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Update on Field Model: Tune and Chromaticity at CERN - March 8, 2011

This update from CERN provides insights into the decay of tune and chromaticity, analysis of reconstruction during ramp, undercorrection at injection, snapback estimates, conclusions, and more on field model dynamics. Stay informed on the latest research developments from CERN.

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Update on Field Model: Tune and Chromaticity at CERN - March 8, 2011

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  1. CERN, 8th March 2011 UPDATE ON FIELD MODEL: TUNE AND CHROMATICITY N. Aquilina, M. Lamont, E. Todesco CERN, Geneva Switzerland

  2. TUNE DECAY • Decay of tune looks 70% of last year • Amplitude: 0.020-0.025 units Time constant: 4000 s • We can try the dynamic correction when we want Tune decayduringseveral injections in 2011 and 2010 (N. Aquilina)

  3. CHROMATICITY DECAY • Decay of chromaticity looks similar to last year • Amplitude: about 20 units Time constant: 1000 s • We can try the dynamic correction when we want Chromaticitydecayduringseveral injections in 2011 and 2010 (N. Aquilina)

  4. RECONSTRUCTION OF CHROMATICITY DURING RAMP • At the end of the ramp the model is perfect (within a few units of chroma) • At injection chroma is undercorrected of about 10-20 units Chromaticityw.r.t. nominal duringramp on 28 February (E. Todesco)

  5. UNDERCORRECTION AT INJECTION • At injection chroma is under corrected of about 10-20 units • The hysteresis of MS can be the cause: • Their setting at injection are about 5 A and 8 A • At 5 A the hysteresis is about 10% • Natural chroma is 82-86 • Nearly 10 units not corrected • Including MS hysteresis we should bring down injection values of about 8 units • Values are ready Chromaticityw.r.t. nominal duringramp on 28 February Measuredhysteresis of the MS (V. Remondino, W. Venturini)

  6. SNAPBACK ESTIMATE • Analysis of two ramps: 25-30 units of chroma during snapback • Today we correct 18 units – are we undercorrecting? Chromaticityduringsnapback in tworamps (M. Lamont)

  7. CONCLUSIONS • New cycle at 100 A implemented in 2011 • And no preinjection porch • Decay: • Same decay of chroma as last year • Smaller decay of tune • Dynamic corrections can be tried • Systematic offeset of about 20 units of chroma at injection • A good fraction can be due to MS hysteresis – added in the model • This should reduce the error in chroma at injection • Model at 3.5 TeV very good (within a few chroma units) • Some uncertainties on the amplitude of snapback • In the range 20-30 units of chromaticity – more analysis needed

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