GAMMA STRENGTH FUNCTIONS AND LEVEL DENSITIES WITHIN THE NUCLEAR SHELL MODEL

Two important quantities for the description of properties of atomic nuclei and the prediction of (n,gamma) cross-sections, are the nuclear level density and the gamma-ray strength function. The former is the average number of states per energy bin, while the latter is the average probability of absorbing or emitting a gamma-ray of a given energy. Recently, several experiments have revealed an enhancement of the gamma-ray strength function in the low energy-gamma region, which could potentially have a large impact on the (n,gamma) reaction rates. One part of the talk will be devoted to the interpretation of this enhancement within the Nuclear Shell Model. On the other part of the talk, a method of calculating nuclear level densities will be presented, which implements statistical methods and uses configuration interaction Shell Model Hamiltonians. The method will be applied on (56;57)Fe, for which many experimental results are available.