SctParSim (Aurora)

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SctParSim

A parametric simulation is a tool to receive a detector response without detailed description of interaction of particles with matter. The simulation is the part of the Aurora project, which is a software suit for SCTF.

Implemented detector subsystems:

  • drift chamber
  • FARICH PID system
  • calorimeter
  • muon system

The parametric simulation yields the detector response in the SCT EDM format thus allowing to analyze its result in the same manner as the result of the full simulation. The tracker and the calorimeter smear particle parameters according to a Gaussian distribution, while the FARICH PID and the muon subsystem use for that purpose the results of a pre-conducted standalone full Geant4 simulations.

How-to use the parametric simulation is demonstrated here

Detector configuration

The detector parameters can be changed in the run script. The detector parameters and their default values are presented below.

SctParSimAlg

Name to change parameter Description Default value
B Detector magnetic field 1.5
mostProbMass The mass of most probable particle 0.13957

TrackSystemTool

Name to change paramater Description Default value
trackRhoMin Inner radius of barrel tracker, m 0.1
trackRhoMax Outer radius of barrel tracker, m 0.8
trackZMin Inner z coordinate of endcup tracker, m 0
trackZMax Outer z coordinate of endcup tracker, m 1
trackMinPt Minimum momentum, GeV 0.05
trackPtProb Registration probabilities for different momentum, {GeV, prob} {{0.1, 0.8}, {0.3, 0.9}, {1, 0.95), {10, 0.99}}
trackRadLen Radiation length in the track system, m 187
trackResParPT Parameterizaton parameters for xy projection 0.00212
trackResParPZ Parameterization parameters for z projection {0.001281, 0.00308}
trackLayerAx The radius of layers anf the location radius of the anod layers, mm {{6.306, 217.306}, {6.644, 227.1}, {7.165, 246.906}, {6.564, 341.938}, {6.794, 352.06}, {7.14, 371.992}, {7.388, 382.95}, {6.651, 467.57}, {6.823, 477.718}, {6.968, 488.097}, {7.12, 498.701}, {7.274, 509.535}, {6.768, 636.322}, {6.898, 646.501}, {7.007, 656.957}, {7.121, 667.581}, {6.791, 750.730}, {6.902, 761.027}, {6.995, 771.472}, {7.091, 782.061}}
trackLayerSt The radius of layers and the location radius of the stereo layers, mm {{6.473, 280.136}, {6.747, 290.136}, {7.182, 310.863}, {7.486, 321.938}, {6.603, 405.941}, {6.799, 416.04}, {7.104, 436.741}, {7.314, 447.606}, {6.741, 533.35}, {6.859, 543.615}, {7.026, 554.088, {7.161, 564.762}, {6.778, 584.801}, {6.919, 595.108}, {7.039, 605.606}, {7.163, 6169.289}, {6.746, 689.948}, {6.865, 700.185}, {7.041, 720.09}, {7.165, 730.775}}

FARICHSystemTool

Name to change paramater Description Default value
farichRhoMin Inner radius of barrel FARICH system, m 0.82
farichRhoMax Outer radius of barrel FARICH system, m 0.9
farichZMin Inner z coordinate of endcup FARICH system, m 1.02
farichZMax Outer z coordinate of encup FARICH system, m 1.273
farichHoleR Hole radius of FARICH system 0.3
parSimFarichFileName The path to the file with response histograms of FARICH ./pi_ms_f1_mppc2_px3_d200_mla4_graph2d.root

CaloSystemTool

Name to change paramater Description Default value
caloRhoMin Inner radius of barrel calorimeter, m 1.09
caloRhoMax Outer radius of barrel calorimeter, m 1.55
caloZMin Inner z coordinate of endcup calorimeter, m 1.293
caloZMax Outer z coordinate of endcup calorimeter, m 1.86
caloCosthmax Maximum cosine 0.9
caloClSize Calorimeter cluster size, m 0.045
caloClSizeEGamma Calorimeter cluster size for gamma, m 0.15
caloEMinBarrel Minimal energy, GeV 0.015
caloEMinEndcup Minimal energy, GeV 0.015
caloResPar Parameterization parameters {1.34e-2, 0.066e-2, 0.0, 0.82e-2}

