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Analysis of schemes for doublet productionJ. F. Esteban Mller, E. ShaposhnikovaLIU-SPS BD WG 30 January 2014Acknowledgments: T. Argyropoulos, H. Bartosik, T. Bohl, G. Iadarola, G. Rumolo, H. TimkoOutlineIntroductionSchemes:LHC at injectionSPS at injectionSPS at 200 GeVSPS at flat topConclusionsAnalysis of schemes for doublet productionJ. F. Esteban Mller#Introduction (I)Special beam made of bunch doublets is considered for scrubbing of the LHCEnhance e-cloud Reduction of the scrubbing time needed (Simulations by G. Iadarola & G. Rumolo)Doublets spacing:Split in the LHC 2.5 nsSplit in the SPS 5 ns: Preferred optionAnalysis of schemes for doublet productionJ. F. Esteban Mller#Introduction (II)Splitting process:

Small energy spread needed to reduce losses and emittance blow-up Minimum initial voltageRF phase shift of 180 or injection to unstable phaseFilamentation Emittance bucket areaParticles move away from unstable phaseWhen particles are around the new stable phase, voltage quickly increased to capture them

Analysis of schemes for doublet productionJ. F. Esteban Mller#Introduction (III)Main issues:Particle lossesEmittance blow-up25 ns high intensity (> 1.5x1011 ppb) Slower acceleration in SPS due to the power limitationSimulations using ESME without intensity effectsLosses and emittance blow-up may be underestimatedMinimum voltage in the SPS was chosen taking into account the beam loading4 different schemes:LHC at injectionSPS at injectionSPS at 200 GeVSPS at flat top800 MHz RF system off during splitting to minimize losses, because it operates in BSMAnalysis of schemes for doublet productionJ. F. Esteban Mller#LHC at injection (I)

Analysis of schemes for doublet productionJ. F. Esteban Mller#LHC at injection (II)

Analysis of schemes for doublet productionJ. F. Esteban Mller#Summary: LHC at injectionAdvantages:Doublets issues restricted only to the LHCNo special RF hardware requiredDisadvantages:High losses at high energyLarge emittance blow-up2.5 ns doublet spacing is less efficient than 5nsAnalysis of schemes for doublet productionJ. F. Esteban Mller#SPS at injection (I)Analysis of schemes for doublet productionJ. F. Esteban Mller#SPS at injection (II)

Analysis of schemes for doublet productionJ. F. Esteban Mller#T. Argyropoulos, H. Bartosik, T. Bohl, G.Iadarola, G. Rumolo, H. TimkoSPS at injection (III)Comparison with measurements:Splitting well reproducedLosses slightly higher in measurements Effects not included in simulations as injection phase error, energy mismatch or intensity effects

SimulationsMeasurementsAnalysis of schemes for doublet productionJ. F. Esteban Mller#Summary: SPS at injectionAdvantages:Acceptable losses and at low energySmall emittance blow upAlready tested during MDsNo special RF hardware requiredDisadvantages:e-cloud can be an issue with this beam at injection energyLow level RF and transverse damper should work from injection to flat topAnalysis of schemes for doublet productionJ. F. Esteban Mller#

SPS at 200 GeV (I)Analysis of schemes for doublet productionJ. F. Esteban Mller#SPS at 200 GeV (II)Emittance blow-up: 0.35 0.82 eVsAcceleration to 450 GeV: Voltage program for 1eVs bucket area (qp = 0.9)Voltage at SPS extraction 7 MVLHC injection: 6 MV emittance blow-up to 1.04 eVs

Analysis of schemes for doublet productionJ. F. Esteban Mller#Summary: SPS at 200 GeVAdvantages:E-cloud weaker at 200 GeVDisadvantages:Special RF hardware required for the phase jumpLonger SPS cycleLarger emittance blow-upHigher losses at higher energy (200 GeV)

Analysis of schemes for doublet productionJ. F. Esteban Mller#

SPS at flat top (I)Analysis of schemes for doublet productionJ. F. Esteban Mller#SPS at flat top (II)Emittance growth: 0.5 1.36 eVsVoltage at SPS extraction 7 MV (2.99 ns bunch length)LHC injection: 6 MVEmittance reduced to 1.2 eVs15% injection losses1% satellites

Analysis of schemes for doublet productionJ. F. Esteban Mller#Summary: SPS at flat topAdvantages:E-cloud weaker at 450 GeVDisadvantages:Special RF hardware required for the phase jumpLarger emittance blow-upHigh losses at high energy in both SPS and LHC

Analysis of schemes for doublet productionJ. F. Esteban Mller#ConclusionsThe preferred scheme is the SPS at injection:5 ns doublet spacingAcceptable losses and at low energySmall emittance blow upAlready tested during MDsNo special RF hardware requiredIf e-cloud is too strong at 26 GeV:SPS scrubbing run with doubletsUse the scheme SPS at 200 GeVAnalysis of schemes for doublet productionJ. F. Esteban Mller#