Diffusive radiation is a new type of radiation predicted to occur in randomly inhomogeneous media due to the multiple scattering of pseudophotons. This theoretical effect is now observed experimentally. The radiation is generated by the passage of electrons of energy $200\mathrm{KeV}–2.2\mathrm{MeV}$ through a random stack of films in the visible light region. The radiation intensity increases resonantly provided the Čerenkov condition is satisfied for the average dielectric constant of the medium. The observed angular dependence and electron resonance energy are in agreement with the theoretical predictions. These observations open a road to application of diffusive radiation in particle detection, astrophysics, soft-x-ray generation, etc.

• Received 24 January 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.044801