TY - JOUR
T1 - Effective proton-neutron interaction near the drip line from unbound states in F 25,26
AU - Vandebrouck, M.
AU - Lepailleur, A.
AU - Sorlin, O.
AU - Aumann, T.
AU - Caesar, C.
AU - Holl, M.
AU - Panin, V.
AU - Wamers, F.
AU - Stroberg, S. R.
AU - Holt, J. D.
AU - De Oliveira Santos, F.
AU - Alvarez-Pol, H.
AU - Atar, L.
AU - Avdeichikov, V.
AU - Beceiro-Novo, S.
AU - Bemmerer, D.
AU - Benlliure, J.
AU - Bertulani, C. A.
AU - Bogner, S. K.
AU - Boillos, J. M.
AU - Boretzky, K.
AU - Borge, M. J.G.
AU - Caamaño, M.
AU - Casarejos, E.
AU - Catford, W.
AU - Cederkäll, J.
AU - Chartier, M.
AU - Chulkov, L.
AU - Cortina-Gil, D.
AU - Cravo, E.
AU - Crespo, R.
AU - Datta Pramanik, U.
AU - Díaz Fernández, P.
AU - Dillmann, I.
AU - Elekes, Z.
AU - Enders, J.
AU - Ershova, O.
AU - Estradé, A.
AU - Farinon, F.
AU - Fraile, L. M.
AU - Freer, M.
AU - Galaviz, D.
AU - Geissel, H.
AU - Gernhäuser, R.
AU - Gibelin, J.
AU - Golubev, P.
AU - Göbel, K.
AU - Hagdahl, J.
AU - Henriques, A.
AU - Machado, J.
N1 - P. Van Isacker and M. Ploszajczak are greatly acknowledged for fruitful discussions and suggestions on how to improve the manuscript. TRIUMF receives funding via a contribution through the National Research Council of Canada. This work was supported in part by NSERC, the NUCLEI SciDAC Collaboration under the US Department of Energy Grants No. DE-SC0008533 and No. DE-SC0008511, the National Science Foundation under Grant No. PHY-1404159, the European Research Council Grant No. 307986 STRONGINT, the Deutsche Forschungsgesellschaft under Grant No. SFB 1245, and the BMBF under Contracts No. 05P15RDFN1 and No. 05P15WOFNA. This work has also been supported by the Spanish MINECO via Projects No. FPA2013-41267-P, No. FPA2015-64969-P, and No. FPA2015-65035-P and by the Portuguese FCT, Project No. PTDC/FIS/103902/2008. Computations were performed with an allocation of computing resources at the Julich Supercomputing Center, Ohio Supercomputer Center (OSC), and the Michigan State University High Performance Computing Center (HPCC)/Institute for Cyber-Enabled Research (iCER). C. A. Bertulani acknowledges support from US DOE Grant No. DE-FG02-08ER41533 and the US NSF Grant No. 1415656. M. Petri acknowledges support from the Helmholtz International Center for FAIR within the framework of the LOEWE program launched by the State of Hesse.
PY - 2017/11/8
Y1 - 2017/11/8
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85033794918&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.96.054305
DO - 10.1103/PhysRevC.96.054305
M3 - Article
AN - SCOPUS:85033794918
SN - 2469-9985
VL - 96
JO - Physical Review C
JF - Physical Review C
IS - 5
M1 - 054305
ER -