IFIN-HH

Address: 30 Reactorului St., Magurele, jud. Ilfov, ROMANIA, Zip RO-077125

Tel: +(4021) 404.23.00, Fax: +(4021) 457.44.40

Nuclear Activation Data Advanced Studies: Theory and Evaluation for Fast Neutrons

Abstract:

This project aims developments of the description of reaction mechanisms which are relevant to incident fast neutrons with energies up to 100 MeV. Firstly, the still open questions of the corresponding pre-equilibrium (PE) emission within statistical processes will be concerned, with reference to their basic assumptions as well as the sensitivity of the PE and statistical model (SM) results to changes of the main model parameters. The answers to these questions will be searched for, in order to avoid compensation of opposite effects due to various less accurate parameter values, by means of :

  1. unitary use of common model parameters for the direct interaction (DI), PE and SM concerned at once,

  2. use of consistent input parameters determined by analysis of various independent data, and

  3. systematic account of whole body of related data for isotope chains and/or nearby atomic elements, while finally as many a s possible analyses over the whole periodic table will be most useful for a comprehensive check of the model achievements.

Uppermost consideration will be given to act in accordance with the main above-mentioned conditions (i-iii). Thus, firstly the unitary use of common model parameters will refer to involvement of the same parameters within various models (DI, PE and SM) concerned at once, for the optical model potential (OMP) and nuclear level density. Secondly, the consistent input parameters there will be obtained by the analysis of various independent data, others than the activation cross sections under investigation, i.e. (a) neutron total cross sections, (b) proton and alpha-particle reaction cross sections, (c) nucleon resonance data, (d) low-lying excited level schemes, and (e) average radiative widths Γγ0exp of the s-wave neutron resonances, endorsed by the analysis of neutron-capture data. There will be thus obtained consistently the parameters of (a) OMP for neutrons, (b) OMP for protons and alpha-particles, (c) the nuclear level density and (d) the lower limit of the excitation energy for their considerations, and (e) the gamma-ray strength functions.

Finally, only a systematic account of whole body of related data for isotope chains and/or nearby atomic elements could provide a comprehensive check of the model achievements.