Experimentelle Untersuchung der direkten Elektron-Positron-Paarerzeugung in Kupfer durch Elektronen von 5,8 MeV kinetischer Energie

Abstract

The direct production of positrons by electrons in copper was investigated using the 5.8 MeV electron beam from the 6 MeV microtron of the Physikalisch-Technische Bundesanstalt. Cross sections were derived from the measurements under the assumption that the positrons produced directly and those produced indirectly by bremsstrahlung photons have the same angular distribution. The values obtained are greater than those calculated numerically by Löns by a factor of 1.3 to 1.45. It is shown that there is an essential contribution of direct positron production to the electron positron conversion factor in thin foils consisting of elements with low atomic number.

The experimental set-up is described in detail. Its main feature is the use of a special positron transmission line with bending magnet in order to overcome background difficulties.