Quasielastic (p,n) reactions induced by polarized protons

Abstract

The differential analyzing power has been measured in the quasielastic ($p,n$) reaction on $^{49}\mathrm{Ti}$, $^{56}\mathrm{Fe}$, $^{64}\mathrm{Ni}$, $^{70}\mathrm{Zn}$, $^{90}\mathrm{Zr}$, $^{96}\mathrm{Zr}$, $^{117}\mathrm{Sn}$, $^{165}\mathrm{Ho}$, and $^{208}\mathrm{Pb}$ at 22.8 MeV. Fits to the experimental data in a macroscopic Lane-model analysis were improved by adding a spin-orbit term ${V}_{\mathrm{so}}^{(1)}$ in the isospin-dependent part of the optical potential. The sign of ${V}_{\mathrm{so}}^{(1)}$ agrees with that given by a simple model and its value does not depend very much on the target nucleus. However, the average value of ${V}_{\mathrm{so}}^{(1)}$ depends on the geometry used for the spin-orbit optical potential, an ambiguity which corresponds to a nearly constant product of the depth and of the diffuseness. A microscopic distorted-wave Born-approximation analysis was made, but due to several ambiguities in the calculation, it has not been possible to determine the isovector spin-orbit part ${v}_{\mathrm{LS}\ensuremath{\tau}}$ of the nucleon-nucleon effective interaction.NUCLEAR REACTIONS Quasielastic ($\stackrel{\ensuremath{\rightarrow}}{\mathrm{p}},n$) reactions on $^{49}\mathrm{Ti}$, $^{56}\mathrm{Fe}$, $^{64}\mathrm{Ni}$, $^{70}\mathrm{Zn}$, $^{90}\mathrm{Zr}$, $^{96}\mathrm{Zr}$, $^{117}\mathrm{Sn}$, $^{165}\mathrm{Ho}$, and $^{208}\mathrm{Pb}$; $E=22.8$ MeV; measured differential analyzing power $A(\ensuremath{\theta})$ macroscopic Lane-model analysis with an isospin-dependent spin-orbit term in the optical potential; microscopic DWBA analysis.