The radionuclide ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ has been produced by the ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}\mathrm{}(p,3p)\mathrm{}{}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ reaction with 100-MeV protons. The cross section for the reaction is $5_{-3\mathrm{}}^{+6\mathrm{}}$ μb. Radiochemical separations were performed to isolate the thorium fraction from uranium, neptunium, protactinium, and fission products. The ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ half-life was determined to be 37.5 ± 1.5 min by measuring the growth and decay of its daughter, 9.1-min ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pa}$. Electromagnetic isotope separation was also performed on the thorium samples, and although the resultant sources were very weak, evidence for several $\gamma$ transitions in the ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ decay was obtained. A partial decay scheme is proposed for ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ that includes excited states in ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pa}$ at 2.1, 112.7, 132, and $\approx 230$ keV. The decay of ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ is compared with the decay of ${}_{}{}^{234}{}_{}{}^{}\mathrm{Th}$, with emphasis on the ${(p_{\frac{1}{2}}-[530]+n_{\frac{1}{2+}}\mathrm{}[631\left]\right)}_{0-,1-}$ bands in ${}_{}{}^{234}{}_{}{}^{}\mathrm{Pa}$ and ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pa}$.

[RADIOACTIVITY ${}_{}{}^{236}{}_{}{}^{}\mathrm{Th}$ from ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}\mathrm{}(p,3p)\mathrm{}$, measured $T_{\frac{1}{2}}$, $E_{\gamma }$, $I_{\gamma }$. ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pa}$ deduced levels, $log\mathrm{ft}$. NUCLEAR REACTIONS ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}\mathrm{}(p,3p)\mathrm{}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}\mathrm{}(p,3\mathrm{pxn})\mathrm{}$, $E=100\mathrm{}$ MeV, measured $\sigma$.]

• Received 7 September 1973

DOI:https://doi.org/10.1103/PhysRevC.8.2364