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The LHC start-up: the few weeks and an outlook

The LHC start-up: the few weeks and an outlook. 2009: chapter 450 GeV and 1.18 TeV 2010: chapter 1e27 (3.5TeV) chapter 1e28 (3.5TeV) and then. background ? what's that ?. Chapter 450 GeV (and 1180 GeV ) 2009. -. +. +. -. -. +. -. mini transv , scans. 5e9p/bch 4x4.

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The LHC start-up: the few weeks and an outlook

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  1. The LHC start-up: the few weeks and an outlook 2009: chapter 450 GeV and 1.18 TeV 2010: chapter 1e27 (3.5TeV) chapter 1e28 (3.5TeV) and then... background ? what's that ?

  2. Chapter 450 GeV (and 1180 GeV) 2009 - + + - - + - mini transv, scans 5e9p/bch 4x4 1.5e10p/bch 4x4 1e10 p/bch 16x16 prime indicates that there was a pilot and a +1000 RF buckets shift 4x4_a 4x4_b’ 4x4_c’ 16x16_a’ wrong RF buckets

  3. Stable beams summary “stage” Total hours 4x4 5e9 p/bch 16 hrs 4x4 1.5e10 p/bch 26 hrs 16x16 1e10 p/bch 1.5 hrs 43.5 hrs Estimated numbers of pp interactions recorded by experiments NOT STABLE BEAMS IN STABLE BEAMS (detectors partly on) (full detector on, with preliminary bkgd subtraction) 450 GeV1.18 TeV450 GeV ALICE: 40k 33k ~400k ( 13k +/+ 120k 0/- dip/sol 180k -/- 81k -/0 ) ATLAS: ~340k ~34k ~540k (of which 220k not nominal fields) CMS: ~110k ~18k ~410k (of which 60k not nominal field) LHCb: ~40k ~320k (of which ~3k with dipole off) LHCf: ~6k showers TOTEM: with T2: 34 k at 450 GeV, 10k at 2.36 TeV , with RP: 2k halo at 450 GeV reason why some detectors did not take data at 1.18 TeV (safety!)

  4. Estimated 2009 integrated lumi at 450 GeV • Approximate numbers (~30%) • Absolute normalisation yet to be checked • Mostly using comparison to results from MC generator (physics, assuming “known cross section”) combined with detector simulation (acceptance) • ALICE 18 ub • ATLAS 12 ub (stable) 19 ub (total) • CMS 9.5 ub (quiet or stable) 16 ub (total) • LHCb 6.7 ub (stable) • In addition, some 10% of that at 2.36 TeV "quiet" beams (depending on expt)

  5. publications... • ALICE, Eur.Phys.J.C65:111-125,2010 • ATLAS, Phys Lett B 688, Issue 1, 21-42 • CMS, JHEP 02 (2010) 041

  6. Chapter 1e27: 3.5 TeV, all physics fills • FillNr 1005, Tue 30.03.2010 13:22 => Tue 30.03.2010 16:29 ~3h • FillNr 1013, Wed 31.03.2010 21:03 => Thu 01.04.2010 05:05 ~8h • FillNr 1019, Sat 03.04.2010 04:23 => Sat 03.04.2010 07:23 ~3h • FillNr 1022, Sun 04.04.2010 17:26 => Mon 05.04.2010 13:29 ~20h • FillNr 1023, Tue 06.04.2010 02:44 => Tue 06.04.2010 14:59 ~12.25h • FillNr 1026, Wed 07.04.2010 10:28 => Wed 07.04.2010 12:52 ~2.5h • FillNr 1031, Sat 10.04.2010 06:13 => Sat 10.04.2010 15:47 ~9.5h • FillNr 1033, Mon 12.04.2010 01:24 => Mon 12.04.2010 03:23 ~2h • FillNr 1034, Mon 12.04.2010 08:54 => Mon 12.04.2010 17:25 ~8.5h • FillNr 1035, Tue 13.04.2010 05:01 => Tue 13.04.2010 09:31 ~4.5h • FillNr 1038, Wed 14.04.2010 05:50 => Wed 14.04.2010 10:53 ~5h • FillNr 1042, Thu 15.04.2010 06:22 => Thu 15.04.2010 08:54 ~2.5h • FillNr 1044, Fri 16.04.2010 05:50 => Fri 16.04.2010 09:12 ~3.5h • FillNr 1045, Sat 17.04.2010 05:55 => Sat 17.04.2010 14:58 ~9h • FillNr 1046, Sun 18.04.2010 06:06 => Sun 18.04.2010 06:55 ~0.8h • FillNr 1047, Sun 18.04.2010 11:28 => Sun 18.04.2010 14:39 ~3.1h • FillNr 1049, Mon 19.04.2010 03:55 => Mon 19.04.2010 05:14 ~1.3h

