In-beam $\gamma$-ray spectroscopy of the neutron-rich platinum isotope $^{200}$Pt toward the $N=126$ shell gap

P.R. John , J.J. Valiente-Dobón , D. Mengoni , V. Modamio , S. Lunardi , D. Bazzacco , A. Gadea , C. Wheldon , T.R. Rodríguez , T. Alexander , G. de Angelis , N. Ashwood , M. Barr , G. Benzoni , B. Birkenbach , P.G. Bizzeti , A.M. Bizzeti-Sona , S. Bottoni , M. Bowry , A. Bracco , F. Browne , M. Bunce , F. Camera , L. Corradi , F.C.L. Crespi , B. Melon , E. Farnea , E. Fioretto , A. Gottardo , L. Grente (1) , H. Hess , Tz. Kokalova , W. Korten (1) , A. Kuşoğlu , S. Lenzi , S. Leoni , J. Ljungvall (2) , R. Menegazzo , C. Michelagnoli , T. Mijatović , G. Montagnoli , D. Montanari , D.R. Napoli , Zs. Podolyák , G. Pollarolo , F. Recchia , P. Reiter , O.J. Roberts , E. Şahin , M.D. Salsac (1) , F. Scarlassara , M. Sferrazza , P.A. Söderström , A.M. Stefanini , S. Szilner (2) , C.A. Ur , A. Vogt , J. Walshe

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière

The neutron-rich nucleus Pt200 is investigated via in-beam γ-ray spectroscopy to study the shape evolution in the neutron-rich platinum isotopes towards the N=126 shell closure. The two-neutron transfer reaction Pt198(Se82, Se80)Pt200 is used to populate excited states of Pt200. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects γ rays coincident with the Se80 recoils, the binary partner of Pt200. The binary partner method is applied to extract the γ-ray transitions and build the level scheme of Pt200. The level at 1884 keV reported by Yates et al. [S. W. Yates, E. M. Baum, E. A. Henry, L. G. Mann, N. Roy, A. Aprahamian, R. A. Meyer, and R. Estep, Phys. Rev. C 37, 1889 (1988)] was confirmed to be at 1882.1 keV and assigned as the (61+) state. An additional γ ray was found and it presumably deexcites the (81+) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even 190−204Pt isotopes, revealing that Pt200 marks the transition from the γ-unstable behavior of lighter Pt nuclei towards a more spherical one when approaching the N=126 shell closure.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

P.R. John, J.J. Valiente-Dobón, D. Mengoni, V. Modamio, S. Lunardi, et al.. In-beam $\gamma$-ray spectroscopy of the neutron-rich platinum isotope $^{200}$Pt toward the $N=126$ shell gap. Phys.Rev.C, 2017, 95 (6), pp.064321. ⟨10.1103/PhysRevC.95.064321⟩. ⟨hal-01555205⟩