2012 LHC Days in Split, Croatia

1. TOTEM Results and Perspectives The TOTEM Collaboration INFN Sezione di Bari and Politecnico di Bari, Bari, Italy MTA KFKI RMKI, Budapest, Hungary Case Western Reserve University, Cleveland, Ohio,USA CERN, Geneva, Switzerland Estonian Academy of Sciences, Tallinn, Estonia Università di Genova and Sezione INFN, Genova, Italy Università di Siena and Sezione INFN-Pisa, Italy University of Helsinki and HIP, Helsinki, Finland Academy of Sciences, Praha, Czech Republic Elastic scattering Total Cross-section Inelastic cross-section Particle Production Diffraction Runs with CMS Future runs Perspectives after the shut-down Karsten Eggert (CWRU) on behalf of the TOTEM collaboration 2012 LHC Days in Split, Croatia Karsten Eggert–

2. Total cross-section Elastic Scattering b Cosmic Ray Physics Diffraction: soft and hard jet  jet TOTEM Physics Overview Karsten Eggert–

3. Inelastic telescopes T1 and T2: T1: 3.1 <  < 4.7 T2: 5.3 <  < 6.5 HF (CMS) IP5 10 m T1 CASTOR (CMS) 14 m T2 TOTEM Detectors (T1, T2 and RP) on both sides of IP5 CMS 24 Roman Potsin the LHC tunnel on both sides of IP5 measure elastic &diffractive protons close to outgoing beam IP5 RP147 RP220 Karsten Eggert–

4. Detectors RP 147 Package of 10 “edgeless” Si-detectors Vertical Pot Vertical Pot Horizontal Pots Vertical Pot Vertical Pot T2 (GEMs) T1 (CSCs) Karsten Eggert–

5. The Roman Pot System at 220 m beam-optical elements (magnets) ydet scattered proton y* y* beam axis IP5 RP220 220m Design considerations: Two independent detection systems with 5 m lever arm redundant trigger scenarios 10 Silicon detectors / RP ~ 10 mm precision Reliable track reconstruction in both projections 5 planes / projection Determine the proton angle in both projections ~ 2 mrad precision Approach the beam as close as possible to ~ 5 – 10 s beam width Space for adding detectors for future upgrades !!! (x*, y*): vertex position (x*, y*): emission angle: t  -p2 (qx* 2 + qy* 2) x = p/p: momentum loss (diffraction) Optimized optics Karsten Eggert–

6. Proton Reconstruction Proton position at a given RP(x, y) is a function of position (x*, y*) and angle (Qx*, Qy*)at IP5: measured in Roman Pots Proton transport matrix reconstructed The effective length and magnification expressed with the phase advance: RP IP5 Elastic proton kinematics reconstruction (simplified): Scattering angle reconstructed in both projections Excellent optics understanding required Karsten Eggert–

7. Beam-Based Roman Pot Alignment (Scraping) A primary collimator cuts a sharp edge into the beam, symmetrical to the centre The top RP approaches the beam until it touches the edge The last 10 mm step produces a spike in a Beam Loss Monitor downstream of the RP • When both top and bottom pots are touching the beam edge: • they are at the same number of sigmas from the beam centre as the collimator • the beam centre is exactly in the middle between top and bottom pot  Alignment of the RPs relative to the beam alignment is very critical and fundamental for any physics reconstruction alignment between pots with overlapping tracks (~ few μm) fine alignment wrt beam using elastic events The RP – beam contacts are also registered as spikes in the trigger rate Karsten Eggert–

8. b*=3.5m (7s) b*=90m (10s) b*=90m (5s) Sector 56 Sector 56 Aperture limitation, tmax Beam halo Sector 45 t = -p2 p/p Elastic pp scattering : proton reconstruction Elastic ppscattering: topology (hit map in RP detectors) y[mm] y[mm] Sector 45Sector56 x[mm] x[mm] Two diagonals analysed independently Karsten Eggert– • Both angle projections can be reconstructed: • Qx = L'xQ*x y = LyQ*y • precise values of L'x=dLx/ds and Ly @ RP locations needed • Need excellent optics understanding b*=3.5m Lx~0 ; Ly~20m @220m (L=√bb*sin Dm)

9. Elastic Scattering: Collinearity Collinearity in qy* Collinearity in qx* Scattering angle on one side versus the opposite side Low x, i.e. |x| < 0.4 mm and 2s cut in Dqy* |ty| (diagonal 1) Beam divergence |ty| (diagonal 2) Missing acceptance inθy* Width in agreement with beam divergence of 17 mrad Qx is measured with 5m lever arm spectrometer Karsten Eggert–

