(n, d) and (n, p) Reactions nearZ=50

Abstract

An emulsion study is reported of charged particles produced by 14-Mev neutron bombardment of ${\mathrm{Rh}}^{103}$, ${\mathrm{In}}^{115}$, ${\mathrm{Sn}}^{116}$, ${\mathrm{Sn}}^{120}$, Sb, and Te. For all but Te (no detectable yield) cross sections and spectra are presented, with distributions over the first 40° of laboratory angle of energy groups from Rh, In, and Sb. Contrary to an assumption common in earlier work, there is strong evidence that the ($n, d$) reaction contributes strongly. Five peaks among the Rh, In, and Sb spectra are identified with pickup transitions, the angular distributions conforming to Butler curves for uniquely predicted (2) or reasonable (3) $l$ values. These values are consistent with target proton orbitals in all five cases. The wide ($n, \mathrm{np}$) group is found at the expected energy in the Rh, In, ${\mathrm{Sn}}^{116}$ and Sb spectra; its angular distribution is anomalous for Rh but displays the expected isotropy in the other three cases. Up to at least 6-Mev excitation the ($n, p$) gross structure is dominated by single-particle effects, the uncontaminated ($n, p$) yield obeying predictions of the Nilsson model as to spectral concentration and angular distribution; the low collective levels excited in ($p, p^{\prime }$) are not observed. Systematic behavior of the direct-interaction radius for ($n, d$) and ($n, p$) and of the reduced width for pickup are found to be reasonable. It is inferred that the parent state for proton pickup with low residual excitation is almost purely a single-particle state in the case of Sb, and has a strong single-particle character in Rh and a very weak one in In.