A. Zucchiatti

Quantum tunneling of the excited rotational bands in the superdeformed nucleus 143Eu

The properties of the thermally excited rotational motion up to the region of rotational damping are studied experimentally in the superdeformed nucleus 143 Eu. The effective lifetime of the excited discrete rotational bands forming ridge structures in ‐ matrices is measured at the EUROBALL array using the DSAM technique, giving a quadrupole momentQt 10 e b, consistent with the deformation of the superdeformed yrast band. In addition, the effective number of excited superdeformed bands is extracted by a statistical analysis of the ridge structure, for transition energies down to the region where the effect of the decay-out into the normal deformed well shows up. The experimental data are compared with microscopic cranked shell model calculations including a residual interaction of surface delta type. Satisfactory agreement between data and theory is obtained when the quantum tunneling of the excited superdeformed states is included in the model.

Effect of E1 decay in the population of superdeformed structures

Abstract Spectra of the yrast and excited superdeformed bands, forming the E2 quasi-continuum, are measured with the EUROBALL array for the nucleus 143 Eu, in coincidence with high-energy γ-rays (Eγ>3 MeV). It is found that the intensity population of the superdeformed states is enhanced by a factor of ≈1.6 when a coincidence with a γ-ray with energy >6 MeV is required, in reasonable agreement with the increase of the line shape of the Giant Dipole Resonance built on a superdeformed configuration. This result shows that when an high energy E1 γ-ray is involved in the decay it is more likely connected with a SD rather than a ND nucleus. In addition, the analysis of the rotational quasi-continuum suggests the presence of a superdeformed component. The data are also compared and found consistent with simulation calculations of the relative intensities of the SD states, including the E1 decay of superdeformed nature.

Population Of Neutron Rich Nuclei Around 48Ca With Deep Inelastic Collisions

The reaction 48Ca+64Ni has been studied in the deep inelastic regime at approximately 6 MeV/A, by the CLARA‐PRISMA setup. Angular distributions of the reaction cross sections have been obtained for the most intense reaction products, taking into account the response function of the magnetic spectrometer. The response of PRISMA has been calculated making use of a MonteCarlo simulation of the transport of the ions in the spectrometer, starting from known events distributions. For the one‐nucleon transfer channels, the experimental data are in good agreement with predictions from a semiclassical multi‐nucleon transfer model.

Reaction dynamics and nuclear structure studies via deep inelastic collisions with heavy-ions: spin and parity assignment in 49Ca

The population and gamma decay of neutron rich nuclei around 48Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions (DIC) on 64Ni, at an energy approximately twice the Coulomb barrier. The reaction properties of the main products are investigated, focusing on total cross sections and angular distributions both integrated in energy and associated to the population of specific excited states. Gamma spectroscopy studies are also performed, giving evidence, for the first time in transfer reactions with heavy ions, of a large spin alignment (~70%), perpendicular to the reaction plane. This makes possible the use of angular distributions and polarization measurements to firmly establish the spin and parity of excited states populated in nucleon transfer channels, as in the case of 49Ca, where candidates for particle-core coupling are investigated. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for a detailed investigation of moderately neutron rich systems.

Reaction Dynamics And Nuclear Structure Via Deep Inelastic Collisions With Heavy-Ions: Search For Particle-Vibration Couplings in [sup 49]Ca

The deep inelastic reaction (DIC) 48Ca+64Ni, at an energy approximately 2.5 times above the Coulomb barrier, was studied using the CLARA‐PRISMA setup at the Laboratori Nazionali di Legnaro. Total cross sections and angular distributions, both energy integrated and associated to the population of selected excited states, are measured for the most intense reaction channels. The γ‐decay of the most intense reaction products is also studied. The use of angular distributions and polarization measurements of γ transitions allows to firmly establish spin and parity of excited states. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for the investigation of moderately neutron rich systems.