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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ LHC Forward Physics Jim Whitmore Penn State University Experiments: ALICE ATLAS CMS FP420 (R&D project) LHCf TOTEM

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ LHC Forward Physics Total cross-section (and luminosity) with a precision of 1% Elastic pp scattering in the range: < |t| = (p ) 2 < 10 GeV 2 Forward Physics: Low-x dynamics Diffractive phenomena: Soft and Hard Inclusive and exclusive Double Pomeron Exchange (DPE) Leading particle and energy flow in the forward direction pA, AA, and p processes (sorry, I will not cover these topics) Many of these topics can be studied best at startup luminosities

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ TOTEM +LHCf +FP420 “We are not studying a possibility of forward physics with LHCb at the moment”

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ General philosophy: Additional detectors near the IP Proton (Roman Pot) detectors: want to detect small scattering angles (~few rad:) and the beam divergence so want large values of *. However, luminosity want small * So expect a selection of * values ( m) RP detectors at m from IP Need to go to 420 m → the “cold” region Forward Detectors

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Roman Pot acceptance Low *: (0.5m): Lumi cm -2 s m: 0.02 < < /400m: < < 0.02 Detectors in the 420 m region are needed to access the low values TOTEM (ATLAS) FP m M2=12sM2=12s = proton momentum loss = p/p Reconstruct with roman pots < 0.1 O(1) TeV “Pomeron beams“ (A. deRoeck)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ T1: 3.1 < < 4.7 T2: 5.3 < < 6.5 T1 T2 CASTOR (CMS) RP1 (147 m) RP2 (180 m) (later option) RP3 (220 m) Experimental Apparatus 10.5 m ~14 m TOTEM + CMS CMS Castor 5.25< <6.5 IP5

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ ~3 m 5 planes with measurement of three coordinates per plane. 3 degrees rotation and overlap between adjacent planes Primary vertex reconstruction Trigger with CSC wires T1 Telescope 3.1< | | <4.7 T2 Telescope Digital r/o pads Analog r/o circular strips 5.3< l l < 6.5 GEM (Gas Electron Multiplier) Telescope: 10 ½ -planes 13.5 m from IP

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Roman Pot unit: - Vertical and horizontal pots mounted as close as possible - TOTEM at the RP: beam ≈ 80 m - Leading proton detection at distances down to 10 beam + d - Need “edgeless” detectors that are efficient up to the physical edge to minimize “d” - Currently two tech. (5-10 m and m dead areas) 0 reconstructed track Tracks Roman Pots Test beam data: RP in SPS beam and the detector is measuring the halo u,v info reconstructed tracks in y BPM

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Forward Detectors in ATLAS IP1 Roman Pots at 240 m Cerenkov Counter (LUCID) = a lumi monitor at 5.4 < < neutral energy at zero degrees (I. Efthymiopoulos)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Scenario Physics: 1 low |t| elastic, tot, min. bias, soft diffraction 2 diffraction 3 large |t| elastic 4 hard diffraction large |t| elastic (under study) * [m] N of bunches N of part. per bunch (x10 11 ) Half crossing angle [ rad] Transv. norm. emitt. [ m rad] RMS beam size at IP [ m] RMS beam diverg. [ rad] Peak luminosity [cm -2 s -1 ]1.6 x x x x Running Scenarios TOTEM (V. Avati, M. Deile)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ pp total cross section and luminosity monitor TOTEM-CMS ATLAS

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ pp total Cross-Section Measure the total rate (N el +N inel ), diff ~ 18 mb and min. bias ~65 mb, with an expected precision of 0.8 % (running for 1 day at L = 1.6 x cm -2 s -1 ). Extrapolate the elastic cross-section to t = 0: systematics dominated: 0.5 % (statistical error after 1 day: 0.07 %) ρ = Re f(0)/Im f(0) unknown; using COMPETE pred.: 0.2 % 1 % ( = ± ) pp total cross section Luminosity-independent measurement using the Optical Theorem : (M. Deile)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Current models predictions: mb Aim of TOTEM: ~1% accuracy (~1 mb) LHC: COMPETE Collaboration fits all available hadronic data and predicts: pp total Cross-Section [PRL (2002)] Cudell et al.

