Spectroscopy along Flerovium Decay Chains: Discovery of ${}^{280}\mathrm{Ds}$ and an Excited State in ${}^{282}\mathrm{Cn}$

Journal Article · Fri Jan 22 00:00:00 EST 2021 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.126.032503· OSTI ID:1761549

Såmark-Roth, A. ; Cox, D. M.; Rudolph, D.; Sarmiento, L. G.; Carlsson, B. G.; Egido, J. L.; Golubev, P.; Heery, J.; Yakushev, A.; Åberg, S.; Albers, H. M.; Albertsson, M.; Block, M.; Brand, H.; Calverley, T.; Cantemir, R.; Clark, R. M.; Düllmann, Ch. E.; Eberth, J.; Fahlander, C. ; Forsberg, U.; Gates, J. M.; Giacoppo, F.; Götz, M.; Götz, S.; Herzberg, R. -D.; Hrabar, Y.; Jäger, E.; Judson, D.; Khuyagbaatar, J.; Kindler, B.; Kojouharov, I.; Kratz, J. V.; Krier, J.; Kurz, N.; Lens, L.; Ljungberg, J.; Lommel, B.; Louko, J.; Meyer, C. -C.; Mistry, A.; Mokry, C.; Papadakis, P.; Parr, E.; Pore, J. L.; Ragnarsson, I.; Runke, J.; Schädel, M.; Schaffner, H.; Schausten, B.; Shaughnessy, D. A.; Thörle-Pospiech, P.; Trautmann, N.; Uusitalo, J.

A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ⁴⁸Ca + ²⁴²Pu and ⁴⁸Ca + ²⁴⁴Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ²⁸⁶Fl and ²⁸⁸Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely ²⁸²Cn. Spectroscopy of ²⁸⁸Fl decay chains fixed Q_α = 10.06(1) MeV. In one case, a Q_α = 9.46(1)-MeV decay from ²⁸⁴Cn into ²⁸⁰Ds was observed, with ²⁸⁰Ds fissioning after only 518 μs. The impact of these findings, aggregated with existing data on decay chains of ^286,288Fl, on the size of an anticipated shell gap at proton number Z = 114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP); European Research Council (ERC); Knut and Alice Wallenberg Foundation; Swedish Research Council (SRC); Spanish Ministry of Science and Innovation
• Grant/Contract Number: AC02-05CH11231; 654002; KAW 2015.0021; VR 2016-3969; FPA2017-84756-C4-2-P
• OSTI ID: 1761549
• Alternate ID(s): OSTI ID: 1766534
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Vol. 126 Journal Issue: 3; ISSN 0031-9007
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English