10. Elastic pp scattering : analysis Collinearity cut (left-right) q*x,45↔q*x,56 q*y,45↔q*y,56 Background subtraction Acceptance correction Karsten Eggert–

11. 2011 with b* = 3.5 m First measurement of the elastic pp differential cross-section First published data in 2011 EPL 95 (2011) 41001 EPL 96 (2011) 21002 Karsten Eggert–

12. Comparison to some models None of the models really fit Better statistics at large t needed (in progress) Karsten Eggert–

13. Elastic pp Scattering at 7 TeV: Differential Cross-Sectiont range : 710-3 GeV2<|t|< 3.5 GeV2 A = 506  22.7syst 1.0stat mb/GeV2 A = 503  26.7syst 1.5stat mb/GeV2 B = 19.9  0.26syst 0.04stat GeV-2 |t|dip= 0.53 GeV2 ~ |t|-7.8 Integrated elastic cross-section: Additional data set under analysis: 2 GeV2 < |t| < 3.5 GeV2 25.4 ± 1.0lumi ± 0.3syst ± 0.03stat mb (90% measured) 24.8 ± 1.0lumi ± 0.2syst ± 0.2stat mb (50% measured) Karsten Eggert–

14. Low t - distribution Constant slope for 0.007 < t < 0.2 GeV2 Individual errors Karsten Eggert–

15. Slope parameter B and elastic cross-section B constant in the range 0.007 < t < 0.2 GeV2 B increases with energy sel / stot increases with energy Karsten Eggert–

16. Elastic scattering – from ISR to Tevatron ISR 7 TeV ~1.4 GeV2 Diffractive minimum: analogous to Fraunhofer diffraction: |t|~ p2q2 • exponential slope B at low |t| increases • minimum moves to lower |t| with increasing s •  interaction region grows (as also seen from stot) • depth of minimum changes  shape of proton profile changes • depth of minimum differs between pp, pˉp  different mix of processes Karsten Eggert–

17. Elastic Scattering and Total Cross-Section at 8 TeV July 2012: runs at b* = 90 m only RP alignment, RPs moving collinearity, low x, common vertex Karsten Eggert–

18. Elastic Scattering and Total Cross-Section at 8 TeV July 2012: runs at b* = 90 m only RP alignment, RPs moving Preliminary t-distributions (unnormalised) TOTEM preliminary TOTEM preliminary • larger |t|: • possible at b*=0.6m • difficult due to 2xSDand other background down to |t| ~ 6 x 10-4: foreseen at b* = 1km Karsten Eggert–

19. based only on elastic scattering via optical theorem based on the measurement of the inelastic cross-section using charged particle detectors Inelastic cross-section is measured with two different detectors and triggers via elastic scattering with RP detectors via inelastic detectors All TOTEM detectors are used Total Inelastic Cross Section Measurement at √s = 7 TeV Karsten Eggert–

20. Direct measurement of the Inelastic Cross-Section at √s=7 TeV T1: 3.1 <  < 4.7 T2: 5.3 <  < 6.5 Karsten Eggert–

21. Inelastic Cross-Section visible in T2 Inelastic events in T2: classification tracks in both hemispheres non-diffractive minimum bias double diffraction tracks T2 T2 tracks in a single hemisphere mainly single diffraction MX > 3.4 GeV/c2 η Corrections to the T2 visible events η • Trigger Efficiency: 2.3 % • (measured from zero bias data with respect to track multiplicity) • Track reconstruction efficiency: 1% • (based on MC tuned with data) • Beam-gas background: 0.54% • (measured with non colliding bunch data) • Pile-up (μ=0.03): 1.5 % • (contribution measured from zero bias data) η σinelastic, T2 visible = 69.7 ± 0.1 (stat) ± 0.7 (syst) ± 2.8 (lumi) mb Karsten Eggert–

