Neutron-proton pairing in the N=Z radioactive fp-shell nuclei $^{56}$Ni and $^{52}$Fe probed by pair transfer

• Published in: Physics letters. B 2022-06, Vol.829
• Main Authors: Le Crom, B., Assié, M., Blumenfeld, Y., Guillot, J., Sagawa, H., Suzuki, T., Honma, M., Achouri, N.L., Bastin, B., Borcea, R., Catford, W.N., Clément, E., Caceres, L., Caamano, M., Corsi, A., de France, G., Delaunay, F., de Séréville, N., Fernandez-Dominguez, B., Fisichella, M., Franchoo, S., Georgiadou, A., Gibelin, J., Gillibert, A., Hammache, F., Kamalou, O., Knapton, A., Lapoux, V., Leblond, S., Macchiavelli, A.O., Marques, F.M., Matta, A., Menager, L., Morfouace, P., Orr, N.A., Pancin, J., Pereira-Lopez, X., Perrot, L., Piot, J., Pollacco, E., Ramos, D., Roger, T., Rotaru, F., Sanchez-Benitez, A.M., Sénoville, M., Sorlin, O., Stanoiu, M., Stefan, I., Stodel, C., Suzuki, D., Thomas, J-C, Vandebrouck, M.
• Format: Article
• Language: English
• Subjects: Nuclear Experiment; Physics
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2022.137057

The isovector and isoscalar components of neutron-proton pairing are investigated in the N=Z unstable nuclei of the fp-shell through the two-nucleon transfer reaction (p, 3 He) in inverse kinematics. The combination of particle and gamma-ray detection with radioactive beams of 56 Ni and 52 Fe, produced by fragmentation at the GANIL/LISE facility, made it possible to carry out this study for the first time in a closed and an open-shell nucleus in the fp-shell. The transfer cross-sections for ground-state to ground-state (J=0 + , T=1) and to the first (J=1 + , T=0) state were extracted for both cases together with the transfer cross-section ratios σ ( 0 + ,T=1 ) / σ ( 1 + ,T=0 ) . They are compared with second-order distorted-wave born approximation (DWBA) calculations. The enhancement of the ground-state to ground-state pair transfer cross-section close to mid-shell, in 52 Fe, points towards a superfluid phase in the isovector channel. For the “deuteron-like” transfer, very low cross-sections to the first (J=1 + , T=0) state were observed both for 56 Ni(p, 3 He) and 52 Fe(p, 3 He) and are related to a strong hindrance of this channel due to spin-orbit effect. No evidence for an isoscalar deuteron-like condensate is observed.