Low Emittance Tuning (LET) . Through Dispersion Free Steering .
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Low Emittance Tuning (LET).Through Dispersion Free Steering.
Low emittance:requirments for SuperB
HER e+εx = 2 nmrad εy = 5 pmrad
LER e−εx = 2.5 nmradεy = 6.2 pmrad
SuperB e+e- collider luminosity is:
This requires very low emittances for both rings:
Low Emittance Tuning (LET) Algorithm
Within the reach of 3rd generation light sources
S.M.Liuzzo PhD at LNF-INFN [Slide 2]
L.E.T. CORRECTORS USED• V & H steerers • Skew quad gradients• Bpm Tilts-Gains (in progress)
Only few measurements:1 to ~10 RM columns , orbit (P) and dispersion (η) TOTAL TIME: 5 min
dispersion
1 Off-diagonal block ORM column
1 diagonal block ORM column
P is the orbit H or V
SVD inversion of RESPONSE MATRIX M determines the Correction
DFS
Coupling
β-beating
Time
• Matrix M simulated from Model• SVD inversion for simultaneous
minimization of dispersion coupling and β-beating
LET compared to ORM and DFS
Vertical Emittance and vertical correctors rms as a function of the eigenvalues
cut used in SVD pseudo-inversion.
Vertical alignment errors corrected with:
Orbit Response MatrixDispersion Free Steering
Low Emittance Tuning
Vertical Correctors rms grows while vertical
emittance is reduced for all correction algorithms
εy
rms V cor.
ORM
DFS
LET
S.M.Liuzzo PhD at LNF-INFN [Slide 4]
Simulations of correction
S.M.Liuzzo PhD at LNF-INFN [Slide 5]
SuperB HER V12 Arcs rms misalignments:
Quadrupoles [0 300]μm ∆H, ∆V
[0 300]μrad ∆φSextupoles
[0 300]μm ∆H, ∆VBPM
Offsets [0 300]μm168 H-V correctors
168 H-V BPM
Produced table of tolerances for SuperB
R.Ba
rtol
ini
Comparison between LET and LOCO
S.M.Liuzzo PhD at LNF-INFN [Slide 6]
Simulations for Diamond
Simulations: 50 machine with random misalignments and bpm offsets, corrected using DFS and LET
εy =5.28 10-12
εy =3.27 10-13
DFS
LET
Correction applied in two iterations using H and V steerers only. No BPM Tilts
Comparison between LET and LOCOMeasurements at Diamond
S.M.Liuzzo PhD at LNF-INFN [Slide 7]
Coupling [%] H emittance [nm] Lifetime [h] Current [mA]
Decay mode900 bounches
150 mA
Initial conditions 21.1 h
After 2 LOCO iterations with skew quad and quad
After 4 LET iterations with skew quad
LETLOCO LOCO
5.9 h
5.5 h
Final Lifetime measurements
preformed after injection
BPM Tilt estimate by LOCO
Coupling estimated from lifetime:
εy =1.6 10-12 m rad (LET)
Same measurements. Parameters
vs iteration number
350 μm (LOCO:700 μm)
Vertical dispersion [m]Lifetime [h]
Coupling from Lifetime [h]Residual Vertical orbit
Residual Vertical orbit + H corrCurrent*Lifetime [mAh]
LET LET REDLOCO BLUE
818 mAh
881mAh
32 μm (LOCO: 1 μm)
5.5 h
5.9 h
0.06 %
0.07 %
Measurements at SLS
S.M.Liuzzo PhD at LNF-INFN [Slide 9]
Measurements aimed to achieve low vertical emittance
Same Tool used for Diamond, modified for direct access to Control System
SWISS LIGHT SOURCE2.4 GeV, 288m, 12 beamlines, 400 mA, 5.4 nm Hor. Emit.
Vertical beam size measurements performed using vertically polarized Syhnchrotron Light Monitor
TUPB27 Proceedings of DIPAC 2007, Venice, Italy
Measurements at SLS
S.M.Liuzzo PhD at LNF-INFN [Slide 10]
Top-up mode400 mA
Normal user operations
Beam size measurement for 3 subsequent correction performed using only
VERTICAL STEERERS
400 μm residual vertical orbit.
Best observedσy =6.8 μm
SLS best σy = 4.9 μm is obtianed using skew quadrupolesTested also
Horizontal correction and Skew quadrupoles correction, but still work is in progress.
Conclusion
S.M.Liuzzo PhD at LNF-INFN [Slide 11]
• LET Algorithm performing well but still not reaching simulation expected results.
• Need to further test and debug to control H corrections and Tilt detection
• Future application in DAΦNE
• Developed and applied Low Emittance Tuning Tool for SuperB.
• Tested and compared algorithm to LOCO at Diamond (skew quarupoles)
• Tested algorithm at SLS with promising starting results. (same tool as dimond)
Summary