  A Coefficient Inverse Problem for the radiative transport equation is
considered. The globally convergent numerical method, the so-called
convexification, is developed. For the first time, the viscosity solution is
considered for a boundary value problem for the resulting system of two coupled
partial differential equations. A Lipschitz stability estimate is proved for
this boundary value problem using a Carleman estimate for the Laplace operator.
Next, the global convergence analysis is provided via that Carleman estimate.
Results of numerical experiments demonstrate a high computational efficiency of
this approach.
