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The TOTEM Experiment at the LHC Physics program Detector overview Giuseppe Latino (University of Siena & Pisa INFN) (on behalf of the TOTEM Collaboration) Rencontres de Moriond – QCD & HEI La Thuile – March 20, 2009 1/16
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TOTEM @ CERN Large Hadron Collider (LHC) 2/16 TOTEM - Total Cross Section - Elastic Scattering - Diffractive Dissociation LHC - p-p collisions at s =14 TeV - L inst up to ~ 10 33 cm -2 s -1 - start up ~ Fall 2009 - 6 experiments Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC TOTEM Collaboration: Bari, Budapest, Case Western Reserve, CERN, Genova, Helsinki, Penn State, Pisa/Siena, Prague, Tallin (~ 80 physicists) Total and Elastic Measurement CMS TOTEM
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T1 T2 Castor (CMS) T2 Castor (CMS) Leading protons: RPs at 147m and 220m Rap gaps & Fwd particle flows: T1 & T2 telescopes Fwd energy flows: Castor & ZDC (CMS) CMS T1 Leading Protons measured at +147m & +220m from IP Leading Protons measured at -147m & -220m from IP TOTEM Experiment TOTEM & CMS @ IP5 3/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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TOTEM Physics Program Overview Stand-Alone - TOT pp with a precision ~ 1-2%, simultaneously measuring: N el down to -t ~10 -3 GeV 2 and N inel with losses < 3% - Elastic pp scattering in the range 10 -3 < |t| ~ (p ) 2 < 10 GeV 2 - 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 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
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5/16 Total Cross Section PP Current models predict at s = 14 TeV: PP = 90 - 130 mb TOTEM goal: absolute error ~ 1mb ( L inst ~ 10 28 cm -2 s -1 ) possibility to distinguish among different models Luminosity independent method: - elastic scattering (down to |t| ~ 10 -3 GeV 2 ) - inelastic scattering proper tracking acceptance in forward region required COMPETE Coll. [PRL 89, 201801 (2002)] (~ ln 2 s ) Optical Theorem : Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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t p 2 2 Predicted at LHC: el pp ~ 18 - 35 mb Elastic Scattering Cross Section d PP el /dt 6/16 (1) * = 1540 m (typical L inst = 1.0 x 10 28 cm -2 s -1 ): |t| min = 0.002 GeV 2 (2) * = 90 m (typical L inst = 1.0 x 10 30 cm -2 s -1 ): |t| min = 0.04 GeV 2 Allowed |t| range depends on beam optics Wide range of predictions; big uncertainties at large |t|; whole |t| range measured with good statistics. Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC N Events/GeV 2 (BSW) Diffractive structure pQCD Photon - Pomeron interference Multigluon (“Pomeron”) exchange e – B |t| ~ 1 day (1) (2) Coulomb int.: CKL formula Dedicated short runs at high- * (and reduced ) are required for precise measurement of the scattering angles of a few rad
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Scenario Physics: 1 low |t| elastic, tot (@ ~1%), MB, soft diffr. 2 low/large |t| elastic, tot (@ ~5%), MB, soft/semi-h. diffr. 3 large |t| elastic, hard diffraction * [m] 154090 2 0.5 N of bunches 43 156 156 936 2808 Bunch spacing [ns] 2025 525 52525 N of part. per bunch (0.6 1.15) x 10 11 1.15 x 10 11 Half crossing angle [ rad] 0092 Transv. norm. emitt. n [ m rad] 13.75 RMS beam size at IP [ m] 45021332 RMS beam diverg. at IP [ rad] 0.32.316 Peak Luminosity [cm -2 s -1 ] 10 28 2 x 10 29 3 x 10 30 10 33 Running Scenarios 7/16 Accessible physics depends on luminosity & * 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 * ( m) 1540 90 2 0.5 L (cm -2 s -1 ) 10 29 10 30 10 32 10 33 TOTEM runs Standard runs Cross section Luminosity beam ang. spread at IP: * = / * ) beam size at IP: * = ( *) Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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Combined Uncertainty in tot 8/16 * = 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 %) Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC Total uncertainty in tot including correlations in the error propagation : * = 90 m : ± 5% * = 1540 m : ± (1 ÷ 2) % Slightly worse in L (~ 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
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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 Charged particles Energy flux TOTEM+CMS dE/d dN ch /d Roman Pots T1,T2 Roman Pots LHC, inelastic collisions CMS 9/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC M M Double Pomeron Exchange Double Diffraction Single Diffraction Elastic Scattering ~ 60 mb 18 - 35 mb 10 - 16 mb 4 - 14 mb 0.2 - 1.5 mb << 1 mb
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10/16 Early TOTEM Measurents ( p = 5 TeV, * = 3m ) T1/T2 Charged multiplicity studies (min. bias and cosmic ray MC generators tuning/val.) Rapidity gap studies (topologies of diffr. events) NDSD DPE 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 GeV 2, (t)/t ~ 0.2/ |t| Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC Acceptance: 0.02 < = p/p < 0.18 Resolution: ( ) ~ 1 6 · 10 -3, ( ) ~ 15 rad
