Discovery of the new isotope $$^{251}Lr$$: Impact of the hexacontetrapole deformation on single-proton orbital energies near the $$\text{Z}$$ = 100 deformed shell gap

Journal Article · 01 December 2022 · Physical Review. C

DOI:https://doi.org/10.1103/physrevc.106.l061301· OSTI ID:1909022

Huang, T. ^[1]; Seweryniak, D. ^[2]; Back, B. B. ^[2]; Bender, P. C. ^[3]; Carpenter, M. P. ^[2]; Chowdhury, P. ^[3]; Clark, R. M. ^[4]; Copp, P. A. ^[2]; He, X. -T. ^[5]; Herzberg, R. D. ^[6]; Hoff, D. M. ^[3]; Jayatissa, H. ^[2]; Khoo, T. L. ^[2]; Kondev, F. G. ^[2]; Morgan, G. ^[7]; Morse, C. ^[4]; Korichi, A. ^[8]; Lauritsen, T. ^[2]; Müller-Gatermann, C. ^[2]; Potterveld, D. H. ^[2] ; Reviol, W. ^[2]; Rogers, A. M. ^[3]; Saha, S. ^[3]; Savard, G. ^[2]; Sharma, K. ^[3]; Stolze, S. ^[2]; Waniganeththi, S. ^[3]; Wilson, G. L. ^[2]; Wu, J. ^[2]; Xu, Y. -F. ^[9]; Zhu, S. ^[10]

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1. Chinese Academy of Sciences, Lanzhou (China); Argonne National Laboratory (ANL), Argonne, IL (United States)
2. Argonne National Laboratory (ANL), Argonne, IL (United States)
3. University of Massachusetts, Lowell, MA (United States)
4. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
5. Nanjing University of Aeronautics and Astronautics (China)
6. University of Liverpool (United Kingdom)
7. Louisiana State University, Baton Rouge, LA (United States)
8. Centre National de la Recherche Scientifique (CNRS), Orsay (France)
9. Nanjing University of Aeronautics and Astronautics, Nanjing (China)
10. Brookhaven National Laboratory (BNL), Upton, NY (United States)

The products of the ^{203, 205}Tl (⁵⁰Ti, 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 $$42^{+42}_{-14}$$ and $$24.4^{+7.0}_{-4.5}$$ ms were observed which were followed by the known α decays of ²⁴⁷Md and ²⁴³Es . They are interpreted as originating from the 1/2^⁻ [521] and 7/2^⁻ [514] single-proton Nilsson states in the hitherto unknown isotope ²⁵¹Lr . From the measured Q_α values the 1/2^⁻ level was placed 117(27) keV above the 7/2^- level in ²⁵¹Lr in contrast to ²⁵⁵Lr where the 1/2^⁻ level is the lowest. Also, the α decay of ²⁵³Lr 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 ²⁵³Lr was measured. The ^{251, 253, 255}Lr Q_α 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 ^{251, 253, 255}Lr 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 ²⁵¹Lr and ²⁵⁵Lr was reproduced only when the hexacontetrapole deformation ϵ₆ was included in the calculations.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: SC0012704; AC02-06CH11357; AC02-05CH11231
• OSTI ID: 1909022
• Alternate ID(s): OSTI ID: 1906168; OSTI ID: 2328538
• Report Number(s): BNL-223792-2022-JAAM; 178979
• Journal Information: Physical Review. C, Vol. 106, Issue 6; ISSN 2469-9985
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
alpha decay
collective models
energy levels and level densities
lifetimes and widths
rare and new isotopes