Decay Scheme, Spin, and Magnetic Moment of 20-minK45

Abstract

We have studied 20-min ${\mathrm{K}}^{45}$ and its decay using a lithium-drifted germanium detector and also by means of the atomic-beam magnetic-resonance method. The $\gamma$-ray studies revealed a new state in ${\mathrm{Ca}}^{45}$ at 1883(3)-keV excitation; the now-measured spin of ${\mathrm{K}}^{45}$ and other evidence indicate that this is a $1d_{\frac{3}{2}}$ hole state. The atomic-beam studies yielded $I=\frac{3}{2}$ for ${\mathrm{K}}^{45}$ and a value for the zero-field hyperfine structure separation $\Delta \nu =204.5873\mathrm{}\left(15\right)\mathrm{}$ Mc/sec. From this we calculate the nuclear magnetic-dipole moment to be $\left|{\mu }_I\mathrm{}\right|=0.1734\left(4\mathrm{}\right)\mathrm{}$ nm (diamagnetically corrected). A calculation based on a model which describes ${\mathrm{K}}^{39}$ through ${\mathrm{K}}^{43}$ with considerable accuracy gives the result ${\mu }_I=+0.218\mathrm{}$ nm. Further calculation yields satisfactory values for the binding energies of ${\mathrm{K}}^{44}$ through ${\mathrm{K}}^{47}$.