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TOTEM Detectors: Setup in CMS CMS HF T1: 3.1 < < 4.7 T2: 5.3 < < 6.5 Inelastic Telescopes: reconstruction of tracks and interaction vertex; trigger capability with acceptance > 95 % T1: 18 - 90 mrad T2: 3 - 10 mrad = - log(tg( /2)) ~14 m 10.5 mT1T2 Detectors on both sides of IP5 11/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC RP220 RP147 ZDC Elastic Detectors (Roman Pots): Elastic Detectors (Roman Pots): position of p scattered elastically at small angles Active area up 1-1.5 mm from beam: 5-10 rad HF
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Horizontal Pot: extend acceptance; overlap for relative alignment using common track. Absolute (w.r.t. beam) alignment from beam position monitor (BPM) Beampipes Roman Pots Each RP station has 2 units, 4m apart. Each unit has 2 vertical insertions (‘pots’) and 1 horizontal 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 + d from beam ( beam ~ 80 m at RP) ‘Edgeless’ detectors to minimize d Horizontal Pot Vertical Pot BPM 12/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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200 m thick beam Roman Pots Each Pot: 10 planes of Si detectors 512 strips at 45 o orthogonal Pitch: 66 m Total ~ 5.1K channels Digital readout (VFAT): trigger/tracking Resolution: ~ 20 m Readout chip VFAT Edgeless Si detector: 50 μm of dead area Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC Integration of traditional Voltage Terminating Structure with the Current Terminating Structure 13/16 Detectors expected to work up to L int ~ 1 fb -1 Installation ongoing: RP220 (147) m fully (partially) equipped by June
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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 T1 Telescope 3m Moriond QCD & HEI – March 20, 2009 1/4 of T1 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 L inst =10 30 cm -2 s -1 Installation foreseen for May/June (if necessary also in September) G. Latino – The TOTEM Experiment at the LHC 14/16
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Moriond QCD & HEI – March 20, 2009 Each arm: 10 planes formed by 20 triple-GEM semi-circular modules, with “back-to-back assembly and overlap between modules 15/16 Test Beam T2 Telescope pads strips Castor Calorimeter (CMS) ~ 0.4 m T2: “GEM” Technology GEM Technology: Gas Detector Rad-hard High rate Good spatial and timing resolution T2 Triple GEM technology adequate to work at least 1 yr at L =10 33 cm -2 s -1 Double readout layer: Strips for radial position (R); Pads for R, Trigger from Pads (1560/chamber) Digital readout (VFAT) for ~ 41.4K ch. Resolution: R ~ 100 m, ~ 1 o Installation ongoing: fully done by May G. Latino – The TOTEM Experiment at the LHC
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16 TOTEM will be ready for data taking at the LHC restart and will run under all beam conditions. 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). of 1-2% (2%) with * = 1540 m (dedicated runs). Measurement of elastic scattering in the range 10 -3 < |t| < 10 GeV 2 Early measurements low *: - study of SD and DPE at high masses - study of SD and DPE at high masses - elastic scattering at high |t| - elastic scattering at high |t| - measurement of forward charged multiplicity - measurement of forward charged multiplicity * = 90 m: - first measurement of tot (and L ) with a precision of ~ 5% (~ 7%) - first measurement of tot (and L ) with a precision of ~ 5% (~ 7%) - elastic scattering in a wide |t| range - elastic scattering in a wide |t| range - inclusive studies of diffractive processes - inclusive studies of diffractive processes - measurement of forward charged multiplicity - measurement of forward charged multiplicity Later: common CMS/TOTEM Physics Programme Summary & Conclusions 16/16 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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Backup Slides Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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= fine structure constant = relative Coulomb-nuclear phase G(t) = nucleon em form factor = (1 + |t|/0.71) -2 = Re/Im f(p p) Measurement of the exponential slope B in the t-range 0.002 - 0.2 GeV 2 needs beams with tiny angular spread large * Model dependent uncertainty due to Coulomb interferences Determination of d /dt at t=0 B1 Coulomb scattering Nuclear scattering Coulomb- Nuclear interference - - - BSW Very approximate formula: West and Yenneie model for Coulomb-Nuclear interference ( (t) = const) Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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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 asymptotic behaviour: 1 / ln s for s pred. ~ 0.13 at LHC Possibilities of measurement La Thuile – March 1, 2008 G. Latino – The TOTEM Experiment at LHC B2
