DA?NE Upgrade DA Optimization

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DA?NE Upgrade DA Optimization

• December 12, 2006
• E.Levichev, P.Piminov, P.Raimondi, M.Zobov

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Optimization algorithm
- chromaticity vector
- sextupole pair

• N small steps for chromaticity correction by
  every sextupole pair along the chromaticity
  vector
• The pair providing the largest DA at the step is
  fixed
• The procedure is repeated until the chromaticity
  is corrected
• 6D aperture optimization is available
• Harmonic sextupole (zero dispersion) is included
  by the gradient search.

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Starting point DA?NE Siddharta
Lattice from Manuela Boscolo
Betatron tunes Qx/Qy 5.103/5.179
Compaction factor a 0.0193
Damping times (ms) tx/ ty/ ts 39.8/34.5/16.1
Horiz emittance (nm-rad) ?x 390
Energy spread ?E/E 3.9?10-4
Natural chromaticity ?x/ ?y -3.2/-25.9)
IP1 betas (m) ßx/ ßy 0.2/0.006
Beam size at IP1 (?m) ?x/?y 284/3.4
) With sextupole term in the wiggler end
pole Corrected chromaticity
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Optics of DA?NE Siddharta
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Optimization scenario

• Original DA
• Optimization of the original DA
• DA tune scan and tune point choosing together
  with the luminosity scan
• Checking of other nonlinear elements octupole
  magnets, wiggler end poles, etc.

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DA at the original tune point
Original sextupoles Sextupoles optimized by the
best pair method
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Luminosity tune scan

• D.Shatilov
• M.Zobov

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DA tune scan
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Optimized tune and DA
Original 5.103, 5.179/non optimized Point from
region 1 5.105, 5.160/optimized Point from
region 2 5.131, 5.116/optimized
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Summary table
Tune Point N?x N?y Comments
5.103, 5.179 13/-16 180 Original
5.103, 5.179 16/-23 250 Original, optimized
5.105, 5.160 20/-26 300
5.131, 5.116 20/-23 270 Coupling resonance
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Off energy DA
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Other nonlinearities adjustment

• Influence of octupoles to the optimized sextupole
  set is negligible
• Wiggler end pole sextupole including in the
  optimization process gives practically the same
  value (10-15 less) as it is now. It seems there
  is no necessity to modify it.

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Summary

• Best sextupole pair optimization provides
  increasing of the DA?NE Upgrade DA
• Tune point with high luminosity and large DA is
  chosen
• No necessity to modify mechanically the wiggler
  pole