COINCIDENT TIME-OF-FLIGHT MEASUREMENTS OF THE VELOCITIES OF FISSION FRAGMENTS FROM CHARGED-PARTICLE-INDUCED FISSION

Journal Article · Mon Feb 10 04:00:00 EST 1964 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.133.B613· OSTI ID:4115801

Whetstone, Jr., S. L.

Measurements were made of the velocities of the coincident fission fragment pairs emitted in the 25.7- and 29.5Mev He/sup 4/-induced fission of U/ sup 233/ and Th/sup 230/, the 25.7- and 29.5-Mev He/sup 4/-induced fission of Th/ sup 232/, and the 12.0- and 14.0-Mev H/sup 2/-induced fission of Th/sup 230/. Previously unpublished data for the 21.8-Mev He/sup 4/-induced fission of U/sup 233/ and Th/sup 232/ are also included. A decrease in average total fragment kinetic energy for symmetric mass division is observed in each case. The relatively large yield of symmetric mass divisions permits a reliable measurement of this effect. The distributions of fragment velocities, masses, and kinetic energies are consistent with the hypothesis of two competing modes of fission. A comparison is made of the primary mass yields obtained in this work with the yields obtained by radiochemical methods to determine the dependence of prompt neutron emission of fragment mass. The neutron emission found. although subject to poorly known and possibly large uncertainties in the radiochemical data, appears to show a rather pronounced structure of just such a nature as might be attributed to fragment-shell effects that persist to these high excitation energies. Such a structure is not observed, however, when the present primary mass data are compared with mass distributions derived from recent fragment double-energy measurements. The time-of-flight mass distributions were corrected for the influence of the prefission neutron emission and the detection solid angle. As a part of the correction, the dependences of the yield of symmetric mass divisions on the excitation energy of the fissioning nuclei were estimated for each of the target-projectile systems. (auth)

• Research Organization: Los Alamos Scientific Lab., N. Mex.
• NSA Number: NSA-18-009391
• OSTI ID: 4115801
• Report Number(s): LADC-5890; 0031-899X
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 133; ISSN PHRVA
• Country of Publication: United States
• Language: English

Related Subjects

ANGULAR DISTRIBUTION
CHARGED PARTICLES
COINCIDENCE METHODS
DEUTERIUM
EMISSION
ENERGY
EXCITATION
FISSION
FISSION PRODUCTS
HELIUM 4
ION BEAMS
MASS
MEASURED VALUES
PHYSICS
PROMPT NEUTRONS
TARGETS
THORIUM 230
THORIUM 233
TIME OF FLIGHT METHOD
URANIUM 233
VELOCITY