Long-wave radiation of relativistic particles, moving along arc in external magnetic field in the presence of rectilinear trajectory upstream of inlet in magnet

Angular distribution of relativistic particles radiation in the field of a deflecting magnet in the presence of a finite rectilinear gap between the point of the beam exit from the gap and the magnet was measured experimentally. It is shown that the observations made are in a satisfactory agreement with the calculation of radiation for the case of the particles moving along an actual trajectory. It turned out that radiation on the rectilinear gap (transition radiation) and radiation on a circumferential segment (synchrotron radiation) interfere strongly therefore, separation of total radiation into transition and synchrotron ones under experimental conditions is not resonable