Possible viscosity effects in neutron-induced fission of /sup 232/Th and /sup 238/U. [Yields]

Conference · Mon Jan 01 04:00:00 EST 1979

OSTI ID:6247473

Gindler, J. E.; Glendenin, L. E.; Wilkins, B. D.

Fission yields induced in the /sup 238/U(n,f) and /sup 232/Th(n,f) reactions were determined as a function of incident neutron energy (E/sub n/). The ratio of /sup 115/Cd-to-/sup 140/Ba yields as a function of E/sub n/ is analyzed by means of the equation Y/sub 1//Y/sub 2/ = exp(2(a/sub 1/(E/sub n/+E/sub 1/)/sup 1/2/ -2(a/sub 2/(E/sub n/+E/sub 2/)/sup 1/2/) to give values of a/sub i/, the level density parameter, and E/sub i/, the excitation energy for E/sub n/=0. The energies E/sub i/ are interpreted on the basis of the liquid drop model with shell and pairing corrections. Values are deduced for the energy dissipated by viscosity effects in the descent from the saddle point to the point where masses are fixed in the fissioning nucleus. These values are 1.7 MeV for /sup 232/Th(n,f) and 4.8 MeV for /sup 238/U(n,f). These values are consistent with the experimental observation that anti ..nu../sub p/ is approx. 0.6 neutron greater for /sup 239/U fission than for /sup 233/Th fission and that strong odd--even (nucleon pairing) effects are found in the fragment total kinetic energy distribution for /sup 230/Th fission but not for /sup 234/U fission. The low dissipation energy values together with the low values of pre-scission kinetic energy deduced by Guet, et al., (Nucl. Phys. A134 (1971)1) indicate a shorter path from the saddle point of the fissioning nucleus to scission than is generally assumed in theoretical calculations. 31 references.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6247473
• Report Number(s): CONF-790507-7
• Country of Publication: United States
• Language: English

Related Subjects

652026* -- Nuclear Properties & Reactions
A=220 & above
Experimental-- Spontaneous & Induced Fission-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALINE EARTH ISOTOPES
BARIUM 140
BARIUM ISOTOPES
BARYON REACTIONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CADMIUM 115
CADMIUM ISOTOPES
CORRECTIONS
DATA
DATA FORMS
DAYS LIVING RADIOISOTOPES
DEFORMATION
ENERGY DENSITY
ENERGY DEPENDENCE
ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCITATION
EXPERIMENTAL DATA
FISSION
FISSION PRODUCTS
FISSION YIELD
GRAPHS
HADRON REACTIONS
INFORMATION
INTERACTIONS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIQUID DROP MODEL
MASS
MATHEMATICAL MODELS
NEUTRON REACTIONS
NUCLEAR DEFORMATION
NUCLEAR MODELS
NUCLEAR REACTION YIELD
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUMERICAL DATA
PAIRING INTERACTIONS
RADIOACTIVE MATERIALS
RADIOISOTOPES
SADDLE-POINT METHOD
SHELL MODELS
SPECTRA
STRONTIUM 89
STRONTIUM ISOTOPES
TARGETS
THORIUM 229 TARGET
THORIUM 232 TARGET
URANIUM 238 TARGET
VISCOSITY
YIELDS