A RECALIBRATION OF THE NBS STANDARD THERMAL NEUTRON FLUX
The Standard Thermal Neutron Flux of the National Bureau of Standards is recalibrated in terms of the thermal neutron absorption cross section of gold. This is accomplished by beta - gamma coincidence counting of activated gold foils approximately 0.001 in. and 0.00025 in. thick in a 4 pi -scintillation counter geometry. The value obtained is 4167 neutrons/cm/sup 2/ sec plus or minus 1.5 per cent. When averaged with a previous calibration made with boron foils the final value for the cadmium difference flux is 4203 neutrons/cm/sup 2/ sec plus or minus 1.5 per cent. Measurement of the cadmium ratio for various thicknesses of gold yields a value of 0.0235 plus or minus 2 per cent for the epithermal flux parameter, r, of Westcott's convention. Using this convention the value of the flux is 4225 neutrons/ cm/sup 2/ sec plus or minus 1.5 per cent. (auth)
- Research Organization:
- National Bureau of Standards, Washington, D.C.
- NSA Number:
- NSA-15-025444
- OSTI ID:
- 4016916
- Journal Information:
- J. Nuclear Energy, Pts. A & B. Reactor Sci. and Technol., Journal Name: J. Nuclear Energy, Pts. A & B. Reactor Sci. and Technol. Vol. Vol: 4
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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