Wire scanners for beam size and emittance measurements at the SLC

The authors describe the design, construction, commissioning and ultimate uses of wire scanners in the SLC (SLAC Linear Collider), focusing on the linear accelerator and upstream systems scanners. Of particular interest is the interaction between the wire and the scattered radiation from the wire with the extreme electric field of the beam. As this field reaches the level of several volts/angstrom, as it does easily at the SLC interaction point (and may in upstream parts of SLC), field emission from the wire may occur. A key feature of SLC operation is the degree of high level active control required to keep it optimized. 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.<>