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ ATLAS’s Plans: ATLAS submitted a Letter of Intent to complement the experiment with a set of forward detectors for luminosity measurement and monitoring as part of a two stage scenario: 1.Short time scale Roman Pots at 240 m from IP1 Probe the elastic scattering in the Coulomb interference region Dedicated detector for luminosity monitoring – LUCID Used also to transfer the calibration from Goal: Determine absolute luminosity at IP1 (2-3% precision) 2. Longer time scale Study opportunities for diffractive physics with ATLAS Propose a diffractive physics program using additional detectors (I. Efthymiopoulos)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Physics interest -- ATLAS Luminosity Measurement – Why? Important for (precision) comparison with theory: e.g. bb, tt, W/Z, n-jet, … cross-section deviations from SM could be a signal for new physics Systematic error dominated by the luminosity measurement (ATLAS-TDR-15, May 1999) (I. Efthymiopoulos)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ pp elastic scattering TOTEM

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ ~1.5 GeV 2 Elastic scattering – from ISR to Tevatron

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ * = 1540 m L = 1.6 x cm -2 s -1 (1) 10 4 per bin of GeV 2 diffractive structure Photon - Pomeron interference pQCD pp 14 TeV BSW model Multigluon (“Pomeron”) exchange e – B |t| -t [GeV 2 ] t p 2 2 d /dt [mb / GeV 2 ] ~1 day (1) (3) wide range of predictions pp elastic scattering cross-section * =18 m L = 3.6 x cm -2 s -1 (3) ~ 1/|t| 8 BSW = Bourrely, Soffer and Wu B(s) = B P ’ ln (s/s 0 ) ~ 20 GeV -2 at LHC

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Observations: fwd diffraction cross section increases diffractive peak shrinks interference dip moves to smaller t at –t 1 GeV 2: d /dt 1/t 8 (3-gluon exchange) little s dependence Elastic Scattering Models (eg. Islam et al) 1/t 8 BSW Desgrolard et al Islam et al

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ R el = el (s)/ tot (s) R diff =[ el (s) + SD (s) + DD (s)] / tot (s) 0.30 el 30% of tot at the LHC ? SD + DD 10% of tot (= mb) at the LHC ? Elastic Scattering- el / tot log(s/s 0 ) (M. Deile)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Low-x at the LHC LHC: due to the high energy can reach small values of Bjorken-x in structure of the proton F(x,Q 2 ) Processes: Drell-Yan Prompt photon production Jet production W production If rapidities below 5 and masses below 10 GeV can be covered x down to Possible with T2 upgrade in TOTEM (calorimeter, tracker) 5< < 6.7 ! Proton structure at low-x !! Parton saturation effects? (A. deRoeck)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Diffractive physics ALICE TOTEM CMS F420 project

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ The accessible physics is a function of the integrated luminosity 2 gluon exchange with vacuum quantum numbers “Pomeron” X Double Pomeron exchange: X Single diffraction: p p p X p p p X p X Y Double diffraction: p p X Y (M. Ruspa)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ % (65%) of all diffractive protons are detected for * = 1540 (90) m largest acceptance detector ever built at a hadron collider Roman Pots TOTEM+CMS T1,T2 Roman Pots dN ch /d dE/d Total TOTEM/CMS acceptance CMS central T1 HCal T2 CASTOR =90m RPs =1540m ZDC Pseudorapidity: = ln tg /2 Energy flux Charged particles CMS + TOTEM: Acceptance 10 7 min bias events, incl. all diffractive processes, in 1 day with * =1540 m

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Soft Diffractive Event rates DPE: pp pXp Acc = 27.8% for detecting both protons ( * = 90 m) ALICE is studying the possibility of implementing a trigger requiring a rapidity gap on both sides of a central region of 1.5 units of rapidity. The selection can include EM energy deposition in the PHOS, protons in the HMPID (RICH), or electrons identified with the TRD, opening the possibility to study heavy flavour production in double diffractive events.

