A study of the states of ${\mathrm{B}}^{11}$ has been made by high-resolution measurements of angular distributions and relative intensities of proton groups from ${\mathrm{B}}^{10}(d, p){\mathrm{B}}^{11}$. The use of Butler analysis and calculated reduced widths leads to the following spin and parity assignments for excited states: 2.14 Mev, ½-; 4.46 Mev, $\frac{5}{2}-$; 5.03 Mev, $\frac{3}{2}-$; 6.76 Mev, $\frac{7}{2}-$; 8.57 Mev, (½+); 8.92 Mev, $\frac{5}{2}+$; 9.19 Mev, $\frac{7}{2}+$; 9.28 Mev, $\frac{5}{2}+$. The states of ${\mathrm{B}}^{11}$ exhibit a subdivision into three classes. The first five levels from ground state to 6.76 Mev, all of odd parity, correspond closely to the theoretical predictions of Kurath. The next four states of 6.81, 7.30, 7.99, and 8.57 Mev presumably result from highly mixed configurations which is evidenced by their weak stripping intensities. The third group consists of three single-particle states of even parity at 8.92, 9.19, and 9.28 Mev. The latter two states form a $\mathrm{jj}$-double level arising from the configuration $p^{6}2s$.

• Received 21 April 1960

DOI:https://doi.org/10.1103/PhysRev.120.211