title: The collection efficiency of an ionization chamber in a pulsed and magnetically swept electron beam: limits of validity of the two-voltage technique.
abstract: The two-voltage method of determining the collection efficiency of an ionization chamber exposed to a pulsed and magnetically swept electron beam depends upon the form of the saturation curve agreeing closely with the formula based on ionic conduction and negligible space charge. The possible disturbing effects of charge transport by free electrons and of overlapping pulses are discussed and the conditions to be satisfied for the reliable use of the method are defined and demonstrated experimentally.
mesh_terms: D004583:Electrons; D006801:Humans; D011874:Radiometry / Q000295:instrumentation*; D011879:Radiotherapy Dosage