Wire scanners for beam size and emittance measurements at the SLC

The SLC wire scanner beam profile monitors provide accurate beam size and emittance measurements for each bunch in the three bunch SLC beam. The beam size measurement error for typical 50GeV SLC linac beams (100μm σ(x,y)) is better than 5μm. Beam profile measurements can be performed throughout much of the SLC with no interruption to normal machine operation and no adverse impact on interaction region detector backgrounds. The linac input and output emittance is determined using sets of four scanners spaced by ∼45 degree betatron phase advance. Each scanner contains three wires, x, y and u (45 degree), from which an estimate of the x-y coupling can be obtained. Advanced high level control software allows the use of wire scanner data in feedback and beam optimization procedures. Non-invasive scans are performed almost continually and the results are logged so that long term trends in emittance can be examined. In this paper the authors describe the design, construction, performance and uses of SLC wire scanners