An intensity profile monitor for the 855 MeV cw MAMI electron beam

An intensity profile monitor has been integrated into the beam diagnostic system of the Mainz microtron MAMI. The monitor consists of two arrays of five 50 μm thick tungsten wires each, stretched from a common center with angles of 18° to each other. The arrays are moved through the electron beam in the horizontal and vertical direction, respectively. For each wire, the beam profile is recorded by measuring the secondary electron emission current which is proportional to the projected beam intensity. The intensity distribution is reconstructed from the ten beam profiles by using a two-dimensional Fourier transformation similar to the method of computer tomography. The data available in digital form are used for an on-line graphical output or as input for a computer-controlled beam handling system.