Current Profile Monitor for Use in Scanning Electron Beam Irradiations

A current profile monitor for the scanning electron beam from the accelerator is described. It utilizes the fact that the electrons scattered through large angles by the exit window of the scanner show a profile similar to that of the main beam at the irradiation site. The scattered electrons are collected by small probes arranged in a linear array parallel to the scanning direction, and the beam profile in this direction is displayed by a storage oscilloscope or an X‐Y recorder. This device has been used for electrons of energies 4–16 MeV from a linear accelerator and proved to be useful for continual monitoring with negligible disturbance to the irradiation in progress.