Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich ${}^{122-131}$Sb${}_{51}$ isotopes

Abstract

The neutron-rich ${}^{122-131}$Sb isotopes were produced as fission fragments in the reaction ${}^9$Be(${}^{238}$U,~f) with 6.2 MeV/u beam energy. An unique setup, consisting of AGATA, VAMOS++ and EXOGAM detectors, was used which enabled the prompt-delayed gamma-ray ($\gamma$) spectroscopy of fission fragments in the time range of 100 ns - 200 $\mu$s. New isomers, prompt and delayed transitions were established in the even-A ${}^{122-130}$Sb isotopes. In the odd-A ${}^{123-131}$Sb isotopes, new prompt and delayed $\gamma$-ray transitions were identified, in addition to the confirmation of the previously known isomers. The half-lives of the isomeric states and the $B(E2)$ transition probabilities of the observed transitions depopulating these isomers were extracted. The experimental data was compared with the theoretical results obtained in the framework of Large-Scale Shell-Model (LSSM) calculations in a restricted model space. Modifications of several components of the shell model interaction were introduced to obtain a consistent agreement with the excitation energies and the $B(E2)$ transition probabilities in neutron-rich Sn and Sb isotopes. The isomeric configurations in Sn and Sb were found to be relatively pure. Further, the calculations revealed that the presence of a single valence proton, mainly in the $g_{7/2}$ orbital in Sb isotopes, leads to significant mixing (due to the $\nu \pi$ interaction) of: (i) the neutron seniorities (${\upsilon }_{\nu }$) and (ii) the neutron angular momentum ($I_{\nu }$). The above features have a weak impact on the excitation energies, but have an important impact on the $B(E2)$ transition probabilities. In addition, a constancy of the relative excitation energies irrespective of neutron seniority and neutron number in Sn and Sb was observed.

arXiv comment23 pages, 18 figures, 10 tables

References in corpus (10)

• AGATA - Advanced Gamma Tracking Array
• The magic nature of 132Sn explored through the single-particle states of 133Sn
• Full $0\hslash \omega$ shell model calculation of the binding energies of the $1f_{7/2}$ nuclei
• Novel shape evolution in Sn isotopes from magic numbers 50 to 82
• High-spin states with seniority v=4,4,6 in 119-126Sn
• Dual Position Sensitive MWPC for tracking reaction products at VAMOS++
• Shell-model study of quadrupole collectivity in light tin isotopes
• Odd tensor electric transitions in high-spin Sn-isomers and generalized seniority
• Is Seniority a Partial Dynamic Symmetry in the First $\nu g_{9/2}$ Shell?
• Generic features of the neutron-proton interaction

Cited by in corpus (5)

• Fast trajectory reconstruction techniques for the large acceptance magnetic spectrometer VAMOS++
• Different seniority states of ${}^{119-126}$Sn isotopes: shell model description
• Advancements of $\gamma$-ray spectroscopy of isotopically identified fission fragments with AGATA and VAMOS++
• Prompt-delayed $\gamma$-ray spectroscopy of neutron-rich ${}^{119,121}$In isotopes
• Partial conservation of seniority in semi-magic nuclei