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P. 1Mario Deile – DIS 2004 Mario Deile CERN on behalf of the TOTEM Collaboration 16.04.2004 TOTEM: Forward Physics at the LHC.

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Presentation on theme: "P. 1Mario Deile – DIS 2004 Mario Deile CERN on behalf of the TOTEM Collaboration 16.04.2004 TOTEM: Forward Physics at the LHC."— Presentation transcript:

1 p. 1Mario Deile – DIS 2004 Mario Deile CERN on behalf of the TOTEM Collaboration TOTEM: Forward Physics at the LHC

2 p. 2Mario Deile – Elastic p-p scattering cross-section d  /dt in the range GeV 2 < –t < 10 GeV 2 Total p-p cross section at 14 TeV with 1% uncertainty using the Optical Theorem (luminosity independent method) Diffractive events (together with CMS). Absolute luminosity measurement and calibration of CMS luminosity monitors Physics Objectives of TOTEM

3 p. 3Mario Deile – Detector Configuration ~14 m CMS T1:  3.1 <  < 4.7 T2: 5.3 <  < m T1 T2 RP1 RP2 RP3 220 m 180 m 147 m

4 p. 4Mario Deile – ~ 90 % of all diffractive protons are detected microstation at 19m ? RPs Total TOTEM/CMS acceptance (  * =1540m) CMS+TOTEM: largest acceptance detector ever built at a hadron collider Roman Pots TOTEM+CMS T1,T2 Roman Pots Charged particles Energy flux CMS + TOTEM: Acceptance dN ch /d  dE/d 

5 p. 5Mario Deile – T1 Telescope: Cathode Strip Chambers Two telescopes (forward and backward) 5 planes of cathode strip chambers (CSC)  coverage = 2  3.1 < |  | < ° rotation from plane to plane to improve pattern recognition ~3m 0.8  1.1 m 3 projections measured ~350 cathode strips / detector, 5 mm pitch; analogue read-out (CMS Buckeye chip); resolution:  x ~ 0.5 mm,  y ~ 0.9 mm ~210 anode wires / det., (  30  m, 3 mm pitch); digital read-out (CMS AD16 chip) provides trigger

6 p. 6Mario Deile – Castor Calorimeter (CMS) Vacuum Chamber 1800 mm 400 mm T2 Telescope: Gas Electron Multiplier T2 GEM Telescope: 8 planes 5.3< l  l < m from IP COMPASS technology Pads (trigger): digital readout via VFAT  x  = 0.06 x  2x2 mm 2  7x7 mm 2 Equidistant strips: analogue readout via APV25 80  m wide, 400  m pitch

7 p. 7Mario Deile – Proton Detectors: Roman Pots Beampipes Measurement of very small p scattering angles (few  rad): Leading proton detectors in RPs approach beam to 10  mm  1.5 mm 2004 prototype

8 p. 8Mario Deile – Proton Detectors: What goes into the Pot? Need full efficiency as close to the detector edge as possible; adequate resolution ~ 20  m The edge is itself an electrode. Electrodes processed through the bulk. SPS testbeam: Effic. transition within ~15  m mm 3D Si Detectors: Planar Si with reduced current-terminating guard structure (only ~70  m): Efficiency [a.u.] edge p+ n+ I surf. Al SPS testbeam: Effic. transition within ~60  m

9 p. 9Mario Deile – TOTEM Beam Optics  Reduce number of bunches (43 and 156) to avoid parasitical interactions downstream. L TOTEM = 1.6 x cm -2 s -1 and 2.4 x cm -2 s -1 Want to measure scattering angles down to a few mrad. Proton trajectory: y(s) = L y (s)  y * + v y (s) y *,L(s) = [  s   ] 1/2 sin  (s) x(s) = L x (s)  x * + v x (s) x * + D x (s) ,v(s) = [  (s)   ] 1/2 cos  (s) Maximise L x (s RP ), L y (s RP ) at s RP of Roman Pot Minimise v x (s RP ), v y (s RP ) at s RP of Roman Pot (parallel-to-point focussing: v = 0)  High-   optics: for TOTEM   = 1540 m Consequences: low angular spread at IP:  *) =  /  *  0.3  rad large beam size at IP:  * =  *  0.4 mm (if  N = 1  m rad)

