EMISSION OF PROMPT GAMMA RAYS IN THERMAL NEUTRON FISSION OF U-235

Technical Report · Tue Jan 01 00:00:00 EST 1963

OSTI ID:4162325

Kapoor, S S; Ramanna, R

The angular distrubutions of prompt fission gamma rays with respect to the direction of selected fission fragments in the thermal neutron fission of U/ sup 235/, were studied for two different gamma energy groups using a gridded ionization chamber-scintillation detector assembly. The ionization chamber measured the fragment kinetic energies and the angles of their tracks with respect to the flight direction of the gamma rays detected by a plastic scintillator placed along the electric field direction of the chamber. A timeof- flight method was used to eliminate fission neutron background. From the measured angular distributions with respect to the direction of the selected light fragments, the laboratory anisotropies {N(0 deg ) -- N(90 deg )}/N(0 deg ) for gamma energies >180 and 510 kev were found to be 14.9% and 12.2%, respectively. For the ratio of the intensities of the gamma rays of energies?180 kev along the direction of the selected light and heavy fragments, a value of (0.985 plus or minus 0.024) was obtained, showing that the laboratory anisotropies with respect to the light and heavy fragments are nearly the same. These measurements definitely show the existence of a significant anisotropy of gamma emission in the emitting fragment system after making allowance for the motion of the fragments. The emission anisotropy is explained as arising due to the polarized angular momenta of the fission fragments, which also enhances the gamma ray emission. The gamma emission from the rotating fragments is discussed with respect to the observed number and the spectrum of the gamma rays. (auth)

• Research Organization: India. Atomic Energy Establishment, Trombay
• NSA Number: NSA-18-001000
• OSTI ID: 4162325
• Report Number(s): AEET/NP/7
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-64
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

PHYSICS
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
ANISOTROPY
BACKGROUND
ELECTRIC FIELDS
EMISSION
ENERGY RANGE
FISSION
FISSION PRODUCTS
GAMMA RADIATION
IONIZATION CHAMBERS
KEV RANGE
MEASURED VALUES
MOMENTUM
MOTION
PARTICLE TRACKS
POLARIZATION
ROTATION
SCINTILLATION COUNTERS
SPECTRA
THERMAL NEUTRONS
URANIUM 235
VELOCITY