Abstract
Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10−21s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.
| Original language | English |
|---|---|
| Pages (from-to) | 965-970 |
| Number of pages | 6 |
| Journal | Nature |
| Volume | 620 |
| Issue number | 7976 |
| DOIs | |
| State | Published - Aug 31 2023 |
Funding
We thank the RIKEN Nishina Center and the Center for Nuclear Study, the University of Tokyo accelerator staff for the excellent beam delivery. This work was supported in part by JSPS KAKENHI grant nos. JP18K03672 and JP18H05404. This work was also supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project ID 279384907 - SFB 1245, the GSI-TU Darmstadt cooperation agreement, the GSI under contract KZILGE1416, the German Federal Ministry for Education and Research (BMBF) under contract nos. 05P15RDFN1 and 05P21PKFN1, the European Research Council (ERC) grant agreement no. 258567 and the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 758027) and the Swedish Research Council grant nos. 2011-5324, 2017-03839 and 2017-04234, 2020-05127. Partial support was also supplied by the French-Japanese International Associated Laboratory for Nuclear Structure Problems, as well as the French ANR-14-CE33-0022-02 EXPAND. This work was also supported in part by the Institute for Basic Science (IBS-R031-D1) in Korea and the US Department of Energy, Office of Science, Office of Nuclear Physics, under award nos. DE-FG02-96ER40963 and DE-SC0018223. This work was also supported in part by the National Science Foundation, USA under grant no. PHY-1102511. Computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) programme. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the US Department of Energy under contract no. DE-AC05-00OR22725, and resources provided by the Swedish National Infrastructure for Computing (SNIC) at Chalmers Centre for Computational Science and Engineering (C3SE) and the National Supercomputer Centre (NSC) partially funded by the Swedish Research Council through grant agreement no. 2018-05973. Y.T. acknowledges the support of the JSPS Grant-in-Aid for Scientific Research grant no. JP21H01114. I.G. has been supported by HIC for FAIR and Croatian Science Foundation under project nos. 1257 and 7194. Z.D. and D.S. have been supported by the National Research, Development and Innovation Fund of Hungary through project nos. TKP2021-NKTA-42 and K128947. T. Otsuka., N.S., N.T., Y.U. and S.Y. acknowledge valuable support from the ‘Priority Issue on Post-K computer’ (hp190160), ‘Program for Promoting Researches on the Supercomputer Fugaku’ (JPMXP1020200105, hp200130, hp210165) and KAKENHI grants (JP17K05433, JP20K03981, JP19H05145, JP21H00117). The material presented here is based on work supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics, under contract no. DE-AC02-06CH11357 (ANL). T. Nakamura acknowledges the support of the JSPS Grant-in-Aid for Scientific Research grant no. JP21H04465. I.V. gratefully acknowledges UKRI (EP/W011956/1) and Wellcome (218261/Z/19/Z) funding. We thank the RIKEN Nishina Center and the Center for Nuclear Study, the University of Tokyo accelerator staff for the excellent beam delivery. This work was supported in part by JSPS KAKENHI grant nos. JP18K03672 and JP18H05404. This work was also supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project ID 279384907 - SFB 1245, the GSI-TU Darmstadt cooperation agreement, the GSI under contract KZILGE1416, the German Federal Ministry for Education and Research (BMBF) under contract nos. 05P15RDFN1 and 05P21PKFN1, the European Research Council (ERC) grant agreement no. 258567 and the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 758027) and the Swedish Research Council grant nos. 2011-5324, 2017-03839 and 2017-04234, 2020-05127. Partial support was also supplied by the French-Japanese International Associated Laboratory for Nuclear Structure Problems, as well as the French ANR-14-CE33-0022-02 EXPAND. This work was also supported in part by the Institute for Basic Science (IBS-R031-D1) in Korea and the US Department of Energy, Office of Science, Office of Nuclear Physics, under award nos. DE-FG02-96ER40963 and DE-SC0018223. This work was also supported in part by the National Science Foundation, USA under grant no. PHY-1102511. Computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) programme. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the US Department of Energy under contract no. DE-AC05-00OR22725, and resources provided by the Swedish National Infrastructure for Computing (SNIC) at Chalmers Centre for Computational Science and Engineering (C3SE) and the National Supercomputer Centre (NSC) partially funded by the Swedish Research Council through grant agreement no. 2018-05973. Y.T. acknowledges the support of the JSPS Grant-in-Aid for Scientific Research grant no. JP21H01114. I.G. has been supported by HIC for FAIR and Croatian Science Foundation under project nos. 1257 and 7194. Z.D. and D.S. have been supported by the National Research, Development and Innovation Fund of Hungary through project nos. TKP2021-NKTA-42 and K128947. T. Otsuka., N.S., N.T., Y.U. and S.Y. acknowledge valuable support from the ‘Priority Issue on Post-K computer’ (hp190160), ‘Program for Promoting Researches on the Supercomputer Fugaku’ (JPMXP1020200105, hp200130, hp210165) and KAKENHI grants (JP17K05433, JP20K03981, JP19H05145, JP21H00117). The material presented here is based on work supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics, under contract no. DE-AC02-06CH11357 (ANL). T. Nakamura acknowledges the support of the JSPS Grant-in-Aid for Scientific Research grant no. JP21H04465. I.V. gratefully acknowledges UKRI (EP/W011956/1) and Wellcome (218261/Z/19/Z) funding.