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ILC.Introductionr1.3 - 15 Sep 2009 - 11:37 - Main.iglesiastopic end

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Structure of the Package

The LDC tracking code is implemented within the framework of Marlin [3] and constitutes a part of the MarlinReco? package [4]. The code includes:

  • Marlin processors performing digitization of the signal in various tracking subdetectors;
  • Marlin processors implementing pattern recognition in TPC and silicon detectors;
  • the track fitting code based on the Kalman filter approach;
  • utility classes facilitating fast and efficient pattern recognition;

The software is compliant with the LCIO data format [5]. The track parameterization follows the ILC convention documented in Ref. [6] T. Kraemer, LC Note LC-DET-2006-004. The track parameters and corresponding covariance matrix are evaluated with the Kalman filter at the point of closest approach to the nominal e+e− interaction point.

Digitization Processors

The digitization of the simulated tracker hits (SimTrackerHits?), produced during the detector simulation run, is performed in two different ways. The first approach is based onthe Gaussian smearing of SimTrackerHits? according to a-priori known and specified spatial point resolutions. This approach is implemented in the processors:
  • - VTXDigiProcessor: performs digitization of SimTrackerHits? in the vertex detector and SIT
  • - FTDDigiProcessor?: performs digitization in the forward tracking discs
  • - TPCDigiProcessor: performs digitization in TPC
All processors require SimTrackerHit? collection names as an input parameters.

The VTXDigiProcessor treats VTX and SIT as cylindrical detectors. The two spatial point resolutions, one in the r − phi projection and another - along z, should be provided by user as a processor parameter.

FTDDigiProcessor? treats forward tracking discs as a rigid measurement planes at fixed positions in z. It is assumed that the hit position in the FTD’s is measured ”isotropically”, thus a user has to provide only spatial point resolution in the r- phi projection.

In the TPCDigiProcessor, the TPC spatial resolution in r- is given by 2(r − ) = 2 0 + D2 • Ldrift where 0 is the constant term, D is the diffusion coefficient and Ldrift is the drift length. Resolution along z axis is assumed to be independent of Ldrift.hits simulados se lleva a cabo con diversos procesadores de Marlin.

Para la digitalización de impactos en el detector de vértices, disponemos de 2 procesadores extras: VTXDigitizer y VTXNoiseHits?.

For the DEPFET-based microvertex detector, a detailed digitization procedure is imple mented in the Marlin processor VTXDigitizer. The procedure takes into account Lorentz effect, charge diffusion, electronic noise and energy loss fluctuations along the charged particle trajectory within the sensitive silicon layer.

El proceso de digitalización de los hits simulados se lleva a cabo con diversos procesadores de Marlin.

... Los procesadores de digitalización de los calorímetros, recogen un SimCalorimeterHit? y produce un CalorimeterHit?. Los depósitos de energía de las capas activas de los calorímetros se convierten en energía físicas. La digitalización de los impactos en las TPC se realiza mediante el smearing en las direcciones r − φ y en z, convirtiendo un SimTrackerHit? en un TrackerHit?. Para la digitalización del sistema de tracking en la zona forward y el detector de vértices se aplican smearing sencillos. El FTD es simulado con una resolución de 7 um en X e Y (esto no son los parametros propuestos por SiLC? debido a las limitaciones tecnicas de la digitizacion de Marlin). De todas formas el resultado es bastante parecido a lo que obtendrias con bandas R y phi a al VELO. El smearing en X e Y nos limita a casos simetricos (donde la resolucion en R e Rphi es igual).

-- Main.iglesias - 02 Feb 2009
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