Levels in ¹¹⁵In populated in the decay of ^115mCd

Abstract

The decay of ^115mCd to ¹¹⁵In is studied. Gamma intensities are measured with a Ge(Li) detector. Two new transitions are observed and placed in the level scheme. The following γ-γ directional correlations are determined (energies in keV): 484.35–933.6, 158.1–1132.5 and 316.1–1132.5. The M1 strengths are derived for two transitions connecting members of the vibrational multiplet: $\text{B(}\text{M}\text{1, 1290.5}\text{13}\text{2}{}^{\mathrm{+}}\text{→ 1132.5}\text{11}\text{2}{}^{\mathrm{+}}\text{) = 0.5 ± 0.1 μ}{}^2{}_0$ and $\text{B(}\text{M}\text{1, 1448.7}\text{9}\text{2}{}^{\mathrm{+}}\text{1132.5}\text{11}\text{2}{}^{\mathrm{+}}\text{) = 0.5 ± 0.3 μ}{}^2{}_0$. The half-life of the 933.6 $\text{7}\text{2}{}^{\mathrm{+}}$ state as measured by the delayed-coincidence technique is $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 57 ± 5}\text{ps}$. The partial half-life of the $\text{933.6}\text{7}\text{2}{}^{\mathrm{+}}\text{→ 828.4}\text{3}\text{2}{}^{\mathrm{+}}$ E2 transition is 55 times less than the Weisskopf estimate. The static quadrupole moment of the $\text{7}\text{2}{}^{\mathrm{+}}$ and $\text{3}\text{2}{}^{\mathrm{+}}$ states is evaluated on the assumption that these levels are members of the proposed rotational band: Q₀ = 2.7 ± 0.3 b. This is in agreement with the corresponding value for the $\text{864.0}\text{1}\text{2}{}^{\mathrm{+}}\text{→ 828.4}\text{3}\text{2}{}^{\mathrm{+}}$ transition, and the result of a recent direct measurement of the static quadrupole moment of the 828.4 $\text{3}\text{2}{}^{\mathrm{+}}$ state. The suggestion that the 1418.0 $\text{9}\text{2}{}^{\mathrm{+}}$ level is also deformed is supported by the fact that the decay occurs preferentially to the 933.6 $\text{7}\text{2}{}^{\mathrm{+}}$ state, whereas no transition connecting the 1448.7 $\text{9}\text{2}{}^{\mathrm{+}}$ state with the 933.6 $\text{7}\text{2}{}^{\mathrm{+}}$ state is observed.