Absolutmessung der teilchenflussdichte schneller elektronen mit einem Faraday-Käfig

Abstract

A method for the absolute measurement of the particle flux density of fast electrons with a Faraday cup device is described. The Faraday cup consists of a graphite cylinder for the total absorption of electrons up to 35 MeV. The charge of electrons collected in a given time interval by the graphite absorber was measured absolutely by a charge-compensation method (accuracy better than 0.5%), and from this particle flux density is determined. The corrections for deficient absorption, ionisation in the remaining gas, backscattering of electrons, production of bremsstrahlung, emission of secondary electrons from the window of the Faraday cup, and the influence of the radiation background were accurately determined for electron energies ranging from 10 to 25 MeV. Hence the total error of the measurement of the particle flux density with this device is about 1%.