Effective proton-neutron interaction near the drip line from unbound states in $^{25,26}$F
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T. Aumann
- Function : Author
C. Caesar
- Function : Author
M. Holl
- Function : Author
V. Panin
- Function : Author
F. Wamers
- Function : Author
S.R. Stroberg
- Function : Author
J.D. Holt
- Function : Author
Francois de Oliveira Santos
- Function : Author
- PersonId : 176640
- IdHAL : francois-de-oliveira-santos
- ORCID : 0000-0003-4539-5985
- IdRef : 157826392
H. Alvarez-Pol
- Function : Author
L. Atar
- Function : Author
V. Avdeichikov
- Function : Author
S. Beceiro-Novo
- Function : Author
D. Bemmerer
- Function : Author
J. Benlliure
- Function : Author
C. A. Bertulani
- Function : Author
S.K. Bogner
- Function : Author
J.M. Boillos
- Function : Author
K. Boretzky
- Function : Author
M.J.G. Borge
- Function : Author
M. Caamano
- Function : Author
E. Casarejos
- Function : Author
W. Catford
- Function : Author
J. Cederkäll
- Function : Author
M. Chartier
- Function : Author
L. Chulkov
- Function : Author
D. Cortina-Gil
- Function : Author
E. Cravo
- Function : Author
R. Crespo
- Function : Author
U. Datta Pramanik
- Function : Author
P. Diaz Fernandez
- Function : Author
I. Dillmann
- Function : Author
Z. Elekes
- Function : Author
- PersonId : 755406
- ORCID : 0000-0003-0571-8719
J. Enders
- Function : Author
O. Ershova
- Function : Author
A. Estrade
- Function : Author
F. Farinon
- Function : Author
L.M. Fraile
- Function : Author
M. Freer
- Function : Author
D. Galaviz
- Function : Author
H. Geissel
- Function : Author
R. Gernhauser
- Function : Author
J. Gibelin
- Function : Author
- PersonId : 11987
- IdHAL : julien-gibelin
- ORCID : 0000-0001-6751-3714
- IdRef : 105736708
P. Golubev
- Function : Author
K. Göbel
- Function : Author
J. Hagdahl
- Function : Author
T. Heftrich
- Function : Author
M. Heil
- Function : Author
M. Heine
- Function : Author
- PersonId : 740800
- IdHAL : marcel-heine
- ORCID : 0000-0001-6219-3635
A. Heinz
- Function : Author
A. Henriques
- Function : Author
H. Hergert
- Function : Author
A. Hufnagel
- Function : Author
A. Ignatov
- Function : Author
H.T. Johansson
- Function : Author
B. Jonson
- Function : Author
J. Kahlbow
- Function : Author
N. Kalantar-Nayestanaki
- Function : Author
R. Kanungo
- Function : Author
A. Kelic-Heil
- Function : Author
A. Knyazev
- Function : Author
T. Kröll
- Function : Author
N. Kurz
- Function : Author
M. Labiche
- Function : Author
C. Langer
- Function : Author
T. Le Bleis
- Function : Author
R. Lemmon
- Function : Author
S. Lindberg
- Function : Author
J. Machado
- Function : Author
J. Marganiec
- Function : Author
A. Movsesyan
- Function : Author
E. Nacher
- Function : Author
M. Najafi
- Function : Author
E. Nikolskii
- Function : Author
T. Nilsson
- Function : Author
- PersonId : 755193
- ORCID : 0000-0001-9604-6377
C. Nociforo
- Function : Author
S. Paschalis
- Function : Author
A. Perea
- Function : Author
M. Petri
- Function : Author
S. Pietri
- Function : Author
R. Plag
- Function : Author
R. Reifarth
- Function : Author
G. Ribeiro
- Function : Author
C. Rigollet
- Function : Author
M. Röder
- Function : Author
D. Rossi
- Function : Author
D. Savran
- Function : Author
H. Scheit
- Function : Author
A. Schwenk
- Function : Author
H. Simon
- Function : Author
I. Syndikus
- Function : Author
J. Taylor
- Function : Author
O. Tengblad
- Function : Author
R. Thies
- Function : Author
Y. Togano
- Function : Author
P. Velho
- Function : Author
V. Volkov
- Function : Author
A. Wagner
- Function : Author
H. Weick
- Function : Author
C. Wheldon
- Function : Author
G. Wilson
- Function : Author
J.S. Winfield
- Function : Author
P. Woods
- Function : Author
D. Yakorev
- Function : Author
M. Zhukov
- Function : Author
A. Zilges
- Function : Author
K. Zuber
- Function : Author
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 $^{26}$F nucleus, composed of a deeply bound $\pi0d_{5/2}$ proton and an unbound $\nu0d_{3/2}$ neutron on top of an $^{24}$O core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a $J^{\pi} = 1^{+}_1 - 4^{+}_1$ multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The $J^{\pi} = 1^{+}_1, 2^{+}_1,4^{+}_1$ bound states have been determined, and only a clear identification of the $J^{\pi} =3^{+}_1$ is missing.
Purpose: We wish to complete the study of the $J^{\pi} = 1^{+}_1 - 4^{+}_1$ multiplet in $^{26}$F, by studying the energy and width of the $J^{\pi} =3^{+}_1$ unbound state. The method was firstly validated by the study of unbound states in $^{25}$F, for which resonances were already observed in a previous experiment.
Method: Radioactive beams of $^{26}$Ne and $^{27}$Ne, produced at about $440A$\,MeV by the FRagment Separator at the GSI facility, were used to populate unbound states in $^{25}$F and $^{26}$F via one-proton knockout reactions on a CH$_2$ target, located at the object focal point of the R$^3$B/LAND setup. The detection of emitted $\gamma$-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 $^{25}$F and two in $^{26}$F.
Results: Based on its width and decay properties, the first unbound state in $^{25}$F is proposed to be a $J^{\pi} = 1/2^-$ arising from a $p_{1/2}$ proton-hole state. In $^{26}$F, the first resonance at 323(33)~keV is proposed to be the $J^{\pi} =3^{+}_1$ member of the $J^{\pi} = 1^{+}_1 - 4^{+}_1$ multiplet. Energies of observed states in $^{25,26}$F 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 of implementing the role of the continuum in theoretical descriptions, or to a wrong determination of the atomic mass of $^{26}$F.
Origin : Files produced by the author(s)
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