AFP and HPS – Forward Proton Projects Marek Taševský Institute of Physics, Academy of Sciences, Prague, Czech rep. LISHEP 2011, Rio de Janeiro - 09/07 2011 History Physics with AFP/HPS Movable Beam pipe Tracking and Timing detectors 1
Forward detectors around ATLAS and CMS TOTEM -T2 CASTOR FSC ZDC TOTEM(now) HPS240 HPS420 I P 5 14 m 16 m 14 0 m 1 4 7 m - 2 2 0 m 4 2 0 m I P 1 LUCID ZDC ALFA(now) AFP220 AFP420 2
Optimal places for AFP/HPS Beam transposrt calculation by HECTOR JINST2, P09005 (2007) For nominal low- β * LHC optics 3
AFP = ATLAS Forward Protons HPS = High Precision Spectrometer Proton leaves the interaction intact, travels through LHC optics and is detected at ~220 m 220-240m, CMS side Taken in Jan 2009 Taken in May 2011 AFP: 2 stations on each side with tracking and timing detectors at ~ 220m 200-220m, ATLAS side HPS: 2 stations on each side with tracking and timing detectors at ~ 240m 4
History: FP420+FP220 → AFP & HPS 2003 Manchester Forward Physics Meetings 2005 FP420 Joint ATLAS & CMS Collaboration 2008 FP420 + R&D Report Michigan State Univ. FP220/240 2008 FP420 R&D Report Univ. of Chicago, Argonne (timing det.) Add FP220 JINST 4 (2009) T10001 2009 CMS HPS R&D Under review ATLAS AFP R&D 2010-2011 Aim for Upgrade Project Upgrade Project Upgrade project 5
History During the R&D phase, a lot of things around tracking detector for FP420 (3D-Si oriented) have been done, investigated, proposed and worked out by UK and other institutes! Detector layout, Module assembly, Mechanical support, Sensor design, Edge response, Irradiation tests, Power supplies, Noise studies, Off-sensor readout, External services, Optical links, Detector control system, Full thermal modeling/stress FP420 R&D Report JINST 4 (2009) T10001 After the drastic budget cuts in UK, AFP/HPS face manpower problems. Some solutions can be used for AFP220/HPS240. ATLAS Technical Proposal: CMS Upgrade R&D Proposal: AFP: A Proposal to install Proton R&D of the Detector Systems for Detectors at 220 m around ATLAS Stage One of the High Precision to Complement the ATLAS High Spectrometer Project Luminosity Physics Program (April 2011) (June 2010) 6
AFP/HPS Concept Add new ATLAS/CMS sub-detectors at 220/240 m (and later at 420 m) upstream and downstream of central detector to precisely measure the scattered protons to complement ATLAS/CMS physics program. These detectors are designed to run at 10 34 and operate with standard optics. What t is is AF AFP/HPS? P/HPS? 1) Array of radiation-hard near-beam Silicon detector Silicon detectors with resolution ~10 m, 1 rad 2) Timing detector Timing detectors with ~10 ps resolution for overlap background rejection (SD+JJ+SD) 3) Hambur Hamburg g Beam Pipe Beam Pipe instead of Roman Pots 4) New Connection Cryostat at 420 m 7
AFP/HPS Time Scale AFP/HPS asks for approval of: Building stations at 220/240 m during the long 2013-2014 shutdown 1) Hamburg movable beam pipes 2) Silicon detectors 3) Timing detectors 4) Precision Beam position monitors Physics: QCD, Diffraction, Two-photon, Extra dimensions, Higgsless models via quartic anomalous couplings Future upgrade (if motivated by physics): adding stations at 420 m 4) New Connection Cryostat at 420m 5) Upgrade or Replacement of Si detectors if necessary Physics: Mass acceptance and resolutions much improved => Diffractive Exclusive Higgs can be studied (or any other resonances) 8
What does AFP/HPS Provide? • Mass and rapidity 220+220 at IP1 of centrally Diffraction Two-photon produced system M s 1 2 1 ln( y / ) 1 2 2 • where 1,2 are the fractional momentum loss of the protons • Mass resolution of Acceptance >40% for wide range of resonance mass 3-5 GeV per event Allows ATLAS/CMS to use LHC as a tunable s gluon-gluon or collider while simultaneously pursuing standard physics program October 9, 2009 AFP Andrew Brandt Barcelona 9 9
Diffraction at LHC: - Forward proton tagging in special runs with ALFA/TOTEM - Combined tag of proton in Forward tagger on one side and remnants of dissociated proton in LUCID/CASTOR on the other side - Central rapidity gap in EM/HAD calorimeters (| η |<3.2) and inner detector (| η |<2.5) - Two rap.gaps on both sides from IP: Inclusive Double Pomeron Exchange: parton from Pomeron brings a fraction β out of ξ into the hard subprocess → Pomeron remnants spoil the gaps Central Exclusive Production: β = 1 → no Pomeron/ Photon remnants AFP/HPS Principal Physics: 1) Single tag (SD) 2) Double tag (DPE, CEP) 10
