The TOTEM Experiment at the LHC

1. The TOTEM Experiment at the LHC • Giuseppe Latino • (University of Siena & Pisa INFN) • (on behalf of the TOTEM Collaboration) • Rencontres de Moriond – QCD & HEI • La Thuile – March 20, 2009 • Physics program • Detector overview 1/16

2. CMS TOTEM Total and Elastic Measurement TOTEM @ CERN Large Hadron Collider (LHC) LHC- p-p collisions ats =14 TeV- Linst up to ~ 1033 cm-2s-1- start up ~ Fall 2009- 6 experiments TOTEM- Total Cross Section- Elastic Scattering - Diffractive Dissociation TOTEM Collaboration: Bari, Budapest, Case Western Reserve, CERN, Genova, Helsinki, Penn State, Pisa/Siena, Prague, Tallin (~ 80 physicists) 2/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

3. TOTEM & CMS @ IP5 Leading Protons measured at -147m & -220m from IP Castor (CMS) Leading Protons measured at +147m & +220m from IP T2 CMS T1 TOTEM Experiment T1 T2 Castor (CMS) Leading protons: RPs at 147m and 220m Rap gaps & Fwd particle flows: T1 & T2 telescopes Fwd energy flows: Castor & ZDC (CMS) 3/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

4. CMS-TOTEM (CMS/TOTEM Physics TDR, CERN/LHCC 2006-039/G-124) - Soft and hard diffraction in SD and DPE (production of jets, bosons, h.f.) - Central exclusive particle production - Low-x physics - Particle and energy flow in the forward region TOTEM Physics Program Overview Stand-Alone - TOTpp with a precision ~ 1-2%, simultaneously measuring: Nel down to -t ~10-3 GeV2 and Ninel with losses < 3% - Elastic pp scattering in the range 10-3< |t| ~ (p)2 < 10 GeV2 - Soft diffraction (SD and DPE) - Particle flow in the forward region (cosmic ray MC validation/tuning) 4/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

5. COMPETE Coll. [PRL 89, 201801 (2002)] (~ ln2 s ) Optical Theorem:  Total Cross Section PP • Current models predict at s = 14 TeV: PP = 90 - 130 mb • TOTEM goal: absolute error ~ 1mb(Linst ~ 1028 cm-2s-1)  possibility to distinguish among different models • Luminosity independent method: - elastic scattering (down to |t| ~ 10-3 GeV2) - inelastic scattering  proper tracking acceptance in forward region required 5/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

6. N Events/GeV2(BSW) Photon - Pomeron interference  Coulomb int.: CKL formula Multigluon (“Pomeron”) exchange e– B |t|  t  p22 Diffractive structure pQCD ~1 day (1) (2) Elastic Scattering Cross Section dPPel/dt Predicted at LHC: elpp ~ 18 - 35 mb Wide range of predictions; big uncertainties at large |t|; whole |t| range measured with good statistics. Allowed |t| range depends on beam optics Dedicated short runs at high-* (and reduced ) are required for precise measurement of the scattering angles of a few rad (1) *= 1540 m (typicalLinst= 1.0 x 1028 cm-2 s-1): |t|min = 0.002 GeV2 (2) * = 90 m (typicalLinst = 1.0 x 1030cm-2 s-1): |t|min = 0.04 GeV2 6/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

7. Cross section Luminosity * (m)1540 902 0.5 L (cm-2 s-1) 1029 10301032 1033 TOTEM runsStandard runs Running Scenarios beam ang. spread at IP:* = ( / *)beam size at IP:* = (*) • Optimal * = 1540m optics requires special injection optics: probably NOT available at the beginning of LHC • ‘Early’ * = 90m optics achievable using the standard LHC injection optics Accessible physics depends on luminosity & * 7/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

