Conference

High Performance Spot Size Monitors

M. Ross

SLAC, Stanford, USA

Abstract

Beam size estimates made using beam-beam deflections are used for optimization of the SLC electron-positron beam sizes. Typical beam sizes and intensities expected for 1996 operations are 2.1 x 0.6um (x,y) at 4E10**10 particles per pulse. Conventional profile monitors, such as scanning wires, fail at charge densities well below this and since the beam-beam deflection does not provide single beam information another method is needed for Interaction Region (IP) beam size optimization. A laser based profile monitor that uses a finely focused 350 nm wavelength tripled YLF pulse has been built and installed in the SLD detector. The pulse traverses the particle path about 29cm away from the IP, just at the edge of the new SLD vertex detector. Compton scattered photons and degraded e+/e- are detected as the beam is steered across the laser pulse. The laser pulse has a transverse size (sigma) of 380nm and a Rayleigh range of 5um. This is adequate for present or planned SLC beams. Design and preliminary results will be presented.

sln 30 April 1996