The ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$($t,\alpha$)${}_{}{}^{233}{}_{}{}^{}\mathrm{Pa}$, ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$($t,\alpha$)${}_{}{}^{235}{}_{}{}^{}\mathrm{Pa}$, ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$($t,\alpha$)${}_{}{}^{237}{}_{}{}^{}\mathrm{Pa}$, ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$($t,\alpha$)${}_{}{}^{229}{}_{}{}^{}\mathrm{Ac}$, and ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$($t,\alpha$)${}_{}{}^{231}{}_{}{}^{}\mathrm{Ac}$ reactions were studied with a 15-MeV triton beam. The reaction results are interpreted in terms of a distorted-wave-Born-approximation analysis. Theoretical cross sections, calculated in the framework of the Nilsson model with pairing and Coriolis interactions included, are compared with experimental values. The following Nilsson proton configurations are identified in all of the residual nuclei: ${1/2}^{+}$[400], ${3/2}^{+}$[402], ${3/2}^{+}$[651], ${1/2}^{-}$[530]. The ${1/2}^{-}$[541] and ${9/2}^{-}$[514] configurations are tentatively assigned. Due to the increase in deformation with neutron number, the ground state configuration of the Pa isotopes changes from ${3/2}^{-}$[530] to ${1/2}^{+}$[400] as $A$ increases.

NUCLEAR REACTIONS ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$($t,\alpha$), ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$($t,\alpha$), ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$($t,\alpha$), ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$($t,\alpha$), and ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$-($t,\alpha$), $E=15\mathrm{}$ MeV, measured $\sigma (E_{\alpha },\theta )$, deduced levels, $J$, $\pi$, $K$, enriched targets.

• Received 8 February 1977

DOI:https://doi.org/10.1103/PhysRevC.15.2019