Studies of the ${\mathrm{B}}^{10}({\mathrm{He}}^3, p){\mathrm{C}}^{12*}$ reaction using 2-Mev ${\mathrm{He}}^3$ ions showed proton groups corresponding to levels in ${\mathrm{C}}^{12}$ at 0, 4.43, 7.65, 9.60, 10.76, 11.82, 12.78, 13.37, 14.03, 15.10, 16.10, and 16.64 Mev±0.10 Mev. The ratio ${\Gamma }_{\gamma }:\Gamma$ was measured to be 0.75(±0.20) for the 15.1-Mev state and 0.02(±0.01) for the 12.78-Mev state. No other alpha unstable level had a measurable ${\Gamma }_{\gamma }:\Gamma$; for the 7.65-Mev state a limit 0.01 is set on this ratio. The gamma-ray de-excitation of the 15.1-Mev state is both to the ground state (97%) and to the 4.43-Mev state (3.1±0.6%). Only a ground state transition was observed from the 12.78-Mev level. These measurements support assignments, $J$, $\pi$, $T$ of 1, +, 1 to the 15.1 level and 1, +, 0 to the 12.78-Mev state. The known properties of ${\mathrm{C}}^{12}$ are in fair agreement with the intermediate coupling shell-model calculations of Kurath. The reactions ${\mathrm{C}}^{13}({\mathrm{He}}^3, \alpha \gamma ){\mathrm{C}}^{12}$(15.1 Mev) and ${\mathrm{B}}^{10}({\mathrm{He}}^3, d){\mathrm{C}}^{11}$ to the ground and first excited state of ${\mathrm{C}}^{11}$ were observed.

• Received 22 December 1958

DOI:https://doi.org/10.1103/PhysRev.114.1040