RADIATION FROM RELATIVISTIC ELECTRONS IN HOMOGENEOUS CONDENSED MATTERAT LARGE ANGLES (MUCH-GREATER-THAN-GAMMA(-1))

The radiation spectra from 900 and 400 MeV electrons in thin Ta, Cu, a nd Sn foils are measured at an angle of 19 degrees with respect to the direction of motion of the beam. The radiation yield and its dependen ce on the electron energy agree satisfactorily with the theory of pola rization bremsstrahlung. This result represents the first direct obser vation of polarization bremsstrahlung from ultrarelativistic electrons in homogeneous condensed matter. (C) 1996 American Institute of Physi cs.