VTXDigitizer Class Reference

Digitizer for Simulated Hits in the Vertex Detector. More...

#include <VTXDigitizer.h>

Inheritance diagram for VTXDigitizer:

Public Member Functions
virtual Processor *	newProcessor ()
virtual void	init ()
	Initialisation member function.
virtual void	processRunHeader (LCRunHeader *run)
	Processing of run header.
virtual void	processEvent (LCEvent *evt)
	Processing of one event.
virtual void	check (LCEvent *evt)
	Produces check plots.
virtual void	end ()
	Termination member function.

Protected Member Functions
void	FindLocalPosition (SimTrackerHit *hit, double *localPosition, double *localDirection)
	Finds coordinates.
void	TransformToLab (double *xLoc, double *xLab)
void	ProduceIonisationPoints (SimTrackerHit *hit)
void	ProduceSignalPoints ()
void	ProduceHits (SimTrackerHitImplVec &simTrkVec)
void	TransformXYToCellID (double x, double y, int &ix, int &iy)
void	TransformCellIDToXY (int ix, int iy, double &x, double &y)
void	PoissonSmearer (SimTrackerHitImplVec &simTrkVec)
void	GainSmearer (SimTrackerHitImplVec &simTrkVec)
void	PrintInfo (SimTrackerHit *simTrkHit, TrackerHitImpl *recoHit)
TrackerHitImpl *	ReconstructTrackerHit (SimTrackerHitImplVec &simTrkVec)
void	TrackerHitToLab (TrackerHitImpl *recoHit)
void	PositionWithinCell (double x, double y, int &ix, int &iy, double &xCell, double &yCell)
void	generateBackground (LCCollectionVec *col)

Protected Attributes
std::string	_colName
	Input collection name.
std::string	_outputCollectionName
std::string	_colVTXRelation
int	_nRun
	Run number.
int	_nEvt
	Event number.
double	_tanLorentzAngle
	tangent of Lorentz angle
double	_cutOnDeltaRays
	cut in MeV on delta electrons used in simulation of charge for each ionisation point
double	_diffusionCoefficient
	Diffusion coefficient in mm for nominla layer thickness.
int	_numberOfLayers
	layer thickness More...
double	_pixelSizeX
double	_pixelSizeY
double	_electronsPerKeV
double	_segmentDepth
double	_currentTotalCharge
std::vector< int >	_laddersInLayer
std::vector< float >	_layerRadius
std::vector< float >	_layerThickness
std::vector< float >	_layerHalfThickness
std::vector< float >	_layerLadderLength
std::vector< float >	_layerLadderHalfWidth
std::vector< float >	_layerPhiOffset
std::vector< float >	_layerActiveSiOffset
std::vector< float >	_layerHalfPhi
std::vector< float >	_layerLadderGap
std::vector< float >	_bkgdHitsInLayer
std::vector< float >	_layerLadderWidth
int	_currentLayer
int	_currentModule
int	_generateBackground
double	_currentParticleMomentum
double	_currentParticleEnergy
double	_currentParticleMass
double	_currentPhi
double	_widthOfCluster
double	PI
double	TWOPI
double	PI2
double	SCALING
int	_produceFullPattern
int	_numberOfSegments
int	_debug
int	_PoissonSmearing
int	_electronicEffects
int	_useMCPMomentum
int	_removeDrays
double	_threshold
double	_currentLocalPosition [3]
double	_currentEntryPoint [3]
double	_currentExitPoint [3]
double	_electronicNoise
double	_segmentLength
IonisationPointVec	_ionisationPoints
SignalPointVec	_signalPoints
MyG4UniversalFluctuationForSi *	_fluctuate
double	_xLayerReco
double	_yLayerReco
double	_zLayerReco
double	_xLayerSim
double	_yLayerSim
double	_zLayerSim
int	_iLayer
int	_nCoveredX
int	_nCoveredY
int	_nCells
int	_totEntries
double	_totMomentum
double	_momX
double	_momY
double	_momZ
double	_eDep
double	_amplX [20]
double	_amplY [20]
double	_amplC [100]
double	_ampl
double	_amplMax
double	_eSum
double	_energyLoss
double	_clusterWidthX
double	_clusterWidthY
double	_ampl33
double	_ampl55
double	_ampl77
int	_ncell33
int	_ncell55
int	_ncell77
int	_storeNtuple
double	_xLocalRecoCOG
double	_yLocalRecoCOG
double	_xLocalRecoEdge
double	_yLocalRecoEdge
double	_xLocalSim
double	_yLocalSim
std::vector< SimTrackerHitImplVec >	_hitsInLayer

Detailed Description

Digitizer for Simulated Hits in the Vertex Detector.

