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In order to shed light on the open question of the seniority conservation in the proton g9/2 orbital in the N=50 isotones [1,2], reduced transition probabilities in 90Zr, 92Mo and 94Ru nuclei, have been determined experimentally for the first time via lifetime measurements at the GANIL laboratory. The unconventional use of multi-nucleon transfer reaction [3] with a differential plunger device [4] allowed to measure lifetimes of the yrast low-spin states despite the presence of isomers in the proton-rich isotones. The required sensitivity to the lifetimes could only be achieved due to the excellent performance of the AGATA+VAMOS++ detection system [5,6].
The B(E2;4+->2+) and B(E2;2+->0+) yrast transitions in 92Mo and 94Ru and for the B(E2;4+->2+) and B(E2;6+->4+) yrast transitions in 90Zr determined in this experiment will be shown. In this contribution these results will be interpreted on the basis of realistic shell-model calculations [7] in the f5/2, p3/2, p1/2, g9/2 valence space, where it emerges that seniority is conserved in the first g9/2 orbital.
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[2] C. Qi, Phys. Lett. B 773 (2017) 616
[3] R. Broda et al. PLB 251 (90) 245
[4] A. Dewald et al., Prog. Part. Nucl. Phys. 67, 786 (2012)
[5] S. Akkoyun, et al., Nucl. Instr. and Methods in Phys. Res. A 668 (2012) 26
[6] M. Rejmund, et al., Nucl. Instr. and Methods in Phys. Res. A 646 (1) (2011) 184
[7] L. Coraggio et al., Phys. Rev. C 100 (2019) 014316 and references therein.
