The recombination correction for an ionisation chamber exposed to pulsed radiation in a 'swept beam' technique. I. Theory
- 1 February 1982
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 27 (2), 201-211
- https://doi.org/10.1088/0031-9155/27/2/001
Abstract
The established theory for the collection efficiency of an ionisation chamber irradiated by a series of uniform short pulses is extended to the more complex case of irradiation in a pulsed and electromagnetically swept electron beam. The radial variation of exposure rate is assumed to be Gaussian with scale constant equal to a, and the pulses are assumed to be uniformly distributed over the area swept out. A formula for the collection efficiency is derived and the influence of varying some of the parameters is studied. The collection efficiency, phi 1, at voltage V1 can be calculated if the two dosemeter readings, Q1 and Q2, at two widely different chamber voltages, V1 and V2, are known, phi 1 depends primarily upon the ratios Q1/Q2 and V1/V2 and to a much lesser extent upon the geometry of the chamber or the ratio of Gaussian scale constant to a typical linear dimension of the field scanned. Charts for calculating phi 1 are provided.Keywords
This publication has 2 references indexed in Scilit:
- Current collection and ionic recombination in small cylindrical ionization chambers exposed to pulsed radiationThe British Journal of Radiology, 1980
- Ionization Measurements at Very High Intensities—Part IThe British Journal of Radiology, 1950