Spectroscopy of Rf257

J. Qian, A. Heinz, T. L. Khoo, R. V.F. Janssens, D. Peterson, D. Seweryniak, I. Ahmad, M. Asai, B. B. Back, M. P. Carpenter, A. B. Garnsworthy, J. P. Greene, A. A. Hecht, C. L. Jiang, F. G. Kondev, T. Lauritsen, C. J. Lister, A. Robinson, G. Savard, R. ScottR. Vondrasek, X. Wang, R. Winkler, S. Zhu

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28 Citations (Scopus)


The isotope Rf257 was produced in the fusion-evaporation reaction Pb208(Ti50,n)Rf257. Reaction products were separated and identified by mass. Delayed spectroscopy of Rf257 and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on α hindrance factors. The excitation energy of the 1/2+[620] configuration in No253 is proposed. The energy of this 1/2+ state in a series of N=151 isotones increases with nuclear charge, reflecting an increase in the N=152 gap. This gap is deduced to grow substantially from 850 to 1400 keV between Z=94 and 102. An isomeric state in Rf257, with a half-life of 160-31+42μs, was discovered by detecting internal conversion electrons followed by α decay. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal conversion electrons, with a half-life of 4.1-1.3+2.4 s, followed by α decay, was also observed. These events might originate from the decay of excited states in Lr257, populated by electron-capture decay of Rf257. Fission of Rf257 was unambiguously detected, with a branching ratio of bRfSF=0.02±0.01.

Original languageEnglish
Article number064319
JournalPhysical Review C - Nuclear Physics
Issue number6
Publication statusPublished - Jun 22 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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