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Plans for physics with 90m

Plans for physics with 90m. What was already done What is left ?. More stuff to do during the last pp running period. 90m runs (ALFA, TOTEM + IP2/8 VdM ?) schedule as two blocks of X hours (goal-driven) Floating MDs (25ns, high µ?) 2 days + 9h

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Plans for physics with 90m

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  1. Plans for physics with 90m What was already done What is left ?

  2. More stuff to do during the last pp running period • 90m runs (ALFA, TOTEM + IP2/8 VdM ?) • schedule as two blocks of X hours (goal-driven) • Floating MDs (25ns, high µ?) 2 days + 9h • LHCb wish for high µ MD: also collide in IP8 when stable beams • Werner Herr: OK if MD stays cat B and only add private bunches • ALICE: sat-main collisions • "as is" (LHC cost free) or with PS tricks (1 h work at inj) • ALICE: B=0 • only if no risk LR effects ? • ALICE: fill with reduced solenoid field • LHCb: reversals every ~100/pb or ~every week / weekandahalf • each <1h at injection

  3. 90m strategy: done • STUDY 1 in May 2011, see MD note • Used one probe bunch per beam (1.2e10). • Established feasibility of 90m optics in IP1/5, performed first optics measurements. • STUDY 2 in June 2011, see MD NOTE • Used two probe bunches per beam (~1e10 and ~2e10 p/bunch). • Operational sequence tested. • Implemented optics corrections from Study 1. • Went to collisions in IP1 and IP5. • Took data with RPs at intermediate distance, > 10 nom (in ADJUST). • STUDY 3 in AUGUST 2011, see MD NOTE • Used 3 bunches of ~7e10 p/bunch and ~3um transverse emittance (the last bunch with a bit lower emittance by removing one screen in SPS). • Iterated operational sequence and established collisions in all IPs. • Performed beam-based alignment of the 8 verticals RPs of TOTEM. • Performed beam-based alignment of TCTs at IP1, IP5 and IP8.

  4. 90m strategy: proposed • To be answered asap: • can we do AC dipole measurements with a couple of bunches with 7e10 ? Yes No STUDY 4 • coll in all IPs 2 or 3x7e10/beam, 2um, • Align ALFA RPs (8xV) ~4h • In shadow :TOTEM RPs (6xH+2V?) • Take data in ADJUST: ~4h V (H) pots to 6 (11)  • AC dipole/optics measurements ~1h ? • Betatron loss maps ~1h • Async dump • coll in all IPs 2 or 3x7e10/beam, 2um, • Align ALFA RPs (8xV) ~4h • In shadow :TOTEM RPs (6xH+2V?) • Take data in ADJUST: ~4h V (H) pots to 6 (11)  • Betatron loss maps + async dump ~1h • collisions in IP1&5 (N=1,...?) Nx1e10/beam, <2um, • AC dipole/optics measurements ? ~1h ? • If not yet done: async dump could be inverted if loss maps completed when all alignment and all loss maps completed STUDY 5 • collisions in IP1&5 Mx7e10, 2um + private collisions in IP2&8 Nx1e11, 3-4um • STABLE BEAMS, take data, ~4h, in //: • - IP1&5: V (H) pots to 10 (12)  • - IP2/8: VdMs, LSC Depending on results: possible repeat of either a fill for data taking in ADJUST (pots very close) or a fill in STABLE BEAMS

  5. Schedule (rough, to be discussed) 90m finish align data in ADJUST loss maps +optics 90m STABLE BEAMS + VdM ? Support needed for Sep 30 / Oct 1: • Experts on the 90m sequence (ALICE polarity !!) • Collimator expert (help RP guys, verify STABLE BEAMS settings) • Optics measurement experts • BLM threshold expert ... recovery b*=1m verifications ALICE reversal intensity ramp up we hope these are the last loss maps before ions (except the 90m loss maps)

  6. RP settings to be used in ADJUST and STABLE BEAMS • To be defined before the 90m Study 4! • Reviewed/approved by rMPP • Typically: • in ADJUST (during/after beam-based alignment, 2-3 x7e10): retract V-RPs half a nombehind the primaries • tight or intermediatecollim ? Tight settings better, of course! H-RPs go further out ... ~11 nom ? • in STABLE BEAMS: for the intermediate collim settings, 10 nom (V) and 12 nom (H) • does it depend on tight/intermediate settings ? • Use correct beta functions at RPs ! • Use agreed value of emittance ! (3.5 um ?) • Final RP settings can only be calculated after determining the beam position by beam-based alignment (on the spot!). Must be used for the loss maps.

  7. Bunch into a RP What happens if we lose a bunch in a RP ? (single pass effect) No detailed simulation available... Can this approach be of any use ? (here, numbers are for illustration) • The inelastic interaction probability for a proton traversing a given thickness (here t = 1 mm) of Aluminium can be estimated as: P = inelas t  No / A = 0.00024 where we used inelas = ~40 10-27 cm2 t = 0.1 cm  = 2.7 g/cm3 A = 27 g/mol No =6 1023 / mol • Therefore, if a bunch of 1e11 protons traverse this piece of Aluminium, approximately 2.4e7 protons will be locally lost and shower into the magnets behind the RP window. • How many protons should be locally lost to create a quench ? • few e9 ???

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