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Status of the TOTEM Experiment and Latest Results

Status of the TOTEM Experiment and Latest Results. Hubert Niewiadomski on behalf of the TOTEM Collaboration. LHCC, 15  June 2011. Inelastic telescopes: charged particle & vertex reconstruction in inelastic events. T1: 3.1 <  < 4.7 T2: 5.3 <  < 6.5. HF (CMS). IP5. ~ 10 m. T1.

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Status of the TOTEM Experiment and Latest Results

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  1. Status of the TOTEM Experiment and Latest Results Hubert Niewiadomskion behalf of the TOTEM Collaboration LHCC, 15 June 2011

  2. Inelastic telescopes:charged particle & vertex reconstruction in inelastic events T1: 3.1 <  < 4.7 T2: 5.3 <  < 6.5 HF (CMS) IP5 ~ 10 m T1 CASTOR (CMS) ~ 14 m T2 Experimental Setup @ IP5 Roman Pots:measure elastic & diffractive protons close to outgoing beam IP5 RP147 RP220

  3. T1 T2 RP 147

  4. The TOTEM experiment is completely installed and running • All Roman Pots at 147 and 220m installed (24 pots) • T1 detectors are installed on both sides • T2 detectors are installed on both sides • Trigger system based on all detectors is running • DAQ is running with an event rate capability of 1 kHz • Special runs with dedicated b* and bunch structures are prepared

  5. Beam based alignment of RPs @220m and data taking (T1,T2,RP220m) (18 May 2011) Scraping exercise: RP220 approached the low intensity beam in 10 mm steps RP220 now ready for routine insertions in 2011 RP approach Beam intensity Beam Loss Data x, y Data taking with RPs @ 220 close to the beams - vertical RPs @ 5σ = 2.2 mm - horizontal RPs @ 7σ = 1 mm - low pile-up Vert Pot Position (mm) Alignment of RP147 planned in August

  6. T2 data 2011 Raw data Very good agreement: - left and right side - bunch and active trigger Pythia PhoJet Unfolded Green band after vertex cuts Low luminosity runs 2010 ‘Plus’ and ‘minus’ T2 sides superimposed - Bunch crossing trigger - T2 detector trigger Taken during scraping exercise only low intensity bunches of 1010 p (low pile-up)

  7. Preliminary dN/dh results (T1) • 3 short periods of data taking with useful conditions for T1(L = 1028 – 1030 cm–2 s–1): March (2.76 TeV), May (7 TeV) • 25 million events collected with different configurations • Data analysis in progress • T1 ready for physics h Distributions (uncorrected) Vertex reconstruction 7TeV Vertex reconstruction is effected by the CMS magnetic field Symmetric distributions obtained – a good starting point

  8. Elastic ppscattering t-range: 0.36 – 3 GeV2

  9. Elastic pp scattering • Several runs were taken during 2010 • with different distances of the Roman pots to the beam center • The 7 s runs were analyzed • The 18 s runs with a total luminosity of 5.8 pb-1 will follow Luminosity Integrated luminosity RP dist. Analysed data files important for large t Karsten Eggert–

  10. Proton reconstruction • Both angle projections reconstructed: Θx* and Θy* • Θx* fromΘx @ RP220 (through dLx/ds) Θx = dLx/ds Θx* • Θy* from y @ RP220 (through Ly) y = LyΘy* • → Excellent optics understanding • Magnet currents measured • Measurements of optics parameters with elastic scatt. • Θleft* = Θright* (proton pair collinearity) • Proton position↔angle correlations • Lx=0 determination, coupling corrections • → Fine alignment • Alignment between pots with overlapping tracks (1μm) • Alignment with respect to the beam – scraping exercise (20μm) • Mechanical constraints between top and bottom pots (10μm) Track based alignment

  11. Cuts and data reduction • Topology • near and far units • diagonals • Low || selection (3σ) • |xRP,45|<3σx @Lx,45=0 • |xRP,56|<3σx @Lx,56=0 • corr. yRP216,45  yRP220,45 • corr. yRP216,56 yRP220,56 • Elastic collinearity (3σ) • θx,45* θx,56* • θy,45* θy,56* Intergrated luminosity : 6.2 nbarn-1 showers • Diagonals analysed independently

  12. Proton tracks of a single diagonal(left-right coincidences) t = -p2q2 Sector 56 x = Dp/p y = LyQy x = LxQx + xD Lx ~ 0 Sector 45

  13. Cuts and data reduction • Topology • near and far units • diagonals • Low || selection (3σ) • |xRP,45|<3σx @Lx,45=0 • |xRP,56|<3σx @Lx,56=0 • corr. yRP216,45  yRP220,45 • corr. yRP216,56 yRP220,56 • Elastic collinearity (3σ) • θx,45* θx,56* • θy,45* θy,56* Intergrated luminosity : 6.2 nbarn-1 showers

  14. Low  = Dp/p cuts yRP near,45  yRP far,45 (dLy/ds0) |x| < 3σx @ Lx = 0

  15. Cuts and data reduction • Topology • near and far units • diagonals • Low || selection (3σ) • |xRP,45|<3σx @Lx,45=0 • |xRP,56|<3σx @Lx,56=0 • corr. yRP216,45  yRP220,45 • corr. yRP216,56 yRP220,56 • Elastic collinearity (3σ) • θx,45* θx,56* • θy,45* θy,56* Intergrated luminosity : 6.2 nbarn-1 showers

  16. Elastic collinearity cuts background signal background signal Data outside the 3σ cuts used for background estimation

