Absolutmessungen des Elementarprozesses der Bremsstrahlungserzeugung

Abstract

Absolute Cross Sections for the Elementary Process of Bremsstrahlung ProductionBremsstrahlnng cross sections differential in electron angle, photon angle and energy have been determined for silver. The energy of the incident electrons was 180 keV, this of the scattered electrons 100 keV. Within the experimental errors we found agreement with the results of the calculations of Elwert and Haug.

Measurement of the absolute cross section for the elementary process of atomic field bremsstrahlung

“…The cross sections obtained in this way are always below the experimental results by a factor of 2-3 and thus must be considered as a deterioriation of the Bethe-Heitler formula. The earlier experiment with silver [7] showed a similar result. Kreuzer and Nakel [3] took one set of measurements for electrons scattered straight forward and photons emitted at 13 ~ with k/To=0.33.…”

“…In an earlier experiment [7] on this elementary process, it turned out that it was very advantageous to use elastic electron scattering as a reference. Therefore we observed simultaneously the elementary process and the elastic electron scattering at the angle 120 ~ .…”

“…Therefore we observed simultaneously the elementary process and the elastic electron scattering at the angle 120 ~ . The arguments for the choice of this angle are explained earlier [7], as is also the way in which the threefold-differential cross section of bremsstrahlung production can be calculated from the cross section of elastic electron scattering, the measured ratio of bremsstrahlung coincidences to the number of elastically scattered electrons, and an experimental quantity called the normalization factor ("Anschlul3fak-tor"). The cross section of elastic electron scattering (gold: 300 keV, 120 ~ needed for the evaluation of our experiment is 405 barns/sr.…”

“…The equipment used here was already once used in an earlier experiment (described in [7]). It was improved to correspond to the requirements of this work.…”

“…As described in an earlier paper [7], the normalization factor ("AnschluBfaktor") depends on the properties of the electron spectrometer and the detectors, and can be determined from a symmetry measurement between the electron spectrometer and the reference detector and the absolute efficiency of the photon detector. Since measurements were done for eight different relative photon energies k/To, eight normalization factors had to be determined using this method.…”