Reconstruction/MdcPatRec/PatBField/include/PatBField/BField.h

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//--------------------------------------------------------------------------
// File and Version Information:
//  $Id: BField.h,v 1.4 2008/09/17 08:30:39 zhangy Exp $
//
// Description:
//  The BField class contains the magnetic field map.  This class is now a
//      virtual class
//
//
// Environment:
//  Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author List:
//      Bob Jacobsen
//      Dave Brown, 12-23-96; Added Kalman filter tracking functions, prepared
//                            for a full field map implementation
//      Fri Sep 25 11:57:57 PDT 1998 - A. Snyder
//      Remove bFieldVectDF and bFieldZDF
//      The are replaced by derivative
//      Dave Brown, 12/20/99  Make this a virtual class, remove the
//      obsolete and dangerous static bFieldNom;
//
// Copyright Information:
//  Copyright (C) 1995, 1996
//
//------------------------------------------------------------------------
 
#ifndef MDCPATREC_BFIELD_H
#define MDCPATREC_BFIELD_H
#include "MagneticFieldSvc/IBesMagFieldSvc.h"
 
namespace MdcPatRec {
 
  class BField {
 
  public:
    BField( IBesMagFieldSvc* magSvc );
    ~BField();
 
    // return the Z component of the magnetic field at a point
    double bFieldZ() const;
 
    // return nominal field
    double bFieldNominal() const;
 
    // print
    void print() const;
 
    // for converting radius*field to GeV/c of transverse momentum
    static const double cmTeslaToGeVc;
    static const double gaussToTesla;
 
  private:
    // nominal field only
    double           _nomFieldZ;
    IBesMagFieldSvc* m_pIMF;
  };
 
} // namespace MdcPatRec
#endif