Longitudinal emittance growth in the Fermilab booster synchrotron

Abstract

In order to shorten the proton bunches in the Fermilab Tevatron collider, it would be quite helpful to reduce the longitudinal emittance for proton bunches generated by the booster synchrotron. A study was undertaken to reevaluate the sources of longitudinal instability and resultant longitudinal emittance growth as a function of booster beam and bunch currents. Employing a novel technique for generating partially populated circumferences of protons, the booster was tested to understand whether increased longitudinal emittance growth was correlated with total current in the synchrotron, consistent with coupled-bunch instability, or with the number of protons per individual bunch. This paper will present findings that indicate that the instability responsible for poor booster emittance performance is consistent with single bunch (or low cavity-Q) instabilities