Prompt fission neutron spectra and average prompt neutron multiplicities

Conference · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5650331

Madland, D G; Nix, J R

We present a new method for calculating the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity anti nu/sub p/ as functions of the fissioning nucleus and its excitation energy. The method is based on standard nuclear evaporation theory and takes into account (1) the motion of the fission fragments, (2) the distribution of fission-fragment residual nuclear temperature, (3) the energy dependence of the cross section sigma/sub c/ for the inverse process of compound-nucleus formation, and (4) the possibility of multiple-chance fission. We use a triangular distribution in residual nuclear temperature based on the Fermi-gas model. This leads to closed expressions for N(E) and anti nu/sub p/ when sigma/sub c/ is assumed constant and readily computed quadratures when the energy dependence of sigma/sub c/ is determined from an optical model. Neutron spectra and average multiplicities calculated with an energy-dependent cross section agree well with experimental data for the neutron-induced fission of /sup 235/U and the spontaneous fission of /sup 252/Cf. For the latter case, there are some significant inconsistencies between the experimental spectra that need to be resolved. 29 references.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5650331
• Report Number(s): LA-UR-83-3074; CONF-8310104-2; ON: DE84001724
• Country of Publication: United States
• Language: English

Related Subjects

652016* -- Nuclear Properties & Reactions
A=220 & above
Theoretical-- Spontaneous & Induced Fission-- (-1987)
653006 -- Nuclear Theory-- Spontaneous & Induced Fission
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BARYON REACTIONS
BARYONS
CALIFORNIUM 252
CALIFORNIUM ISOTOPES
DATA
DECAY
ELEMENTARY PARTICLES
EVAPORATION MODEL
EVEN-EVEN NUCLEI
FERMIONS
FISSION
FISSION FRAGMENTS
FISSION NEUTRONS
HADRON REACTIONS
HADRONS
HEAVY NUCLEI
INFORMATION
ISOTOPES
MATHEMATICAL MODELS
MULTIPLICITY
NEUTRON REACTIONS
NEUTRON SPECTRA
NEUTRONS
NUCLEAR FRAGMENTS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
NUMERICAL DATA
OPTICAL MODELS
PROMPT NEUTRONS
RADIOISOTOPES
SPECTRA
SPONTANEOUS FISSION
TARGETS
THEORETICAL DATA
URANIUM 235 TARGET
YEARS LIVING RADIOISOTOPES