Angular Distribution of Pb L X-Rays Excited by 3 MeV Protons

We have measured the angular distribution of Pb Ll and L¿ x-rays in the case of lead where the targets were typically 100 ug/cm2 thick with a 400 ug/cM2 layer of silver evaporated on each side. Spectra were obtained at 25, 45, 65, 90, 115, 135 and 155 and ratios of Pb L x-rays to the isotropic Ag K x-rays were taken. The most readily interpretable case is Ll since this transition involves only the Lm subshell. Atter correcting for x-ray absorption in the target assuming it to be layered (i.e. neglecting diffision of the Ag in the Pb) we find a small deviation from isotropy, which is expected due to enhanced depopulation of M=0 substates at small impact parameter collisions. The velocity dependence of the alignment parameter A2 has been calculated using PWBA and screened as well as unscreened wave functions. Our results for A2 agree with these calculations. Further work is under consideration.