivalent proportional counter were tested in performance for various neutron and gamma-ray dose rates. The three systems used are a conventional analogue system, a real time system and a digital pulse processing system. The Tandetron accelerator at the McMaster Accelerator Laboratory was used to produce a mixed neutron-gamma field via the ⁷Li(p,n) reaction. The proton energy ranged from 1.8 to 2.5 MeV with the current set at 100, 200 and 300 muA. The digital system displayed the fastest pulse processing speed. Microdosimetric spectra from the three systems were consistent and both neutron and gamma-ray dose rates showed good agreement in most cases. At neutron dose rates higher than 20 mGy/min the data from the digital system was reliable while systematic deviations were observed for the other two systems.