8. * = 90 m 1540 m • Extrapolation of elastic cross-section to t = 0: ± 4 % ± 0.2 % • Total elastic rate (strongly correlated with extrapolation): ± 2 %± 0.1 % • Total inelastic rate: ± 1 % ± 0.8 % (error dominated by Single Diffractive trigger losses) • Error contribution from (1+2): ± 1.2 % (using full COMPETE error band d/ = 33 %) Combined Uncertainty in tot • Total uncertainty intot including correlations in the error propagation: b* = 90 m : ±5%b* = 1540 m: ± (1 ÷ 2) % Slightly worse inL(~ total rate squared) : ± 7 % (± 2 %) Precise Measurement with * = 1540 m requires: improved knowledge of optical functions; alignment precision < 50 m * = 90 m required for early tot measurement during the first year of LHC running at s = 10 TeV 8/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

9. LHC, inelastic collisions T1,T2 T1,T2 ~ 60 mb Charged particles Roman Pots Roman Pots dNch/dh Elastic Scattering 18 - 35 mb CMS Energy flux 10 - 16 mb Single Diffraction M dE/dh TOTEM+CMS CMS 4 - 14 mb Double Diffraction Double Pomeron Exchange 0.2 - 1.5 mb M << 1 mb CMS/TOTEM Common Physics Program CMS + TOTEM  largest acceptance detector ever built at a hadron collider: the large  coverage and p detection on both sides allow the study of a wide range of physics processes in diffractive interactions 9/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

10. SD DPE ND SD Early TOTEM Measurents (p = 5 TeV, * = 3m) Roman Pots • Sing. Diff. (horizontal RPs): dSD/dM at high masses, 1.4 < M < 4.2 TeV, (M)/M < 10 % • DPE (horizontal RPs): dDPE/dM at high masses, 0.2 < M < 1.8 TeV, (M)/M < 10 % • El. Scatt. (vertical RPs): dES/dt for 2 < |t| < 10 GeV2, (t)/t ~ 0.2/|t| Acceptance: 0.02 <  = p/p < 0.18 Resolution: () ~ 1  6 · 10-3, () ~ 15 rad T1/T2 • Charged multiplicity studies (min. bias and cosmic ray MC generators tuning/val.) • Rapidity gap studies (topologies of diffr. events) 10/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

11. Inelastic Telescopes: reconstruction of tracks and interaction vertex; trigger capability with acceptance > 95 % T1:3.1 << 4.7 T2: 5.3 <  < 6.5  T1: 18 - 90 mrad T2: 3 - 10 mrad h = - log(tg(/2)) T1 10.5 m T2 ~14 m Elastic Detectors (Roman Pots):position of p scattered elastically at small angles Active area up 1-1.5 mm from beam: 5-10 rad RP220 RP147 ZDC TOTEM Detectors: Setup in CMS Detectors on both sides of IP5 CMS HF HF 11/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

12. Beampipes Horizontal Pot Vertical Pot BPM Roman Pots Units installed into the beam vacuum chamber allowing to put proton detectors as close as possible to the beam Protons at few rad angles detected at 10 + dfrom beam (beam ~ 80m at RP)  ‘Edgeless’ detectors to minimize d Each RP station has 2 units, 4m apart. Each unit has 2 vertical insertions (‘pots’) and 1 horizontal Horizontal Pot: extend acceptance; overlap for relative alignment using common track. Absolute (w.r.t. beam) alignment from beam position monitor (BPM) 12/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

13. 200m thick Integration of traditional Voltage Terminating Structure with the Current Terminating Structure beam Readout chip VFAT Roman Pots Each Pot: • 10 planes of Si detectors • 512 strips at 45o orthogonal • Pitch: 66 m • Total ~ 5.1K channels • Digital readout (VFAT): trigger/tracking • Resolution: ~ 20 m Detectors expected to work up to Lint ~ 1 fb-1 Installation ongoing: RP220 (147) m fully (partially) equipped by June Edgeless Si detector: 50 μm of dead area 13/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

14. Each arm: • 5 planes with 3 coordinates/plane, each formed by 6 trapezoidal CSC detectors • 3 degrees rotation and overlap between adjacent planes • Trigger with anode wires • Digital readout (VFAT) for ~ 13.5K ch. • Resolution: ~ 1 mm 3m 1/4 of T1 T1 Telescope Ageing studies at CERN GIF: no loss of performance during 12-month test, with ~ 0.07 C/cm accumulated charge on wires, a dose equivalent to ~ 5 years at Linst=1030 cm-2s-1 Installation foreseen for May/June (if necessary also in September) 14/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

