g-factor measurements at RISING: The cases of ¹²⁷Sn and ¹²⁸Sn

¹ Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences - BG-1784 Sofia, Bulgaria, EU
² Physics Division, School of Science and Technology, Università di Camerino and INFN, Sezione di Perugia I-62032 Camerino (Macerata), Italy, EU
³ Weizmann Institute of Science - Rehovot 76100, Israel
⁴ LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble F-38026 Grenoble Cedex, France, EU
⁵ Dipartimento di Fisica, Università di Padova and INFN, Sezione di Padova - I-35131 Padova, Italy, EU
⁶ GSI Helmholtzzentrum für Schwerionenforschung GmbH - Planckstr. 1, D-64291 Darmstadt, Germany, EU
⁷ The Henryk Niewodniczański Institute of Nuclear Physics, PAN - PL-31342 Kraków, Poland, EU
⁸ Dipartimento di Fisica, Università degli Studi di Milano and INFN, Sezione di Milano - I-20133 Milano, Italy, EU
⁹ IKP, Universität zu Köln - D-50937, Köln, Germany, EU
¹⁰ Department of Physics, University of Surrey - Guildford, GU2 7XH, UK, EU
¹¹ Department of Physics, Lund University - S-22100 Lund, Sweden, EU
¹² CSNSM, Université Paris-Sud 11, CNRS/IN2P3 - F-91405 Orsay-Campus, France, EU
¹³ Faculty of Physics, St. Kliment Ohridski University of Sofia - BG-1164 Sofia, Bulgaria, EU
¹⁴ Horia Hulubei National Institute of Physics and Nuclear Engineering - R-077125, Bucharest, Romania, EU
¹⁵ Instituto de Estructura de la Materia, CSIC - E-28006 Madrid, Spain, EU
¹⁶ Instituut voor Kern- en Stralingsfysica, K.U. Leuven - Celestijnenlaan 200D, B-3001 Leuven, Belgium, EU
¹⁷ IEP, Warsaw University - PL-00681 Warsaw, Poland, EU
¹⁸ Institut für Strahlenphysik, FZ Dresden-Rossendorf - D-01314, Dresden, Germany, EU
¹⁹ INFN - Laboratori Nazionali di Legnaro - I-35020 Legnaro (Padova), Italy, EU
²⁰ Department of Physics and Centre of Mathematics for Applications, University of Oslo - N-0316 Oslo, Norway

^a liliya@inrne.bas.bg

Received: 6 June 2010
Accepted: 10 August 2010

Abstract

We report on g-factor measurements of the 19/2⁺ T_1/2=4.5(3) μs isomer in ¹²⁷Sn and the 10⁺ T_1/2=2.69(23) μs isomer in ¹²⁸Sn. These isomers were produced and spin-aligned in relativistic heavy-ion fragmentation at GSI and were selected and separated by the GSI fragment separator (FRS). The γ-rays of the isomeric decay were detected by the RISING γ-ray spectrometer. The method of time-differential perturbed angular distributions was utilized. The measured g-factors, g(19/2⁺; ¹²⁷Sn)=− 0.17(2) and g(10⁺; ¹²⁸Sn)=− 0.20(4), are compared with shell model calculations. The measured g-factors confirm the predominantly νh_11/2^{− 2} and ν(s_1/2^{− 1}h_11/2⁻²) character of the 10⁺ and 19/2⁻ isomers in ¹²⁸Sn and ¹²⁷Sn, respectively. The results demonstrate the feasibility of the method for similar measurements in exotic neutron-rich nuclei.