Bunch - Length and Beam - Timing Monitors in the SLC Final Focus

During the 1997/98 luminosity run of the Stanford Linear Collider (SLC), two novel RF-based detectors were brought into operation, in order to monitor the interaction-point (IP) bunch lengths and uctuations in the relative arrival time of the two colliding beams. Both bunch length and timing can strongly a ect the SLC luminosity and had not been monitored in previous years. The two new detectors utilize a broad-band microwave signal, which is excited by the beam through a ceramic gap in the nal-focus beam pipe and transported outside of the beamline vault by a 160-ft long X-Band waveguide. We describe the estimated luminosity reduction due to bunch-length drift and IP timing uctuation, the monitor layout, the expected responses and signal levels, calibration measurements, and beam observations.