Ambient betatron motion and its excitation by ghost lines in Tevatron
  Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time varying ghost lines in the betatron spectra are reported. 
Vladimir Shiltsev, Giulio Stancari, Alexander Valishev (Fermilab)
physics.acc-ph