Digitization follows the procedure adopted in the CMS software package.
For each Simulated Tracker Hit the intersection points with
the inner and outer boundaries of sensitive Si layer are calculated.
Track segment within a layer is approximated with the line.
It is divided by n subsegments, where n can be specified by a user
via external Processor parameter. For each subsegment the charge
is simulated according to Landau distribution as expected for Silicon.
The charge transfer from the middle point of track subsegment (referred
hereafter to as ionisation point)
to the outer collection plane is performed taking
into account Lorentz effect in the magnetic field
It is assumed that on the collection plane the electron cloud from
each ionisation point is spread according to the Gaussian distribution
whose width is proportional to the square-root of the drift distance.
The charge on each fired pixel is then calculated as a sum of contributions
from n Gaussians. The VTX ladder is assumed to have matrix of rectangular pixels
(In the future I plan to implement possibility of variying pixel size with
the z coordinate).
The output of the processor is the collection of Reconstructed Tracker Hits.
Each reconstructed hit is assigned the position of the center-of-gravity of
the cluster of fired pixels. Lorentz effect is corrected for.

Input collections and prerequisites

Processor requires collection of simulated vertex tracker hits.
If such a collection with the user specified name does not exist
processor takes no action.

Output

Processor produces an output collection of the Tracker Hits. Collection has name "VTXTrackerHits".

Parameters

CollectionName	name of input SimTrackerHit collection (default parameter value : "vxd01_VXD", taken from Mokka)
TanLorentz	tangent of the Lorentz angle (default parameter value : 0.8)
CutOnDeltaRays	cut on the energy of delta-electrons (in MeV) (default parameter value : 0.03)
Diffusion	diffusion coefficient for the nominal active layer thickness (in mm) (default parameter value : 0.002)
LayerThickness	thickness of the active Silicon layer (in mm) (default parameter value : 0.03744)
PixelSizeX	pixel size along direction perpendicular to beam axis (in mm) (default value : 0.025)
PixelSizeY	pixel size along beam axis (in mm) (default value : 0.025)
ElectronsPerMeV	number of electrons produced per MeV of deposited energy (default parameter value : 270.3)
Threshold	threshold on charge deposited on one pixel (in electons) (default parameter value : 200.0)
LaddersInLayer	vector of integers, numbers of phi-ladders in each layer (default parameter values : 8, 8, 12, 16, 20; taken from Mokka database for VXD model vxd01)
LadderRadius	vector of doubles, radii of layers (in mm) (default parameter values : 15.301, 26.301, 38.301, 49.301, 60.301; taken from Mokka database for VXD model vxd01)
ActiveLadderOffset	vector of doubles, offset of active Si layer along phi-angle (in mm) for each layer (default parameter values : 1.455, 1.39866, 2.57163, 3.59295, 4.42245)
LadderHalfWidth	vector of doubles, half-width of the ladders in each layer (in mm) (default parameter values : 6.5, 11.0, 11.0, 11.0, 11.0; taken from Mokka database for VXD model vxd01)
LadderGaps	vector of doubles, gaps between two symmetric ladders (+/-z) in mm (default parameter values : 0.0, 0.04, 0.04, 0.04, 0.04; taken from Mokka database)
PhiOffset	vector of doubles, offset in phi angle for starting ladder in each layer (default parameter values : 0, 0, 0, 0, 0; taken from Mokka database for VXD model vxd01)
SegmentLength	segment length along track path which is used to subdivide track into segments (in mm). The number of track subsegments is calculated as int(TrackLengthWithinActiveLayer/SegmentLength)+1 (default parameter value : 0.005)
WidthOfCluster	defines width in Gaussian sigmas to perform charge integration for a given pixel (default parameter value : 3.0)
ElectronicEffects	flag to switch on gaussian smearing of signal (electronic noise) (default parameter value : 1)
ElectronicNoise	electronic noise in electrons (default parameter value : 100)
GenerateBackground	flag to switch on pseudo-generation of pair background hits Background hits are uniformly generated in cosQ and Phi (default parameter value : 0)
BackgroundHitsPerLayer	expected mean value of background hits accumulated in each layer over readout time. This number is calculated as Number of background hits per bunch crossing times number of bunch crossings over integration time. (default values : 34400 23900 9600 5500 3100 corresponding to 100 overlaid bunch crossings)
Debug	boolean variable, if set to 1, printout is activated (default parameter value : 0)

Author

A. Raspereza, MPI Munich

Member Data Documentation

int VTXDigitizer::_numberOfLayers

protected

layer thickness

layer half-thickness

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The documentation for this class was generated from the following file:

• VTXDigitizer.h