Report from Chamonix (Feb 6-10)

1. UPO 17/2/12 Report from Chamonix (Feb 6-10) Jeff’s Unofficial Notes from the last two days of the meeting UPO 17/2/2012

2. UPO 17/2/12 Report from Chamonix (Feb 6-10) - Jeff’s unofficial notes • 2012 • 8 TeV, 50ns, 5-7E33, goal of additional 15 fb-1 (fairly conservative) • Check points: end June (lumi on track?), September (physics?)  reconsider LS1 start date • MD periods in 2012 (after data for summer conf) target post-LS1 operation: • 25ns (scrubbing and operational studies) • develop “Batch Compression” scheme in injectors (mostly parasitic) • Lumilevelling in LHC via beam displacement • last MD period - determine quench limit (optimize UFODump threshold) • Note: Goal is 25ns post LS1 (50ns held as a fallback – still appears in tables). • LS1 • Starts after HI run ~ Nov 17. 20 months long (baseline CMS need 21.5). Startup in September 2014. • A ~ two month delay in the start would be considered at end June if <5fb-1 delivered by then. • All splices will be measured and clamped. The 20 months assumes 15% need to be re-soldered – duration not highly dependent on this. Many fingers replaced…

3. UPO 17/2/12 Report from Chamonix • LS1 Startup • Power tests and magnet training are included in the 20 months (we can be in UXC with new safety measures). Training should be weeks for 6.5TeV, but months for 7TeV  6.5 • Injector chain will startup in 2014 (including extensive period for SPS scrubbing…) • Issues for post-LS1 • R2E (“Radiation-to-Electronics”: Single Event Error) • ~70 Beam Dumps in 2011 due to R2E. Mitigation in YETS. Predict 30-50 in 2012 • Continuous work on shielding/moving electronics and replacing (eg. FPGA in 1000 power converters) using all LS’s and all winter stops… • Rate from: Vacuum conditions (uncertain at 25ns) and collimator losses (well predicted) • Hope is to maintain a dump rate <~1 week (with continuous effort) • UFOs • Rate in 2011: 16000 candidate UFOs below dump threshold (~85% in Arcs and ~15% in MKI kickers). Only 17 caused dumps in stable beam [or something like that] • Rate in Arcs dropped from 10/hour to 2/hour through 2011 • Loss pattern well modeled by [charged] dust particles • UFO rate does not change with energy, but amplitude versus dump threshold does: at 6.5 predict 108 Beam Dumps per year (at same dump threshold as present) • In last 2012 MD will try to measure quench thresholds  expect to increase threshold • Limited 25ns MD period in 2011 indicated much higher rate (per bunch) at 25ns. Will measure in 2012 MD • Expect a higher rate after LS1. How high?

4. UPO 17/2/12 Report from Chamonix • LIU (LHC Injector Upgrade) and LS1.5 • Batch compression schemes in PS: increase brightness (Np/ε) but with slightly fewer bunches (at 25ns). Lumi increase x1.3 • Linac: Concern for longevity of present Linac. Linac4 can be ready by 2015, but has much lower performance unless PSB injection changed to H-. • Linac4(H-) in LS1.5 does not improvement, but allows spread of work • PSB: (a) upgrade injection to H- (ready 2016, will take 7 months, but work could start during HI running); and (b) extraction to PS 1.42.0 GeV. Target LS2. • PS: RF upgrade for beam loading (LS2) • SPS: (a) RF upgrade for beam loading, (b) aC coating (amorphous carbon) for e-cloud (entire pipe!) . Both target LS2. Plan for aC coating will wait to see how successful scrubbing is in the SPS in late 2014. (Confident of success with coating, not scrubbing) • SPS e-cloud likely to limit emittancevs bunch intensity. If aC needed, this work (only) will take ~1.5 years in LS2 • Note • LS1.5 will probably remain an option (only) until after performance is assessed after LS1 startup

5. 4) B. Goddard LIU project timeline PSB H- injection could be available PSB-PS transfer 1.4 GeV 2 GeV Linac 4 ready Chamonix 2012 LS1 for injectors LS2 for injectors 2019 2012 2013 2014 2015 2016 2017 2018 SPS aC coating, 200 MHz power upgrade completed Injectors commissioned • Length of LS2: minimum 12months • Required by SPS 200 MHz • 18 m if new 850 kW cooling not ready 2016 • 2019 commissioning: several months

6. UPO 17/2/12 Report from Chamonix • LHC • Beam-beam effects and collimators good for….up to 4E34? • For b*>0.5m (lower needs crab cavities in LS3) • Lumi level with beam offset will be tested in 2012 MD (with b* later) • (Note: fill length unlikely to be much longer than 5.5hr average in 2011) • No Projections shown – only example tables with personal judgment • Seem fairly confident of batch compression… but not emittance conservation from PS into LHC - electron cloud mitigation, RF upgrades, transfer improvements… • These issues are much less severe at 50ns than 25ns – 50ns remains in the slides shown for “ultimate reach” • The examples shown are either (a) conservative numbers, or (b) what might be possible on paper

7. Performance reach of LHC after LS1, Werner Herr Chamonix 2012 M.Pojer and R.Schmidt …already above nominal luminosity Will take time! Integrated luminosity of up to 70 fb-1

8. UPO 17/2/12 Report from Chamonix • CMS Guidance (template) • We will (probably) not be given a new schedule for LS1.5, LS2, LS3 until after LS1 startup • By the end of 2012 they should be more confident in 25ns operation • We will not get good lumi estimates until after LS1 startup • If small emittance with high bunch intensity cannot be transferred into the LHC, the experiments could be faced with a choice between lower lumi@25ns versus lumi leveling at our maximum comfort level at 50 • We need a stable upgrade strategy which (a) limits likelihood that the detector will impose a severe lumi-leveling restriction, (b) allows us to adjust late in the game to changes in the schedule and projections • Simplest version could be something like: • Operate at sustained <PU> “TBD>30” by 2016 • And “TBD>”50 by 2019 • Integrated Lumi at start of LS2 and start of LS3 • Will pick this up again at the next UPO