Experimental investigation of the long-wavelength radiation of relativistic particles moving along the arc of a circle

We measure experimentally the angular distribution of radiation by relativistic particles in the field of a bending magnet with a rectilinear segment between the point of emergence of the beam and the magnet. We show that the observations are in agreement with the calculated radiation for motion of particles along the actual trajectory. It turns out that the radiation from the rectilinear segment (transition radiation) and from the circular arc (synchrotron radiation) strongly interfere, and therefore division of the total radiation into transition radiation and synchrotron radiation makes no sense under these experimental conditions.