  7. Chapter 1e27 • 2x2, 1 coll. pair, ~1.1e10 p/bch • b* = 11-10-11-10 m • 1022: record fill of Chapter 1e27 • long lumi lifetime • 20 hours stable beams • ~100/ub

  8. Beam spot parameters (luminous region)

  9. Beta star values for now, 2010 (3.5 TeV), unsqueezed • From BE-ABP (Glenn, Vanbavinckhove, Rogelio Garcia Tomas, Rama Calaga and Ryoichi Miyamoto et al) Betx Beterrx Betxmdl Bety Beterry Betymdl Beam1 IP1 11.54 0.2017 11.00 12.74 0.45 11.00 IP2 9.205 0.115 9.99 8.92 0.398 9.99 IP5 11.85 0.27 10.99 10.73 0.47 11.00 IP8 10.20 0.69 9.99 11.35 1.24 10.00 Beam2 IP1 9.89 0.27 11.01 12.70 0.15 10.98 IP2 11.54 0.145 9.99 12.04 0.07 10.00 IP5 10.74 0.21 10.96 11.15 0.40 10.98 IP8 9.45 0.15 10.07 9.19 0.05 10.01

  10. Transverse growth, fill 1022 Lumi region PRELIMINARY ooovtx resolution unfolded

  11. beam-gas imaging (rather than background...)

  12. Squeeze 11 m to 2 m 10 m to 2 m 40 min

  13. Collimation Momentum Cleaning Dump Protection Col. IR2 IR5 IR8 IR1 2 m optics exposes IR’s as expected! Protected by tertiary collimators. Ralph Assmann and collimation team

  14. Hump... Ralph Steinhagen currently, lumi life time (>10 h!!) dominated by transverse emittance growth

  15. First squeezed stable beams All experiments: L > 1.1 × 1028 cm-2 s-1 factor ~10 achieved(confirmed by experiments) New golden orbit: “All IP to 2 m and optimized (stable beams)” Lost 20-30% of luminosity after first 3 hours of physics (5h30 to 8h30)! (seems consistent with measured emittance growth)

  16. Chapter 1e28 Fill 1058 • First physics fill with b* = 2m in all IPs • 3 bunches on 3 bunches (2 collisions per IP) IP1 (ATLAS) IP2 (ALICE) IP5 (CMS) IP8 (LHCb)

  17. Integrated lumi (delivered, in STABLE BEAMS) (modulo some possible luminometers down time...) PRELIMINARY

  18. Mini scans, reproducibility • Courtesy of Simon White

  19. vdM scans First tests of van der Meer scans (two dimensional) • Use small bunch charge ~1e10 p/bch • No long-range beam-beam effects • zero crossing angle (IP1 and 5) => minimize systematics => will allow a first determination of absolute luminosity Did: IP5 (3x3, 2 colliding pairs + one parasitic collision) IP8 (2x2, 1 colliding pair, net internal angle due to sepctrometer bump) IP1 (2x2, 1 colliding pair) No time for IP2, to be done soon.

