Stochastic model of angular distributions of fragments originating from the fission of excited compound nuclei

Journal Article · Fri Aug 15 04:00:00 EDT 2008 · Physics of Atomic Nuclei

DOI:https://doi.org/10.1134/S106377880808005X· OSTI ID:21402525

Karpov, A V ^[1]; Adeev, G D ^[2]

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1. Joint Institute for Nuclear Research (Russian Federation)
2. Omsk State University (Russian Federation)

The anisotropy of angular distributions of fission fragments and the average multiplicity of prescission neutrons were calculated within a stochastic approach to fission dynamics on the basis of three-dimensional Langevin equations. This approach was combined with a Monte Carlo algorithm for the degree of freedom K (projection of the total angular momentum I onto the fission axis). The relaxation time {tau}{sub K} in the coordinate K was considered as a free parameter of the model; it was estimated on the basis of a fit to experimental data on the anisotropy of angular distributions. Specifically, the relaxation time {tau}{sub K} was estimated at 2 x 10{sup -21} s for the compound nuclei {sup 224}Th and {sup 225}Pa and at 4 x 10{sup -21} s for the heavier nuclei {sup 248}Cf, {sup 254}Fm, and {sup 264}Rf. The potential energy was calculated on the basis of the liquid-drop model with allowance for finiteness of the range of nuclear forces and for the diffuseness of the nuclear surface. A modified one-body viscosity mechanism featuring a coefficient k{sub s} that takes into account the reduction of the contribution from the wall formula was used to describe collective-energy dissipation. The coefficient k{sub s} was also treated as a free parameter and was estimated at 0.5 on the basis of a fit to experimental data on the average prescission multiplicity of neutrons.

• OSTI ID: 21402525
• Journal Information: Physics of Atomic Nuclei, Journal Name: Physics of Atomic Nuclei Journal Issue: 8 Vol. 71; ISSN 1063-7788; ISSN PANUEO
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
ANISOTROPY
BARYONS
CALCULATION METHODS
CALIFORNIUM 248
CALIFORNIUM ISOTOPES
COMPOUND NUCLEI
DATA
DAYS LIVING RADIOISOTOPES
DEGREES OF FREEDOM
DISTRIBUTION
ELEMENTARY PARTICLES
ENERGY
EQUATIONS
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FERMIONS
FERMIUM 254
FERMIUM ISOTOPES
FISSION
FISSION FRAGMENTS
HADRONS
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
INFORMATION
ISOTOPES
LANGEVIN EQUATION
LIQUID DROP MODEL
MATHEMATICAL MODELS
MONTE CARLO METHOD
MULTIPLICITY
NEUTRONS
NUCLEAR FORCES
NUCLEAR FRAGMENTS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
NUMERICAL DATA
ODD-EVEN NUCLEI
POTENTIAL ENERGY
PROTACTINIUM 225
PROTACTINIUM ISOTOPES
RADIOISOTOPES
RELAXATION TIME
RUTHERFORDIUM 264
RUTHERFORDIUM ISOTOPES
SECONDS LIVING RADIOISOTOPES
SPONTANEOUS FISSION RADIOISOTOPES
STOCHASTIC PROCESSES
THORIUM 224
THORIUM ISOTOPES
THREE-DIMENSIONAL CALCULATIONS
VISCOSITY