10 p. 10Mario Deile – Running Scenarios Scenario (goal) 1 low |t| elastic,  tot, min. bias 2 diffractive physics, large p T phenomena 3 intermediate |t|, hard diffraction 4 large |t| elastic  * [m] N of bunches Half crossing angle [  rad] Transv. norm. emitt. [  m rad] N of part. per bunch 0.3 x x x RMS beam size at IP [  m] RMS beam diverg. [  rad] Peak luminosity [cm -2 s -1 ] 1.6 x x ( ) x x Runs at  * = 0.5 m, L = (10 33  ) cm -2 s -1 not yet part of TOTEM programme but under study.

11 p. 11Mario Deile – Standalone and with CMS Standalone running: forseen only for elastic scattering and total cross-section. Common running: –DAQ and Trigger must be CMS-compatible (hardware and software) –TOTEM can act as a CMS subdetector. –TOTEM can trigger CMS: Trigger from the Roman Pots must arrive at CMS within the CMS trigger latency: Very tight for the Pot at 220 m, but still feasible. Pots farther than 220 m from IP (none foreseen yet) cannot trigger!

12 p. 12Mario Deile – Level-1 Trigger Schemes p p p p p T1/T2 RP CMS Elastic Trigger: Signal: 500 Hz Background: 20 Hz Single Diffractive Trigger: Signal: 200 Hz Background: < 1 Hz ? (using vertex reconstruction in T1/T2) Double Diffractive Trigger: Signal: 100 Hz Central Diffractive Trigger: Signal: 10 Hz Background: 2 Hz Minimum Bias Trigger: Signal: 1 kHz Backgrounds under study! (L = 1.6 x cm -2 s -1 )

13 p. 13Mario Deile – Pomeron exchange ~ e –B|t| diffractive structure Photon - Pomeron interference   L dt = and cm -2 pQCD ~ |t| –8 Elastic Scattering Cross-Section

14 p. 14Mario Deile – Coulomb region  5  [lower s, RP closer to beam] Interference,  meas.5   5  [as above], standard  * = 1540 m Pomeron exchange5   0.1  * = 1540 m Diffractive structure0.1  1  * = 1540 m, 18 m Large |t| – perturb. QCD1  10  * = 18 m Region |t| [GeV] 2 Running Scenario Elastic Scattering: t-Acceptance

15 p. 15Mario Deile – Elastic Scattering: Resolution t-resolution (2-arm measurement)  -resolution (1-arm measurement) Test collinearity of particles in the 2 arms  Background reduction.

16 p. 16Mario Deile – Current models predictions: mb Aim of TOTEM: ~1% accuracy Total p-p Cross-Section LHC: TEVATRON ISR UA4 UA5 LHC Cosmic Rays COMPETE Collaboration fits: [PRL (2002)]

17 p. 17Mario Deile – Measurement of  tot Luminosity-independent measurement of the total cross-section using the Optical Theorem: Measure the elastic and inelastic rate with a precision better than 1%. Extrapolate the elastic cross-section to t = 0. Or conversely: Extract luminosity:

18 p. 18Mario Deile – Extrapolation of Elastic Cross-Section to t = 0 EffectExtrapolation uncertainty Statistics ):10 7 events0.07 % Uncertain functional form of d  /dt 0.5 % Beam energy uncertainty0.05 %0.1 % Beam / detector offset 20  m 0.08 % Crossing angle 0.2  rad 0.1 % Total0.53 % Non-exponential d  /dt fitted to Slope parameter according to BSW Model

19 p. 19Mario Deile – Measurement of the Total Rate N el + N inel  [mb] T1/T2 double arm trigger loss [mb] T1/T2 single arm trigger loss [mb] Uncertainty after extrapolation [mb] Minimum bias Single diffractive Double diffractive Double Pomeron1~ 0.2 (using leading p and CMS) 0.02 Elastic Scattering Acceptance single diffraction simulated extrapolated detected Loss at low masses Extrapolation of diffractive cross-section to large 1/M 2 using d  /dM 2 ~ 1/M 2. Total: 0.8 %

