Finding mechanisms responsible for the spectral distribution of electron beams produced by a linear accelerator

The measured electron spectra of linear accelerators from several manufacturers differ in comparison to the spectral form and width. As part of our investigations of linac performance and stability, we analyzed the electron spectra of our linacs. After building a spectrometer the electron spectra were measured. The measured spectral widths were comparable with the results published in the literature. It appeared that the phase of the recycled radio pulse in combination with the limited bandwidth of the bending magnet are responsible for unusual (multipeak) electron spectra. The scatter filters only have a relatively small widening effect on the spectrum. There was no indication that multipeak or wide spectra are related to linac instabilities.