Atomic nuclei are groups of fermions, neutrons and protons, interacting through electroweak and strong forces. Likewise to what happens in atomic physics, nuclei are organized in shell structures, namely different properties such as binding energies, transition probabilities or the distances between quantum energy levels, assume peculiar values when the amount of protons or neutrons equal certain characteristic numbers. However, differently from atomic physics, the average field which keeps together nucleons is generated by the nucleons themselves, making the nucleus an extraordinary laboratory for the study of many body physics. Moreover, certain types of interactions exist, like the pairing one which couple together nucleons to certain spin configurations, governing quantum properties unique in nature. Another characteristic of nuclei is that mass numbers may vary from few units (like for instance for Helium or Lithium) to some hundreds of units (like for Uranium, last stable), with different values in the neutron or proton number. To this huge variety are associated different properties like lifetimes of ground and excited states, the kind of nuclear decay (gamma, beta, alfa, fission). Through suitable nuclear reactions one can synthesize and study properties of nuclei not available in nature, both from the point of view of nuclear structure and from the one of the reaction mechanism. The classes of experiments which are performed in nuclear physics are therefore extremely broad. One ranges from the study of ground state properties, like the mass, the electric and magnetic moments, to those of structure, like excited levels and the gamma transition probabilities, to the study of nuclear reactions with the partial or total reassembling of colliding nuclei, like transfer or fusion reactions, or the formation of nuclei through fission, break-up channels, or nucleus fragmentation. The Legnaro National Laboratory has a long tradition in nuclear physics research and is equipped with frontier accelerators and instrumentation able to compete with the best world centres in the field of heavy ions at energies close to the Coulomb barrier. LNL is one of the four national facilities funded by INFN with the mission of providing research infrastructures in nuclear physics and nuclear physics based applications for Italian and foreign users. The main research area is on nuclear structure and reaction dynamics, using heavy ion beams provided by the 15 MV Tandem coupled to the superconducting booster ALPI and the heavy ion injector PIAVE. Nuclear structure and reaction dynamics studies at bombarding energies close to the Coulomb barrier are based on dedicated instrumentation developed during the last years, i.e. large gamma arrays, magnetic spectrometers and particle detector arrays.
The goal is the study of exotic nuclei far from the stability valley, at the limits of existence of the nuclear system, created in nuclear reactions induced by stable and unstable bundles in international collaborations where members of the LNL group have a strong leadership.
Studies with GALILEO
- High spin states
- Collectivity and shell model
- Isospin symmetries and isospin mixing in N=Z nuclei
- Spectroscopy at the dripline
- Shell stability and evolution in neutron rich nuclei
- Symmetries at the critical point
- New region of deformation
- Lifetime measurements
Instrumentations: GALILEO GAMIPE NEDA TRACE LaBr3 SPIDER PLUNGER
Reaction mechanism is focused on near and sub-barrier fusion reactions, elastic, inelastic and multinucleon transfer, break-up processes, nuclear temperature studies at low bombarding energies.
Studies with PISOLO (heavy-ions fusion reactions) and PRISMA (quasi-elastic reactions)
- Multinucleon transfer
- Nuclear superfluidity (pair transfer)
- Elastic and inelastic scattering
- Near and sub-barrier fusion
Studies with EXOTIC (properties of light radioactive nuclei produced via secondary reactions)
- Reactions with secondary beams
- Quasi-elastic scattering
- Break-up processes
Studies with GARFIELD and FAZIA
- Multifragmentation at low excitation energies
- Nuclear level density
- Collective modes
- Cluster structure
Nuclear researches in collaboration with CERN
LNL groups are also involved in important nuclear physics activities with experiments carried out at other laboratories, for example at CERN. Two main experiments are:
ALICE designed to match the characteristics of the LHC lead beams, via heavy-ion relativistic collisions one forms a highly excited system to study a new matter state called Quark Gluon Plasma (QGP) which appeared at the early stage of the universe. LNL is an official Tier-2 site, so gives an important contribution to the computing of the experiment.
n_TOF devoted to measure neutron cross sections with high energy resolution in a wide range of energies of interest for Nuclear Astrophysics, for applications to new technologies for the production of Nuclear Energy and for Medical applications.