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A high eta (3-5) Micromegas tracker, to study hard W L W L W L W L scattering with CMS

A high eta (3-5) Micromegas tracker, to study hard W L W L W L W L scattering with CMS. Theodoros Geralis Institute of Nuclear Physics NCSR Demokritos. Physics Motivation High luminosity CMS upgrade A high eta tracker in CMS Micromegas technology Detector requirements Prospects.

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A high eta (3-5) Micromegas tracker, to study hard W L W L W L W L scattering with CMS

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  1. A high eta (3-5) Micromegas tracker, to study hard WLWLWLWL scattering with CMS TheodorosGeralis Institute of Nuclear Physics NCSR Demokritos • Physics Motivation • High luminosity CMS upgrade • A high eta tracker in CMS • Micromegas technology • Detector requirements • Prospects HEP2012: Recent Developments in High Energy Physics and Cosmology Ioannina, 5 – 8 April 2012, Greece Theo Geralis

  2. Higgs production and decays – LHC regime Main production mechanisms Decay modes of SM Higgs dominant at LHC sH(120) ~ 30 pb second largest at LHC sH(120) ~ 5 pb Most useful H decay modes: ZZ  4 leptons, WW  lnln, gg, tt, bb? Depends on competing backgrounds and resolution we can achieve in a given channel….

  3. SM Higgs boson searches • SM Higgs mechanism provides one possibility • to explain the EWK Symmetry Breaking. • LEP/SLD EWK data indicate a low mass Higgs • with mH ~ 100 GeV • Direct searches at LEP have given lower limits: • mH > 115 GeV • At LHC, CMS + ATLAS have narrowed the Higgs allowed space: • 115 GeV < mH < 127 GeV • or • mH > 600 GeV • EWK precision measurements favor a light Higgs with SM like couplings (WW, ZZ)

  4. EWK theory is renormalizable Each one of the diagrams WWWW (below) diverges as and the sum still diverges softly as Breaking of unitarity at ~ 1TeV scale We need a scalar to restore unitarity: Higgs allows to preserve unitarityin WW, WZ, ZZ scattering Work pioneered by ..

  5. LHC Higgs Physics scenarios (I) A light Higgs is discovered:  Is it a Standard Model Higgs ? Study relative Higgs Branching Ratios  Is it entirely responsible for the EWK Symmetry Breaking e.g. in SUSY models the lightest Higgs h will couple with a multiplicative factor (<1): sin(β-α).ghWW with β: tanβ=v2/v1, where v2, v1 are the two vacuum expectation values and α the mixing angle between the two CP even neutral higgs states. In that case WWWW will become strong until it crosses the next Higgs pole. If there are other resonant exotic particlese.g. KK excitations, these modes will show up in the WW channel and the unitarity problem will be postponed for a scale > ~5 TeV.  We will have to study these scenarios via the vector boson scattering (WW, WZ and ZZ)

  6. LHC Higgs Physics scenarios (II) A light Higgs is NOT discovered:  Scalar resonance i.e. Higgs is very heavy  very broad Higgs  Vector resonance, e.g. “ρTC”, V+-0BESSWZ  New dynamical mechanism for the EWK Symmetry Breaking with strong interactions among VLVL  We will have to study these scenarios via the vector boson scattering (WW, WZ and ZZ)

  7. WWWW Cross Section calculation 1) EWK ChiralLagrangianin a series of increasing dimensions 2) Build model independent higher dimensions operators 3) Impose constraints in parameters from Unitarity, Causality and Precision experiments WW generator exists: WHIZARD Signal: usdcWW 6.5 pb • Destructive interference • σ(WW  WW) = 8.5 fb !!! • (still with high uncertainties) 0.002 pb 0.2 pb It can be studied in High Luminosity LHC era : 300 – 3000 fb-1 Background: Brehmstralung Theo Geralis

  8. Example:LHC discovery potential for V01 V01 is the Kaluza-Klein excitation of the Z0 boson in Higgsless models at Theo Geralis

  9. The Vector Boson fusion/scattering at LHC • - scattering can be resonant or not; • if non-resonant best channel is WL+WL+l+nl+n but just an excess of events • -resonant models are much more appealing! Event selection • Requires: Forward jet tagging and central jet vetoing! • BUT: at HLHC/SLHC forward jet tagging and central jet vetoing suffer from • big pile up, but calo method nonetheless applicable! Forward tracking would help much! • SLHC (3000 fb-1) a ~7s excess expected in W+W-scattering from • a strong coupling model (1TeV Higgs) over SM bkgd;

