0000000001109207
AUTHOR
F. Negoita
New shape isomer in the self-conjugate nucleus $^{72}$Kr
A new isomeric ${0}^{+}$ state was identified as the first excited state in the self-conjugate ($N=Z$) nucleus $^{\mathrm{72}}\mathrm{K}\mathrm{r}$. By combining for the first time conversion-electron and gamma-ray spectroscopy with the production of metastable states in high-energy fragmentation, the electric-monopole decay of the new isomer to the ground state was established. The new ${0}^{+}$ state is understood as the band head of the known prolate rotational structure, which strongly supports the interpretation that $^{\mathrm{72}}\mathrm{K}\mathrm{r}$ is one of the rare nuclei having an oblate-deformed ground state. This observation gives in fact the first evidence for a shape isomer…
Beta-decay half-lives at the N = 28 shell closure
Abstract Measurements of the beta-decay half-lives of neutron-rich nuclei (MgAr) in the vicinity of the N =28 shell closure are reported. Some 22 half-lives have been determined, 12 of which for the first time. Particular emphasis is placed on the results for the Si isotopes, the half-lives of which have been extended from N =25 to 28. Comparison with QRPA calculations suggests that 42 Si is strongly deformed. This is discussed in the light of a possible weakening of the spin–orbit potential.
Normal and intruder configurations in $^{34}$Si populated in the $\beta^-$ decay of $^{34}$Mg and $^{34}$Al
The structure of Si34 was studied through γ spectroscopy separately in the β− decays of Mg34 and Al34 at the ISOLDE facility of CERN. Different configurations in Si34 were populated independently from the two recently identified β-decaying states in Al34 having spin-parity assignments Jπ=4− dominated by the normal configuration π(d5/2)−1⊗ν(f7/2) and Jπ=1+ by the intruder configuration π(d5/2)−1⊗ν(d3/2)−1(f7/2)2. The paper reports on spectroscopic properties of Si34 such as an extended level scheme, spin and parity assignments based on log(ft) values and γ-ray branching ratios, absolute β feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 tr…