Decay Scheme ofDy159

The electron capture decay of ${\mathrm{Dy}}^{159}$ has been shown to occur appreciably only to the 58-kev state and ground state of ${\mathrm{Tb}}^{159}$, with branching ratios of 37% and 63%, respectively. The $K$ internal conversion coefficient of the 58-kev transition has been measured to be ${\alpha }_K={{8.5}_{-1.2\mathrm{}}}^{+0.7\mathrm{}}$, which is consistent with a predominantly $M1\mathrm{}$ transition, with the possibility of some $E2\mathrm{}$ mixing. The orbital electron capture ratio to the 58-kev state of ${\mathrm{Tb}}^{159}$ was obtained as $\frac{P_{\mathrm{LM}\cdots }}{P_K}=0.17\mathrm{}\pm 0.15$. From this value, a minimum decay energy to the ground state of ${\mathrm{Tb}}^{159}$ was assigned as 230 kev. The upper limit on transitions to the 138-kev and 364-kev states of ${\mathrm{Tb}}^{159}$ was placed at 0.1%. A spin and parity of $\frac{3}{2}-$ was assigned to the ground state of ${\mathrm{Dy}}^{159}$ from a consideration of $log\mathrm{ft}$ values. An upper limit of 450 kev was placed on the decay energy to the ground state of ${\mathrm{Tb}}^{159}$.