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Measure > 90 (65)% of leading protons with RPs at * = 1540 (90) m and diffractive system X with T1, T2 and CMS. Events/GeV-day DPE Scenario (2) (4) * (m) = Exchange of color singlets (“Pomerons”) rapidity gaps diffractive system X proton:p 2 ’ proton:p 1 ’ rapidity gap min max 2 = – ln 1 = – ln

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Hard Diffractive Events Diffractive events with high p T particles produced M M hard Double Pomeron Exchange hard p p jet 1 (p T 1 ) jet 2 (p T 2 ) jet 3 (p T 3 ) p gg u d u Single diffraction: pp p + 3j Double pomeron Ex: pp pjjXp = 1 b p T > 10 GeV Acc = 29.3% (for * =90 m, prel.) (V. Avati)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Exclusive Double Pomeron Exchange TOTEM-CMS FP420 (with ATLAS/CMS) H p p

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Exclusive Double Pomeron Exchange Quantum numbers are defined for exclusive particle production Gluonic states c, b, Higgs, supersymmetric Higgs,….. M X 2 = s Motivation from KMR calculations (e.g. hep-ph ) Selection rules mean that central system is (to a good approx) 0 ++ H → b-bbar: QCD b-bbar bkgd suppressed by J z =0 selection rule If you see a new particle produced exclusively with proton tags you know its quantum numbers Tagging the protons means excellent mass resolution (~ GeV) irrespective of the decay products of the central system Proton tagging may be the discovery channel in certain regions of the MSSM Trigger studies were discussed by M. Ruspa

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Diffractive: H bb Yuk. coupling, M H, 0 ++ Inclusive: H,A wide bump m H =140 m H =160 L=60 fb -1 55 Tasevsky et al From A. Martin’s parallel session talk SUSY Higgs: h, H, A, (H +, H -- )

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ From A. Martin’s parallel session talk (pp p + H + p) ~ 3 fb at LHC for SM 120 GeV Higgs L(LHC)~60 fb -1 ~10 observable events after cuts + efficiency Alan’s Conclusions There is a very strong case for installing proton taggers at the LHC, far from the IP ---- it is crucial to get the missing mass M of the Higgs as small as possible The diffractive Higgs signals beautifully complement the conventional signals. Indeed there are significant SUSY Higgs regions where the diffractive signals are advantageous ---determining M H, Yukawa H bb coupling, 0 ++ determin n ---searching for CP-violation in the Higgs sector Higgs needs L ~ cm -2 s -1, i.e. a running scenario for = 0.5 m : trigger problems in the presence of overlapping events (see M. Ruspa’s talk) install additional Roman Pots in cold LHC region (420 m) at a later stage

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ The aim of FP420 is to install high precision silicon tracking and fast timing detectors close to the beams at 420 m from ATLAS and/or CMS. (See B. Cox’s talk in the diffractive parallel session) FP420 Project FP420 turns the LHC into a glue-glue collider where you know the beam energy of the gluons to ~ 2 GeV. With nominal LHC beam cm -2 s -1 : 220 m: 0.02 < < m: < < 0.02 1 2 s = M 2 With √s = 14TeV, M H = 120 GeV on average: 1% Hence the need for FP420

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Forward physics: connection to cosmic rays ALICE TOTEM LHCf

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Issues in UHE cosmic rays 29 th ICRC Pune 1. Spectrum / GZK Cutoff

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Composition X max (g/cm 2 ) Energy (eV) Measurements of the very forward energy flux (including diffraction) and of the total cross section are essential for the understanding of cosmic ray events At LHC pp energy : 10 4 cosmic events km -2 year -1 > 10 7 events at the LHC in one day p Fe Issues in UHE cosmic rays (O. Adriani)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ UHE Cosmic Rays Interpreting cosmic ray data depends on hadronic simulation programs Forward region poorly known/constrained Models differ by factor 2 or more Need forward particle/energy measurements e.g. dE/d … Cosmic ray showers: Dynamics of the high energy particle spectrum is crucial p Fe

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Model Predictions: pp at the LHC Predictions in the forward region within the CMS/TOTEM acceptance

