Tevatron study report: Losses vs chromaticity 11/26/02

During the end-of-store study on November 26, 2002, we measured the proton and pbar beam lifetimes and loss rates at 980 GeV as a function of the vertical and horizontal chromaticity. Unlike in previous studies, the two chromaticities were lowered simultaneously. There was no noticable change in the beam lifetime or in the loss rate over about 10 units of chromaticity. Only a gradual 10% increase was seen in the p-bar horizontal Schottky power until an abrupt quench occurred at a cromaticity setting 10 units lower than nominal. This quench appeared to have been caused by the loss of the pbar beam. T. Sen has explained this pbar instability by the large chromaticity difference between protons and antiprotons, which arises from the long-range collisions