Fission Cross Sections Library
Development of Model Code and Theoretical Data Library on Heavy Nucleai Fission Cross-Sections in a Wide Energy Range
Tech Area / Field
- PHY-PFA/Particles, Fields and Accelerator Physics/Physics
- FIR-NOT/Nuclear and Other Technical Data/Fission Reactors
8 Project completed
Senior Project Manager
Khlopin Radium Institute, Russia, St Petersburg
- Forschungszentrum Karlsruhe Technik und Umwelt, Germany, Karlsruhe
Project summaryThe accumulation of a large file of nuclear data for a wide energy range of incident particles and different nuclear targets is at the moment urgent need for successful development of new nuclear technologies. The technical and basic restrictions on an opportunity to obtain required data by an experimental way dictate the necessity to use model codes for calculations of fission cross-sections and particle emission having a rather high degree of reliability for development of library of calculated nuclear data. Comparison of theoretical results and known to the present time experimental data shows on essential discrepancies of results, especially in energy region from 20 up to 200 MeV where the cross-sections yet appreciably vary as with growth of energy of incident particles and at transition from a nucleus to a nucleus.
It is planned in this work to develop a new code which will be specially oriented to the description of transitive energy region from the well-investigated low-energy physics to the physics of intermediate energy where the basic contribution to the mechanism of reaction brings in the intranuclear cascade. In the proposed model code it is supposed to use modern models for the description of the mechanism of the intranuclear cascade, preequilibrium particle emission as well for both evaporation of particles and mechanism of nuclear fission. The results of the intranuclear cascade stage simulation will be further used as entrance data for preequilibrium particle emission calculation and detailed description multichance fission will be kept. It allows calculating reaction cross-sections in the uniform approach in an indicated energy range. The application of modern model representations about fission barriers and dynamics, about behavior of density of levels on a barrier and other necessary physical parameters of calculations will allow increasing the reliability of the approach. The comparison with known experimental data and calculations of other authors will allow to test a new code and to form necessary libraries of the basic physical parameters of calculations. Systematic reaction cross-section calculations for nuclei of middle and heavy nuclear weight in a wide energy range will give us possibility to prepare a modern library of theoretical data in an international format like EXFOR in the energy range required for development of new nuclear technologies, space and medical purposes.
In V.G.Khlopin Radium institute the large experience on theoretical study of reaction of fission and other nucleon-induced reactions with energy up to 1 GeV in nuclei of middle and heavy weight is saved. Study of structures observable in the behavior of low-energy fission cross-section has resulted in development of new models for the level density on a fission barrier with inclusion of the appropriate block in the widely used program STAPRE. Calculations of potential energy surfaces have allowed obtaining data on behavior of fission barriers values for different nuclei and excitation energies. Besides, in the institute the work connected to the description of cross-sections of various reactions in intermediate energy region were carried out during the long time. The planned model code will base on the best modern approaches for the calculations of fission cross-sections and other nuclear reactions developed as in Radium institute and other groups for transitive energy area. The code will include the following items:
- The detailed description of evaporation of particles from an exited nucleus and fission chances with account of all competing processes how it is made in the most modern version of the code STAPRE-H but with inclusion of a library for the quantum characteristics of lowest states like in the code GNASH;
- Physically correct inclusion of direct processes on the basis of an intranuclear cascade method how it is made in the code CEM95 which is the most modern version of cascade-exciton model. The results of intranuclear cascade calculations will serve as an entrance data for the preequilibrim emission calculations. It allows describing cross-sections of reactions in the uniform approach within the whole energy region.
Potential role of foreign collaborators
Participation of foreign collaborators will allow to collect the most complete files of experimental data on cross-sections of nuclear fission and emission of particles in transitive energy region and to compare results of the developed approach with model approaches and results of calculations of other groups. The joint of efforts will allow to develop the most acceptable approach and to develop the modern software package and library of calculated data for successful development of the future nuclear technologies.
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