FISSION FRAGMENT VELOCITY DISTRIBUTION AND COINCIDENT GAMMA SPECTRA FOR Cf$sup 25$$sup 2$

Technical Report · Sat Oct 31 04:00:00 EST 1959

OSTI ID:4258405

Fraser, J S; Milton, J C.D.

The velocitics of both fragments from the spontaneous fission of Cf/sup 252/ were measured by the time-of-flight method. The pulse-height spectrum produced by the prompt gamma rays in a large NaI(Tl) crystal was recorded simultaneously with the velocity data. The average total kinetic energy of the fragments before neutron emission was found to be 181.9 plus or minus 5 Mev. The full width at half maximum of the kinetic-energy distributions decreases from 22 Mev near symmetric fission to 17 Mev at the most probable mass ratio of 1.33 then increases to 20 Mev for the more asymmetric modes. The widths of the kinetic-energy distributions were corrected for neutron recoil and tae average total kinetic energy for the effect of the angular dispersion of the fragments by the prompt neutrons. The corrected width of the kinetic-energy distribution at the most probable mass ratio (17 Mev) is in agreement with the corresponding fluctuation in fragment excitation energy that is required to explain the known prompt-neutronnumber distribution. The yield of gamma rays shows a pronounced dip in the region where the mass of one of the fragments is close to that of the doubly-magic nucleus /sub 50/Sn/sup 132/. There is some evidence that the average gamma-ray energy is higher in this region. A similar but less pronounced trend is indicated in the region where the light fragment is near the 50-neutron shell. The influence of the /sub 50/Sn/sup 132/ core is also seen in the kinetic- energy distribution. (auth)

• Research Organization: Atomic Energy of Canada Ltd., Chalk River, Ont.
• NSA Number: NSA-13-006960
• OSTI ID: 4258405
• Report Number(s): A/CONF.15/P/199; AECL-609
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANGULAR DISTRIBUTION
CALIFORNIUM 252
COINCIDENCE METHODS
CRYSTALS
DISPERSIONS
DISTRIBUTION
EMISSION
ENERGY
EXCITATION
FISSION
FISSION PRODUCTS
GAMMA RADIATION
GAMMA SPECTROMETERS
MEASURED VALUES
NEUTRONS
NUCLEAR MODELS
PHYSICS AND MATHEMATICS
PRODUCTION
RECOILS
SHELL MODELS
SODIUM IODIDES
SPECTRA
TIN 132
VELOCITY
WIDTH