THEORETICAL RESEARCHES IN NUCLEAR REACTIONS AND NUCLEUS STRUCTURE

1. Theoretical studies of mechanisms of nuclear reactions with nucleons

The mechanism of reactions initiated in nucleus-targets having intermediate atomic weight or heavy by neutrons and protons with low and intermediate energies represents a subject of protracted researches, which have been proceeded by theoretical group of Radium Institute already in 70-s of the last century

These researches include the development of models and codes destined to define:

• Reaction start point within the limits of optical model ( Ч ТБНЛБИ ПРФЙЮЕУЛПК НПДЕМЙ (design of optical microscopic and phenomenological potentials of neutron and proton interaction with actinoid range nuclei);
• The contribution of direct and pre-equilibrium processes on the basis of intranuclear cascade model version designed at the Institute and exciton model for multiple particle emission;
• Statistical appearance of the mechanism of evaporation of nucleons and activated particles, as well as nuclear fission;
• Fragmentation of cold (f-decay and cluster decay) and excited nuclei.

2. Investigations in nucleus structure

• The study of shell effects generating in various nuclei both near the ground state and in overstrained nuclei in fission run;
• The study of quasi-particle states and coupling in wide ranges of nuclei and excitation energies;
• Nucleus mass description on the basis of difference correlation method;
• Description of mean-square nucleus radiuses within the limits of dynamical model, taking into account shell effects.

3. Theoretical study of heavy nuclei fission mechanism

Nuclear fission study represents the main direction in theoretical researches and covers in reality the whole spectrum of the values observed. On the basis of modern models and codes theoretical group carries out the following valuations:

• Nuclear fission cross-sections from W to Cf within wide energy range of nucleons attacking (up to 1 GeV) - on the basis of models and codes, developed;
• Fission fragment mass and charge distributions within the frames of oscillation model and statistical model under various excitations of nuclei;
• Description of triplex nuclear fission;
• Evaluation of characteristics of neutrons evaporable by fission fragments.

Cross-section of proton-initiated uranium fission. Our evaluation is shown with full line	Distribution of fragments of uranium fission caused by neutrons with energies of 0.4 and 14 MeV

• " No 964 (1999-2001) "Development of program package and creation of design data library for heavy nuclear fission cross-sections within wide energy range". " No 2524 (2003-2006) " Development of nuclear data library for heavy nuclear reactions with nucleons within wide energy range".