Di Nitto, Antonio and La Rana, Giovanni and Moro, Renata and Vardaci, Emanuele (2011) Evidence for a spin-aligned neutron–proton paired phase from the level structure of 92Pd. [Pubblicazione in rivista scientifica]

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Tipologia del documento:	Pubblicazione in rivista scientifica
Titolo:	Evidence for a spin-aligned neutron–proton paired phase from the level structure of 92Pd
Autori:	Autore Email Di Nitto, Antonio [non definito] La Rana, Giovanni [non definito] Moro, Renata [non definito] Vardaci, Emanuele [non definito]
Data:	6 Gennaio 2011
Numero di pagine:	4
Dipartimento:	Scienze fisiche
Sezione di dipartimento:	Fisica dei Nuclei e delle Radiazioni
Numero identificativo:	10.1038/nature09644
URL ufficiale:	http://www.nature.com/nature/journal/v469/n7328/fu...
Titolo del periodico:	Nature
Data:	6 Gennaio 2011
ISSN:	0028-0836
Volume:	469
Numero:	7328
Intervallo di pagine:	pp. 68-71
Numero di pagine:	4
Parole chiave:	Experimental nuclear physics
Numero identificativo:	10.1038/nature09644
Settori scientifico-disciplinari del MIUR:	Area 02 - Scienze fisiche > FIS/04 - Fisica nucleare e subnucleare
Informazioni aggiuntive:	Preprint in fedOA: <http://www.fedoa.unina.it/7886>
Depositato il:	18 Feb 2011 12:25
Ultima modifica:	30 Apr 2014 19:43
URI:	http://www.fedoa.unina.it/id/eprint/7887

Abstract

hell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin–orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron–proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus 92Pd. Gamma rays emitted following the 58Ni(36Ar,2n)92Pd fusion–evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron–proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron–proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

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