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Background: The chain of Sm isotopes exhibits a wide range of nuclear shapes and collective behavior. While the onset of deformation for N>82 has been well studied both experimentally and theoretically, fundamental data is lacking for some Sm isotopes with N<82. Purpose: Electromagnetic transition rates represent a sensitive test of theoretical nuclear structure models. Lifetime measurements are furthermore complementary to Coulomb excitation experiments, and the two methods together can give access to spectroscopic quadrupole moments. Method: The lifetime of the 21+ state in 140Sm was measured with the recoil-distance Doppler shift technique using the reaction 124Te(20Ne, 4n)140Sm at 82 MeV. Theoretical calculations were performed based on a mapped collective Hamiltonian in five quadrupole coordinates (5DCH) and the Gogny D1S interaction. Results: The lifetime of the 21+ state in 140Sm was found to be 9.1(6) ps, corresponding to a B(E2;21+→0+1) value of 51(4) Weisskopf units. The theoretical calculations are in very good agreement with the experimental result. Conclusions: The B(E2;21+→0+1) value for 140Sm fits smoothly into the systematic trend for the chain of Sm isotopes. The new beyond-mean field calculations are able to correctly describe the onset of collectivity in the Sm isotopes below the N=82 shell closure for the first time. [ABSTRACT FROM AUTHOR]

The lifetime τ(02+) of 152Gd has been measured using fast electronic scintillation timing (FEST) with an array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3) detectors. 152Gd was produced via an (α,n) reaction on a gold backed 149Sm target. The measured lifetime of τ(02+)=96(6)ps corresponds to a reduced transition strength of B(E2;02+->21+)=111(7) W.u. and an E0 transition strength of ρ²(E0)=39(3)×10-3 to the ground state. This result provides experimental support for the validity of a correlation that would be a novel indicator for a quantum phase transition (QPT). [ABSTRACT FROM AUTHOR]

High field quantum electrodynamics experiments will be conducted in the E6 experimental area of the Extreme Light Infrastructure-Nuclear Physics building. Here electrons and protons will be accelerated up to relativistic energies by multi-petawatt laser beam-target interactions. In this respect, the requirements for radiological safety measures are similar to those associated with the operation of conventional high energy accelerators. The paper presents a FLUKA simulation approach to the shielding assessment of the individual experiments. Updated source terms were used in order to compute ambient dose equivalent rates throughout E6 and neighbouring areas and check the compliance of the results with legal dose constraints. We investigated the effectiveness of an 'all-purpose' beam dump at E6 and the practicality of local muon shielding.

Low energy heavy charged particle accelerators are generators of ionizing radiation, due to the ion beam interactions into the machine components, targets and surrounding materials. Nowadays there are available computational tools allowing realistic estimates of radiation doses and residual activity of the activated components. These evaluations are further used to design the radiological safety system required by licensing and operation of the equipment.This paper presents results of measurements and numerical simulations of the radiation doses and residual activity, at the recently commissioned Bucharest 3 MV Cockcroft-Walton type Tandetron accelerator presently used mainly for Ion Beam Analysis (IBA) research.