Operational status of the Brookhaven National Laboratory Accelerator Test Facility

The design and operation of a 50-MeV electron linear accelerator utilizing a low emittance ( gamma epsilon =5 to 10 mm-mrad) radio-frequency gun operating at an output energy of 5 MeV and a charge of 1 nC are described. Design calculations, early radio-frequency measurements, and operational experience with the electron gun utilizing a dummy cathode in place of the proposed photocathode emitter are given. The dynamics of the electron beam coming off the photocathode has been modeled with the programs PARMELA and MASK. General agreement as to the expected characteristics of the electron beam at the RF-gun exit has been obtained using the two programs. It was also verified that, with proper matching of the transverse beam, no increase of the transverse normalized emittance occurs at the linac due to the fundamental RF mode.<>