In-beam measurement of the circular polarization of continuous gamma-ray spectra

A forward-scattering and a transmission-type polarimeter have been constructed to measure the circular polarization of γ-rays in heavy-ion reactions. The polarimeters were designed to provide large counting efficiencies necessary for particle-γ coincidence experiments. A doubly symmetric detector arrangement was used in-beam to minimize systematic errors. The polarization sensitivity of the forward-scattering polarimeter was determined from Monte Carlo calculations and by using a 90Sr-90Y source of polarized bremsstrahlung. The applicability of the transmission-type polarimeter in the case of continuous γ-ray spectra is discussed. (orig.)