  10. Higgs pair production and Higgs self couplingpossible justification for SLHC/HLHC….. Higgs pair productioncan proceed through two Higgs bosons radiated independently (from VB, top) and fromtrilinear self-coupling terms proportional to HHHSM HHHSM +…. triple H coupling: HHHSM = 3mH2/v cross sections for Higgs boson pair production in various production mechanisms and sensitivity to lHHH variations very small cross sections, hopeless at LHC (1034), some hope at SLHC channel investigated, 170 < mH < 200 GeV (ATLAS): gg  HH  W+ W– W+ W–  l±njj l±njj withsame-sign dileptons - very difficult! total cross section and HHH determined with ~ 25% statistical error for6000 fb-1 provided detector performances are comparable to present LHC detectors  arrows correspond to variations of HHH from 1/2 to 3/2 of its SM value

  11. WZ vector resonance in VB scattering If no Higgs found, possibly a new strong interaction regime in VLVL scattering, this could become the central issue at the SLHC! For ex.: Vector resonance(r-like) in WLZL scattering from Chiral Lagrangian model M = 1.5 TeV, leptonic final states, 300 fb-1 (LHC) vs 3000 fb-1 (SLHC) lepton cuts: pt1 > 150 GeV, pt2 > 100 GeV, pt3 > 50 GeV; Etmiss > 75 GeV These studies require both forward jet tagging and central jet vetoing! Expected (degraded) SLHC performance is included Note event numbers! increased cm energy/ VLHC even better!! at LHC: S = 6.6 events, B = 2.2 events at SLHC: S/B ~ 10

  12. The CMS (Compact Muon Solenoid) detector

  13. Simulation of a Higgsevent in CMS CMS detector design and optimisation (geometrical acceptance, energy- momentum resolution required, detector technique choices for subdetectors) have been done with the Higgs search in mind

  14. Experimental conditions at 2x1034 cm-2 s-1 (25nsec) - SLHC/HLHC ~ 40 - 50 pile-up events per bunch crossing for operation at 2x1034cm-2s-1 and 25 nsec bunch separation - High Luminosity LHC regime (compared to ~ 300 pile-up events for the 25 nsec and ~ 400 pile-ups in 50 nsec for ultimate SLHC scenarios previously discussed for ~1035cm-2s-1) dnch/dh/crossing ≈ 250 and ≈ 1250 tracks in tracker acceptance per crossing H  ZZ  eemm, mH = 300 GeV, in CMS Generated tracks, pt > 1 GeV/c cut, i.e. all soft tracks removed! I. Osborne 1032cm-2s-1 1035cm-2s-1 If same granularity and integration time: tracker occupancy and radiation dose in central detectors increases by factor ~ 2, pile-up noise in calorimeters by ~ 1.4 relative to 1034 effect on: electron, iden./purity, b-tagging performance, jets, tagging jets, e, isolation cuts etc.

  15. LHC operation in 2012 : pile-up L~3.3x1033cm-2s-1 40 reconstructed vertices! High PU run October 25, 2011 Event with 20 reconstructed Difficulties with forward tagging jets! Identify jet vertex with tracks and false jets from tracks piling in jet cone

  16. Importance of VFCAL/feasibility of forward jet tagging at SLHC at ~1035 cm-2 s-1 Forward jet tagging needed to improve S/B in VB fusion/scattering processes pp  qqH, qqVV ….,but could also be crucial if no Higgs found by then! Or elementary H or not? “tagging jet” Forward tracking (beyond 2.4) would enormously help reducing false jets from pile-up as well as real jets from pile-up Vertices, but technique must sustain very high rates and minimize albedo to tracker Calo method should still work at 1035: increase forward calo granularity, reduce jet reconstruction cone from 0.4 to ~ 0.2, optimise jet algorithms to minimize false jets

  17. Foreseeable changes to detectors for 1035cm-2s-1 overview • changes to CMS: • Trackers, to be replaced due to increased occupancy to maintain performance, need improved radiation hardness for sensors and electronics - present Si-strip technology is OK at R > 60 cm - present pixel technology is OK for the region ~ 10 < R < 60 cm • Calorimeters: ~ OK - endcap HCAL scintillators in CMS to be changed - endcap ECAL VPT’s and electronics may not be enough radiation hard - desirable to improve granularity of very forward calorimeters - for jet tagging • Muon systems: ~ OK - acceptance reduced to |h| <~ 2.0 to reinforce forward shielding • Trigger(L1), to be replaced, L1(trig.elec. and processor) new ideas to include tracker in trig. VF calorimeter for “jet tagging” Forward tracking??