MuonSystemTool

Name to change paramater Description Default value
muonRhoMin Inner radius of barrel muon system, m 1.87
muonRhoMax Outer radius of barrel muon system, m 2.15
muonZMin Inner z coordinate of endcup muon system, m 1.88
muonZMax Outer z coordinate of endcup muon system, m 2.16
parSimMuonFileNameMu The path to the file with response histograms of muon system (muon) ./g4beamline_mu_plus_100k_parse.root
parSimMuonFileNamePi The path to the file with response histograms of muon system (pion) ./g4beamline_pi_plus_100k_parse.root

Parameterization

Drift chamber

The track resolution is described here.

The parametric simulation has two options in the tracker to the particle identification: an ionisation clusters counting (dNcl/dx) and dE/dx. The model of calculation the specific number of ionization clusters is taken from a TraPID option by F. Gracagnolo (The presentation on "Joint Workshop on Future tau-charm factory" in December 4--7, 2018). An energy losing is calculated using the resolution model from BaBar experiment. The \sigma \left( \frac{dE}{dx} \right) is parameterized as

\sigma \left( \frac{dE}{dx} \right) = \alpha \left( \frac{dE}{dx} \right) ^\beta dx^\gamma

where α, β, γ is tuned on BaBar data.

  • Momentum resolution as a function of momentum depending on polar angle for π+

  • The dependence of the dE/dx on the momentum in the tracker system

  • The dependence of the specific number of ionization clusters on the momentum in the tracker system

FARICH PID system

The FARICH PID system works using the results of the full GEANT4 simulation. The system output is the particle speed and number of photons.

  • The dependence of the particle β factor on the momentum in the FARICH PID system

  • The dependence of the number of photoelectron on the βγ factor in the FARICH PID system for different angles (black - 10°, red - 30°, green - 45°)

Calorimeter

The calorimeter resolution is \sigma_E = e_0 \bigoplus \frac{e_1}{E} \bigoplus \frac{e_2}{\sqrt{E}} \bigoplus \frac{e_3}{E^{0.25}}, the coefficients (e0, e1 etc.) are taken from the D. Epifanov presentation on Super C-Tau factory workshop in May 27, 2018.

There are two cluster sizes to gammas / electrons and other particles.

Reconstruction

The cross-linking data obtained by the track system and the calorimeter is implemented. This is implemented taking into account the geometric intersection of the calorimeter clusters.

The algorithm for the cross-linking data obtained by the track system and the calorimeter:

  • union of geometrically intersecting calorimetric clusters
  • finding a match between calorimetric clusters and tracks
  • recalculating cluster characteristics (time, energy, cluster size, conversion point)

  • The reconstruction efficiency for different particle types

Muon system

The muon system works using the results of a reconducted stand-alone simulation on G4BeamLine. The system is a cylinder of eight absorber and sensitive polystyrene layers. The absorber is iron.

  • The probability distribution for muons and pions to reach a certain layer in the muon system

Output collection

The output ROOT-file contains:

  • allGenParticles - MC particles
    • pdgId
    • charge
    • vertex - x, y, and z coordinates
    • p4 - momentum (px, py, pz) and mass
  • Particles - the particle characteristics after the parametric simulation
    • pdgId
    • charge
    • vertex - x, y, z coordinates
    • p4 - measured momentum (px, py, pz) and the most probability particle mass
    • dedx
    • dedx_err
    • dncldx - cluster counting
    • dedxPid
    • dncldxPid
    • farichPid
    • muPid
  • TrackState - the helix characteristics (the track)
    • phi
    • theta
    • qOverP
    • d0
    • z0
    • referencePoint - x, y and z coordinates
  • CaloClusters
    • energy
    • time
    • position - x, y and z coordinates of the calorimeter entry point
  • MuonHits
    • layer - the last layer that registered a particle
  • FARICHHits
    • cellId
    • time
    • beta
    • beta_err
    • nphe0
    • nphe

The more characteristics have intuitive names.

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