22. Inelastic Cross-Section σinelastic, T2 visible σinelastic Missing inelastic cross-section • Events visible in T1 but not in T2: 2.0 % • (estimated from zero bias data) • Rapidity gap in T2 : 0.57 % • (estimated from T1 gap probability transferred to T2) • Central Diffraction: T1 & T2 empty : 0.54% • (based on MC, correction max 0.25σCD , quoted in systematic error) • Low Mass Diffraction :3.7% ± 2% (syst) • (Several models studied, correction based on QGSJET-II-4, • imposing observed 2hemisphere/1hemisphere event ratio and the effect of ‘secondaries’) • Possibility of measuring low mass diffraction with a single proton trigger • needs clean beam conditions to avoid beam halo background σinelastic = 73.7 ±0.1(stat)±1.7(syst)±2.9(lumi) mb Karsten Eggert– Corrections for non visible events: tracks in T1 (& T2 empty) Estimated from BX data ~ 2% Rapidity gap in T2: estimated from T1 gap probability transferred to T2 h-region (scaled by fraction of T2 1hemi only events (no tracks in T1) taking MC estimated experimental rap gap survival in T2 region in account:)~ 0.5 % Central Diffraction: T1 & T2 empty (based on MC) Correction max ~ 0.25 x sCD: as cross section is unknown, quoted in syst error Corrections for non visible events: tracks in T1 (& T2 empty) Estimated from BX data ~ 2% Rapidity gap in T2: estimated from T1 gap probability transferred to T2 h-region (scaled by fraction of T2 1hemi only events (no tracks in T1) taking MC estimated experimental rap gap survival in T2 region in account:)~ 0.5 % Central Diffraction: T1 & T2 empty (based on MC) Correction max ~ 0.25 x sCD: as cross section is unknown, quoted in syst error

23. MX>3.4 GeV/c2 (T2 acceptance) S. Ostapchenko arXiv:1103.5684v2 [hep-ph] x/sSDdsSD/dx QGSJET-II-4 SIBYLL/PYTHIA8 low mass contribution Inelastic Cross Section : low mass diffraction Correction based on QGSJET-II-4 sMx < 3.4 GeV = 2.7 ± 1.5 mb • By comparison with the measured inelastic cross-section (using the total cross-section) • the low mass single diffraction can be determined: • stot – sel = 73.2 ± 1.3 mb • Mx < 3.4 GeV = 2.2 ± xx mb (preliminary) • Possibility of measuring low mass diffraction with a single proton trigger • needs clean beam conditions to avoid beam halo background Karsten Eggert–

24. 3 Ways to the Total Cross-Section stot= (98.0 ± 2.5) mb (ρ=0.14[COMPETE]) June 2011 (EPL96): stot = (98.3 ±2.8) mb Oct. 2011 (PH pre.): stot = (98.6 ±2.2) mb different bunch intensities ! stot= (99.1 ± 4.3) mb Excellent agreement between cross-section measurements at 7 TeV using - runs with different bunch intensities, - different methods. Karsten Eggert–

25. Cross-sections with different methods COMPETE extrapolation: r = 0.141  0.007 done before TOTEM measurement Karsten Eggert–

26. Luminosity determination and ratios Luminosity calibration: Estimated by CMS Estimated by TOTEM 1) L= 82/mb ± 4% L= 83.7/mb ± 3.8% 2) L= 1.65/mb ± 4% L= 1.65/mb ± 4.5 % Luminosity and ρ independent ratios: σel/ σtot = 0.257 ± 2% σel/ σinel=0.354 ± 2.6% Summary: The cross-section measurements are in excellent agreement using: runs with different bunch luminosities different methods Karsten Eggert–

27. A First, Very Crude r Estimate at 7 TeV From optical theorem: r < 0.32 (95% CL), or, using Bayes’ approach (with uniform prior |r| distribution): |r| = 0.145  0.091[COMPETE extrapolation: r = 0.141  0.007] E710/E811: r = 0.135 ± 0.044 TOTEM, 7 TeV Not so exciting, but … Karsten Eggert–

28. r Measurement: Elastic Scattering at Low |t| Optical Theorem: Total (Coulomb & nuclear) Coulomb scattering dominant Coulomb-Nuclear interference Nuclear scattering • a= fine structure constant • = relative Coulomb-nuclear phase G(t) = nucleon el.-mag. form factor = (1 + |t| / 0.71)-2 r=  /  [Telastic,nuclear(t = 0)] Measurement of r by studying the Coulomb – Nuclear interference region down to |t| ~ 6 x 10-4 GeV2 Reachable with b* ~ 1000 m still in 2012 if RPs can approach beam centre to ~ 4s Karsten Eggert–

29. How to reach the Coulomb-Nuclear Interference Region ? RP window position (real s for en=2mm rad) √s = 8 TeV √s = 13 TeV push b* to > 2000 m good t-resolution needs parallel-to-point focussing in both x and y (phase advance p/2) RP approach the beam to ~ 4 s Beam emittance en < 2 mm rad  Challenging but possible Additional magnet cables needed. To be installed during LS1 Karsten Eggert–

