Studying Gamow-Teller transitions and the assignment of isomeric and ground states at $N=50

• Main Authors: Mollaebrahimi, Ali, Hornung, Christine, Dickel, Timo, Amanbayev, Daler, Kripko-Koncz, Gabriella, Plaß, Wolfgang R, Andrés, Samuel Ayet San, Beck, Sönke, Blazhev, Andrey, Bergmann, Julian, Geissel, Hans, Górska, Magdalena, Grawe, Hubert, Greiner, Florian, Haettner, Emma, Kalantar-Nayestanaki, Nasser, Miskun, Ivan, Nowacki, Frédéric, Scheidenberger, Christoph, Bagchi, Soumya, Balabanski, Dimiter L, Brencic, Ziga, Charviakova, Olga, Constantin, Paul, Dehghan, Masoumeh, Ebert, Jens, Gröf, Lizzy, Hall, Oscar, Harakeh, Muhsin N, Kaur, Satbir, Kankainen, Anu, Knöbel, Ronja, Kostyleva, Daria A, Kurkova, Natalia, Kuzminchuk, Natalia, Mardor, Israel, Nichita, Dragos, Otto, Jan-Hendrik, Patyk, Zygmunt, Pietri, Stephane, Purushothaman, Sivaji, Reiter, Moritz Pascal, Rink, Ann-Kathrin, Roesch, Heidi, Spătaru, Anamaria, Stanic, Goran, State, Alexandru, Tanaka, Yoshiki K, Vencelj, Matjaz, Weick, Helmut, Winfield, John S, Yavor, Michael I, Zhao, Jianwei
• Format: Journal Article
• Language: English
• Published: 27.09.2022
• Subjects: Physics - Nuclear Experiment
• DOI: 10.48550/arxiv.2209.13713

Direct mass measurements of neutron-deficient nuclides around the $N=50$ shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, 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 $1\times 10^{-7}$ using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new $Q_\mathrm{EC} = 5437\pm67$ keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions ($0^+\longrightarrow1^+$) as $B(\text{GT})=2.94^{+0.32}_{-0.28}$. Investigation of this result in state-of-the-art shell model approaches sheds light into a better understanding of the GT transitions in even-even isotones at $N=50$. The excitation energy of the long-lived isomeric state in $^{94}$Rh was determined for the first time to be $293\pm 21$ keV. This, together with the shell model calculations, allows the level ordering in $^{94}$Rh to be understood.