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Neutron transport (also known as neutronics) is the study of the motions and interactions of neutrons with materials. Nuclear scientists and engineers often need to know where neutrons are in an apparatus, in what direction they are going, and how quickly they are moving.
The Monte Carlo method for radiation particle transport has its origins at LANL dates back to 1946. [3] The creators of these methods were Stanislaw Ulam, John von Neumann, Robert Richtmyer, and Nicholas Metropolis. [4] Monte Carlo for radiation transport was conceived by Stanislaw Ulam in 1946 while playing Solitaire while recovering from an ...
In the case of time-independent monochromatic radiation in an elastically scattering medium, the RTE is [1] (,) = (,) + (,) (, ′) ′where the first term on the RHS is the contribution of emission, the second term the contribution of absorption and the last term is the contribution from scattering in the medium.
The FERMIAC employed the Monte Carlo method to model neutron transport in various types of nuclear systems. Given an initial distribution of neutrons, the goal of the process is to develop numerous "neutron genealogies", or models of the behavior of individual neutrons, including each collision, scattering, and fission. When a fission occurs ...
The classic example of such a system is a fluid with temperature gradients in space causing heat to flow from hotter regions to colder ones, by the random but biased transport of the particles making up that fluid. In the modern literature the term Boltzmann equation is often used in a more general sense, referring to any kinetic equation that ...
Neutron flux in asymptotic giant branch stars and in supernovae is responsible for most of the natural nucleosynthesis producing elements heavier than iron.In stars there is a relatively low neutron flux on the order of 10 5 to 10 11 cm −2 s −1, resulting in nucleosynthesis by the s-process (slow neutron-capture process).
This involves computing exact or approximate solutions of the transport equation, and there are various forms of the transport equation that have been studied. Common varieties include steady-state vs time-dependent, scalar vs vector (the latter including polarization), and monoenergetic vs multi-energy (multi-group).
The Placzek transient is a discontinuity of the neutron flux, and derivatives of the flux, at integer multiples of . The transient results from the fact that after the 1st generation, every neutron can have at minimum an energy of E m i n = α E {\displaystyle E_{min}=\alpha E} due to elastic scattering.