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Spin distribution measurements were performed for the reaction 64Ni + 100Mo at three beam energies ranging from 230 to 260 MeV. Compound nucleus (CN) spin distributions were obtained channel selective for each evaporation residue populated by the de-excitation cascade. A comparison of the spin distribution at different beam energies indicates that its slope becomes steeper and steeper with increasing beam energy. This change in slope of the spin distribution is mainly due to the onset of fission competition with particle evaporation at higher beam energies.

We measured excitation functions for the main transfer channels in the 116Sn+60Ni reaction from above to well below the Coulomb barrier. The experiment has been performed in inverse kinematics, detecting the lighter (target-like) ions with the magnetic spectrometer PRISMA at very forward angles. The comparison between the data and microscopic calculations for the present case and for the previously measured 96Zr+40Ca system, namely superfluid and near closed shells nuclei, should significantly improve our understanding of nucleon-nucleon correlation properties in multinucleon transfer processes.

The heavy ion reaction 22Ne+208Pb at 128 MeV of bombarding energy has been studied using the PRISMA-CLARA experimental setup at Legnaro National Laboratories. Elastic, inelastic and one nucleon transfer cross sections have been measured. The experimental results are presented in parallel with the analysis on existing data for the unstable 24Ne nucleus, from the reaction 24Ne+208Pb at 182 MeV (measured at SPIRAL with the VAMOS-EXOGAM setup). The β2C charge deformation parameter for both 22Ne and 24Ne has been determined by a DWBA analysis of the experimental angular dis- tributions, showing a strong reduction for 24Ne.

The neutron-rich isotopes of tungsten, osmium and platinum have different shapes in their ground states and present also shape transitions phenomena. Spectroscopic information for these nuclei is scarce and often limited to the gamma rays from the decay of isomeric states. For the neutron-rich even-even osmium isotopes 194Os and 198Os, a shape transition between a slightly prolate deformed to an oblate deformed ground state was deduced from the observed level schemes. For the even-even nucleus lying in between, 196Os, no gamma ray transition is known. In order to elucidate the shape transition and to test the nuclear models describing it, this region was investigated through gamma-ray spectroscopy using the AGATA demonstrator and the large acceptance heavy-ion spectrometer PRISMA at LNL, Italy. A two-nucleon transfer from a 198Pt target to a stable 82Se beam was utilized to populate medium-high spin states of 196Os. The analysis method and preliminary results, including the first life-time measurement of isomeric states with AGATA, are presented.

The region of neutron-rich nuclei beyond 208Pb has been very difficult to explore due to its high mass and exoticity. However, recent experimental improvements allowed one to perform a quite extended isomer decay spectroscopy of these nuclei.

The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni) towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+) value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.

Isospin mixing induced by the Coulomb interaction has been studied in the compound nucleus 80Zr at T~2 MeV produced in the fusion-evaporation reaction 40Ca+40Ca at Ebeam = 136 MeV. The isospin impurity was measured using the first step of the Giant Dipole Resonance γ decay. The preliminary value of the Coulomb spreading width has been extracted via statistical model analysis of the measured γ spectrum.

A measurement of the high-lying states in 208Pb has been made using 17O beams at 20 MeV/u. The gamma decay following inelastic excitation was measured with the detector system AGATA Demonstrator based on segmented HPGe detectors, coupled to an array of large volume LaBr3:Ce scintillators and to an array of Si detectors. Preliminary results in comparison with (γ,γ’) data, for states in the 5-8 MeV energy interval, are presented.

The ability of a cluster of three segmented Ge crystals (“AGATA module”) acting as a Compton polarimeter to measure the linear polarization of gamma rays has been investigated at an energy close to 511 keV. Partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of 104Pd a and 108Pd.

We measured excitation functions for the main transfer channels in the 116Sn+60Ni reaction at different bombarding energies from above to well below the Coulomb barrier. The experiment has been performed in inverse kinematics, detecting the lighter (target-like) ions with the magnetic spectrometer PRISMA at very forward angles. Good mass, nuclear charge and kinetic energy resolutions have been achieved. The comparison between the data and microscopic calculations for the present case and for the previously measured 96Zr+40Ca system, namely superfluid and near closed shells nuclei, should significantly improve our understanding of nucleon-nucleon correlation properties in multinucleon transfer processes.

The study of the evolution of nuclear shells far from stability provides fundamental information about the shape and symmetry of the nuclear mean field. Nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Of particular interest is the region of 78Ni where the large neutron excess coincides with a double shell closure. We have recently measured the B(E2; 0+ → 2+) of the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory of the Michigan State University. The 74Ni secondary beam has been produced by fragmentation of 86Kr at 140 AMeV on a thick Be target. Selected radioactive fragments impinged on a secondary 197Au target where the measurement of the emitted γ-rays allows to extract the Coulomb excitation cross section and related structure information. Preliminary B(E2) values do not point towards an enhancement of the transition matrix element and the comparison to what was already measured by Aoi and co-workers in [1] opens new scenarios in the interpretation of the shell evolution of the Z=28 isotopes.

Multinucleon transfer cross sections in the system 40Ca+96Zr have been measured at bombarding energies ranging from the Coulomb barrier to ~ 25% below. Target-like (lighter) recoils in inverse kinematics have been completely identif ed in A,Z and Q-value with the large solid angle magnetic spectrometer PRISMA. The experimental slopes of the neutron transfer probabilities at large internuclear separation are consistent with the values derived from the binding energies. A phenomenological interpretation of the transfer probabilities indicates the presence of enhanced values for the even number of neutron transfers.

Multinucleon transfer reactions have been investigated in 40Ar+208Pb with the Prisma+Clara set-up. The experimental differential cross sections of different neutron transfer channels have been obtained at three different angular settings taking into account the transmission through the spectrometer. The experimental yields of the excited states have been determined via particle-γ coincidences. In odd Ar isotopes, we reported a signif cant population of 11/2− states, reached via neutron transfer. Their structure matches a stretched conf guration of the valence neutron coupled to vibration quanta.