Setsuro FUJIIE,Thierry RAMOND Breit-Wigner Formula at Barrier Tops (329K, PDF) ABSTRACT. For non-critical energies, the asymptotic behaviour of the scattering phase and of the time-delay are known to be described by a Weyl type formula and the Breit-Wigner formula respectively. We consider here the case of critical energy levels in dimension 1. We obtain the semiclassical asymptotics of the scattering phase and of the time-delay, uniformly with respect to the energy in a neighborhood of a critical value.