Spin and Branching of the 2750-keV Level inK37

Previous work has shown that the spin of the 2750-keV level in ${}_{}{}^{37}{}_{}{}^{}\mathrm{K}$ is either ${\frac{3}{2}}^{+}$ or ${\frac{5}{2}}^{+}$. To resolve the ambiguity, two experiments have been carried out and are reported here. The linear polarization of the ground-state $\gamma$ ray from the 2750-keV level has been measured. The weak cascade from the 2750-keV level through the doublet near 1.37 MeV has been shown to involve the 1380-keV level. These results exclude a spin of ${\frac{3}{2}}^{+}$ for the 2750-keV level, and the spin is established to be ${\frac{5}{2}}^{+}$.