Operational experience with using collimators to remove halo in the Tevatron collider

It is pointed out that in the case of the Tevatron collider the signal will be proportional to the luminosity. One form of noise comes from large emittance particles interacting on the beam pipe walls near the experiment. Scraping these particles with a collimator may reduce the signal a little bit but can reduce the noise greatly. The key is striking a balance and scraping enough to reduce background without losing much luminosity. Operational experience with the Tevatron collider shows how this can be done. Scrapers have also been used to produce very small emittance beam (~5 π) for E710, an experiment measuring very-small-angle elastic scattering and the total cross section