Operational Health Physics Aspects of a Microtron Accelerator for a Free Electron Laser

More than a year of operation of a new energy tunable (11-22 MeV) circular microtron accelerator at AT&T Bell Laboratories has resulted in conditions approaching those required for free electron laser (FEL) operation in the far infrared. Design criteria of any accelerator facility is, of course, unique to the application for that facility. Guides like NCRP 51 'Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities" were used to establish a safe working environment for personnel. An add on use for this machine involved the need to generate positrons from the beam dump and to direct the positron beam into a room between the microtron beam dump tunnel and the beam dump room of a 1.5 MeV electron accelerator. Appropriate shielding reduced the gamma levels to 0.2 mR/hr and the neutron levels to background. The rf radiation is less than 16 volts per meter over a frequency range from 0.5 to 6000 Mhz.