30. The b* = 1000 m Optics MD in June: first unsqueeze to 1km achieved 14 September: • special beam optics with b* = 1000 m fully commissioned • collisions in IP1 and IP5 found • vertical emittances en ~ 2 mm rad • 4 vertical TOTEM RPs (out of 8) aligned at ~4 s • time slot ended  no physics data taken yet, diagnostic data on halo background being analysed • Physics run scheduled for October 2012 Karsten Eggert–

31. Perspectives on Diffractive Physics, e.g. Double Pomeron Exchange MPP2 = 12s Rapidity Gap Dh =-ln1 -ln2 CMS h TOTEM Scattered proton Scattered proton • β* = 90m optics runs: • DPE protons of -t > 0.02GeV2 detected by RP • nearly complete ξ-acceptance • σDPE measurement method: Karsten Eggert–

32. Correlation between the forward proton(s) and particles in T2 DP SD (low x) Karsten Eggert–

33. Single diffraction large x Single diffraction large x  Rapidity Gap Dh = -ln MX2 =  s h Karsten Eggert–

34. Diffractive Analyses Ongoing T2 T1 T1 T2 Based on b* = 90 m (7 TeV) run in Oct. 2011 (RP @ 4.8s – 6.5s): • Central Diffraction(d2sDPE / dt1 dt2, sDPE ) • Single Diffraction(dsSD/dt , dsSD/dx , sSD ) • Double DiffractionSelect diff. masses 3.4 GeV < M < 10 GeV requiring tracks in both T2s, veto on T1s  Extend studies over full h range with CMS (2012 data) Karsten Eggert–

35. Charged Particle Pseudorapidity Density dN / dh T2 [T1] EPL 98 (2012) 31002 • Analyses in progress: • T1 measurement at 7 TeV (3.1 < |h| < 4.7) • NEW: combined analysis CMS + TOTEM (0 < |h| < 6.5) on low-pileup run of 1st May 2012 (8 TeV): common trigger (T2, bunch crossings), both experiments read out • NEW: parasitical collision at b* = 90 m (7 July 2012) •  vertex at ~11m  shifted h acceptance: Karsten Eggert–

36. Joint Data Taking with CMS • Realisation of common running much earlier than ever anticipated • Hardware: electrical from RP220 to CMS  trigger within CMS latency • Trigger: bi-directional level-1 exchange  same events taken • Synchronisation: orbit number and bunch number in data streams • Offline:- common repository for independently reconstructed data- merging procedure  common n-tuples Karsten Eggert–

37. Joint Data Taking with CMS May 2012: low pileup run: b* = 0.6 m, s = 8 TeV, T1 & T2 & CMS read out dN/dh, correlations, underlying event July 2012: b* = 90 m, s = 8 TeV, RP & T1 & T2 & CMS read out stot, sinel with CMS, soft & semi-hard diffraction, correlations • Abundant material for analysis activities throughout LS1 • Analyses starting: • hard diffraction: p + dijets (90m runs) • combined dNch / dh and multiplicity correlations Karsten Eggert–

38. Runs Planned for 2012 / 2013 • b* = 1000 m: scheduled for 24 October study interference region, measure r • RP insertions in normal physics runs (b* = 0.6 m) - hard diffraction together with CMS (high diffractive masses reachable) - study of closest possible approach of the horizontal RPs (i.e. acceptable beam losses) essential for all near-beam detector programmes at high luminosity after LS1 • Collimators needed behind the RP to protect quadrupoles • request a low-pileup run (m ~ 5 %) with RPs at b* = 0.6 m (in May RPs were not aligned) study soft central diffraction final states with 2 leading protons defining Pomeron-Pomeron mass M2 = x1 x2 sgood x resolution at b* = 0.6 m s(M) ~ 5 GeV • participation in the p-Pb runs with insertions of the RPs on the proton side  study diffractive/electromagnetic and quasi-elastic p-Pb scatteringp-Pb test run in September with CMS was successful(T2 trigger given to CMS) Karsten Eggert–

39. To be done this year Together with CMS studies on: Rapidity distribution over the full acceptance range Diffractive di-jets Double Pomeron Exchange Single Diffraction Double Diffraction Elastic scattering and cross-sections at √s = 8 TeV Measurement of r with b*=1000 m Preparation for Diffractive Di-jet production at highest luminosities in view of the new forward set-up after LS1 p-A data taking in 2013 Finalize the three papers in the pipe-line Karsten Eggert–

40. The End Karsten Eggert–