Vandebrouck, M., Lepailleur, A., Sorlin, O et al. (47 more authors) (2017) Effective proton-neutron interaction near the drip line from unbound states in 25,26 F. Physical Review C. 054305. ISSN 2469-9993
Abstract
Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F26 nucleus, composed of a deeply bound π0d5/2 proton and an unbound ν0d3/2 neutron on top of an O24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a Jπ=11+-41+ multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The Jπ=11+,21+,41+ bound states have been determined, and only a clear identification of the Jπ=31+ is missing. Purpose: We wish to complete the study of the Jπ=11+-41+ multiplet in F26, by studying the energy and width of the Jπ=31+ unbound state. The method was first validated by the study of unbound states in F25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne26 and Ne27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F25 and F26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the R3B/LAND setup. The detection of emitted γ rays and neutrons, added to the reconstruction of the momentum vector of the A-1 nuclei, allowed the determination of the energy of three unbound states in F25 and two in F26. Results: Based on its width and decay properties, the first unbound state in F25, at the relative energy of 49(9) keV, is proposed to be a Jπ=1/2- arising from a p1/2 proton-hole state. In F26, the first resonance at 323(33) keV is proposed to be the Jπ=31+ member of the Jπ=11+-41+ multiplet. Energies of observed states in F25,26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F26.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | ©2017 American Physical Society. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Health Sciences (York) The University of York The University of York > Faculty of Sciences (York) > Physics (York) |
Depositing User: | Pure (York) |
Date Deposited: | 04 Dec 2017 12:00 |
Last Modified: | 30 Nov 2024 01:08 |
Published Version: | https://doi.org/10.1103/PhysRevC.96.054305 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevC.96.054305 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:124815 |