H y p a t i a hy brid p upil s a nalysis t ool for i nteractions in a tlas
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H Y P A T I A HY brid P upil’s A nalysis T ool for I nteractions in A tlas. http://hypatia.phys.uoa.gr / applet. HYPATIA of Alexandria. First woman mathematician Alexandria, Egypt ( 370-418 A . D . ). Proton – proton Collisions. Beam energy: 3.5, 4 TeV

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H Y P A T I A HY brid P upil’s A nalysis T ool for I nteractions in A tlas

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H Y P A T I AHYbrid Pupil’s Analysis Tool for Interactions in Atlas

http://hypatia.phys.uoa.gr/applet


HYPATIA of Alexandria

First woman mathematician

Alexandria, Egypt(370-418 A.D.)


Proton – proton Collisions

  • Beam energy: 3.5, 4 TeV

  • 2 x 3.5 TeV = 7 or 8 TeV

  • Some of the particles produced are unstable and decay instantly


ATLAS

Particletracksappear as lines on the detectors

Thelengthof each track is determined by particle type

Each particle leaves a traceonly on specific detectors according to its type


HY.P.A.T.I.A.

Canvas

Displays events in various forms depending on particle type and user preference.

Can do zoom, pan, rotate, pick tracketc


HY.P.A.T.I.A.

Track Momenta

Displays the quantities that describe each track (type, momentum, charge, φ, θ)

Histograms

Created automatically from the tracks of the invariant mass table


HY.P.A.T.I.A.

Η → 4ℓ

Invariant Mass

Main event analysis window.

Displays the user selected tracks from various events. Calculates invariant masses.

Creates Histograms.


Laboratory Exercise


Laboratory Exercise

Detection and mass calculation of particles – Real Events

Known particles:

Z → μ- + μ+ Z → e- + e+

2 tracks, opposite charge, isolated

Invariant mass 91,2GeV

Small missing energy ETMiss

J/ψ → μ- + μ+ J/ψ → e- + e+

2 tracks, opposite charge, not diametrical

Invariant mass 3GeV

Small missing energyETMiss<15GeV


Laboratory Exercise

Detection and mass calculation of particles – Real Events

Known particles:

Υ → μ- + μ+ Υ → e- + e+

2 tracks, opposite charge

Invariant mass 9,5 GeV

Small missing energy ETMiss

Background events

Usually one lepton (W boson decay)

Leptons from quark decays are in jets (non-isolated tracks)

Cosmic rays : diametrical tracks on both detector views

Large missing energy ETMiss (because of neutrinos)


Laboratory Exercise

Identification of electrons - muons

e : charged particles, usually isolated that leave a trace in the E/M calorimeter

μ : charged particles that leave a trace in the muon chambers


Detection and mass calculation of particles- Histogram

Laboratory Exercise


Detection and mass calculation of particles –

Dimuon spectrum

Laboratory Exercise

+???


Discover Higgs!


Laboratory Exercise

“Discover Higgs”

H → 2 Z →4l

Z → e- + e+ή Z → μ- + μ+

H  2 e- + 2 e+

H  2 μ-+ 2 μ+

Η  e- + e++ μ- + μ+

Isolated tracks

6 GeVpT Cut

Invariant mass of 4tracks (Z boson pairs)


Laboratory Exercise

“Discover Higgs”

H → 2 γ

Photons do not carry charge

Photons have 0 mass

Photons leave NO tracks

Photons deposit energy on the E/M Calorimeter

Converted photons

γ  e- e+(Invariant mass ≈ 0)


Track examples


Laboratory Exercise


Recap


So, what are we looking for??

  • Z → e- + e+orZ → μ- + μ+91,2 GeV

  • Y→ e- + e+orY→ μ- + μ+ 9,5 GeV

  • J/ψ→ e- + e+or J/ψ→ μ- + μ+3,1 GeV

  • Unknown particles→ e- + e+or→ μ- + μ+

  • H → 2 Z →4l (very few events)?GeV

    For all the above enter tracks which have sum of charge=0

  • H → 2 γ? GeV

  • Background


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