A DETERMINATION OF THE ABSOLUTE NEUTRON FISSION CROSS SECTION OF U$sup 23$$sup 5$
The absolute neutron fission cross section of U/sup 235/ at 0.0253 ev has been determined by measuring ( sigma /sub t/ sigma /sub f/) at 5.3 A and combining this with scattering, absorption, and relative fission cross section measurements. Two multiplate ionization chambers, one containing B/sup 10/ and the other U/sup 235/, were constructed. The flux is determined by making the two chambers as alike as possible and comparing counting rates in the same neutron beam. The amounts of U/sup 235/ and B/sup 10/ in the beam are determined by transmission measurements. After corrections for chamber efficiencies, residual differences between chambers, and incoherent scattering, a value for (1 + alpha ) = 1.171 plus or minus 0.009 at 5.3 A was obtained where alpha = ( sigma / sub n gamma / sigma /sub f/). This leads to a value of 580 plus or minus 7 barns as the absolute fission cross section at 0.0253 ev. These results are independent of the absolute neutron cross section of B/sup 10/. (auth)
- Research Organization:
- Columbia Univ., New York. Pupin Cyclotron Lab.; Columbia Univ., New York. George B. Pegram Lab.
- NSA Number:
- NSA-13-017053
- OSTI ID:
- 4239179
- Report Number(s):
- CU-186
- Country of Publication:
- United States
- Language:
- English
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