Occurrence of a chiral-like pair band and a six-nucleon noncollective oblate isomer in 120I

B. Moon, C. B. Moon, G. D. Dracoulis, R. A. Bark, A. P. Byrne, P. A. Davidson, G. J. Lane, T. Kibédi, A. N. Wilson, C. Yuan, B. Hong

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


We report for the first time two distinctive features in the odd–odd nucleus 120I: a pair of doublet bands and a high-spin isomer built on the πh11/2νh11/2 configuration. For producing the excited states of 120I, a fusion-evaporation reaction 118Sn(6Li, 4n) at E=lab48 MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with Z=53. The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the πh11/2νh11/2 configuration. In contrast, the high-spin isomer with a half-life of 49(2) ns at spin-parity Jπ=25+ can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the 114Sn core: three protons (g7/2)1(d5/2)1(h11/2)1 and three neutrons (h11/2)3. This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of 114Sn with Z=50 and N=64.

Original languageEnglish
Pages (from-to)602-606
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Publication statusPublished - 2018 Jul 10

Bibliographical note

Funding Information:
We would like to thank the technical staff of the ANU 14 UD accelerator for their support. Dr. C. Yuan acknowledges the National Natural Science Foundation of China ( 11775316 ).

Publisher Copyright:
© 2018 The Author(s)


  • Chiral-like pair band
  • In-beam γ-ray spectroscopy
  • Iodine
  • Isomer

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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