First lifetime investigations of N > 82 iodine isotopes: The quest for collectivity



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Benito García, Jaime and Fraile Prieto, Luis Mario and Sánchez Tembleque, Víctor and Vedia Fernández, María Victoria and otros, ... (2021) First lifetime investigations of N > 82 iodine isotopes: The quest for collectivity. Physical review C, 104 (1). ISSN 2469-9985

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We report on spectroscopic information and lifetime measurements in the neutron-rich I-135,I-137,I-139 isotopes. This is the first lifetime data on iodine isotopes beyond N = 82. Excited states were populated in fast neutron-induced fission of U-238 at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid nu-ball spectrometer. The level schemes of the I-135,I-137,I-139 isotopes are revised in terms of excited states with up to maximum spin-parity of (33/2(+)), populated for the first time in fast neutron-induced fission. We provide first results on the lifetimes of the (9/2(1)(+)) and (13/2(1)(+)) states in I-137 and I-139, and the (17/2(1)(+)) state in 137I. In addition, we give upper lifetime limits for the (11/2(1)(+)) states in I135-139, the (15/2(1)(+)) state in I-137, the (17/2(1)(+)) state in I-139, and reexamine the (29/2(1)(+)) state in I-137. The isomeric data in I-13(5) are reinvestigated, such as the previously known (15/2(1)(+)) and (23/21) isomers with T-1/2 of 1.64(14) and 4.6(7) ns, respectively, as obtained in this work. The new spectroscopic information is compared to that from spontaneous or thermal-neutron induced fission and discussed in the context of large scale shell-model (LSSM) calculations for the region beyond Sn-132, indicating the behavior of collectivity for the three valence-proton iodine chain with N = 82, 84, 86.

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©2021 American Physical Society. Artículo firmado por 72 autores. The authors would like to thank the operators of the ALTO facility for providing the reliable beams used during the experiment. Additionally, we thank the FASTER Collaboration for the technical support given. GAMMA-POOL and LOANPOOL are acknowledged for loaning the clover and Phase-I HPGe detectors. The FATIMA Collaboration is acknowledged for loaning the LaBr3(Ce) detectors. Some of the coauthors of this work were supported by the STFC UK Nuclear Data Network, the STFC (Grants No. ST/L005743/1 and No. ST/P005314), the Marion Redfearn Trust, BMBF (NUSTAR.DE Grants No. 05P15RDFN1 and No. 05P19PKFNA), and MINECO Grants No. FPA2015-65035-P and No. RTI2018-098868-B-I00. Part of the collaboration has received funding from the European Union's HORIZON 2020 Program under Grant Agreement No. 654002. G.H. and R.L. acknowledge support from the IDEX-API grant. P.H.R., S.M.C., M.B., and A.B. acknowledge support from the UK Government Department of BEIS via the National Measurement System, and the STFC consolidated grant. A.B., R.-B.G., and N.W. are supported by the DFG under Grant No. BL 1513/1-1. F.Z. received support from the Research Council of Norway under Contract No. 263030. M.P.-S. received funding from the Polish National Science Centre under Grants No. 2019/33/N/ST2/03023 and 2020/36/T/ST2/00547. A.K. was partially funded by Grant No. 2020/39/B/ST2/02346.

Uncontrolled Keywords:Nuclear-data sheets; Neutron-rich nuclei; Shell-model; Yrast excitations; SN-132; Generation; Fission; Isomer; Decay
Subjects:Sciences > Physics > Nuclear physics
ID Code:67857
Deposited On:21 Sep 2021 09:07
Last Modified:21 Sep 2021 13:02

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