Download presentation
Presentation is loading. Please wait.
Published byJoleen Phelps Modified over 9 years ago
1
Andrew Brandt – September 19 2003Small-x 2003 – 1 Forward Physics with ATLAS Luminosity measurement for ATLAS 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.McDonald, 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 Thanks to: Michael Rijssenbeek for his slides!.
2
Andrew Brandt – September 19 2003Small-x 2003 – 2 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: e.g.: bb, tt, W/Z, jet, …, H, SUSY, … Cross section gives additional info – Precision comparison with other expt’s Luminosity from: – LHC Machine parameters (~5-10%) – Rates of well-calculable processes Dedicated Luminosity monitor: LUCID Relative precision on the measurement of H BR for various channels, as function of m H, at L dt = 300 fb –1. The dominant uncertainty is from Luminosity: 10% (open symbols), 5% (solid symbols). (ATL-TDR-15, May 1999)
3
Andrew Brandt – September 19 2003Small-x 2003 – 3 The ATLAS Detector Calorimetry: TAS R 501243678 Barrel FCAL LUCID Tracking EndCap RP ZDC/TAN Diffraction/Proton Tagging Region y 109 -chambers Tracking: ATLAS has insufficient forward coverage for Total Rate measurement
4
Andrew Brandt – September 19 2003Small-x 2003 – 4 Services In/Out To UXA PMTs Inner radius of LUCID ~7 cm, outer radius ~20cm ~17< |z| <~19 m 5.2< | | <6.2 LUCID ATLAS – Luminosity Monitor ATLAS – Luminosity Monitor (J. Pinfold et al.)
5
Andrew Brandt – September 19 2003Small-x 2003 – 5 Baseline Luminosity with CNI optics and Coulomb Normalization – Roman Pots at 220-240 m – Scintillating strip detectors – Integrate into L1 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 proof of principle: CLC at CDF! Cross checks with: – W/Z rates – Double photon exchange production of muon pairs – Elastic slope of dN/dt| t=0 plus machine L – others…
6
Andrew Brandt – September 19 2003Small-x 2003 – 6 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…
7
Andrew Brandt – September 19 2003Small-x 2003 – 7 Coulomb Normalization of L Possible with very high β* (≥ 2500 m) optics (3500m now dead): *=3500 m optics: A. Faus-Golfe, M. Haguenauer, J. Velasco, "Luminosity determination using Coulomb scattering at the LHC", presented at EPAC2002, June 2002 Normalization of the scattering amplitude at t 0 to the exactly calculable Coulomb amplitude: determines Luminosity L directly (and measure σ tot, ρ 0, b, … ) L / L ~ 2% (UA4 experience) Need closest possible approach to the beam Very-small-angle detectors in Roman Pots UA4 ?? LHC ISR RHIC Caveat: Phase and shape of F N (s,t) ! V.Kandrát, M.Lokajíček, PL B 544 (2002) 132.
8
Andrew Brandt – September 19 2003Small-x 2003 – 8 Elastic Scattering in CNI Regime Need: t min t CNI = 8 EM / tot 7 10 –4 GeV 2 For ε N ≃1 10 m, k σ =15, t min = p B m p k σ 2 ε N β* = 6 10 –4 GeV 2 * ≳ 2500 mε N ≃1 10 mk σ =15p B m p k σ 2 ε N β* Detector: beam size (rms) d = √(β d ε N ), k σ d ≳ 1.5 mm d ≳ 80 m Roman Pot detectors between Q5-Q6 or Q6-Q7 (z 220-240 m) – L eff 500 m, =x /L eff, x ∈ {~1.5 mm, 25 mm} t min = (p min ) 2 4×10 –4 GeV 2 t max (p max ) 2 0.12 GeV 2 – Precision needed: t/t ≃ 1‰ x O (10 m) need “self-calibrating” detectors – L / L 2% Positions at z >300 m possible, but difficult 240 m 220 m dN/dt shape is crucial!
9
Andrew Brandt – September 19 2003Small-x 2003 – 9 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/Workshop03/ or via the Luminosity and Forward Physics WG webpage
10
Andrew Brandt – September 19 2003Small-x 2003 – 10 Requirements for Roman Pot Detectors “Dead space” d 0 at detector’s edge near the beam the beam: d 0 ≲ 100 m (full/flat efficiency away from edge) Detector resolution: d = 30 m (10 m for p leading measurement) Same d = 30 m (10 m) relative position accuracy between opposite detectors (e.g. partially overlapping detectors, …) Radiation hardness: 100 Gy/yr (10 5-6 Gy/yr at full L ) Operate with the induced EM pulse from circulating bunches (shielding, …) Rate capability: O (Mhz) (40 MHz); time resolution t = O (ns) Readout and trigger compatible with ATLAS TDAQ Other: – Simplicity, Cost – extent of R&D needed, time scale, manpower, … – issues of LHC safety and controls
11
Andrew Brandt – September 19 2003Small-x 2003 – 11 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 /d t | N dip/structure in d /d t at | t |≈0.5 GeV 2 ? Regge Pomeron & Odderon à la D&L transition to pQCD at | t | ≈ 8 GeV 2 – Roman Pots at 220-240 m
12
Andrew Brandt – September 19 2003Small-x 2003 – 12 Single and Double Diffraction Soft Pomeron Exchange: production of a forward colorless system… P exchange Study of QCD Requires: – Accurate p leading 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… IP p (ξ, t) M 2 = ξ s I P
13
Andrew Brandt – September 19 2003Small-x 2003 – 13 Central (hard) Diffraction Double Pomeron Exchange: production of a central colorless bosonic system… Requires: – Accurate p leading measurement ( E <<0.10 ) – Central measurement, e.g. M = gg, H, … – Rapidity gap detection… Δη = lnξ Simulations by S. Tapprogge et al., (Helsinki Group, preprint HIP-2003/EXP) Predictions for ex(in)clusive production: – “Calibrated” with TeVatron data – Predictions for LHC vary – Many talks/discussions on DPE at this conference: DPE is THE main argument (towards the Hi-P T community) for doing Forward Physics at LHC! IP IP p (ξ 1 ) p (ξ 2 ) M 2 = ξ 1 ξ 2 s
14
Andrew Brandt – September 19 2003Small-x 2003 – 14 Acceptance for Central Production Combined acceptance of: All detectors - - - - 420 m + 215 m ____ 215 m alone - - 420 m alone without 308 / 338 m location: 10-15 % loss in acceptance J.Kalliopuska, J.Mäki, N.Marola, R.Orava, K.Österberg, M.Ottela, S.Tapprogge; Helsinki Group, preprint HIP-2003-11/EXP IP IP p (ξ 1 ) p (ξ 2 ) M 2 = ξ 1 ξ 2 s
15
Andrew Brandt – September 19 2003Small-x 2003 – 15 Resolution on Central Mass Simple method: Use estimate from most distant station first 420 m 308 m 215 m ~ 4% 1% (small large ) Only exclusive process simulated J.Kalliopuska, J.Mäki, N.Marola, R.Orava, K.Österberg, M.Ottela, S.Tapprogge; Helsinki Group, preprint HIP-2003-11/EXP
16
Andrew Brandt – September 19 2003Small-x 2003 – 16 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)!
17
Andrew Brandt – September 19 2003Small-x 2003 – 17 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: – Double photon muon pair process: simulation underway… – W/Z production monitors: needs detailed study… Forward Physics: – 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) Preparing a draft internal proposal (Fall ’03) Next meeting at Orsay, Sept. 29 th ( Manchester in December)
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.