Introduction to nuclear structure, studied mainly through gamma spectroscopy. Experimental methods and comparison with nuclear models.
Introduction to nuclear reactions. Nuclear potentials. Elastic cattering and absorption. Resonances.
Reaction mechanisms and decay of excited nuclei. Heavy ion collisions.
NUCLEAR STRUCTURE:
1) J. D. Jackson, "Classical Electrodynamics", John Wiley and Sons.
2) C. A. Bertulani, "Nuclear Physics in a Nutshell", Princeton University Press.
3) R. F. Casten, "Nuclear Structure from a Simple Perspective", Oxford University Press.
NUCLEAR REACTIONS:
1) C. A. Bertulani and P. Danielewicz, "Introduction to nuclear reactions", Institute of Physics Publ., Graduate Student Series in Physics;
2) W. Noerenberg, "Basic concepts in the description of collisions between heavy nuclei", in: "Heavy ion collisions", edited by R. Bock, North-Holland Comp., Vol. 2, Ch. 1;
3) D. Durand, E. Suraud and B. Tamain, "Nuclear dynamics in the nucleonic regime", Institute of Physics Publ., Series in Fundamental and Applied Nuclear Physics
Learning Objectives
The course aims at introducing the student to research topics concerning the structure of nuclei far from stability, and the reaction mechanisms in nuclear collisions, giving both examples of experimental results and indications about current models.
Prerequisites
It is strongly advised to attend this course after having attended the course of "Nuclear Physics".
Teaching Methods
CFU: 6
Number of lecture hours: 48
Type of Assessment
Oral examination.
Course program
NUCLEAR SPECTROSCOPY
Excited levels in nuclei and their properties.
Gamma decay: solutions of Maxwell's equations in the radiation zone; multipole expansion of the electromagnetic field; properties of multipole fields (angular momentum and parity); expression of the transition rates; Weisskopf estimates. Angular distribution of multipole radiation. Comparison with experimental data: measurement of multipolarity of a transition; gamma-gamma angular correlations (measurement of angular momentum); internal conversion process (measurement of parity); Coulomb excitation process (measurement of transition probability).
Radioactive beams: methods of producing radioactive beams ISOL and fragmentation techniques. Nuclear physics experiments: study of the properties of nuclei far from the stability valley. Detection techniques for experiments with radioactive ion beams.
Introduction to nuclear models: short review of the independent particle model and the collective geometric model.
Interacting boson model and algebraic approach to describe the atomic nuclei. Hamiltonian composed of creation and destruction operators of pairs of identical nucleons, treated as bosons. Generators, Casimir operators and irreducible representation of the U(6) group. Dynamical symmetries of the Hamiltonian; comparison between the model prediction and the experimental data.
Nilsson model to describe nuclei deformed in the ground state: eigenfunctions of the Nilsson hamiltonian in the two limits of small and large deformation. Coupling between the rotational and single-particle degrees of freedom. Eigenfunctions of the unified hamiltonian. Effects of the Coriolis interaction on the rotational bands.
NUCLEAR REACTIONS
Models for the nucleon-nucleon potential with two-body operators, with meson exchanges and rudiments of "effective field theories".
Nuclear potential "in medium" obtained with Brueckner methods; semi-empirical nuclear potentials (Skyrme, Gogny).
Diffusion from central potential, scattering matrix, cross section for elastic scattering and absorption, transmission coefficients.
Shape resonances in the elastic and absorption channels, interference between resonant and non-resonant components.
Classification of reactions with light ions: direct and fusion reactions. Optical model and diffraction phenomena. Nuclear temperature and level density.
Compound Nucleus (CN) formation and statistical decay into open channels, according to the Hauser-Feshbach method.
Phenomenology of heavy-ion collisions at low energies: fusion-evaporation and fusion-fission processes.
Phenomenology and models of sequential fission, competition with neutron emission; chain reactions.
Rudiments about the synthesis of super-heavy elements (SHE).
Deeply inelastic collisions (DIC): observables and experimental correlations (Wilczynski-plot, diffusion-plot); reaction binarity;
TKE (Total Kinetic Energy) as leading observable to describe the reaction; energy and angular momentum dissipation, mass diffusion and drift;
characteristic relaxation times for the different internal degrees of freedom.
Rudiments about isospin physics with heavy ions far from stability valley.
Rudiments about reactions at higher energies (event characterization, nuclear equation of state)
and about stellar processes (astrophysical factor, nucleosynthesis, s- and r-processes).