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Fast and slow processes in the fragmentation of /sup 238/U by 85 MeV/nucleon /sup 12/C

Journal Article · · Phys. Rev. C; (United States)
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Target fragment distributions were measured using radiochemical techniques for 48 different fragments (28< or =A< or =185) from the interaction of 85 MeV/nucleon /sup 12/C with /sup 238/U. The laboratory system angular distributions are forward peaked and generally flat beyond 90/sup 0/. When compared to similar distributions from the 85 MeV/nucleon /sup 12/C+/sup 197/Au reaction, the U target fragment distributions are less forward peaked, consistent with lower momentum transfer. The (A = 80--120) fission fragment distributions were symmetric about 90/sup 0/ in the moving frame, indicative of a ''slow'' process in which statistical equilibrium has been established. The average fissioning system angular momentum was deduced to be 25-35 h. The observation that the fragments with low N/Z showed more anisotropic distributions than fragments with high N/Z was accounted for in firestreak model calculations as being due to a single reaction mechanism with varying amounts of deposition energy. The lightest (A<60) and heaviest (A = 139-169) members of the central fission-like bump in the mass distribution had moving frame angular distributions that were asymmetric in the moving frame. Furthermore, the heavy fragment complement of the /sup 46/Sc distribution was similar in shape to the /sup 146/Gd distribution, suggesting these fragments were produced in a new intermediate energy reaction mechanism, a fast, non-equilibrium, very asymmetric fission of a heavy nucleus.

Research Organization:
The Studsvik Science Research Laboratory, S-61182 Nykoeping, Sweden
OSTI ID:
5957369
Journal Information:
Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 33:3; ISSN PRVCA
Country of Publication:
United States
Language:
English

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Related Subjects

652026* -- Nuclear Properties &amp; Reactions
A=220 &amp; above
Experimental-- Spontaneous &amp; Induced Fission-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
ASYMMETRY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CARBON 12 REACTIONS
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DATA
DAYS LIVING RADIOISOTOPES
DETECTION
DIFFERENTIAL CROSS SECTIONS
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
ENERGY RANGE
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FISSION
FISSION FRAGMENT DETECTION
FRAGMENTATION
GADOLINIUM 146
GADOLINIUM ISOTOPES
GEV RANGE
GEV RANGE 01-10
HEAVY ION REACTIONS
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
RADIATION DETECTION
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
SCANDIUM 46
SCANDIUM ISOTOPES
SECONDS LIVING RADIOISOTOPES
TARGETS
URANIUM 238 TARGET