Abstract

The level structures of the very neutron-rich nuclei 128Pd82 and 126Pd80 have been investigated for the first time. A new isomer with a half-life of 5.8(8) μs in 128Pd is proposed to have a spin and parity of 8+ and is associated with a maximally aligned configuration arising from the g9/2Pd proton subshell with seniority υ = 2. The level sequence below the 8+ isomer is similar to that in the N = 82 isotone 130Cd, but the electric quadrupole transition that depopulates the 8+ isomer is more hindered in 128Pd than in 130Cd, as expected in the seniority scheme for a semi-magic, spherical nucleus. For 126Pd, three new isomers with Jπ = (5-), (7-), and (10+) have been identified with half-lives of 0.33(4) μs, 0.44(3) μs, and 23.0(8) ms, respectively. The smaller energy difference between the 10+ and 7- isomers in 126Pd than in the heavier N = 80 isotones can be interpreted as being ascribed to the monopole shift of the h11/2 neutron orbit. The nature of the N = 82 shell closure scrutinized with these characteristic isomers is discussed.

Highlights

  • The concept of magicity is of supreme importance for many-body fermionic systems in a confined space

  • The stability of atomic nuclei, which consist of a number of sub-atomic particles called protons and neutrons, is much influenced by a shell structure and its resulting magic numbers; nuclei with specific numbers of nucleons (2, 8, 20, 28, 50, 82 both for protons and for neutrons, and 126 for neutrons) near the β-stability line necessitate relatively high energies to remove one or two nucleons compared to the neighboring isotopes

  • For the last few decades, the study of exotic nuclei using radioactive isotope (RI) beams revealed that the aforementioned magic numbers are not necessarily universal and are subjected to a change in some regions of light-mass nuclei with highly unbalanced ratios of protons and neutrons [1, 2]

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Summary

Introduction

The concept of magicity is of supreme importance for many-body fermionic systems in a confined space. The nature of the N = 82 shell closure will be discussed in terms of the seniority isomerism in the N = 82 isotones, as well as the effect of the monopole interaction between the g9/2 proton and h11/2 neutron subshells.

Results
Conclusion
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