期刊
PHYSICAL REVIEW C
卷 105, 期 3, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevC.105.L031304
关键词
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资金
- Swedish Research Council [621-2014-5558, 2019-04880]
- STFC [ST/G000697/1, ST/P005314, ST/P003982/1]
- UK Department for Business, Energy and Industrial Strategy via the National Measurement Office
- BMBF [05P19PKFNA]
- Helmholtz Research Academy Hesse for FAIR (HFHF)
- GSI FE [KJOLIE1820]
- National Measurement System program unit of the UK's Department for BGS
- IN2P3-GSI
- Spanish MICINN [RTI2018-098868-B-100]
- Ministerio de Ciencia e Innovacion [PID2019-104714GB-C21]
- Swedish Research Council [2019-04880] Funding Source: Swedish Research Council
- Vinnova [2019-04880] Funding Source: Vinnova
Lifetime measurements of low-lying states in the semimagic nucleus Ru-94 were conducted using a fast timing detector array. The experiment revealed unexpected enhancements and prohibitive transitions, which provided stringent tests for nucleon-nucleon interactions employed in theoretical model calculations.
Direct lifetime measurements via gamma -gamma coincidences using a fast timing detector array consisting of LaBr3(Ce) scintillators has been applied to determine the lifetime of low-lying states in the semimagic (N = 50) nucleus Ru-94. The experiment was carried out as the first in a series of FAIR-0 experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in Ru-94 were populated primarily via the beta-delayed proton emission of Pd-95 nuclei, produced in the projectile fragmentation of an 850 MeV/nucleon Xe-124 beam impinging on a 4 g/cm(2) Be-9 target. While the deduced E2 strength for the 2(+) -> 0(+) transition in the yrast cascade follows the expected behavior for conserved seniority symmetry, the intermediate 4(+) -> 2(+) transition exhibits a drastic enhancement of transition strength in comparison with pure-seniority model predictions as well as standard shell model predictions in the f pg proton hole space with respect to doubly magic Sn-100. The anomalous behavior is ascribed to a subtle interference between the wave function of the lowest seniority v = 2, I-pi = 4(+) state and that of a close-lying v = 4 state that exhibits partial dynamic symmetry. In addition, the observed strongly prohibitive 6(+) -> 4(+) transition can be attributed to the same mechanism but with a destructive interference. It is noted that such effects may provide stringent tests of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations.
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