Neutral particles are fired at normal incidence into a purely absorbing slab of…

PHYSICS · Multi-part · Fermi University Physics · Mathematical Methods for Physics · Computational Physics · Monte Carlo and lattice simulation of physical systems

Error, Chance and the Machine, Ch Monte Carlo integration and variance reduction

Problem

Neutral particles are fired at normal incidence into a purely absorbing slab of thickness L=4L = 4 mean free paths ℓ\ell. Each particle's free path is sampled by s=−ℓln⁡us = -\ell\ln u with uu uniform on (0,1)(0,1); if s<Ls < L the particle is absorbed, otherwise it is transmitted. In a run of N=1×105N = 1\times10^5 histories, nT=1832n_T = 1832 particles are transmitted. ((a)) Give the estimated transmission fraction and its standard error, treating each history as a Bernoulli trial. ((b)) Compare with the analytic transmission e−L/ℓe^{-L/\ell} and state whether the simulation is consistent with it.

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