High-spin spectroscopy in \(^{207}\)At: Evidence of a 29/2\(^{+}\) isomeric state

• Published in: arXiv.org 2023-04
• Main Authors: Yadav, Khamosh, Deo, A Y, Madhu, Sahoo, Dhananjaya, Srivastava, P C, Saket Suman, Tandel, S K, Sharma, A, Ahmed, I, Katre, K, Devi, K Rojeeta, Dutt, Sunil, Kumar, Sushil, Yashraj, Muralithar, S, Singh, R P
• Format: Article
• Language: English
• Subjects: Gamma rays; Half-life; Isomers
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2211.02406

Yrast and near-yrast states above the known 25/2\(^{+}\) isomer in \(^{207}\)At are established for the first time. The level scheme is extended up to 47/2\(\hbar\) and 6.5 MeV with the addition of about 60 new \(\gamma\)-ray transitions. The half-life of the 25/2\(^{+}\) isomer is revisited and a value of \(T_{1/2}\) = 107.5(9) ns is deduced. Evidence of a hitherto unobserved 29/2\(^{+}\) isomer in \(^{207}\)At is presented. A systematic study of \(B(E3)\) values for the transitions de-exciting the 29/2\(^{+}\) isomer in the neighboring odd-\(A\) At isotopes suggests a half-life in the 2\(-\)4.5 \(\mu\)s range for this state in \(^{207}\)At. The experimental results are compared with large-scale shell-model calculations performed using the KHM3Y effective interaction in the \(Z\) = 50\(-\)126, \(N\) = 82\(-\)184 model space and an overall good agreement is noted between the theory and the experiment. A qualitative comparison of the excited states and the isomers with analogous states in neighboring nuclei provides further insight into the structure of \(^{207}\)At.