Asymptotic of response for pulsed neutron sources according to the limit of experimental time

This paper is devoted to the analysis of the asymptotic of response of a subcritical neutron multiplying system to the pulsed neutron source, taking into consideration the limited time of observation. The paper shows that the exponential drop observed in a number of the experiments corresponds to the 'truncated' operator, introduced in the paper, and not to the asymptotic for the initial operator of the kinetic equation. It is proved that the square of this operator is completely continuous, so the solution may be approximated with a sum of exponents; the first of these determines the asymptotic.