The new Bonn frozen spin target for experiments with real photons

Abstract

The new Bonn frozen spin target developed for spin physics experiments with tagged photons from the Bonn electron accelerator ELSA is described. Special investigations were necessary to fulfill the demands of a wide angular detection system, including frozen spin operation and large acceptance windows. Proton polarization values of 98% have been achieved in a dilution refrigerator at a magnetic field of 5.0 T with a butanol target sample. The temperature dependence of the relaxation time at a holding field of 0.35 T is presented. Future plans for spin experiments will be discussed briefly.