Helda

Helsingin yliopisto

Helsingfors universitet

University of Helsinki

Browsing by Subject "LIFETIMES"

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Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes : Coulomb excitation of Hg-182, Hg-184, Hg-186 and Hg-188

Wrzosek-Lipska, K.; Rezynkina, K.; Bree, N.; Zielinska, M.; Gaffney, L. P.; Petts, A.; Andreyev, A.; Bastin, B.; Bender, M.; Blazhev, A.; Bruyneel, B.; Butler, P. A.; Carpenter, M. P.; Cederkall, J.; Clement, E.; Cocolios, T. E.; Deacon, A. N.; Diriken, J.; Ekstrom, A.; Fitzpatrick, C.; Fraile, L. M.; Fransen, Ch.; Freeman, S. J.; Garcia-Ramos, J. E.; Geibel, K.; Gernhauser, R.; Grahn, T.; Guttormsen, M.; Hadinia, B.; Hadynska-Klek, K.; Hass, M.; Heenen, P. -H.; Herzberg, R. -D.; Hess, H.; Heyde, K.; Huyse, M.; Ivanov, O.; Jenkins, D. G.; Julin, R.; Kesteloot, N.; Kroell, Th.; Kruecken, R.; Larsen, A. C.; Lutter, R.; Marley, P.; Napiorkowski, P. J.; Orlandi, R.; Page, R. D.; Pakarinen, J.; Patronis, N.; Peura, P. J.; Piselli, E.; Prochniak, L.; Rahkila, P.; Rapisarda, E.; Reiter, P.; Robinson, A. P.; Scheck, M.; Siem, S.; Chakkal, K. Singh; Smith, J. F.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van Duppen, P.; Van de Walle, J.; Voulot, D.; Warr, N.; Wiens, A.; Wood, J. L. (2019)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0 + 1,2, 2(1,2)(+) and 4(1)(+) states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.
Shape coexistence in Hg-178

Müller-Gatermann, C.; Dewald, A.; Fransen, C.; Auranen, K.; Badran, H.; Beckers, M.; Blazhev, A.; Braunroth, T.; Cullen, D. M.; Fruet, G.; Goldkuhle, A.; Grahn, T.; Greenlees, P. T.; Herzan, A.; Jakobsson, U.; Jenkins, D.; Jolie, J.; Julin, R.; Juutinen, S.; Konki, J.; Leino, M.; Litzinger, J.; Nomura, K.; Pakarinen, J.; Peura, P.; Procter, M. G.; Rahkila, P.; Ruotsalainen, P.; Sandzelius, M.; Saren, J.; Scholey, C.; Sorri, J.; Stolze, S.; Taylor, M. J.; Uusitalo, J.; Zell, K. O. (2019)

Lifetime measurements of excited states in Hg-178 have been performed using the Rh-103(Kr-78, p2n) reaction at a beam energy of 354 MeV. The recoil-decay tagging (RDT) technique was applied to select the Hg-178 nuclei and associate the prompt gamma rays with the correlated characteristic ground-state alpha decay. Lifetimes of the four lowest yrast states of Hg-178 have been determined using the recoil distance Doppler-shift (RDDS) method. The experimental data are compared to theoretical predictions with focus on shape coexistence. The results confirm the shift of the deformed prolate structures to higher lying states but also indicate their increasing deformation with decreasing neutron number.