  18. A new tracker has to be installed in the high eta region (3 – 5) Tracker in 3<|η|<5 Theo Geralis

  19. Detector Requirements • High Pile up  vertex finding with Δz~1mm • ~20 – 100 μm single point precision (function of η) • Radiation hard detector • (will depend on the final detector location along z axis) • Affordable to build • Long term stability Micromegas detector is considered as a good candidate To be confirmed by a proposed R&D Theo Geralis

  20. TheMicromegas principle Spacers h=50μm Hole diameter=50μm, pitch=100μm • Excellent x-y resolution • Good Energy resolution • Very low background • Excellent stability • Radiation hard • Cheap • Variety of applications • (X-rays, tracking, neutron det. • TPC detector, Visible photon • det. ) Micromegas: MICRO MEshGAseous Structure detector

  21. Micromegas development - Bulk technology Woven Inox mesh 30 µm Readout plane + mesh all in one vacrel 128 µm Bulk Micromegas The pillars are attached to a woven mesh and to the readout plane Typical mesh thickness 30 μm, gap 128 μm Uniformity, robustness, lower capacity, easy fabrication, no support frame, small surrounding dead region: • Large area detectors • Curved surfaces • Mass production! Well established technique Readout pads pad pillar

  22. Microbulk Micromegas detector Micromesh 5µm copper Readout plane + mesh all in one Kapton 50 µm Microbulk Technology The pillars are constructed by chemical processing of a kapton foil, on which the mesh and to the readout plane are attached. Mesh is a mask for the pillars! Good properties: uniformity, clean materials, stability, good Energy resolution (<13% FWHM @ 6 keV), low mass detector, very flexible structure. IMPRESSIVE: low background Improvement from ~10-4 ~10-7cts/keV/cm2/s BUT: It is fragile and the mesh can not be replaced Complex procedure to produce it, particularly in conjunction with the x-y readout Readout pads Fake 2D It works thanks to charges diffusion

  23. The ATLAS muon project MAMMA:a successful sLHC detector case talk by G. Tsipolitis P. Colas et al., NIMA535(2004)506 ATLAS resistive planes MAMA project I. Giomataris

  24. Micromegas on a resistive thin ceramic substrate Readout pixels or strips is an independent element In a first prototype: 300 mm thick alumina+ruthenium oxide 10 mm layer This was the anode plane of a standard Bulk Micromegas Signal propagates through capacitive coupling without loss (~ 90% pass through) Ceramic provide large dynamic range of dielectric constants

  25. Micromegas activities at INP (since 2001):Built the first 4 Micromegas detectors, used in CAST, in collaboration with Saclay and CERN CAST MicroMegas Assembly phase at INP CAST MicroMegas in operation

  26. Micromegas activities at INP :Prototype mM TPC: INP Design/Construction Application: Fission studies 32 x 1ΜΩ Aluminum Housing Plexiglas Cage E field shaper Cf source Energy spectrum Nuclei Energy spectrum: Sum of Strips’ Energy 252Cf  nA1 + 252 – n – (4)A2 + (n,α) Theo Geralis

  27. Micromegas activities at INP :Micromegas for sLHC - Collaboration INP, NTUA Development of Radiation hard muon detectors for super LHC (operate at ~106 neutrons.cm-2s-1. Tests performed also in the Tandem accelerator) RD51 telescope: Collaborative effort INP/NTUA • RD51 Telescope (tracker): • 3 x-y Micromegas detectors • In the H6 SPS beam. The detectors • Were machined and built at INP • Data Acquisition system. It was • developed at INP Telescope in RD51 Test beam Later development: MAMMA Achieved space precision: ~45 μm, with 500 μm pitch can do ~25 μm, with 250 μm pitch See talks by T. Alexopoulos and G. Tsipolitis Telescope Cosmics setup Theo Geralis

  28. Summary of physics possibilities at the SLHC - phases I and II • EW physics: refine TGC limits, start looking for QGC ie WWW, WWZ final states with all W  l Z ll • extend search/exclusion of FCNC top decay modes t Zc, c…. • - extend (phase I) the discovery domain for massive MSSM Higgs bosons A, H, H± in  and decay modes, as  and efficiencies should be little degraded by a factor of ~ 2 in pileup rate relative to nominal • In the Higgs sector (phase II): • precision measurements would allow to clarify the structure of the Higgs sector of the theory, ie more doublets, or singlets, whether Higgs is fundamental or composite, the nature of fermion masses (Higgs couplings to matter) • What is needed: • WW, ZZ, WZ scattering at large invariant masses, • double-Higgs production, • Higgs decay branching ration measurements at the 10% level or better • study new rare H decay modes (H  , • - extend search/exclusion of new gauge bosons, KK excitations • - extend or complement - or exclude further - SUSY spectrum

  29. Conclusions • Irrespectively whether a Higgs is discovered or not • Vector Boson scattering (WW, WZ, ZZ) offers a great • tool for studying the nature of the EWSB and possibly • physics BSM. • This is a high luminosity study since the cross sections • are low and is planned for the sLHC/HLHC era. • The LHC experiments have to strengthen • 1) their forward jet tagging with a refined resolution, • 2) their forward tracking capability at high eta to • resolve vertex ambiguities from the high pile up • Micromegas is already among the detectors to be used • for the ATLAS muon system at high eta. • We propose an R&D within CMS to study the Micromegas • technology as a possibility for tracking at high eta (3-5) Theo Geralis

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