44 research outputs found
Resonance capture of neutrons in infinite homogeneous media
In a previous paper, a variational principle was introduced for 1 - p, the capture probability for neutrons slowing down in a homogeneous medium of infinite extent. In the present paper, the variational principle is used together with simple but accurate trial functions to obtain expressions for (i) corrections to the commonly used 'narrow resonance' formula for capture and (ii) interference effects in the capture of neutrons by closely spaced resonances
Time-dependent collision cascades
We use the linearized Boltzmann equation to discuss the time dependence of atomic collision cascades. The atoms are presumed to interact via a power-law potential, the power being denoted (-2/a). We wish to ascertain whether the equation, and/or certain special solutions, show striking changes in behavior at certain special values of a. We find a value of a which distinguishes energy-conserving cascades from anomalous cascades, and another which signals the failure of the linear approximation. Scaling, and also the emergence of similarity solutions, are discussed
Nonlinear saturation of electrostatic waves: mobile ions modify trapping scaling
The amplitude equation for an unstable electrostatic wave in a multi-species
Vlasov plasma has been derived. The dynamics of the mode amplitude is
studied using an expansion in ; in particular, in the limit
, the singularities in the expansion coefficients are
analyzed to predict the asymptotic dependence of the electric field on the
linear growth rate . Generically , as
, but in the limit of infinite ion mass or for
instabilities in reflection-symmetric systems due to real eigenvalues the more
familiar trapping scaling is predicted.Comment: 13 pages (Latex/RevTex), 4 postscript encapsulated figures which are
included using the utility "uufiles". They should be automatically included
with the text when it is downloaded. Figures also available in hard copy from
the authors ([email protected]
Spectral representations for the memory kernel characterizing self-diffusion
Approximate spectral representations are developed for the memory kernel which characterizes self-diffusion. These spectral representations are based upon approximate eigenfunctions constructed via the Rayleigh variational principle. A heuristic model is developed first in an effort to provide physical insight into the nature of the approximations employed, and then a number of specific trial functions are examined. These trial functions include sums of identical one- and two-particle functions as well as linear combinations of hydrodynamical variables. The results from these spectral representations indicate that the long-time behavior of the memory kernel (and thereby of the momentum autocorrelation function) is sensitive to the long-range effects of the interparticle potential. In addition, the equivalence of most of these spectral representations to specific low-order perturbation approximations is demonstrated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45130/1/10955_2005_Article_BF01026732.pd
INTEGRAL NEUTRON THERMALIZATION. Annual Summary Report, October 1, 1963- September 30, 1964
Recommended from our members
Brookhaven National Laboratory Reports
Report issued by the Brookhaven National Laboratory discussing a hazards report on replacing the research center's current fuel elements with new highly enriched elements. As stated in the introduction, "this report is a summary of the studies, both theoretical and experimental, which have been made so far of the nuclear properties of the "new" pile, of the stability of the new fuel elements, and of the safety and practicability of operation of the "new" pile" (p. 2). This report includes tables, and illustrations
Lectures from the Second Neutron Physics Conference
http://deepblue.lib.umich.edu/bitstream/2027.42/93610/1/mmpp001.pd