Competition between allowed and first-forbidden β decays of at 208 and expansion of the Po 208 level scheme

Abstract

The structure of Po208 populated through the EC/β+ decay of At208 is investigated using γ-ray spectroscopy at the ISOLDE Decay Station. The presented level scheme contains 27 new excited states and 43 new transitions, as well as a further 50 previously observed γ rays which have been (re)assigned a position. The level scheme is compared to shell model calculations. Through this analysis approximately half of the β-decay strength of At208 is found to proceed via allowed decay and half via first-forbidden decay. The first-forbidden transitions predominantly populate core excited states at high excitation energies, which is qualitatively understood using shell model considerations. This mass region provides an excellent testing ground for the competition between allowed and first-forbidden β-decay calculations, important for the detailed understanding of the nucleosynthesis of heavy elements.

Metadata

Item Type:

Article

Authors/Creators:

Brunet, M.
Podolyák, Zs
Berry, T. A.
Brown, B. A.
Carroll, R. J.
Lica, R.
Sotty, Ch
Andreyev, A. N. https://orcid.org/0000-0003-2828-0262
Borge, M. J.G.
Cubiss, J. G. https://orcid.org/0000-0002-5076-8654
Fraile, L. M.
Fynbo, H. O.U.
Gamba, E.
Greenlees, P.
Harkness-Brennan, L. J.
Huyse, M.
Judson, D. S.
Konki, J.
Kurcewicz, J.
Lazarus, I.
Madurga, M.
Marginean, N.
Marginean, R.
Marroquin, I.
Mihai, C.
Nácher, E.
Negret, A.
Pascu, S.
Page, R. D.
Perea, A.
Phrompao, J.
Piersa, M.
Pucknell, V.
Rahkila, P.
Rapisarda, E.
Regan, P. H.
Rotaru, F.
Rudigier, M.
Shand, C. M.
Shearman, R.
Simpson, E. C. (es1034@york.ac.uk)
Stora, T.
Tengblad, O.
Van Duppen, P.
Vedia, V.
Vinals, S.
Wadsworth, R. https://orcid.org/0000-0002-4187-3102
Warr, N.
De Witte, H.

Funding Information: The authors would like to thank the operators of the ISOLDE facility for providing the beam for this experiment. The research leading to these results received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 654002. Support from the European Union Seventh Framework through ENSAR Contract No. 262010, as well as the Science and Technology Facilities Council (U.K.) through Grants No. ST/P005314/1, No. ST/L005743/1, No. ST/J000051/1, No. ST/L005670/1, and No. ST/P004598/1, the German BMBF under Contract No. 05P18PKCIA and “Verbundprojekt 05P2018” as well as Spanish MINECO Grants No. FPA2015-65035-P and No. FPA2017-87568-P, FWOVlaanderen (Belgium), GOA/2015/010 (BOF KU Leuven), the Excellence of Science Programme (EOS-FWO), the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12), the Polish National Science Centre under Contracts No. UMO-2015/18/M/ST2/00523 and No. UMO-2019/33/N/ST2/03023, National Science Foundation (U.S.) Grant No. PHY1811855, and the Romanian IFA project CERN-RO/ISOLDE is acknowledged. P.H.R. acknowledges support from the U.K. Department for Business, Energy and Industrial Strategy via the National Measurement Office. Publisher Copyright: © 2021 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

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