Ion recombination loss in ionization chambers irradiated by proton beams.

Abstract

Ionization chambers have been used widely for measurements of radiation dose. Calculation of the dose from measurements with these detectors is based on the assumption that ions produced in the chamber are collected without any losses by ion recombination phenomena. A great deal of theoretical and experimental work has been carried out on ion recombination losses for radiations such as X rays, gamma rays, and electrons (Greening, 1964; Boag, 1966; Ellis & Read, 1969; Geiger et al, 1980; Yamamoto et al, 1980). The ion recombination loss for low LET radiations can be treated by general recombination theory provided that the chamber is used at atmospheric pressure. For some of the heavy charged particle radiations, most of the ion recombination can be described by columnar recombination theory. However, there are few publications describing the ion recombinations for proton beams. This paper describes ion recombination for high energy proton beams in a parallel plate ionization chamber filled with several gases.