Measurement facility for new acceleration techniques

Interest in developing new, high gradient acceleration techniques is growing rapidly. Experimental investigation of new concepts, however, lags noticeably behind the ideas. To a large extent this situation arises simply because the very specialized beams and diagnostics required to make the necessary measurements are not available. A facility is being constructed at ANL which will permit the direct measurement of wake fields for a variety of experimental conditions. A single, short bunch of 22 MeV electrons from an existing linac is manipulated to form two separate pulses which can be set to a specified time and space separations. Normally, the leading pulse will be an intense, full energy pulse of a few times 1010 electrons less than 10 psec in length. The trailing witness pulse will be at roughly 3/4 the energy of the leading pulse, will contain fewer electrons, and will have the same pulse length as the leading driver pulse. Energy gain/loss and deflections of each pulse will be measured after the bunch doublet has passed through the wake structure under test. Design specifications and project status are presented