New sub-μs isomers in125,127,129Snand isomer systematics of

R. Lozeva¹,

G. S. Simpson²,

H. Grawe³

et al.

Abstract

New sub-µs isomers have been observed in the neutron-rich Sn isotopes. 125,127,129 Sn nuclei have been produced in a relativistic fission reaction of 238 U on a 9 Be target at 750 A·MeV and by the fragmentation of 136 Xe at 600 A·MeV populating high-spin yrast states. In addition to the already known µs isomers, three new ones with sub-µs half-lives have been observed. These yrast isomers are the high-spin members of the ν(d −1 3/2 h −2 11/2 ) and νh −n 11/2 , seniority v = 3 multiplets leading to isomeric (23/2 + ) and (27/2 − ) states, respectively. Added to the already known 19/2 + µs isomers in this region the current work completes the systematic information of neutron-hole excitations toward the filling of the last h 11/2 orbital at N = 82. The results are discussed in the framework of state-of-the-art shell-model calculations using realistic interactions.

Isomer spectroscopy ofCd127

“…Spins and parities were assigned to the excited states in 127 Cd on the basis of intensity balances, reduced transition probabilities, and the experimental information on the level scheme of the 129 Sn isotone [13]. According to the β − decay studies of 127 Cd, (3/2 + ) is assigned to the β − decaying ground state [14] with pure νd 3/2 neutron character.…”

“…According to the β − decay studies of 127 Cd, (3/2 + ) is assigned to the β − decaying ground state [14] with pure νd 3/2 neutron character. The systematics of odd-mass Cd and Sn isotopes [12,13] …”

“…Monopole tuning following A −1/3 scaling of the two-body matrix elements (TBME) was performed to reproduce the single hole energies (SHE) in 132 Sn as described in Refs. [3,13]. For the open proton-neutron (πν) space two modifications were introduced.…”

“…Further details will be given in a forthcoming paper [17]. Effective charges e π = 1.5e and e ν = 0.7e for protons and neutrons and a spin g factor of g s = 0.7g free s for magnetic transitions were used [3,13]. Calculations were performed with the code OXBASH [18].…”

Review of metastable states in heavy nuclei

“…An excellent example is provided by the long chain of isomers discovered in the tin isotopes ( [51,52] and references therein) and attributed to the νh [52] (see also Lozeva et al [53]). Note the right-hand scale which is adjusted for the difference in geometrical factors for the seniority-two and seniority-three cases.…”