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 ${}^{7}{\hbox {Li}}({\rm p},{\rm n})$ reaction. The proton energy ranged from 1.8 to 2.5 MeV with the current set at 100, 200 and 300 $\mu$A. 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.