High-spin structures of five N=82 isotones: 136Xe, 137Cs, 138Ba, 139La, and 140Ce

A. Astier (1) , M. -G. Porquet (1) , Ts. Venkova (2) , D. Verney (3) , Ch. Theisen (4) , G. Duchene (5) , F. Azaiez (3) , G. Barreau (6) , D. Curien (5) , I. Deloncle (1) , O. Dorvaux (5) , B. J. P. Gall (5) , M. Houry (4) , R. Lucas (4) , N. Redon (7) , Marc Rousseau (5) , O. Stezowski (7)

1 CSNSM SNO
2 CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
3 IPNO - Institut de Physique Nucléaire d'Orsay
4 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
5 IPHC - Institut Pluridisciplinaire Hubert Curien
6 ACEN - Aval du cycle et Energie Nucléaire
7 IPNL - Institut de Physique Nucléaire de Lyon

Five N=82 isotones have been produced in two fusion-fission reactions and their gamma-rays studied with the Euroball array. The high-spin states of 139La have been identified for the first time, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis,spin values have been assigned to some states of 136Xe and 137Cs. Several cascades involving gamma-rays of 139La have been found to be delayed, they deexcite an isomeric state with T1/2= 315(35) ns located at 1800-keV excitation energy. The excited states of these five N=82 isotones are expected to be due to various proton excitations involving the three high-j subshells located above the Z=50 shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in 136Xe, 137Cs, and 138Ba.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

A. Astier, M. -G. Porquet, Ts. Venkova, D. Verney, Ch. Theisen, et al.. High-spin structures of five N=82 isotones: 136Xe, 137Cs, 138Ba, 139La, and 140Ce. Physical Review C, 2012, 85, pp.064316. ⟨10.1103/PhysRevC.85.064316⟩. ⟨in2p3-00705628⟩