Tevatron study report: measuring pbar tunes with tan s-system, beam separation, and pbar removal from 12 Mar 03 2002

*visiting from CERN - 1 - AB-Note-2003-010 (MD) TEVATRON STUDY REPORT: MEASURING PBAR TUNES WITH TAN'S-SYSTEM, BEAM SEPARATION, AND PBAR REMOVAL 12/03/02 F. ZIMMERMANN*, G. ANNALA, V. SHILTSEV, D.STILL, C.Y. TAN, X.L. ZHANG During a dedicated machine study on December 03, 2002, we measured tunes of all individual pbar bunches by exciting them with the tune meter and detecting the resulting signals on the pbar Schottky monitors. We found that the horizontal tune is significantly lower for the first bunch in each train, and some evidence that the vertical tune of the last bunch is also below the average. This behavior is exactly opposite to the theoretical prediction. Separating the beams at B0 and D0, we could infer the head-on beam-beam tune shift experienced by the pbars. The horizontal tune shift was consistent with the expectation, about 0.006 at this intensity. Vertically the measured tune shift was significantly smaller than expected. Finally, we made a new attempt of cross-calibrating the available beam-size detectors by scraping. After removing 10% of the pbars, this experiment was terminated by a quench.