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ The dominant contribution to the energy flux is in the very forward region In this forward region the highest energy measurements of 0 cross section were done by UA7 (E=10 14 eV, y = 5÷7) Simulation of an atmospheric shower due to a eV proton. The direct measurement of the production cross section as function of p T is essential to correctly estimate the energy of the primary cosmic rays (LHC: eV) Measurement of Photons and Neutral Pions in the Very Forward Region of LHC LHCf (O. Adriani)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ INTERACTION POINT Detector II Tungsten Scintillator Silicon strips Detector I Tungsten Scintillator Scintillating fibers Beam line 140 m Experimental Method: 2 independent detectors on both sides of IP IP1 (ATLAS) LHCf The vacuum tube contains two counter- rotating beams. The beams transition from one beam in each tube to two beams in the same tube. Detectors will be installed in the TAN region, 140 m away from the Interaction Point, in front of luminosity monitors Charged particle are swept away by magnets LHCf will cover up to y → ∞ (O. Adriani)

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ There are plans at the LHC for a wide range of Forward and Diffractive measurements that can be achieved at a variety of different luminosities: Measure total cross-section tot with a precision of 1% Measure elastic scattering in the range <|t|< 8 GeV 2 A study of soft and hard diffractive physics: semi-hard diffraction (p T > 10 GeV) hard diffraction Inclusive DPE Studies of Exclusive Double Pomeron Exchange events Studies of very forward particle production Connection with UHE Cosmic ray phenomena Special exotics (centauro’s, DCC’s in the forward region) Summary

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Extra slides

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Elastic Scattering: = Re f(s,0)/Im f(s,0) TOTEM Ref + (s,0)/Imf + (s,0) (analyticity of the scattering amplitude via dispersion relations) constant/lns with s

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Number of pileup events per bunch crossing = = Lumi* cross section * bunch time width * total lhc bunches / filled bunches = = cm -2 s -1 * 10 4 (cm^ 2 /m^ 2 ) * (m 2 / b) * 110 mb * (b/mb) * 25 (ns) * (s/ns) * 3564 / 2808 35 1x10 32 0 1x10 33 3.5 2x10 33 7 Pile-up: numbers! 1 mb = cm -2 s -1 PHOJET: ALL PROCESSES 110 mb NONDIF.INELASTIC 51 mb ELASTIC 33 mb DOUBLE POMERON 1.95 mb SINGLE DIFFR.(1) 7.66 mb SINGLE DIFFR.(2) 7.52 mb DOUBLE DIFFRACT. 9.3 mb Number of pileup events per bunch crossing = = Lumi* cross section * bunch time width * total lhc bunches / filled bunches = = cm -2 s -1 * 10 4 (cm^ 2 /m^ 2 ) * (m 2 / b) * 51 mb * (b/mb) * 25 (ns) * (s/ns) * 3564 / 2808 17 This number is valid in the central detector region, but must be corrected for the elastic and diffractive cross section in the forward region! Selection of diffractive events with rapidity gap selection only possible at luminosities below cm -2 s -1, where event pile-up is absent

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ TOTEM Experiment (symmetric about IP5) T1 & T2 RP

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ FP420 Acceptance and Resolution 3 mm 5 mm 7.5 mm 10 mm 3 mm + 3 mm 22 mm 30 mm 25 mm MB apertures

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Planar technology: Testbeam 40 m dead area Detector 1 Detector 2 active edges (“planar/3D”) planar technology CTS (Curr. Termin. Struct.) 50 m dead area10 m dead area 66 m pitch Add here photo of RP Active edges: X-ray measurement m Signal [a.u.] 5 m dead area Strip 1 Strip 2 Edgeless silicon detectors for the RP 10 planes/pot

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Diffraction at * = 1540 m Acceptance Diffractive protons are observed in a large -t range: = p/p; t=-(p ) 2 90% are detected -t > 2.5x10 -3 GeV 2 < < 0.1 resolution ~5x10 -3 kinematically excluded RP at 220 m acc. < 10%

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Diffraction at * = 90 m Acceptance Resolution in : = 4x10 -4 (prel.) L<2x10 31 cm -2 s - 1

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April 23, 2006 DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba, Japan, 20-24/April/ Diffraction at * = 0.5 m

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