Exotic decay of Cs 115

P. Das, Ushasi Datta, S. Chakraborty, A. Rahaman, O. Tengblad, B. K. Agrawal, A. Becerril, J. Cederkall, J. Dey, A. Gottberg, Sk Md Adil Imam, M. Kowalska, J. Kurcewicz, M. Lund, S. Mandal, M. Madurga, N. Marginean, R. Marginean, C. Mihai, I. MarroquinE. Nacher, A. Negret, S. Pascu, A. Perea, E. Rapisarda, F. Rotaru, J. Ray, P. Sharma, T. Stora, C. Sotty, V. Vedia, N. Warr, R. Wadsworth

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The detailed study of the β+/EC decay of the very neutron-deficient and alpha-unbound nucleus Cs115 is presented. The measurement was performed at the ISOLDE, CERN where delayed charged particles and γ rays were detected. The observed delayed γ rays are in agreement with the previously reported characteristics γ rays of Xe115. Based on the experimental observations, the tentative ground-state spin of Cs115 is suggested to be 7/2+ or 9/2+. Furthermore, the measured decay branching ratio of delayed protons exceeds the previously reported value. Additionally, new delayed α-branching ratio and several reconstructed proton and α-unbound excited states of Xe115 are being reported for the first time. The properties of proton-unbound states at excitation energies from 3.9-7.9 MeV have been obtained by fitting the delayed proton spectrum via the Bayesian method. The measured lifetimes of these proton-unbound states are in the order of zeptoseconds.

Original languageEnglish
Article number064304
Number of pages6
JournalPhysical Review C
Issue number6
Publication statusPublished - 5 Dec 2023

Bibliographical note

Funding Information:
The authors are thankful to the team members of the accelerator facility of CERN and RIB operation scientists at ISOLDE, CERN for smooth operation of the experiment. We are sincerely thankful to Sukalyan Chattopadhyay for insightful comments and critical review of the manuscript. The present study was financially supported by SEND project grants (PIN:11-R&D-SIN-5.11-0400) from the Department of Atomic Energy (DAE), Govt. of India, the Project No. PID2019-104390GB-100 by the Spanish Funding Agency (AEI/FEDER, EU), the German BMBF under Contract No. 05P21PKC11 and Verbundprojekt 05P2021 and ENSER2 (European Nuclear Science and Applications Research)-HORIZON 2020 Grant No 654002, Europe. P.D. acknowledges with thanks for the financial support provided by CSIR vide file number 09/489(0111)/2019-EMR-I.

Publisher Copyright:
© 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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