Ionization beam-profile monitor at HIMAC

A prototype non-destructive beam-profile monitor employing tandem-type MCPs has been designed and tested at HIMAC. The monitor can measure the vertical beam profile of a circulating ion beam in the synchrotron. In a series of tests, however, it was found that the monitor had a defect in the accuracy of the measured profiles. It was caused by an electric field distortion in the work area. The electric field was improved so as to create a uniform equipotential distribution with the aid of a 3D-field simulation code. The field-shaping electrodes were replaced to longer ones, and the applied voltages of each electrode were changed to the optimum values. The monitor has been successfully used for studies of electron cooling as well as monitoring the beam under normal-mode operation in the HIMAC synchrotron.