20 p. 20Mario Deile – Accuracy of  tot Extrapolation to t = 0 Total rate N el + N inel  = 0.12 ± 0.02

21 p. 21Mario Deile – ~ 90 % of all diffractive protons are seen in the Roman Pots (assuming ).  =  p / p can be measured with a resolution of ~ 5 x Diffraction at high    Acceptance A < 5 % A > 95 % %  * = 1540 m

22 p. 22Mario Deile –  y = – ln  y max = 6.5 Trigger via Roman Pots  > 2.5 x Trigger via rapidity gap  < 2.5 x  * = 1540 m:   = 0.5% L  2.4 x cm -2 s -1  * = 200  400 m:   ~ 1 ‰ L  cm -2 s -1  * = 0.5 m:   ~ 1 ‰ L > cm -2 s -1 Detection Prospects for Double Pomeron Events In collaboration with CMS dN/dy – ln   – ln   y pp CMS CMS + TOTEM p1p1 p2p2 p2’p2’ p1’p1’ P M 2 =     s P  * = 0.5 m

23 p. 23Mario Deile – Exclusive Production by DPE: Examples Advantage: Selection rules: J P = 0 +, 2 +, 4 + ; C = +1  reduced background, determination of quantum numbers. Good  resolution in TOTEM: determine parity: P = (-1) J+1  d  /d  ~ 1 +– cos 2  Particle  excl Decay channelBR Rate at 2x10 29 cm -2 s -1 Rate at cm -2 s -1 (no acceptance / analysis cuts)  c0 (3.4 GeV) 3  b [KMRS]  J/     +  –  +  – K + K – 6 x / h 46 / h 62 / h 1900 / h  b0 (9.9 GeV) 4 nb [KMRS]    +  – / d3 / d H (120 GeV) 0.1  100 fb assume 3 fb bb / y1 / y Higgs needs L ~ cm -2 s -1, i.e. a running scenario for   = 0.5 m: try to modify optics for enhanced dispersion, try to move detectors closer to the beam, install additional Roman Pots in cold LHC region at a later stage.

24 p. 24Mario Deile – Status and Outlook TDR was submitted to the LHCC in January Extensive test-beam programme in summer/autumn A TDR on the common CMS/TOTEM physics programme will be submitted in early 2005

25 p. 25Mario Deile –

26 p. 26Mario Deile – GEMs at high luminosities Test results from COMPASS, HERA-B and LHCb have shown:  Rate: Exposed to 350 MeV π +, π – and p beam (~ 10 5 / mm 2 s) at PSI i.e. rates expected in T2 at L=10 33 cm -2 s -1 (incl. background)  Ageing: tests at high rate: no sign of ageing observed after 7 mC / mm 2 (equiv mip / mm 2 or 1 year (10 7 s) at L=10 32 cm -2 s -1 )  Time resolution: 12.5 ns with Ar/CO 2 easily identifies bunches with 75 ns spacing  Sparking: Spark probability measured to be very low at gains of ~10 4, no damage after 5000 sparks The detector technology is proven and well adapted to the requirements for the T2 telescope up to cm -2 s -1 luminosity. Problem: radiation hardness of the electronics to be tested.

27 p. 27Mario Deile – L(s) High   Optics: Lattice Functions LyLy LxLx vxvx vyvy v(s) Parallel-to-point focussing achieved at 220 m (RP station 3) for both x and y !

28 p. 28Mario Deile – Dominant background: beam halo: reduction only by 2-arm coincidence. T1/T2: beam-gas suppression by vertex reconstruction:  (r) = 3 mm,  (z) = 45 mm Trigger Logic and Background Suppression Each Roman Pot houses: 6 tracking planes (analogue APV 25 readout) 4 trigger planes (digital VFAT readout)

29 p. 29Mario Deile – Diffraction at high    Acceptance (2)


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