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Details on Optics Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC B3 = p/p ; t = t x + t y ; t i ~ -(p i *) 2 (x *, y * ): vertex position at IP ( x *, y * ): emission angle at IP Proton transport equation: x = L x x * + v x x * + D y = L y y * + v y y * 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) Example same sample of diffractive protons at different * - low *: p detected by momentum loss ( ) - high *: p detected by trans. momentum (t y )
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21 L = ( *) 1/2 sin( (s)) Idea: L y large L x =0 v y = 0 y (220) = /2 x (220) = (parallel-to-point focussing on y) (m) hit distribution (elastic) x = L x x * + v x x * +D y = L y y * + v y y * Optical Functions ( * = 90 m) v = ( / *) 1/2 cos( (s)) 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 B4 = p/p (x *, y * ): vertex position at IP ( x *, y * ): emission angle at IP t = t x + t y t i ~ -(p i * ) 2 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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Detector distance to the beam: 10 +0.5mm -t = 0.01 GeV 2 -t = 0.002 GeV 2 Beam * = 1540 m *=2 m *=90 m log(-t / GeV 2 ) 0.002 0.06 4.0 Acceptanc e Roman Pots Acceptances B5 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC Det. dist. 1.3 mm 6 mm = 1540 m L = 10 28 – 2 x 10 29 95% of all p seen; all = 90 m L = 10 29 – 3 x 10 30 65% of all p seen; all = 0.5 – 2 m L = 10 30 – 10 34 p with seen; all t = 0.5m - 2m resolved RP 220m Elastic Scattering (RP220)
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0.1--30 Elastic Scattering 0.02--1 Double Pomeron 0.10.32.87 Double diffractive 0.62.5-14 Single diffractive 0.060.060.358 Minimum bias Uncertainty after Extrapolation (mb) Single arm T1/T2 Double arm T1/T2 (mb) Trigger Losses (mb): Acceptance simulated extrapolated detected Pythia generator Loss at low masses Total 0.8% Error on B6 Measurement of TOT at 1% T / T ~ [(0.006) 2 + (0.002) 2 + (0.012) 2 ] ~ 0.014 Moriond QCD & HEI – March 20, 2009 Inelastic + Elastic Error Extrapolation t=0 Error
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Forward Physics: VHE Cosmic Ray Connection B7 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 … Total multiplicity in T2 (5< <7) p-p collisions @ LHC as predicted by generators tipically used to model hadronic showers generated by VHE CR Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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Expected Radiation Dose in CMS/TOTEM Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC B8 In 1 year @ L inst = 10 34 cm -2 s -1 At RPs locations =>
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Planar technology with CTS (Current Terminating Structure ) 50 µm I2I2 I1I1 + - biasing ring Al p+p+ n+n+ cut edge current terminating ring Al SiO 2 n-type bulk p+p+ 50 µm AC coupled microstrips made in planar technology with novel guard-ring design and biasing scheme 50 μm of dead area B9 Si CTS Edgeless Detectors for Roman Pots bias gard/clean-up ring (CR) Integration of traditional Voltage Terminating Structure with the Current Terminating Structure Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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T1 Cathode Strip Chamber (CSC) B10 Cathode strips – 5mm pitch Detector design similar to CMS CSC muon chamber Gas Mixture Ar/CO 2 /CF 4 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=10 30 cm -2 s -1 Anode wires – 3mm pitch Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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Gas Electron Multiplier (GEM) 5 µm Cu 70 µm 55 µm 50 µm Kapton 70 µm 140 µm B11 Electrons Ions T2 GEM: Developed at CERN (F. Sauli ~ 1997) Used in COMPASS, LHCb, … Gas Detector “Rad-hard”, high rate, good spatial and timing resolution and timing resolution Electrodes: 50 m kapton + 2x5 m Cu Density: 50-100 holes/mm 2 Electric field (channel) ~ 100 KV/cm (V gem = 500 V) electron cascade (V gem = 500 V) electron cascade Gain: 10 - 100 GEM Technology Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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T2 Triple-GEM Detectors HV Divider Gas in/out Cooling Digital R/O pads VFAT for Trigger 17 VFAT / module pads strips 65( ) x 24( = 1560 pads Pads: x = 0.06 x 0.018 ~2x2 mm 2 - ~7x7 mm 2 Strips: 256x2 (width 80 m, pitch 400 m) Ar/CO 2 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=10 33 cm -2 s -1 B12 Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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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 B13 Standardization for all detectors: identical front-end electronics (VFAT chips); identical DAQ and trigger cards Moriond QCD & HEI – March 20, 2009 G. Latino – The TOTEM Experiment at the LHC
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