Analyzing power in the continuum of the ( [formula omitted]) and ( [formula omitted]) reactions on 12C, 27Al, 58Ni, 90Zr, 209Bi at Ep = 72 MeV

Abstract

We have measured cross sections and analyzing powers in the continuum of the ( p , αx) and ( p, τx ) reactions for 12C, 27Al, 58Ni, 90Zr and 209Bi target nuclei, using 72 MeV polarized protons. The systematics we have found in the behaviour of the differential cross section and of the analyzing power of the ( p, αx) reaction is discussed and similarities in the shape of the 4He and 3He angular distributions are pointed out. For the 27 Al( p , α x) and the 90 Zr( p , αx) reactions as well as for the 58 Ni( p , τ x) reaction, a comparison with theoretical predictions of recently developed direct-reaction models is presented. It is shown that the MSDR model can describe successfully the cross section and the analyzing power of the ( p , α x) reaction in the continuum. The influence of quasi-free processes in the ( p , α x) reaction is demonstrated. We have found a surprisingly large analyzing power of the ( p , α x) reaction at backward angles, especially for heavy nuclei, contrary to expectations from conventional preequilibrium models.