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Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron

Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron. Mike Martens, Jerry Annala, Pierre Bauer, Vladimir Shiltsev, Gueorgui Velev 2005 Particle Accelerator Conference Knoxville, Tennessee May 16, 2005. b 2 Drift & Snapback. 980 GeV Flattop.

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Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron

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  1. Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron Mike Martens, Jerry Annala, Pierre Bauer, Vladimir Shiltsev, Gueorgui Velev 2005 Particle Accelerator Conference Knoxville, Tennessee May 16, 2005 PAC 2005, May 16, 2005

  2. b2 Drift & Snapback 980 GeV Flattop Effects discovered during Tevatron commissioning 150 GeV Injection Porch Tevatron Energy Ramp 90 GeV Reset b2 snaps back at start of ramp b2 drifts at 150 Gev PAC 2005, May 16, 2005

  3. What’s New • “Discovery” of Tune and Coupling Drift • Documented and compensated for first time in Run II • Challenge of Run II beam intensities • From 66 to 3636 • Improved Magnet Measurements • P. Bauer (MOPA001), G. Velev (TPAPO29) • Beam Measurements • Focus of this talk • Improved compensation algorithms • Better understanding of dynamic effects • Elimination of the “Dry Squeeze” Pre-cycle PAC 2005, May 16, 2005

  4. Tune Drifts in the Tevatron Horizontal Tune Vertical Tune PAC 2005, May 16, 2005

  5. Coupling Drifts in the Tevatron Horizontal Tune Vertical Tune PAC 2005, May 16, 2005

  6. Tune Snapback on the Ramp After fixes 0.02 tune units 153 Gev Desired tunes (red lines) at 0.575 and 0.583 • Large tune/coupling excursions near start of ramp (150  153 Gev): • Tune/coupling changes of (0.02 tune units, 0.02 minimum tune split) • Variations fixed with tune/coupling snapback correction at start of ramp. PAC 2005, May 16, 2005

  7. Magnitude of Drifts Magnitude of drifts requires compensation using corrector magnets. *After 1 hour on Injection Porch PAC 2005, May 16, 2005

  8. Explore dependence of ramp history with offline magnet measurements. Example: Magnitude of drift depends on flattop time b2 (units @ 1 inch) Saturates after 1 hour at flattop. Time at flattop (min) PAC 2005, May 16, 2005

  9. Parameterization of Dynamic Effects Fast drift for few secs, then log drift with ts = ~300 sec Gaussian Snapback More drift means longer snapback time. PAC 2005, May 16, 2005

  10. Chromaticity in the Tevatron b2      Measure Measure Measure Calculate Calculate Measure/estimate average b2 in the Tevatron dipoles PAC 2005, May 16, 2005

  11. Measured b2 Drift in Tevatron PAC 2005, May 16, 2005

  12. Measurement of snapbackat the start of Tevatron Ramp 1 hour front porch 6 sec. front porch b2,hysteretic (E) = -4.75 + 0.063  E + 0.00049  (E)2 PAC 2005, May 16, 2005

  13. Measurement of snapback 6 sec front porch: b2(t) = b2,hyst + 0.21exp(-(t/1.45)2) 1 hour front porch: b2(t) = b2,hyst + 1.69exp(-(t/4.75)2) PAC 2005, May 16, 2005

  14. Tune Drift @ 150 Gev After correction algorithm was implemented We like (t) < 0.002 Why does the tune drift? Is it related to b2 drift? PAC 2005, May 16, 2005

  15. Conclusions • Chromaticity, Tune, and Coupling Drift and Snapback have been measured in the Tevatron. • Understanding has been improved and led to updated correction algorithms. • Agreement between magnet measurements and Tevatron measurements PAC 2005, May 16, 2005

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