Measurement of the Transport Mean Free Path of Thermal Neutrons inD2O by a Boron Poisoning Method

Proceedings of the Brookhaven Conference on Neutron Thermalization, April 30 to May 2, 1962. Volume I. The Scattering Law. Volume Ii. Neutron Spectra in Lattices and Infinite Media. Volume Iii. Experimental Aspects of Transient and Asymptotic Phenomena. Volume Iv. Theoretical Aspects of Transient and Asymptotic Phenomena

“…(35) n LLi, a n s Once the normalization constants, C are given, the WKB eigenfunctions (29) are specified at all points other than the turning points, e and e . In the vicinity of these points once can use the exact solution, which is a combination of Bessel functions of order one-third, (13), or one can join the I'JKB solutions "by eye.…”

“…The technique of poisoning a moderator in order to measure independently the diffusion coefficient and the absorption cross section has been used extensively on D2O (14,29), on graphite (30), and on H2O (11,23,31). Several authors have discussed the importance of "Diffusion…”

“…We shall start from the following premises: a) we investigate only thermal neutrons, i.e., the spectrum has no Fermi component; b) there are no sources in the investin;ated medium; c) the absorption is small. Following [29], we seek the solutions of the kinetic equation …”

“…It is customary to take f (r) ~ I, in which case the theory of Bessel functions leads to analytic expressions for the integrals in (29).…”