Forward Physics with ATLAS D Bocian M Boonekamp

Forward Physics with ATLAS D. Bocian, M. Boonekamp, A. Brandt, E. Brash, B. Caron, K. De, I. Efthymiopoulos, A. Faus-Golfe, P. Grafstrom, W. Guryn, M. Haguenauer, A. Hamilton, V. Hedberg, B. Jeanneret, J. Lamsa, C. Leroy, M. Lokajicek, G. Lolos, J-P. Martin, J. Mc. Donald, Z. Papandreou, J. Pinfold, M. Rijssenbeek, E. Rosenberg, V. Simak, J. Soukup, H. Takai, V. Telnov, S. Tapprogge, W. Turner, S. Valkar, J. Velasco, A. Verdier, S. White, Y. Yao • • Luminosity measurement for ATLAS Forward Physics with ATLAS Thanks to: Michael Rijssenbeek for his slides!. Andrew Brandt – September 19 2003 1

Luminosity Measurement • • • Goals of the ATLAS Luminosity and Forward Physics Group: – – Measure L with ≲ 2% accuracy Study opportunities for diffractive physics with ATLAS Most important LHC characteristics: Luminosity L and CM Energy s Luminosity measurement needed for: – Precision comparison with theory: – Precision comparison with other expt’s – – LHC Machine parameters (~5 -10%) Rates of well-calculable processes • • e. g. : bb, tt, W/Z, jet, …, H, SUSY, … Cross section gives additional info Luminosity from: Dedicated Luminosity monitor: LUCID Relative precision on the measurement of H BR for various channels, as function of m. H, at Ldt = 300 fb– 1. The dominant uncertainty is from Luminosity: 10% (open symbols), 5% (solid symbols). (ATL-TDR-15, May 1999) Andrew Brandt – September 19 2003 2

The ATLAS Detector Calorimetry: Tracking: R ATLAS has insufficient forward coverage for Total Rate measurement -chambers Barrel Diffraction/Proton Tagging Region End. Cap Tracking 0 1 RP FCAL 2 Andrew Brandt – September 19 2003 3 4 LUCID 5 6 TAS 7 8 9 ZDC/TAN 10 y 3

ATLAS – Luminosity Monitor (J. Pinfold et al. ) Services In/Out To UXA PMTs LUCID ~17< |z| <~19 m 5. 2< | | <6. 2 Inner radius of LUCID ~7 cm, outer radius ~20 cm Andrew Brandt – September 19 2003 4

Baseline • Luminosity with CNI optics and Coulomb Normalization – – – • Roman Pots at 220 -240 m Scintillating strip detectors Integrate into L 1 Trigger LUCID for relative L monitoring Dedicated detector: • • bundle of projective Cerenkov cones: 5 layers of 40 tubes each low mass (6 kg), rad hard, quartz fiber readout Fproof of principle: CLC at CDF! • Cross checks with: – – W/Z rates Double photon exchange production of muon pairs Elastic slope of d. N/dt|t=0 plus machine L others… Andrew Brandt – September 19 2003 5

Extensions • Diffractive cross sections – need RP pairs at intermediate locations: 90, 150 m – possibly forward calorimetry (TAS region) • Large-|t| studies (t in dip region and beyond) – need RP pairs at intermediate locations: 90, 150 m and smaller? • DPE Higgs production… – need additional RP pairs at cryogenic locations: 330 m, 420 m – forward calorimetry (TAS region) might be attractive… Andrew Brandt – September 19 2003 6

Coulomb Normalization of L Possible with very high β* (≥ 2500 m) optics (3500 m now dead): • b*=3500 m optics: A. Faus-Golfe, M. Haguenauer, J. Velasco, "Luminosity determination using Coulomb scattering at the LHC", presented at EPAC 2002, June 2002 Normalization of the scattering amplitude at t 0 to the exactly calculable Coulomb amplitude: ? ? determines Luminosity L directly (and measure σtot, ρ0, b, …) • • • L/L ~ 2% (UA 4 experience) Need closest possible approach to the beam Very-small-angle detectors in Phase and shape of F (s, t) ! Roman Pots. Caveat: V. Kandrát, M. Lokajíček, PL B 544 (2002) 132. Andrew Brandt – September 19 2003 ISR RHIC UA 4 LHC N 7

Elastic Scattering in CNI Regime • • Need: t min< t. CNI = 8 EM/ tot 7 10– 4 Ge. V 2 For εN ≃1 10 -6 m, kσ=15, t min= p. Bmp kσ 2εN/β* = 6 10– 4 Ge. V 2 2500 m Detector: beam size (rms) d = √(βdεN/g) , kσ d ≳ 1. 5 mm Roman Pot detectors between Q 5 -Q 6 or Q 6 -Q 7 (z 220 -240 m) – – Leff 500 m, =x /Leff, b* ≳ bd ≳ 80 m x ∈ {~1. 5 mm, 25 mm} tmin = (p min)2 4× 10– 4 Ge. V 2 tmax (p max)2 0. 12 Ge. V 2 Precision needed: t/t ≃ 1‰ x O(10 m) need “self-calibrating” detectors d. N/dt shape is crucial! – L/L 2% • Positions at z >300 m possible, but difficult 240 m 220 m Andrew Brandt – September 19 2003 8

