Elastic Scattering of Vector Polarized 6 Li on 4 He

The elastic scattering of 6Li from 4He has been subject of recent investigations1,2). In all cases the observed angular distributions of the differential cross section show pronounced structures at intermediate and backward angles. These structures have been interpreted1,2) as due to the elastic transfer of a deuteron between the two 4He-cores. In order to obtain a more detailed information on the reaction mechanism a study of the vector analyzing power for this reaction had been started using the polarized 6Li beam of the Heidelberg EN-tandem3). The experiment has been performed at 22.8 MeV beam energy and scattering angles of 35 < θcm < 150°. As 4He target a gas cell was used which was specifically constructed to allow for measurements of the left-right asymmetry. The entrance and exit windows consisted of Havar-foils of 2.1 mg/cm2. The target has been operated at pressures around 500 torr 4He corresponding to an effective target thickness between 30 and 80 μg/cm2. Taking into account the energy loss in the entrance foil and in the gas target the beam energy at the active volume of the gas cell is Elab ≈ 21.3 MeV. The scattered 6Li- and the rescattered 4He-nuclei have been detected with ΔE-E telescopes. Relative and absolute normalization of the data has been obtained by measuring the Rutherford scattering of 6Li from a 3.6% Kr-admixture to the 4He-gas.