Studying Gamow-Teller transitions and the assignment of isomeric and ground states at N = 50
Ali Mollaebrahimi, C. Hornung, T. Dickel, Daler Amanbayev, Gabriella Kripkó-Koncz, W. R. Plaß, Samuel Ayet San Andrés, Sönke Beck, A. Blazhev, J. Bergmann, H. Geißel, M. Górska, Hubert Grawe, Florian Greiner, E. Haettner, N. Kalantar‐Nayestanaki, Ivan Miskun, F. Nowacki, C. Scheidenberger, S. Bagchi, D. L. Balabanski, Z. Brencic, Olga Charviakova, P. Constantin, Masoumeh Dehghan, Jens Ebert, Lizzy Gröf, O. Hall, M.N. Harakeh, Satbir Kaur, A. Kankainen, R. Knöbel, D. Kostyleva, N. Yu. Kurkova, N. Kuzminchuk, I. Mardor, D. Nichita, Jan-Hendrik Otto, Z. Patyk, S. Piétri, S. Purushothaman, M. P. Reiter, Ann-Kathrin Rink, Heidi Roesch, A. Spătaru, Goran Stanić, A. State, Y. Tanaka, M. Vencelj, H. Weick, John S. Winfield, Michael I. Yavor, J. Zhao
Abstract
Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below 100Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of 124Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of 98Cd and 97Rh. A new QEC=5437±67 keV was obtained for 98Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+⟶1+) as B(GT)=2.94−0.28+0.32. Investigation of this result in state-of-the-art shell model approaches accounting for the first time experimentally observed spectrum of GT transitions points to a perfect agreement for N=50 isotones. The excitation energy of the long-lived isomeric state in 94Rh was determined for the first time to be 293±21 keV. This, together with the shell model calculations, allows the level ordering in 94Rh to be understood.