  17. Background and resolution determination –– signal –– background –– combined B/S = (8±1)% σ*=17.8rad (beam divergence) Data Combined background (t) -t [GeV2] θx/sqrt(2) Signal to background normalisation Signal vs. background (t) (also as a function of θy) σ* → t-reconstruction resolution: |t|=0.4GeV2: B/S = (11±2)% |t|=0.5GeV2: B/S = (19±3)% |t|=1.5GeV2: B/S = (0.8±0.3)%

  18. ty-acceptancecorrections |t|<0.36GeV2removed |ty| (diagonal 1) Beam divergence |ty| (diagonal 2) Missing acceptance inθy* Correctionerror (ty): 0.31 GeV2 : 30% 0.33 GeV2 : 11% 0.35 GeV2 : 2% 0.4 GeV2 : 0.8% 0.5 GeV2 : 0.1%

  19. -acceptance correction Total -acceptancecorrection Accepted (t) Diagonal 1 1 2 3 4 5 6 Θ*  |t|<0.36GeV2removed Diagonal 2 Accepted (t) Critical at low t-acceptance limit

  20. Final unfolded distribution | Systematic normalisation uncertainty30%

  21. Elastic Scattering – from ISR to Tevatron ISR ~ 1.7 GeV2 ~ 0.7 GeV2 ~1.5 GeV2

  22. Comparison to somemodels Betterstatisticsatlarge t needed

  23. Future analyses of existing data RP – 18 s2010 data (5.8 pbarn-1) – Double Pomeron Exchange, RP +T1 and T2 (2011 data from 6 low L pilots) 2. Inelastic detectors T1 and T2 (data from 2011) – Pseudorapiditydistributions (including RP information) – Multiplicity distributions and correlations Future runs 2011 • RP 220 m fully validated (14 s vert., 17 shoriz. in normal runs):(large-t elastic scattering, β*=1.5 m) • RP 147 m beam based alignment with data taking (August)(diffraction) • β*= 90 m optics • – First MD (done): successful for separated beams • – Next MD (28. June): establish collisions and ~1hour data taking for opticsdiagnostics • – Physics starting in August /September • Low-t (10 -2 GeV2) elastic scattering • Total cross-section (extrapolation to t=0 possible)

  24. Backup

  25. Outlook: Measurement of r in the Coulomb-nuclear Interference Region? Aim: get also the last ingredient to stot from measurement rather than theory (eN = 3.75 mm rad) (eN = 1 mm rad) • might be possible at sqrt(s)=7 TeV with RPs at 6 s • incentive to develop very-high-b* optics before reaching 14 TeV !e.g. try to use the same optics principle as for 90m and unsqueeze further.

  26. Optics

  27. Optics verification Triplet dLx/ds dLy/ds MQY MQML dLy/ds|s=220m measured by TOTEM Lx Ly s: Lx=0 measured by TOTEM

  28. s: Lx(s)==0 determination • Four fits per diagonal, 8 in total, diagonals averaged Top 45 bottom 56, 45 near s=214.463 m Top 45 bottom 56, 45 far s=220 m a=2.229 a=-3.142 Interpolation: Lx(s) = 0 for s = 217.8 m (nominally 222.1m)

  29. Θyvs. y, coupling , beam 1 Preliminary fits, fit direction rather needs to be orthogonal, better numbers from Jan’s alignment needed (dLy/ds) / Ly near =3.9210-3m-15 % Nominally: 2.710-3m-1 re14/re34 far=36mrad5 % Nominally: 0 Constraint for triplet strenghts matching Constraint for triplet rotation matching

  30. Beam 2 • (dLy/ds) / Ly=2.61510-3m-15 % (nominally 1.30410-3m-1) • re14/re34 far=31.8mrad 5 % (nominally 0)

  31. Matched parameters • Perturbation of (nominal) actual LHC settings • 30 parameters per beam • Magnet positions, rotations, k • Beam energy, displacement, crossing angle, harmonics... • Selected fitted parameters • 6 strengths per beam (MQXA, MQXB, MQXB, MQXA, MQY, MQML) • 6 corresponding rotations per beam • Mean  per beam • Total of 26 fitted parameters

  32. Constraints • TOTAL of 36 • LHC design constraints (a total of 26): • sigma(k)/k = 0.1% • sigma (rot) = 1mrad • Sigma()/  = 10-3 • Measured constraints of individual arms (a total of 8): • (dLy/ds)/Ly; near unit rotation (coupling); far unit rotation (coupling) • s: Lx==0 (1m precision) • Measured elastic scattering kinematics constraints between arms (a total of 2): • Ratio of Ly56 / Ly45 (0.2% precision) • Ratio of (dLx/ds56) / (dLx/ds 45) (0.5 % precision)

  33. Matching solution Strong correlations between fitted parameters Principle Component Analysis (PCA) ideally should be applied 2/NDF = 25.8/(36-26)=2.6 (would be lower in correlations are elmininated) Matching results within the LHC tolerance Abs(Pulls) of constraints Abs(Pulls) of fitted parameters

  34. Analysis steps detailed

  35. Analytical unfolding Smearing only due to beam divergence Detector resolution negligible (divergence uncertainty) Verified by MC based approach Verified by stringent selection cuts

  36. Unfolding verification MC vs. Analytical unfolding

  37. Data transformations (after selection cuts)diagonal top 45 bottom 56 alone Raw data Acceptance corrected 4 5 6 1 2 3 1 – raw data (signal + background) 2 – estimated background 3 – estimated background acceptance corrected 4 – raw data acceptance corrected 5 – raw data acceptance corrected - background 6 – final unfolded distribution

  38. The Roman Pot System at 220 m and 147 m fully installed TOTAL: 24 pots Karsten Eggert–

  39. Installation of the RP system at 147 m Karsten Eggert–

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