Study of neutron propagation in multigroup transport by space asymptotic methods

In this work the space asymptotic theory is used for the study of the propagation of neutron pulses in multigroup transport. Pulsed experiments are of interest in the study and characterization of source-driven subcritical systems. The model allows for an exact analytic treatment, although it can be applied only to highly idealized configurations. Therefore, the objective of the investigation is to obtain a good physical insight into the phenomena and to derive highly accurate results to be used as benchmarks. The solution is obtained by a combined application of the Fourier and Laplace transforms. The inversion of the Laplace transform is attained by the use of the residue theorem, which, through the study of the singularities of the transformed solution, allows interesting physical considerations. The solution is exact until the particles, moving with a finite velocity, reach the external boundary of the system. Numerical results for some typical propagation problems are presented for one-dimensional plane systems.