The energies of the excited states in very neutron-rich (42)Si and (41,43)P have been measured using in-beam gamma-ray spectroscopy from the fragmentation of secondary beams of (42,44)S at 39A MeV. The low 2(+) energy of (42)Si, 770(19) keV, together with the level schemes of (41,43)P, provides evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that (42)Si is best described as a well-deformed oblate rotor.
The European Strategy Forum on Research Infrastructures (ESFRI) has selected in 2006 a proposal based on ultra-intense laser fields with intensities reaching up to 10-10 W cm called 'ELI' for Extreme Light Infrastructure. The construction of a large-scale laser-centred, distributed pan-European research infrastructure, involving beyond the state-of-the-art ultra-short and ultra-intense laser technologies, received the approval for funding in 2011-2012. The three pillars of the ELI facility are being built in Czech Republic, Hungary and Romania. The Romanian pillar is ELI-Nuclear Physics (ELI-NP). The new facility is intended to serve a broad national, European and International science community. Its mission covers scientific research at the frontier of knowledge involving two domains. The first one is laser-driven experiments related to nuclear physics, strong-field quantum electrodynamics and associated vacuum effects. The second is based on a Compton backscattering high-brilliance and intense low-energy gamma beam (<20 MeV), a marriage of laser and accelerator technology which will allow us to investigate nuclear structure and reactions as well as nuclear astrophysics with unprecedented resolution and accuracy. In addition to fundamental themes, a large number of applications with significant societal impact are being developed. The ELI-NP research centre will be located in Măgurele near Bucharest, Romania. The project is implemented by 'Horia Hulubei' National Institute for Physics and Nuclear Engineering (IFIN-HH). The project started in January 2013 and the new facility will be fully operational by the end of 2019. After a short introduction to multi-PW lasers and multi-MeV brilliant gamma beam scientific and technical description of the future ELI-NP facility as well as the present status of its implementation of ELI-NP, will be presented. The science and examples of societal applications at reach with these electromagnetic probes with much improved performances provided at this new facility will be discussed with a special focus on day-one experiments and associated novel instrumentation.
The 0 þ 2 state in 34 Si has been populated at the GANIL-LISE3 facility through the decay of a newly discovered 1 þ isomer in 34 Al of 26(1) ms half-life. The simultaneous detection of e þ e À pairs allowed the determination of the excitation energy Eð0 þ 2 Þ ¼ 2719ð3Þ keV and the half-life T 1=2 ¼ 19:4ð7Þ ns, from which an electric monopole strength of 2 ðE0Þ ¼ 13:0ð0:9Þ Â 10 À3 was deduced. The 2 þ 1 state is observed to decay both to the 0 þ 1 ground state and to the newly observed 0 þ 2 state [via a 607(2) keV transition] with a ratio Rð2Gathering all information, a weak mixing with the 0 þ 1 and a large deformation parameter of ¼ 0:29ð4Þ are found for the 0 þ 2 state, in good agreement with shell model calculations using a new SDPF-U-MIX interaction allowing np-nh excitations across the N ¼ 20 shell gap.
The structure of 44S has been studied by using delayed γ and electron spectroscopy. The decay rates of the 02+ isomeric state to the 2(1)+ and 0(1)+ states, measured for the first time, lead to a reduced transition probability B(E2: 2(1)+→0(2)+)=8.4(26) e(2) fm4 and a monopole strength ρ2(E0: 0(2)+→0(1)+)=8.7(7)×10(-3). Comparisons to shell model calculations point towards prolate-spherical shape coexistence, and a two-level mixing model is used to extract a weak mixing between the two configurations.
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