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Low Emittance Tuning (LET). Through Dispersion Free Steering.

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Low emittance: requirments for SuperB HER e+ ε x = 2 nmrad ε y = 5 pmrad HER e+ ε x = 2 nmrad ε y = 5 pmrad LER e ε x = 2.5 nmrad ε y = 6.2 pmrad LER e ε x = 2.5 nmrad ε y = 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 3 rd generation light sources Within the reach of 3 rd generation light sources S.M.Liuzzo PhD at LNF-INFN [Slide 2]

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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 Matrix M simulated from Model SVD inversion for simultaneous minimization of dispersion coupling and β-beating

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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 Matrix Dispersion Free Steering Low Emittance Tuning Vertical Correctors rms grows while vertical emittance is reduced for all correction algorithms 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 Matrix Dispersion Free Steering Low Emittance Tuning Vertical Correctors rms grows while vertical emittance is reduced for all correction algorithms εyεy εyεy rms V cor. ORM DFS LET S.M.Liuzzo PhD at LNF-INFN [Slide 4]

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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 φ Sextupoles [0 300]μm H, V BPM Offsets [0 300]μm 168 H-V correctors 168 H-V BPM SuperB HER V12 Arcs rms misalignments: Quadrupoles [0 300]μm H, V [0 300]μrad φ Sextupoles [0 300]μm H, V BPM Offsets [0 300]μm 168 H-V correctors 168 H-V BPM Produced table of tolerances for SuperB

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R.Bartolini 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 ε y = ε y = DFS LET Correction applied in two iterations using H and V steerers only. No BPM Tilts

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Comparison between LET and LOCO Measurements at Diamond S.M.Liuzzo PhD at LNF-INFN [Slide 7] Coupling [%] H emittance [nm] Lifetime [h] Current [mA] Decay mode 900 bounches 150 mA Decay mode 900 bounches 150 mA Initial conditions 21.1 h After 2 LOCO iterations with skew quad and quad After 2 LOCO iterations with skew quad and quad After 4 LET iterations with skew quad LET LOC O 5.9 h 5.5 h Final Lifetime measurements preformed after injection BPM Tilt estimate by LOCO

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Coupling estimated from lifetime: ε y = m rad (LET) Coupling estimated from lifetime: ε y = 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 corr Current*Lifetime [mAh] LET LET RED LOCO BLUE LET RED LOCO BLUE 818 mAh 881mAh 32 μm (LOCO: 1 μm) 5.5 h 5.9 h 0.06 % 0.07 %

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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 SOURCE 2.4 GeV, 288m, 12 beamlines, 400 mA, 5.4 nm Hor. Emit. SWISS LIGHT SOURCE 2.4 GeV, 288m, 12 beamlines, 400 mA, 5.4 nm Hor. Emit. Vertical beam size measurements performed using vertically polarized Syhnchrotron Light Monitor Vertical beam size measurements performed using vertically polarized Syhnchrotron Light Monitor TUPB27 Proceedings of DIPAC 2007, Venice, Italy Resolution

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Measurements at SLS S.M.Liuzzo PhD at LNF-INFN [Slide 10] Top-up mode 400 mA Normal user operations Top-up mode 400 mA Normal user operations Beam size measurement for 3 subsequent correction performed using only VERTICAL STEERERS Beam size measurement for 3 subsequent correction performed using only VERTICAL STEERERS 400 μm residual vertical orbit. Best observed σ y =6.8 μm Best observed σ y =6.8 μm SLS best σ y = 4.9 μm is obtianed using skew quadrupoles SLS best σ y = 4.9 μm is obtianed using skew quadrupoles Tested also Horizontal correction and Skew quadrupoles correction, but still work is in progress. Tested also Horizontal correction and Skew quadrupoles correction, but still work is in progress.

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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 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) 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

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