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VELO DQM and Central Exclusive Dimuon Production at LHCb

VELO DQM and Central Exclusive Dimuon Production at LHCb. Ciarán Hickey (University College Dublin). Outline. Brief introduction to LHCb and the VErtex LOcator (VELO) Update of VELO DQM TWiki and GUI Analysis of central exclusive dimuon production at LHCb. The LHCb Experiment.

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VELO DQM and Central Exclusive Dimuon Production at LHCb

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  1. VELO DQM and Central Exclusive Dimuon Production at LHCb Ciarán Hickey (University College Dublin) Summer Student Sessions, August 16th 2011

  2. Outline Brief introduction to LHCb and the VErtexLOcator (VELO) Update of VELO DQM TWiki and GUI Analysis of central exclusive dimuon production at LHCb Summer Student Sessions, August 16th 2011

  3. The LHCb Experiment Calorimeters RICH detectors Trackers Muon chambers VErtexLOcator (VELO) Magnet Scintillating pad detector (SPD) Summer Student Sessions, August 16th 2011

  4. The VELO detector Summer Student Sessions, August 16th 2011 Silicon strip detector made up of 2 retractable halves of 21 modules each Each module has both an r and φ sensor Needed to precisely locate both primary and secondary vertices

  5. VELO Data Quality Monitoring Summer Student Sessions, August 16th 2011 A number of macros are used to produce plots detailing VELO performance during a run. The plots are usually (and most easily) accessed from the VELO monitoring GUI.

  6. Update to VELO GUI TWiki page Summer Student Sessions, August 16th 2011 • There are 16 tabs in the GUI using a total of 20 macros • Updated/wrote documentation for each macro including: • Asummary of plots produced by the macro • Usage • Ideal behaviour • Examples of ideal and bad plots • Known problems

  7. Update to the monitoring GUI Summer Student Sessions, August 16th 2011

  8. Update to the monitoring GUI Summer Student Sessions, August 16th 2011

  9. Update to the monitoring GUI Summer Student Sessions, August 16th 2011

  10. Update to the monitoring GUI Summer Student Sessions, August 16th 2011

  11. Update to the monitoring GUI Summer Student Sessions, August 16th 2011

  12. 3. Analysis of Central Exclusive Dimuon Production at LHCb (carried out with G.P. McGread, University of Cambridge) Summer Student Sessions, August 16th 2011

  13. What is central exclusive dimuon production? Summer Student Sessions, August 16th 2011 Central = Particles are produced far from the beam line Exclusive = Class of reactions whereby the colliding particles remain intact. Additional particles are produced by photon and/or gluon propogators, i.e. A + B → A + X + B Dimuon = Two muons, a μ+μ- pair, are produced At LHCb we are studying: p + p → p + μ+μ- + p Examples:

  14. Online cuts to the data Summer Student Sessions, August 16th 2011 • Hardware Trigger Settings: • Less than 10 SPD hits. • Single muon with a transverse momentum, pt > 400 MeV/c2 or two muons both with pt > 80 MeV/c2. • Software Trigger Settings: • Invariant mass of dimuon candidate is > 1 GeV/c2 and its pt < 900 MeV/c2 or its mass is > 2.7 GeV/c2.

  15. Offline cuts Summer Student Sessions, August 16th 2011 Red = All dimuon candidates passing the triggers Blue = Required that; the number of long tracks = 2, number of backward tracks = 0 and the pseudorapidity is in the range 2<η<4.5 Green = Additional requirement that the total number of tracks = 2

  16. Dimuon Invariant Mass Spectrum Summer Student Sessions, August 16th 2011

  17. Invariant Mass Distributions of J/Ψ and Ψ(2S) Summer Student Sessions, August 16th 2011 • J/Ψ: • Gaussian fit gives mean of 3090.9±0.3 MeV/c2 • PDG value of mass is 3096.916±0.011 MeV/c2 • Ψ(2S): • Gaussian fit gives mean of 3678±3 MeV/c2 • PDG value of mass is 3689.09±0.04 MeV/c2

  18. Conclusions Summer Student Sessions, August 16th 2011 • We can see clear signals of ψ(2S), J/ψ, φ and ρ, ω from 2011 LHCb data. • More analysis needed in order to determine the exclusivity of these events. • It is also necessary to calculate the efficiencies, purity, effective luminosity and background so that the cross sections can be calculated, σ = (pN)/(εLeff). • Special thanks to Dr. Ronan McNulty, Stephen Farry and GráinneMcGread.

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