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Phys. Rev. C 65, 034313 (2002) [9 pages]

β-decay studies of 135–137Sn using selective resonance laser ionization techniques

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J. Shergur1, B. A. Brown2, V. Fedoseyev3, U. Köster4, K.-L. Kratz5, D. Seweryniak1,6, W. B. Walters1, A. Wöhr1, D. Fedorov7, M. Hannawald5, M. Hjorth-Jensen8, V. Mishin3, B. Pfeiffer5, J. J. Ressler1, H. O. U. Fynbo4, P. Hoff9, H. Mach10, T. Nilsson4, K. Wilhelmsen-Rolander11, H. Simon4, A. Bickley1, and the ISOLDE Collaboration4
1Department of Chemistry, University of Maryland, College Park, Maryland, 20742-2021
2Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321
3Institute of Spectroscopy, Russian Academy of Sciences, RU-142092 Troitsk, Russia
4Experimental Physics Division, ISOLDE, CERN, CH-1211 Geneva 23, Switzerland
5Institut für Kernchemie, Universität Mainz, D-55099 Mainz, Germany
6Physics Division, Argonne National Laboratory, Argonne, Illinois 60439
7Petersburg Nuclear Physics Institute, RAS 188350, Gatchina, Russia
8Department of Physics, University of Oslo, NO-0316 Oslo, Norway
9Department of Chemistry, University of Oslo, NO-1163 Oslo, Norway
10Department of Neutron Research, Uppsala University, S-61182 Nyköping, Sweden
11Department of Physics, Stockholms Universitet, S-11385 Stockholm, Sweden

Received 30 June 2001; published 22 February 2002

The decays of the very neutron rich Sn isotopes 135–137Sn were studied at CERN/ISOLDE using isotopic and isobaric selectivity achieved by the use of a resonance ionization laser ion source and mass spectroscopy, respectively. Neutron decay rates, γ-ray singles, and γ-γ coincidence data were collected as a function of time. The half-life (T1/2) and delayed neutron emission probability (Pn) values of 135Sn were measured to be 530(20) ms and 21(3)%, respectively. For 136Sn, a T1/2 of 250(30) ms was determined along with a Pn value of 30(5)%. For 137Sn, a T1/2 of 190(60) ms and a Pn value of 58(15)% were deduced. Identification of low-energy transitions in 135Sb was made possible by comparison of laser-on and laser-off γ-ray spectra. Those data combined with γ-γ coincidence spectra were used to construct a level scheme for 135Sb that includes an unexpectedly low first excited state at 282 keV. A ground state β branch of 33.2% was measured by following the growth and decay of the 135Sb daughter. Shell-model calculations are consistent with the observed 135Sb level structure and can account for a lowered first excited state.


©2002 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevC.65.034313
DOI: 10.1103/PhysRevC.65.034313
PACS: 23.40.-s, 29.30.-h, 26.30.+k, 27.60.+j

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