1. Discovery of the new isotope Lr251: Impact of the hexacontetrapole deformation on single-proton orbital energies near the Z=100 deformed shell gap
- Author
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Huang, T, Seweryniak, D, Back, BB, Bender, PC, Carpenter, MP, Chowdhury, P, Clark, RM, Copp, PA, He, X-T, Herzberg, RD, Hoff, DEM, Jayatissa, H, Khoo, TL, Kondev, FG, Morgan, G, Morse, C, Korichi, A, Lauritsen, T, Müller-Gatermann, C, Potterveld, DH, Reviol, W, Rogers, AM, Saha, S, Savard, G, Sharma, K, Stolze, S, Waniganeththi, S, Wilson, GL, Wu, J, Xu, Y-F, and Zhu, S
- Subjects
Nuclear and Plasma Physics ,Synchrotrons and Accelerators ,Physical Sciences ,Nuclear and plasma physics - Abstract
The products of the Tl203,205(Ti50,2n) fusion-evaporation reactions were studied using the recently commissioned Argonne Gas-Filled Analyzer at Argonne National Laboratory. Two α-decay activities with energies of 9210(19) and 9246(19) keV and half-lives of 42-14+42 and 24.4-4.5+7.0 ms were observed which were followed by the known α decays of Md247 and Es243. They are interpreted as originating from the 1/2-[521] and 7/2-[514] single-proton Nilsson states in the hitherto unknown isotope Lr251. From the measured Qα values the 1/2- level was placed 117(27) keV above the 7/2- level in Lr251 in contrast to Lr255 where the 1/2- level is the lowest. Also, the α decay of Lr253 was studied in more detail and a new α line at 8660(20) keV was found and a new half-life value of 2.46(32) s for an isomeric state in Lr253 was measured. The Lr251,253,255Qα values were compared with predictions of various mass models. The relative energies of the 1/2-[521] and 7/2-[514] single-proton Nilsson states in Lr251,253,255 isotopes were compared with results of the cranking shell model with pairing treated using the particle-number-conserving method. The level separation and, in particular, the level order change between Lr251 and Lr255 was reproduced only when the hexacontetrapole deformation 6 was included in the calculations.
- Published
- 2022