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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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A wave of new U.S.-U.K. deals ahead of Trump’s state visit
President Trump will arrive in the United Kingdom this week for a state visit that promises to include the usual pomp and ceremony alongside the signing of a landmark new agreement on U.S.-U.K. nuclear collaboration.
C. H. Blanchard
Nuclear Science and Engineering | Volume 3 | Number 2 | February 1958 | Pages 161-170
Technical Paper | doi.org/10.13182/NSE58-A25458
Articles are hosted by Taylor and Francis Online.
The spatial moments ,, and are calculated exactly for all energies below the source energy, for a point, isotropic source in an infinite, homogeneous medium in which there is no absorption and in which the scatterers scatter like hydrogen but with a 1/υ cross section. For a monoenergetic source these moments are approximately consistent with a diffusion (Yukawa) radial distribution of the very low energy neutrons. Integration over a fission-like source spectrum, exp (—αE), gives moments consistent with a radial distribution of the very low energy neutrons of the form of a first collision density, r-2 exp (—r/λ), but with a mean free path λ approximately twice the mean free path at the average source energy. The results are compared with those given by the first collision approximation.