June Workshop on Roman Pot Detectors • • Parallel effort on RP detectors… Aim: focus on a (single? ) appropriate technology for TOTEM/CMS and ATLAS http: //efthymio. home. cern. ch/efthymio/LHC-LUMI/Workshop 03/ or via the Luminosity and Forward Physics WG webpage Andrew Brandt – September 19 2003 9

Requirements for Roman Pot Detectors • • • “Dead space” d 0 at detector’s edge near the beam: d 0 ≲ 100 m (full/flat efficiency away from edge) Detector resolution: d = 30 m (10 m for pleading measurement) Same d = 30 m (10 m) relative position accuracy between opposite detectors (e. g. partially overlapping detectors, …) • • Radiation hardness: 100 Gy/yr (105 -6 Gy/yr at full L) • • • Rate capability: O(Mhz) (40 MHz); time resolution t = O(ns) Operate with the induced EM pulse from circulating bunches (shielding, …) Readout and trigger compatible with ATLAS TDAQ Other: – – – Simplicity, Cost extent of R&D needed, time scale, manpower, … issues of LHC safety and controls Andrew Brandt – September 19 2003 10

Forward Physics Interest… Possible extension of ATLAS baseline physics: • (Soft) Diffractive cross sections are large: – – • el 26 mb, SD DD 13 mb (i. e. close to Pumplin bound!) need only modest L Elastic and Total cross section measurements: – tot, elastic, Re(f. N)/Im(f. N), d el/dt |N – Roman Pots at 220 -240 m • • • dip/structure in d /dt at |t|≈0. 5 Ge. V 2? Regge Pomeron & Odderon à la D&L transition to p. QCD at |t| ≈ 8 Ge. V 2 Andrew Brandt – September 19 2003 11

Single and Double Diffraction • Soft Pomeron Exchange: • production of a forward colorless system… IPP exchange Study of QCD p (ξ, t) IP M 2 = ξ s • Requires: – Accurate pleading measurement ( E <<0. 10, small |t|) – Forward & Central measurement – large range for rapidity gap detection… • Needs additional forward coverage for case of ATLAS… NO plans so far… Andrew Brandt – September 19 2003 12

Central (hard) Diffraction • • • Double Pomeron Exchange: production of a central colorless bosonic system… Requires: – Accurate pleading measurement ( E <<0. 10) – Central measurement, e. g. M = gg, H, – Rapidity gap detection… Δη = lnξ … Simulations by S. Tapprogge et al. , p (ξ 1) IP M 2 = ξ 1ξ 2 s IP p (ξ 2) (Helsinki Group, preprint HIP-2003/EXP) Predictions for ex(in)clusive production: – “Calibrated” with Te. Vatron data – Predictions for LHC vary – Many talks/discussions on DPE at this conference: DPE is THE main argument (towards the Hi-PT community) for doing Forward Physics at LHC! Andrew Brandt – September 19 2003 13

Acceptance for Central Production p (ξ 1) J. Kalliopuska, J. Mäki, N. Marola, R. Orava, K. Österberg, M. Ottela, S. Tapprogge; Helsinki Group, preprint HIP-2003 -11/EXP IP IP M 2 = ξ 1ξ 2 s p (ξ 2) Andrew Brandt – September 19 2003 • Combined acceptance of: • without 308 / 338 m location: 10 -15 % loss in acceptance All detectors - - 420 m + 215 m ____ 215 m alone - - 420 m alone 14

Resolution on Central Mass J. Kalliopuska, J. Mäki, N. Marola, R. Orava, K. Österberg, M. Ottela, S. Tapprogge; Helsinki Group, preprint HIP-2003 -11/EXP • Simple method: Use estimate from most distant station first • • ~ 4% 420 m 308 m 215 m 1% (small x large x) • Only exclusive process simulated Andrew Brandt – September 19 2003 15

Measurement of Central Diffraction • requires TWO additional very small angle detector pairs at very large distance: – – – 308/338 m, and 420 m; i. e. in COLD part of LHC • • needs to break into LHC cryostats! μStations? accuracy: O(10 μm), and edge-less Hi-L running: rad-hard detectors need VERY strong physics arguments to convince LHC(C)! Andrew Brandt – September 19 2003 16

Summary - Plans • Luminosity Baseline: CNI measurement + LUCID – – Coulomb normalization seems possible – intensive optics studies (with LHC/TOTEM – V. Avati) continue Development of Roman Pots and Detectors (with LHC/TOTEM – M. Oriunno) • • Luminosity Monitoring: LUCID well underway: Other Monitors: • Forward Physics: • • Preparing a draft internal proposal (Fall ’ 03) Next meeting at Orsay, Sept. 29 th (Manchester in December) – – Double photon muon pair process: simulation underway… W/Z production monitors: needs detailed study… – – – Detailed simulation study is very promising (Helsinki preprint) presumes Roman Pots for ATLAS (as for CNI; and beyond 300 m? ? ) Initial trigger studies for 215 m (just enough time) Andrew Brandt – September 19 2003 17