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An overview of the main directions of present-day studies with quasimonochromatic γ beams are discussed with an emphasis on the research opportunities which will be offered at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest in Romania. Experiments with γ beams at the extremes of high temperature and high neutron-to-proton ratios are outlined. Some of the experimental setups for nuclear structure, reaction and astrophysics studies, which are available at ELI-NP, are described. Perspectives for studies of exotic nuclei within the Gamma Factory experiment at CERN are discussed. The expected fission-fragment yields at the Gamma Factory are presented. The perspectives for nuclear structure studies with γ rays with orbital angular momentum are outlined. [ABSTRACT FROM AUTHOR]

Nuclear mass is a key property of atomic nuclei. The accurate determination of nuclear masses provides information for the nuclear shell structure and nuclear deformations. The FRS Ion Catcher experimental setup at GSI, Darmstadt was used to perform mass measurements of 252Cf fragments using a multiple-reflection time-of-flight mass spectrometer. The reported results are compared to previous measurements and their implication in the estimation of two-neutron separation energy is discussed. [ABSTRACT FROM AUTHOR]

Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double-β decay, and stimulated atomic two-photon transitions. For the electromagnetic nuclear interaction, the observation of the competitive double-γ decay from 137mBa has opened up the nuclear structure field for detailed investigation of second-order processes through the manifestation of off-diagonal nuclear polarisability. Here, we confirm this observation with an 8.7σ significance, and an improved value on the double-photon versus single-photon branching ratio as 2.62 × 10−6(30). Our results, however, contradict the conclusions from the original experiment, where the decay was interpreted to be dominated by a quadrupole-quadrupole component. Here, we find a substantial enhancement in the energy distribution consistent with a dominating octupole-dipole character and a rather small quadrupole-quadrupole component in the decay, hindered due to an evolution of the internal nuclear structure. The implied strongly hindered double-photon branching in 137mBa opens up the possibility of the double-photon branching as a feasible tool for nuclear-structure studies on off-diagonal polarisability in nuclei where this hindrance is not present. Second order effects can play an important role in highlighting nuclear structure properties. Here, the authors show how the second-order nuclear transitions in the form of double-gamma decay in 137Ba help understanding atomic nuclei. [ABSTRACT FROM AUTHOR]

Background: Nuclei in the A " 190 mass region show gradual shape changes from prolate through nonaxial deformed shapes and ultimately towards spherical shapes as the Pb region is approached. Exploring how this shape evolution occurs will help us understand the evolution of collectivity in this region. Purpose: The level scheme of the 192 Au nucleus in A "190 region was studied in order to deduce its deformations. Methods: High-spin states of 192Au have been populated in the 186W("B, 5n) reaction at a beam energy of 68 MeV and their ? decay was studied using the YRAST Ball detector array at the Wright Nuclear Structure Laboratory (WNSL), Yale University. Results: Based on double and triple ?-ray coincidence data the level scheme of 192 Au has been extended up to Ip = 32+ at an excitation energy of ~6 MeV. Conclusion: The results are discussed in the framework of pairing and deformation self-consistent total Routhian surface (TRS) and cranked shell model (CSM) calculations. The comparison of the experimental observations with the calculations indicates that this nucleus takes a nonaxial shape similar to other Au nuclei in this region. [ABSTRACT FROM AUTHOR]

Lifetimes of excited states in 128Ce were measured using the recoil distance Doppler-shift (RDDS) and the Doppler-shift attenuation (DSAM) methods. The experiments were performed at the Wright Nuclear Structure Laboratory of Yale University. Excited states of 128Ce were populated in the 100Mo(32Si,4n) reaction at 120 MeV and the nuclear γ decay was measured with an array of eight Clover detectors positioned at forward and backward angles. The deduced yrast transition strengths together with the energies of the levels within the ground-state (gs) band of 128Ce are in agreement with the predicted values for the X(5) critical point symmetry. Thus, we suggest 128Ce as a benchmark X(5) nucleus in the mass A ≈ 130 region. [ABSTRACT FROM AUTHOR]

The measured spectroscopic quadrupole moments and deduced deformations of the 194,196Pb(11-) intruder isomers are reevaluated, making use of the recently measured magnetic moments of these states. This adjustment is necessary since the quadrupole moments were obtained from Level Mixing Spectroscopy measurements, being sensitive to the ratio of the quadrupole interaction frequency and the magnetic moment. The results confirm the moderate deformation of the states. A systematic comparison between the updated experimental and the available theoretical values is presented. [ABSTRACT FROM AUTHOR]

Isomer shifts have been determined in 111-129Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1/2+ and the 3/2+ ground states to the 11/2- isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction with the known quadrupole moments. This intuitive interpretation is supported by covariant density functional theory. [ABSTRACT FROM AUTHOR]

First and preliminary results of an experiment aimed at measuring g-factors of isomeric states in neutron-rich nuclei in the vicinity of 68Ni are reported. Isomers near the predicted N=40 sub-shell closure in 69Cu, 67Ni and 66Co have been populated in the fragmentation of a 76Ge, 61.4 MeV/u beam onto a 145 mg/cm2 9Be target at GANIL. Here we report the results for the 357(2) ns, Iπ=13/2+ isomer in 69Cu for which a preliminary gyromagnetic ratio of |g|=0.195(9) was derived. The Larmor precession of the spin-oriented isomeric ensemble was measured by recording γ–ion correlations in a 20 μs time window. This pioneering experiment has indicated interesting nuclear structure information and shows promising possibilities for future studies of this kind. [Copyright &y& Elsevier]