Studies ofJDependence in Neutron Pickup Reactions

Abstract

The dependence of the form of angular distributions on the total angular momentum transfer ($J$ dependence) has been studied for the following reactions: ${\mathrm{Fe}}^{56}(p, d){\mathrm{Fe}}^{55}$ at 18.5, 20.0, 22.4, 25.7, and 27.5 MeV; ${\mathrm{Ni}}^{58}(p, d){\mathrm{Ni}}^{57}$ at 20.0, 25.4, and 27.5 MeV; ${\mathrm{C}}^{12}(p, d){\mathrm{C}}^{11}$, ${\mathrm{S}}^{32}(p, d){\mathrm{S}}^{31}$, and ${\mathrm{Pb}}^{208}(p, d){\mathrm{Pb}}^{207}$ at about 28 MeV and ${\mathrm{Fe}}^{56}({\mathrm{He}}^3, \alpha ){\mathrm{Fe}}^{55}$ at 30 and 40 MeV. Pronounced $J$ dependence was found to persist for both $l=1\mathrm{}$ and $l=3\mathrm{}$ transfers in the ${\mathrm{Fe}}^{56}(p, d){\mathrm{Fe}}^{55}$ and ${\mathrm{Ni}}^{58}(p, d){\mathrm{Ni}}^{57}$ reactions over the entire energy range; changes with energy are gradual but definite. The spin dependence of $l=2\mathrm{}$ distributions in the ${\mathrm{S}}^{32}(p, d){\mathrm{S}}^{31}$ reaction is equally striking, but essentially no $J$ dependence was observed for either $l=1\mathrm{}$ or $l=3\mathrm{}$ transfer in the ${\mathrm{Pb}}^{208}(p, d){\mathrm{Pb}}^{207}$ reaction. Apparent $Q$ dependence makes the interpretation of the ${\mathrm{C}}^{12}(p, d){\mathrm{C}}^{11}$ results ambiguous. The ${\mathrm{Fe}}^{56}({\mathrm{He}}^3, \alpha ){\mathrm{Fe}}^{55}$ reaction revealed small but noticeable phase differences between ${\frac{5}{2}}^{-}$ and ${\frac{7}{2}}^{-}$ distributions. Analysis of the ${\mathrm{Fe}}^{56}(p, d){\mathrm{Fe}}^{55}$-distributions with the distorted wave Born approximation was not successful in explaining the results. Finite-range nonlocal calculations including spin-orbit forces in both incoming and outgoing channels and/or modified neutron form factors predicted little $J$ dependence.