1. Lifetimes and shape-coexisting states of( 99)Zr
- Author
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Spagnoletti, P., Simpson, G., Kisyov, S., Bucurescu, D., Regis, J-M, Saed-Samii, N., Blanc, A., Jentschel, M., Koster, U., Mutti, P., Soldner, T., de France, G., Ur, C. A., Urban, W., Bruce, A. M., Bernards, C., Drouet, F., Fraile, L. M., Gaffney, L. P., Ghita, D. G., Ilieva, S., Jolie, J., Korten, W., Kroll, T., Lalkovski, S., Larijarni, C., Lica, R., Mach, H., Marginean, N., Paziy, V, Podolyak, Zs, Regan, P. H., Scheck, M., Smith, J. F., Thiamova, G., Townsley, C., Vancraeyenest, A., Vedia, V., Warr, N., Werner, V, Zielinska, M., Spagnoletti, P., Simpson, G., Kisyov, S., Bucurescu, D., Regis, J-M, Saed-Samii, N., Blanc, A., Jentschel, M., Koster, U., Mutti, P., Soldner, T., de France, G., Ur, C. A., Urban, W., Bruce, A. M., Bernards, C., Drouet, F., Fraile, L. M., Gaffney, L. P., Ghita, D. G., Ilieva, S., Jolie, J., Korten, W., Kroll, T., Lalkovski, S., Larijarni, C., Lica, R., Mach, H., Marginean, N., Paziy, V, Podolyak, Zs, Regan, P. H., Scheck, M., Smith, J. F., Thiamova, G., Townsley, C., Vancraeyenest, A., Vedia, V., Warr, N., Werner, V, and Zielinska, M.
- Abstract
Lifetimes of intermediate-spin states in two rotational bands of Zr-99 have been measured. These states were populated following the neutron-induced fission of U-235 at the PF1B beamline of the Institut Laue-Langevin, Grenoble, during the EXILL-FATIMA campaign. The nucleus Zr-99(59) exhibits shape coexistence and lies precisely on the border of an abrupt change in ground-state deformation when going from N = 58 to N = 60, making its study interesting for understanding the mechanisms involved in the rapid onset of deformation here. The B(E2) values extracted for decays in the nu 3/2[541] band allow quadrupole deformations of beta(2) = 0.34(1) and 0.26(3) to be determined for the 821.6- and 1236.6-keV members, whereas beta(2) = 0.32(3) was found for the 850.5-keV member of the nu 3/2[411] band. Some of the excited states known in Zr-99 have been reasonably described with interacting boson-fermion model (IBFM) calculations. Type-II shell evolution is proposed to play a major role in modifying single-particle energies in Zr-99.
- Published
- 2019