An inverse problem for the linear Boltzmann equation with a time-dependent coefficient

In this paper, we study the stability in the inverse problem of determining the time-dependent absorption coefficient appearing in the linear Boltzmann equation from boundary observations. We prove in dimension n >= 2 that the absorption coefficient can be uniquely determined in a precise subset of the domain from the albedo operator. We derive a logarithm-type stability estimate in the determination of the absorption coefficient from the albedo operator in a subset of our domain, assuming that it is known outside this subset. Moreover, we prove that we can extend this result to the determination of the coefficient in a larger region, and then in the whole domain, provided that we have much more data. We prove also an identification result for the scattering coefficient appearing in the linear Boltzmann equation.