Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254Rf
David, H. M., Chen, J., Seweryniak, D., Kondev, F. G., Gates, J. M., Gregorich, K. E., . . . Zhu, S. (2015). Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254Rf. Physical Review Letters, 115 (13), 132502. doi:10.1103/PhysRevLett.115.132502
Published inPhysical Review Letters
Chen, J. |
Nair, C. |
Qiu, Y. |
© 2015 American Physical Society. Published in this repository with the kind permission of the publisher.
Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247ð73Þ μs have been discovered in the heavy 254Rf 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 Kπ ¼ 8−, ν2ð7=2þ½624; 9=2−½734Þ two-quasineutron and the Kπ ¼ 16þ, 8−ν2ð7=2þ½624; 9=2−½734Þ ⊗ 8−π2ð7=2−½514; 9=2þ½624Þ 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 ¼ 150 isotones. The four-quasiparticle isomer is longer lived than the 254Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2ð1.1Þ μs. The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state.