RADIATIVE CAPTURE OF FAST NEUTRONS
Technical Report
·
OSTI ID:4305741
A new and universal method for measurement of radiative capture cross sections has been developed. The method is applicable to the measurement of capture cross sections for nearly all nuclides and can be used with neutrons of any energy from the thermal region to a few Mev. Monoenergetic neutrons from 150 kev to 1 Mev have been used to date. A pulsed and collimated neutron beam is passed through the capturing sample at the center of a large liquid scintillator. Capture is detected by counting the capture gamma radiation in the scintillator in coincidence with the pulsed beam. The cross section is determined by comparison with the fission plus capture rate in a sample of U/sup 235/ since the cross sections for these processes are well-known. The samples consist of a large number of thin discs 3.7 cm in a diameter and 1 mm or lean in thickness, separated by several millimeters. The resulting sample is reasonably transparent to the capture gamma radiation produced in it. The liquid scintillator is a cylinder approximately 1 meter in diameter and length, with an axial cylindrical opening 7 cm in diameter. The neutron beam passes along the axial tube and through samples. The techniques of this experiment allow one to measure the radiative capture cross section of any substance which is not too radioactive and which can be obtained in quantities of one-tenth mole or more. The accuracy so far achieved is about 10% or 1 millibarn, whichever is larger. The energy range covered is 150 kev to 1 Mev, and preparations are underway to extend the range down to 30 kev. The upper limit on neutron energy arises from the necessity of rejecting those pulses due to slowing down of scattered neutrons and to gamma rays from inelastic scattering. The elements studied to date are Ni, Mo, In, Ta, Au, Cr, Fe, Zr, Nb, U/sup 235/, U/sup 238/, Pu/sup 239/, Cd, and Cu. (auth)
- Research Organization:
- Los Alamos Scientific Lab., N. Mex.
- NSA Number:
- NSA-12-014970
- OSTI ID:
- 4305741
- Report Number(s):
- A/CONF.15/P/667
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
BACKGROUND
CADMIUM
CAPTURE
CHROMIUM
COINCIDENCE METHODS
COPPER
CROSS SECTIONS
CYLINDERS
ENERGY RANGE
ERRORS
FAST NEUTRONS
FISSION
GAMMA DETECTION
GAMMA RADIATION
GOLD
INDIUM
INSTRUMENTS
IRON
ISOTOPES
KEV RANGE
LIQUIDS
MEASURED VALUES
MEV RANGE
MOLYBDENUM
NEUTRON BEAMS
NICKEL
NIOBIUM
PHYSICS
PLATES
PLUTONIUM 239
PULSES
SCINTILLATION COUNTERS
STANDARDS
TANTALUM
TARGETS
THICKNESS
URANIUM 235
URANIUM 238
ZIRCONIUM
CADMIUM
CAPTURE
CHROMIUM
COINCIDENCE METHODS
COPPER
CROSS SECTIONS
CYLINDERS
ENERGY RANGE
ERRORS
FAST NEUTRONS
FISSION
GAMMA DETECTION
GAMMA RADIATION
GOLD
INDIUM
INSTRUMENTS
IRON
ISOTOPES
KEV RANGE
LIQUIDS
MEASURED VALUES
MEV RANGE
MOLYBDENUM
NEUTRON BEAMS
NICKEL
NIOBIUM
PHYSICS
PLATES
PLUTONIUM 239
PULSES
SCINTILLATION COUNTERS
STANDARDS
TANTALUM
TARGETS
THICKNESS
URANIUM 235
URANIUM 238
ZIRCONIUM