Properties of Low-Lying States inSc44

Abstract

A study has been made of the properties and decay modes of the 146-keV and 68-keV excited states of ${\mathrm{Sc}}^{44}$ populated by electron capture in ${\mathrm{Ti}}^{44}$. Relative 78-, 68-, and 146-keV $\gamma$-ray intensities are found to be 106.2, 100, and 0.10, respectively. Absolute $K$-shell internal conversion coefficients ${{\alpha }_{68}}^K=0.123\mathrm{}\pm 0.023$ and ${{\alpha }^K}_{78}=0.031\mathrm{}\pm 0.005$ have been determined. The $g$ factor of the 68-keV state has been measured by a magnetically perturbed $\gamma -\gamma$ angular-correlation experiment as +0.342±0.006. $E2\mathrm{}$ admixtures $Q_{68}=(7.0\mathrm{}\pm 2.0)\%$ and $Q_{78}\le 1.2\%$ have been deduced from $\gamma -\gamma$ angular-correlation results and the conversion measurements. A (1.9±1.5)% electron-capture branch to the 68-keV state has been observed. Spin and parity assignments of 1+, 1+, and 2+ are most probable for the 146-keV, 68-keV, and ground states of ${\mathrm{Sc}}^{44}$. A remarkably large hindrance factor (≥6.6×${10}^9$) is determined for the 146-keV $M1\mathrm{}$ transition. All other $M1\mathrm{}$ and $E2\mathrm{}$ transition rates are strongly hindered except for the $E2\mathrm{}$ component of the 68-keV transition, for which an enhancement of 16 is observed.