15. Each arm: • 10 planes formed by 20 triple-GEM semi-circular modules, with “back-to-back assembly and overlap between modules • Double readout layer: Strips for radial position (R); Pads forR, f • Trigger from Pads (1560/chamber) • Digital readout (VFAT) for ~ 41.4K ch. • Resolution:R ~ 100 mm,  ~ 1o GEM Technology: • Gas Detector • Rad-hard • High rate • Good spatial and timing resolution strips T2: “GEM” Technology T2 Triple GEM technology adequate to work at least 1 yr at L=1033 cm-2s-1  pads Castor Calorimeter (CMS) Test Beam ~ 0.4 m T2 Telescope Installation ongoing: fully done by May 15/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

16. Summary & Conclusions • TOTEM will be ready for data taking at the LHC restart and will run under all beam conditions. • Measurement of total pp cross-section (and L) with a precision of 1-2% (2%) with * = 1540 m (dedicated runs). • Measurement of elastic scattering in the range 10-3< |t| < 10 GeV2 • Early measurements • low *: - study of SD and DPE at high masses - elastic scattering at high |t| - measurement of forward charged multiplicity • * = 90 m: - first measurement of tot (and L) with a precision of ~ 5% (~ 7%) - elastic scattering in a wide |t| range - inclusive studies of diffractive processes - measurement of forward charged multiplicity • Later: common CMS/TOTEM Physics Programme 16 16/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

17. Backup Slides Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

18. Coulomb scattering Coulomb- Nuclear interference Nuclear scattering - - - BSW Determination of d/dt at t=0 Model dependent uncertainty due to Coulomb interferences Very approximate formula: West and Yenneie model for Coulomb-Nuclear interference ((t) = const) a = fine structure constant • = relative Coulomb-nuclear phase G(t) = nucleon em form factor = (1 + |t|/0.71)-2 r = Re/Im f(pp) Measurement of the exponential slope B in the t-range 0.002 - 0.2 GeV2 needs beams with tiny angular spread  large* B1 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

19. asymptotic behaviour: • 1 / ln s for s   pred. ~ 0.13 at LHC Possibilities of  measurement Try to reach the Coulomb region and measure interference: • move the detectors closer to the beam than 10+ 0.5 mm • run at lower energy @ √s < 14 TeV B2 La Thuile – March 1, 2008 G. Latino – The TOTEM Experiment at LHC

20. Details on Optics Proton transport equation: x = Lxx* + vxx* + D y = Lyy* + vyy * Optical functions: - L (effective length); - v (magnification); - D (machine dispersion) Describe the explicit path of particles through the magnetic elements as a function of the particle parameters at IP.  Define t and  range (acceptance)  = p/p;t = tx + ty; ti ~ -(pi*)2 (x*, y*): vertex position at IP (x*,y*): emission angle at IP Example same sample of diffractive protons at different * - low *: p detected by momentum loss () - high *: p detected by trans. momentum (ty) B3 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

21. Optical Functions (* = 90 m) L = (*)1/2 sin((s)) v = (/*)1/2 cos((s)) hit distribution (elastic) x = Lxx* + vxx* +D y = Lyy* + vyy *  Idea: Lylarge Lx=0 vy= 0 y(220) = /2x(220) =  (parallel-to-point focussing on y) (m)‏ Optical functions: - L (effective length) - v (magnification) defined by  (betatron function) and  (phase advance); - D (machine dispersion)  describe the explicit path of particles through the magnetic elements as a function of the particle parameters at IP  = p/p (x*, y*): vertex position at IP (x*,y*): emission angle at IP t = tx + ty ti ~ -(pi*)2 B4 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

22. RP 220m b*=1540 m Acceptance Detector distance to the beam: 10+0.5mm b*=90 m x resolved b = 0.5m - 2m b*=2 m -t = 0.01 GeV2 -t = 0.002 GeV2 * = 1540 m Beam 0.002 0.06 4.0 log(-t / GeV2) Roman Pots Acceptances Elastic Scattering (RP220) Det. dist. 1.3 mm 6 mm B5 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

