Realization of a large-acceptance Faraday Cup for 3 MeV electrons

The design, construction, installation, and testing of a Faraday Cup intended to measure the current of a 3 MeV, 1 μA electron beam is described. Built as a current monitor for a Møller scattering measurement at the MIT High Voltage Research Laboratory, the device combines a large angular acceptance with the capability to measure a continuous, low energy beam. Bench studies of its performance demonstrate current measurements accurate to the percent level at 1 μA. The Faraday Cup was designed and constructed at MIT and has been in use at the HVRL since 2017, providing a significantly more detailed measurement of beam current than was previously available.