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Abstract |
The neutron-rich rare isotope W-190 is discussed as a candidate for a prolate-oblate transitional nucleus with maximum gamma-softness. The collectivity of this isotope is assessed for the first time by the measurement of the reduced E2 transition probability of its first 2(+) state to the ground state. The experiment employed the FAst TIming Array (FATIMA), comprised of 36 LaBr3(Ce) scintillators, which was part of the DESPEC setup at GSI, Darmstadt. The 4(1)(+) and 2(1)(+) states of W-190 were populated subsequently to the decay of its 127(12) μs isomeric J(pi )= 10(-) state. The mean lifetime of the 2(1)(+) state was determined to be tau = 274(28) ps, which corresponds to a B(E2; 2(1)(+ )-> 0(1)(+)) value of 95(10) W.u. The results motivated a revision of previous calculations within an energy-density functional-based interacting boson model-2 approach, yielding E2 transition properties and spectroscopic quadrupole moments for tungsten isotopes. From comparison to theory, the new data suggest that W-190 is at the transition from prolate to oblate structure along the W isotopic chain, which had previously been discussed as a nuclear shape-phase transition. |
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Address |
[Sahin, E.; Werner, V.; Mistry, A. K.; Rudigier, M.; Pietralla, N.; Ahmed, U.; Alhomaidhi, S.; Cortes, M. L.; Hubbard, N.; John, P. R.; Kern, R.; Koseoglou, P.; Roesch, H. A.; Wiederhold, J.] Tech Univ Darmstadt, Inst Kernphys, D-64289 Darmstadt, Germany, Email: e.sahin@gsi.de; |
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