23. (mb) Double arm T1/T2 Single arm T1/T2 Uncertainty after Extrapolation (mb) Minimum bias 58 0.3 0.06 0.06 Single diffractive 14 - 2.5 0.6 Double diffractive 7 2.8 0.3 0.1 Extrapolation t=0 Error Inelastic + Elastic Error Double Pomeron 1 - - 0.02 Elastic Scattering 30 - - 0.1 Measurement of TOT at 1% Loss at low masses Pythia generator simulated extrapolated Acceptance detected Trigger Losses (mb): Total 0.8% T/T ~ [(0.006)2 + (0.002)2 + (0.012)2] ~ 0.014 Error on r B6 Moriond QCD & HEI – March 20, 2009

24. Total multiplicity in T2 (5<<7) Forward Physics: VHE Cosmic Ray Connection p-p collisions @ LHC as predicted by generators tipically used to model hadronic showers generated by VHE CR Interpreting cosmic ray data depends on hadronic simulation programs. Forward region poorly known/constr. Models differ by factor 2 or more. Need forward particle/energy measurements e.g. dN/d, dE/d… B7 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

25. Expected Radiation Dose in CMS/TOTEM In 1 year @ Linst = 1034 cm-2s-1 At RPs locations => B8 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

26. I1 I2 current terminating ring biasing ring Al - + SiO2 p+ p+ n-type bulk Integration of traditional Voltage Terminating Structure with the Current Terminating Structure cut edge Al n+ 50µm Si CTS Edgeless Detectors for Roman Pots Planar technology with CTS (Current Terminating Structure) bias gard/clean-up ring (CR) AC coupled microstrips made in planar technology with novel guard-ring design and biasing scheme 50 μm of dead area 50 µm B9 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

27. Cathode strips – 5mm pitch Anode wires – 3mm pitch T1 Cathode Strip Chamber (CSC) • Detector design similar to CMS CSC muon chamber • Gas Mixture Ar/CO2/CF4 • Max size: ~ 1m x 0.68 m • Gas gap: 10 mm • Anode wires: 30m, 3mm pitch • Cathode strips: 4.5 mm width, 5mm pitch • Digital readout (VFAT) Ageing studies at CERN Gamma Irradiation Facility: no loss of performance during 12-month test, with ~0.07 C/cm accumulated charge on wires corresponding to a dose equivalent to ~ 5 years at L=1030cm-2s-1 B10 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

28. Ions 70 µm 5 µm Cu 50 µm Kapton 140 µm 55 µm 70 µm Electrons Gas Electron Multiplier (GEM) GEM Technology • Developed at CERN (F. Sauli ~ 1997) • Used in COMPASS, LHCb, … • Gas Detector • “Rad-hard”, high rate, good spatial and timing resolution • Electrodes: 50 m kapton + 2x5 m Cu • Density: 50-100 holes/mm2 • Electric field (channel) ~ 100 KV/cm (Vgem = 500 V) electron cascade • Gain: 10 - 100 T2 GEM: B11 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

29. Cooling 17 VFAT / module HV Divider strips Gas in/out 65() x 24(= 1560pads Pads: x  = 0.06 x 0.018 • ~2x2 mm2 - ~7x7 mm2 Strips:256x2(width 80 m, pitch 400 m) Digital R/O pads VFAT for Trigger pads T2 Triple-GEM Detectors • Ar/CO2 70/30 gas mixture • Operating gas gain M = 8000 • Digital readout (VFAT) • T2 Triple GEM technology adequate to work at least 1 yr at L=1033 cm-2s-1 B12 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC

30. Totem Electronics VFAT Chip • Developed at CERN by the Micro-Electronics group • 128 channels of tracking front- end with digital storage and data transmission • 8 programmable trigger outputs • Designed for radiation tolerance Standardization for all detectors: identical front-end electronics (VFAT chips); identical DAQ and trigger cards B13 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC