Evaluating importance maps for TRIPOLI-4 R using deterministic or on-line methods

However, the estimation of the response of a particle detector in a strongly attenuated radiation field is very computationally intensive. Radiation-protection problems, by definition, fall into this class, and are therefore intractable with Monte-Carlo methods unless suitable variance-reduction techniques are applied. A common need for variance-reduction methods is to evaluate particle tracks with respect to their expected contribution to the sought detector response. Any function providing such an estimate for each point of the phase space is generally known as an $importance\ map$. For a certain class of variance-reduction algorithms, the provably optimal choice for the importance function is represented by the adjoint flux, i.e. the solution of the adjoint fixed-source Boltzmann equation. .