Lifetimes of excited states in triaxially deformed $^{107}$Tc and $^{109,111,113}$Rh

T.W. Hagen , A. Görgen , W. Korten (1) , L. Grente (1) , M.D. Salsac (1) , F. Farget (2) , T. Braunroth , B. Bruyneel (1) , I. Celikovic (2) , E. Clément (2) , G. de France (2) , O. Delaune (2) , A. Dewald , A. Dijon (2) , M. Hackstein , B. Jacquot (2) , J. Litzinger , J. Ljungvall (3) , C. Louchart (1) , C. Michelagnoli , D.R. Napoli , F. Recchia , W. Rother , E. Sahin , S. Siem , B. Sulignano (1) , Ch. Theisen (1) , J.J. Valiente-Dobon

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 GANIL - Grand Accélérateur National d'Ions Lourds
3 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière

Lifetimes of excited states in$^{107}$Tc,$^{109}$Rh,$^{111}$Rh, and$^{113}$Rh were measured at GANIL using the Recoil-Distance Doppler Shift method. The neutron-rich nuclei were produced in fission reactions in inverse kinematics with a$^{238}$U beam impinging on a$^{9}$Be target. Fission fragments were identified event-by-event in the ray-tracing spectrometer VAMOS++ and correlated with prompt $\gamma$ rays observed around the target position with the EXOGAM Ge detector array. Several lifetimes were obtained for states in the positive-parity yrast bands in the four nuclei and compared to triaxial particle-rotor calculations. The results clarify the configuration for the strongest positive-parity band in$^{107}$Tc and suggest a gradual increase of triaxial deformation with atomic number Z, reaching almost maximum triaxiality for the neutron-rich Rh nuclei.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

T.W. Hagen, A. Görgen, W. Korten, L. Grente, M.D. Salsac, et al.. Lifetimes of excited states in triaxially deformed $^{107}$Tc and $^{109,111,113}$Rh. Eur.Phys.J.A, 2018, 54 (3), pp.50. ⟨10.1140/epja/i2018-12482-9⟩. ⟨hal-01757853⟩