Decay and Fission Hindrance of Two- and Four-Quasiparticle Isomers in
Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247 ( 73 ) μ s have been discovered in the heavy 254 Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K π = 8 - , ν 2 ( 7 / 2 + [ 624 ] , 9 / 2 - [ 734 ] ) two-quasineutron and the K π = 1 6 + , 8 - ν 2 ( 7 / 2 + [ 624 ] , 9 / 2 - [ 734 ] ) Ⓧ 8 - π 2 ( 7 / 2 -[ 514 ] , 9 / 2 + [ 624 ] ) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N = 150 isotones. The four-quasiparticle isomer is longer lived than the 254 Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2 ( 1.1 ) μ s . The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1391944
- Journal Information:
- Physical Review Letters, Vol. 115, Issue 13; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
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