Abstract

The $\beta$ decay of the neutron-rich $^{134}$In and $^{135}$In was investigated experimentally in order to provide new insights into the nuclear structure of the tin isotopes with magic proton number $Z=50$ above the $N=82$ shell. The $\beta$-delayed $\gamma$-ray spectroscopy measurement was performed at the ISOLDE facility at CERN, where indium isotopes were selectively laser-ionized and on-line mass separated. Three $\beta$-decay branches of $^{134}$In were established, two of which were observed for the first time. Population of neutron-unbound states decaying via $\gamma$ rays was identified in the two daughter nuclei of $^{134}$In, $^{134}$Sn and $^{133}$Sn, at excitation energies exceeding the neutron separation energy by 1 MeV. The $\beta$-delayed one- and two-neutron emission branching ratios of $^{134}$In were determined and compared with theoretical calculations. The $\beta$-delayed one-neutron decay was observed to be dominant $\beta$-decay branch of $^{134}$In even though the Gamow-Teller resonance is located substantially above the two-neutron separation energy of $^{134}$Sn. Transitions following the $\beta$ decay of $^{135}$In are reported for the first time, including $\gamma$ rays tentatively attributed to $^{135}$Sn. In total, six new levels were identified in $^{134}$Sn on the basis of the $\beta \gamma \gamma$ coincidences observed in the $^{134}$In and $^{135}$In $\beta$ decays. A transition that might be a candidate for deexciting the missing neutron single-particle $13/2^+$ state in $^{133}$Sn was observed in both $\beta$ decays and its assignment is discussed. Experimental level schemes of $^{134}$Sn and $^{135}$Sn are compared with shell-model predictions. Using the fast timing technique, half-lives of the $2^+$, $4^+$ and $6^+$ levels in $^{134}$Sn were determined.

Highlights

  • The region around 132Sn, the heaviest doubly magic nucleus far from the valley of β stability, is of great relevance for the development of the theoretical description of neutron-rich nuclei

  • Properties of nuclei around 132Sn are important for modeling the rapid neutron capture nucleosynthesis process (r process), since the A ≈ 130 peak in the r-process abundance pattern is linked to the N = 82 shell closure [9,10,11,12]

  • In the case of even-A tin isotopes above N = 82, information on excited states was obtained for 134Sn, 136Sn, and 138Sn [14,16,23,24]

Read more

Summary

Introduction

The region around 132Sn, the heaviest doubly magic nucleus far from the valley of β stability, is of great relevance for the development of the theoretical description of neutron-rich nuclei. The 133Sn nucleus, with only one neutron outside the doubly magic 132Sn, is the heaviest odd-A tin isotope for which excited states were reported so far [13,15,17,18,19,20,21,22]. This nuclide has been extensively studied for over two decades to gain information about neutron (ν) single-particle

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call