Deflected protons at 220 m from IP1 Diffractive beam-1 protons deflected at 220m (IP1): - similar picture for IP5 Diffractive protons deflect horizontally in a BEAM 1 region ~2x2 cm 2 outwards the ring 1) Only horizontal detectors needed 2) Region of interest is ~2x2 cm 2 . (fully covered by exactly one ATLAS new FE-I4 chip – simplifies the sensor design!) 3) Acceptance 0.02 < ξ < 0.2 10-15 σ beam LHC apertures Protons tracked through LHC optics using FPTrack or HECTOR 11
Two-photon production Photon induced processes - Similar to diffraction, but smaller t - di-lepton and WW production dominate at small masses Diffraction J. De Favereau et al, arXiv: 0908.2020 Exclusive di-leptons: Exclusive WW: Calibration candle for AFP/HPS New Physics – Anomalous couplings Provides energy scale resolution of 10 -4 ! - Quartic couplings γγ→ WW, ZZ Steeply falling mass spectrum: - Precise test of the ElectroWeak sector 420m: store-by-store calibration - Triple and quartic couplings reduce amplitude at HE 220m: needs weeks to collect suff. - Higgsless and Extra-dimension models predict couplings to which AFP/HPS is sensitive (~10 -6 GeV 2 ) statistics 12
Exclusive di-leptons: LHC follows Tevatron Highest mass e+e- event CDF: γγ → μ + μ -: PRL 102 (2009) 242001 γγ → e + e - : PRL 98 (2007) 112001 M. Albrow, LISHEP2011 J. Hollar, DIS2011 CMS 7 TeV, 2010 data (40 pb -1 ) p T, μ > 4 GeV | η μ | < 2.1 m μμ > 11.5 GeV 2 148 events Good description by LPAIR 13 C. Limbach, ATLAS
Exclusive WW: Anomalous quartic couplings at high lumi P. J. Bell et al., EPJC64 (2009) 25 K. Piotrzkowski et al., PRD 63 (2001) 071502 O. Kepka et al. (ATLAS): PRD81 (2010) 074003 σ (M WW ) ~ 5 GeV Low background Sensitivity wrt OPAL Without AFP: 10 2 better With AFP : 10 4 better! 14
Diffraction with small pile-up Soft Diffraction - Large cross section (~30% of σ inel - serves to predict the effect of PU) - One day of data taking in a special run with negligible pile-up - Calibrate gap size by ξ precisely measured in AFP/HPS: Δη ~ -ln ξ - AFP/HPS gives information about ξ = (0.015, 0.2) → Δη = (~2, ~4) large mass spectrum [K. Goulianos, hep-ph/0407035] Hard Diffraction SD CEP Dijets in SD, DPE and CEP: Repeat CDF measurements. SD: σ (SD jj )/ σ (ND jj ) = F D jj (x)/F jj (x) get F D jj ( β ,Q 2 ) and S 2 from known (HERA) PDFs . ξ < 0.1 → 0(1) TeV Pom. beams: → ~ 10 -3 & Q 2 ~10 4 GeV 2 DPE: σ (DPE jj )/ σ (ND jj ): vary gap size → Sudakov effects and enhanced absorption PRD 77 (2008) 052004 CEP: Observed in CDF Reduce the factor 3 uncertainty in KMR predictions for LHC Measure R jj and constrain unintegrated gluon density 15
Possible Upgrade: add a station at 420 m Low mass CEP Higgs Advantages: I) Mass resolution much better from AFP/HPS than Central det. FP420 R&D Collab., JINST4 (2009) T10001 II) Central system produced in a J Z = 0, C-even, P-even state: - strong suppression of CEP gg→bb background (by (m b /M X ) 2 ) - produced central system is 0 ++ → just a few events are enough to determine Higgs quantum numbers! Standard searches need high stat. ( φ -angle correlation of jets in VBF of Higgs) and coupling to Vector Bosons III) Information about Yukawa coupling Hbb! Disadvantages: Low signal x-section; affected by Pile-up H →bb, nomix, μ = 200 GeV SM: Higgs discovery challenging MSSM: Tevatron 1) higher x-sections than in SM in certain scenarios and certain phase-space regions exclusion 2) the same BG as in SM region EPJC 53 (2008) 231 & EPJC 71 (2011) 1649 LEP using proposed FD(220&420) Exclusion Experim. efficiencies from CERN/LHC 2006-039/G-124 Four luminosity scenarios (ATLAS+CMS): region 60 fb -1 ; 60 fb -1 x 2; 600 fb -1 ; 600 fb -1 x2 16
Movable beam pipe - Movable beam pipe (Hamburg beam pipe, MBP) technique used to move the detectors to and from the beam – in horizontal direction. - First used at PETRA collider, then proven to be viable at ZEUS (for e-tagger) - Takes less space than Roman Pots + easy access - It will host position as well as timing detectors at 220 and 420 m. - MBP uses standard LHC components (bellows, …), small RF impact - From LHC point of view, HBP is an instrumented collimator (uses the same motors but does not go as close to the beam as the collimators) and in fact, it will be operated from the LHC CR 17
Movable beam pipe Torino one-pocket design Louvain two-pocket design [D. Dattola, March 2011] Movable beam pipe design needs to be finalized soon – it will go to the tunnel first! Requires involvement of the LHC beam division. 18
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