ANGULAR-DISTRIBUTION OF HARD PHOTONS FROM 1.2 GEV CHANNELING ELECTRONS IN SI

We have measured the angular distribution of high energy tagged photons emitted from 1.2 GeV electrons in an aligned Si crystal. The angular distribution is appreciably broader when the electron beam is parallel to the crystal axis [110] than in the case of random orientation. Moreover, for slightly oblique entrance, the angular distribution is asymmetric around the beam direction. Similar behaviors have been observed also in the angular distribution of the electron beam which passed through the Si crystal. The relation between these angular anomalies and the previously reported intensity anomaly is discussed.