<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math>-ray spectroscopy of low-lying yrast and non-yrast states in neutron-rich <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Kr</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>94</mml:mn><mml:mo>,</mml:mo><mml:mn>95</mml:mn><mml:mo>,</mml:mo><mml:mn>96</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>
R.-B. Gerst, A. Blazhev, K. Moschner, P. Doornenbal, A. Obertelli, K. Nomura, J.-P. Ebran, S. Hilaire, J. Libert, G. Authelet, H. Baba, D. Calvet, F. Château, S. Chen, A. Corsi, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, V. Lapoux, T. Motobayashi, M. Nııkura, N. Paul, J.-Y. Roussé, H. Sakuraï, C. Santamaria, D. Steppenbeck, R. Taniuchi, Т. Уесака, Takashi Ando, T. Arıcı, F. Browne, A. M. Bruce, R. J. Caroll, L. X. Chung, M. L. Cortés, M. Dewald, B. Ding, F. Flavigny, S. Franchoo, M. Górska, A. Gottardo, J. Jolie, A. Jungclaus, J. Lee, M. Lettmann, B. D. Linh, J. Liu, Z. Liu, C. Lizarazo, S. Momiyama, S. Nagamine, N. Nakatsuka, C. R. Nita, C.R. Nobs, L. Olivier, R. Orlandi, Z. Patel, Zs. Podolyák, M. Rudigier, T. Saito, C. Shand, P.-A. Söderström, I. Stefan, V. Vaquero, V. Werner, K. Wimmer, Z. Y. Xu
Abstract
We report on $\ensuremath{\gamma}$-ray spectroscopy of low-lying excited states in the neutron-rich $^{94,95,96}\mathrm{Kr}$ isotopes measured as part of the ``Shell Evolution And Search for Two-plus energies At RIBF'' (SEASTAR) campaign at the RIKEN Radioactive Isotope Beam Factory. Excited yrast and non-yrast states were observed, and half-lives extracted via geant4 simulations. In $^{94,96}\mathrm{Kr}$ candidates for the ${3}_{1}^{\ensuremath{-}}$ state were identified. For $^{95}\mathrm{Kr}$, the prompt SEASTAR data were combined with delayed spectroscopic data measured with the EURICA array to observe transitions on top of the known ${(7/2)}^{+}$ isomer at a level energy of 195.5(3) keV. The comparison of the new experimental results with five-dimensional collective Hamiltonian (5DCH) and mapped interacting boson model (IBM) calculations, both using the Gogny D1M interaction, could suggest oblate-prolate shape coexistence already in $^{96}\mathrm{Kr}$.