Analyzing power in the continuum of the (p, αx) and (p, τx) reactions on 12C, 27Al, 58Ni, 90Zr, 209Bi at Ep = 72 MeV

We have measured cross sections and analyzing powers in the continuum of the ($\text{p}$, αx) and ($\text{p}\text{, τx}$) 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 ($\text{p}\text{, αx)}$ reaction is discussed and similarities in the shape of the ⁴He and ³He angular distributions are pointed out. For the ${}^{27}\text{Al}\text{(}\text{p}\text{, α}\text{x}\text{)}\text{and the}{}^{90}\text{Zr}\text{(}\text{p}\text{, αx)}$ reactions as well as for the ${}^{58}\text{Ni}\text{(}\text{p}\text{, τ}\text{x}\text{)}$ 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 $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction in the continuum. The influence of quasi-free processes in the $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction is demonstrated. We have found a surprisingly large analyzing power of the $\text{(}\text{p}\text{, α}\text{x}\text{)}$ reaction at backward angles, especially for heavy nuclei, contrary to expectations from conventional preequilibrium models.