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Hanft, R.

Paper Title Page
MOPLT120 Proposals for Improvements of the Correction of Sextupole Dynamic Effects in the Tevatron Dipole Magnets 818
 
  • P. Bauer, G. Ambrosio, J. Annala, J. DiMarco, R. Hanft, M. Lamm, M. Martens, P. Schlabach, D. Still, M. Tartaglia, J. Tompkins, G. Velev
    Fermilab, Batavia, Illinois
  
  It is well known that the sextupole (b2) components in the superconducting dipole magnets decay during the injection plateau and snap back rapidly at the start of the ramp to flat top current. These so-called dynamic effects were originally discovered in the Tevatron. They are compensated for by the chromaticity correctors distributed around the ring. Imperfect control of the chromaticity during the snapback can contribute to beam loss and emittance growth. A thorough investigation of the chromaticity correction in the Tevatron was launched in the context of Run II, including beam chromaticity measurements and extensive magnetic measurements on a series of spare Tevatron dipole magnets. The study has yielded new information about the effect of the powering history on the dynamic b2. A companion paper at this conference describes in detail the results of these magnetic measurements [reference to George Velev's paper]. Study findings have given directive to new proposals for improvement of the b2 snapback correction in the Tevatron, including a revised functional form for the snapback algorithm and the elimination of the beam-less pre-cycle. This paper reports the results of beam studies performed recently to test these improved procedures.  
WEPKF075 Measurements of Sextupole Decay and Snapback in Tevatron Dipole Magnets 1780
 
  • G. Velev, J. Annala, P. Bauer, J. DiMarco, H. Glass, R. Hanft, R. Kephart, M. Lamm, M. Martens, P. Schlabach, C. Sylvester, M. Tartaglia, J. Tompkins
    Fermilab, Batavia, Illinois
  
  To optimize the performance of the Fermilab Tevatron accelerator in Collider Run II, we have undertaken a systematic study of the drift and subsequent snapback of dipole magnet harmonics. The study has mostly focused on the dynamic behavior of the normal sextupole component, b2, as measured in a sample of spare Tevatron dipoles at the Fermilab Magnet Test Facility. We measured the dependence of the decay amplitude and the snapback time on Tevatron ramp parameters and magnet operational history. A series of beam studies was also performed [*]. This paper summarizes the magnetic measurement results and describes an optimization of the b2 correction scheme which is derived from these measurements.

* P.Bauer et al. These proceedings.