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Draft : Which beams in the injectors fulfil HL-LHC Upgrade Scenario 1 goals?. S. Gilardoni et al. RLIUP technical meeting 18/10/2013. Agenda. Summary of US1 beam parameters Possible production schemes 3-splitting BCMS Summary of issues in the injectors: PSB
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Draft : Which beams in the injectors fulfil HL-LHC Upgrade Scenario 1 goals? S. Gilardoni et al. RLIUP technical meeting 18/10/2013
Agenda • Summary of US1 beam parameters • Possible production schemes • 3-splitting • BCMS • Summary of issues in the injectors: • PSB • Space charge: L4 connection • PS • Space charge: PSB@2 GeV • Headtail instability • Longitudinal stability : Finemet cavity • Electron cloud : transverse damper • SPS • Space Charge: well matched to PS space charge • Maximum available RF power: 200 MHz LL and HL upgrade • Electron cloud: effect on emittance or intensity?
Performance summary (US1-LHC vs. US1-LIU) 200 MHz Power upgrade necessary to match the requirements of US1 with unchanged longitudinal parameters at LHC injection. Transverse emittance required increased 1 μm emittances not requested any longer (see O. Brunning talk)
Challenges of the traditional schemes High intensity injected in PSB: • every PSB bunch is split 12 times (to get finally 72 bunches at 25 ns spacing, less for BCMS) • Space-charge issue • Today limited brilliance due to multiturn injection process Long waiting time at PS injection: • Space-charge issue. • Headtail instability. Long waiting time at SPS injection: • Space-charge. • TMCI instabilities • Many RF systems involved: • Longitudinal instabilities and limitations to be overcome in all the machines Beam quality is an issue: • PS-SPS very sensitive to difference in relative bunch population • LHC final luminosity very sensitive to degradation of transverse emittance
Basic Principles of US1Injector upgrade Overcome main limitations of LHC injectors (brief intro summary): • Space charge current limitations • PSB injection : Increase injection energy in the PSB from 50 to 160 MeVLinac4 (160 MeV H-) to replace Linac2 (50 MeV H+)Prove operation with Laslett larger than |0.36| @ 160 MeV (today |0.7|, required max. |0.5|) • PS injection: Increase injection energy in the PS from 1.4 to 2 GeVProve operation with Laslett larger than |0.31| @ 2 GeV • SPS injection if confirm current operational limitProve operation with Laslett larger than |0.21| • Transverse/Longitudinal stability limits • Transient beam loading and CBI in the PS • RF limitations in SPS • Electron cloud related issues • Wideband transverse damper in SPS • SPS vacuum chamber coating+scraping+wide band damper • Upgrade the PSB , PS and SPS to make them capable to accelerate and manipulate a higher brightness beam (feedbacks, cures against electron clouds, hardware modifications to reduce impedance, improve beam instrumentations…)
PS intensity limitations Acceleration/Bunch splittings Longitudinal CBI Transient beam loading Transition crossing Flat top: Longitudinal CBI Electron cloud Transverse instabilities Injection flat bottom: Space charge Headtail instability
S. Gilardoni – HB2012 SPS intensity limitations 450 GeV Injection flat bottom: Capture losses Longitudinal instability Space charge TMCI Along the whole cycle: Longitudinal instability Electron cloud 26 GeV
Conclusions • US1 requirements can be fulfilled if the 200 MHz power upgrade is added to PSB@2GeV • 200 MHz Power upgrade necessary to match the requirements of US1 with unchanged longitudinal parameters at LHC injection (bunch length in particular) • “Matching” of maximum Laslett tune shift currently achieved during normal operations with L4 and PSB@2GeV in all injectors • Possible to produce a large range of emittances, down to 1 mum if needed