Fast-timing study of the l -forbidden 1/2+→3/2+ M1 transition in Sn 129

R. LicǍ, H. Mach, L. M. Fraile, A. Gargano, M. J G Borge, N. MǍrginean, C. O. Sotty, V. Vedia, A. N. Andreyev, G. Benzoni, P. Bomans, R. Borcea, L. Coraggio, C. Costache, H. De Witte, F. Flavigny, H. Fynbo, L. P. Gaffney, P. T. Greenlees, L. J. Harkness-BrennanM. Huyse, P. Ibáñez, D. S. Judson, J. Konki, A. Korgul, T. Kröll, J. Kurcewicz, S. Lalkovski, I. Lazarus, M. V. Lund, M. Madurga, R. MǍrginean, I. Marroquín, C. Mihai, R. E. Mihai, A. I. Morales, E. Nácher, A. Negret, R. D. Page, J. Pakarinen, S. Pascu, V. Paziy, A. Perea, M. Pérez-Liva, E. Picado, V. Pucknell, E. Rapisarda, P. Rahkila, F. Rotaru, J. A. Swartz, O. Tengblad, P. Van Duppen, M. Vidal, R. Wadsworth, W. B. Walters, N. Warr

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The levels in Sn129 populated from the β- decay of In129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 12+ state and the 32+ ground state in Sn129 are expected to have configurations dominated by the neutron s12 (l=0) and d32 (l=2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we have measured the half-life of the 12+ 315.3-keV state, T12= 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T12 value by the renormalization of the M1 effective operator for neutron holes.

Original languageEnglish
Article number044303
Number of pages7
JournalPhysical Review C
Issue number4
Publication statusPublished - 4 Apr 2016

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