  20. IP5 vdM scan

  21. Lumi evolution test crossing angle IP1 4 coll pairs 5e10 p/bch LHCf Weak bosons (W, Z) 4 coll pairs 2e10 p/bch 23.4 - ... 2m 3x3 1.1e10 p/bch 4 coll pairs 5e9 p/bch charm, D’s, J/Psi 30.3 - 19.4 10m 2x2 1.1e10 p/bch Apr 23 November 7

  22. the next 4 weeks or so Commissioning • 450 GeV N=5-10e10p/bch commissioning • put collimators in ramp • introduce post-squeeze separation collapse • finish dump protection for intensity increase at 3.5 TeV • revisit collimation at 450 GeV (1e11p/bch) • Stable beams • 450 GeV at 5e10p/bch 4x4 or 1e11p/bch 2x2, 1 or 2 fills (~1e6 inelastics/IP) • 3.5 TeV at 2e10p/bch 2x2, 2m • 3.5 TeV at 4.5e10p/bch 2x2, 2m • 3.5 TeV at 4.5e10p/bch 4x4, 2m • 3.5 TeV at 8e10p/bch 4x4, 2m TO BE DISCUSSED THIS WEEK

  23. Lumi evolution why 1/fb ??

  24. LHC, a parton collider e+ e- + - • e+e- collider • LHC Z clockwise proton anticlockwise proton many “partons” (quarks, gluons, and antis...) Parton Distribution Functions + - q q Z

  25. the “Master Plot” [nb] Simplified: • For a given center-of-mass energy (s), the larger the mass of the produced system, the steeper the curve • Absolute cross section scales and details of s-behaviour, depend on types of partons involved (gluons, quarks, antiquarks) and on couplings (strong, weak, etc.) • NB: physics bkg typically increase less fast with s than physics signal W (MW=80 GeV) Z (MZ=91 GeV)

  26. Pedagogical example: Z’ Calculated from eq. (3.16) in arxiv:hep-ph/9805494v1 from A.Leike / TeV / TeV

  27. State of the Art: Tevatron Higgs search 2004 2005 2006 2007 2008 2009 Projected integrated lumi how much by end 2010 ? end 2008 per Expt "run until it breaks" 10 fb-1 8 fb-1 6 fb-1 GRAPH DATE: 12 JAN 2009 end 2009 per Expt per experiment recorded 2010 2011 time (years)

  28. Higgs 95% CL at LHC, H weak bosons, indicative Combined HWW + HZZ: lumi for 95% CL Compare sensitivity to Tevatron with 8 fb-1 ( only HWWll ) Tevatron expect 1.9σ sensitivity at m=160 with 8fb-1(one expt)‏ • Energy s1/2 14  10  6 TeV • Lumi needed 0.1  0.2  0.6 fb-1 Ecm dependence from ATLAS G4 simulation of eνμν channel assuming gg→H dominant Int. lumi scale uncertainty is ~50% • Massive loss of sensitivity below 6 TeV To challenge Tevatron at s1/2 = 7 TeV, we need ~500 pb-1g.d.

  29. Z' resonance Needed luminosity for 95%CL exclusion at mZ’ = 1 TeV : s1/2 : 14  10  6 TeV Lumi: 13  30  110 pb-1 Z': Heavy partner of the Z (SSM)‏ • Very clean experimental signal: Z'→ℓℓ • Tevatron 95% CL limit at mZ' =1 TeV ATLAS fast simulation 5 discovery 95% CL limit with ~100 pb-1 g.d. for mZ'1TeV, with s1/2 = 7 TeV 5 discovery possible with ~300 pb-1g.d.

  30. LHCb (1)     b s b s W • B cross section does not vary as drastically as for high mass objects (b-bbar is “light“ , ~10 GeV). Thus, the request to go to highest possible energy is milder. • Need ~0.5 fb-1at s1/2  7 TeV to surpass Tevatron in Bs physics ?? BR(Bs0μ+μ-) (x10-9) LHCb 90% C.L. exclusion limits at 8 TeV

  31. Thank you for your attention

  32. IP1 vdM scan

  33. IP8 vdM scan

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