An apparatus for measuring the beam emittance of the Tohoku AVF cyclotron

An emittance-measuring system for beams from an AVF (azimuthally varying field) cyclotron was designed, constructed and tested, and has been proved to be very useful for operation and adjustment of the cyclotron. This system, based on the one-slit—multidetector method and controlled by microcomputers, can give an elliptical phase-space contour of a beam within one minute. An example of characteristics of an extracted beam is shown for a set of parameters of the cyclotron for 20 MeV protons.