CD2 LATTICE IMPROVEMENTS

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CD2 LATTICE IMPROVEMENTS

• Reduction in Number of Elements
• Quintuplets in ID straight sections
  replaced by Triplets -2 Quads -1 Sext
• To allow tune and beta function matching
  add trim Quad in dispersion region
• plus Sextupole for symmetry 1Quad 1
  Sext (net -1 Q -1 Sext family)
• Eliminate one sextupole in short ID for reduced
  Beta-X in Quadrupole of SID
• Add Length to ID straight sections
• Vacuum Group better defined transition
  section to undulators/wigglers
• Short ID length 5 ? 6.6m and Long ID 8 ?
  8.6m
• Add Three Pole Wiggler in dispersion region
• TPW active length 20cm with 2mradian
  central bend gt 1T plus 20cm free space
• Impact on emittance ??x 0.18 to 0.2nm for 15-
  TPW
• 15 (8.6m LIDs 6.6m SIDs 4 0.40m(0.20m)
  TPWs ) 252m
• 32.2 Circumference783.3m (25 CDR 780.3m)

S.L. Kramer for the NSLS-II Team
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Other Considerations

• Variable bend radius dipoles
• Theoretical improvement from iso-magnetic
  field case
• lt of 3X reduction, but already DBA 2X MEDBA
• DW yields clear and controllable factor of
  4 to 5X
• Higher power radiated from dipole reduces DW
  affect
• High field at low dispersion end of dipole makes
  overlap of dipole radiation with ID more
  troublesome
• i.e. Decker distortions maybe needed for XBPMs

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CD2 Lattice Functions

• Quadrupole Triplets in ID Straight sections, Trim
  quadrupole in center of Dispersion
• Circumference 783.3m ( 780.3m CDR)

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CDR Lattice Functions

• Quintuplets allow greater flexibility for beta
  functions in ID and tune scan range
• For constant emittance constraint Johan showed
  not needed for wiggler/ID matching

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Impact of Triplets in IDs

• Matching Conditions in ID Given ßx,y ,, ax,y0
  need to match
• ßx ax at entrance to dipole for emittance
  2-Qs needed
• also match ßy ay over some range for
  dispersion 1-Q okay, 2-Qs better
• Dispersion region one Q needed for achromatic
  condition 2-Q for peak ?x
• Symmetry requires ax,y0 and ßx,y separation in
  middle, tunes

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CDR Quad Closed Orbit Amplif. Factor

• Misalignment of quadrupole centers, drive large
  Closed Orbit Distortion
• Closed Orbit Amplification Factors (COAF)
  defined as RMS(cod)/ RMS(error)
• 50X in both planes or 100µm RMS Quad.
  misalignment? 5mm offset of COD in lattice

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CD2 Closed Orbit Amplif. Factors

• Stronger Quadrupole Focusing COAFs
  (52,56)?(58,64) Increased in SID Y 12 ?19

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CD2 Magnet Alignment Tolerances

• Quadrupole and Sextupoles have centers measured
  to a
• resolution of 10 and 15 µm with pulsed wire
  technique
• Allow 2X for resolution, alignment Tolerance
  lt30µm on girder
• Girder alignment Tolerance in tunnel lt100µm (as
  achieved elsewhere )
• girder amplification factors (3.8,3.1) in ID
  are 3 to 5X less than COAF

Std(COD) for 315 seeds with girder alignment
dX,dY10µm random at both ends
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DA and Diffusion Map CD2
Using 8 sextupole families
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DA and Diffusion Map CDR
Using 11 sextupole families
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DA for Corrected Alignment Toler.
Alignment Tolers. Girders Dipoles 100
µm Quads Sexts. 30 µm BBA BPMs acc.
10 µm
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Tune shift controlled but dP/P 3
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Changes in Source Parameters
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CD2 Lattice Parameters
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Summary and RD Work

• Reduction of quadrupoles in ID straight sections
• Increased ID length for vacuum transitions and
  components
• Added possibility for 15 TPWs to provide sources
  for NSLS beam line migration
• Need improve sextupole and nonlinear tuning
• Need further study of field tolerances
• Only linear impact of TPWs calculated