BellField.cc

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/* Copyright 2008-2010, Technische Universitaet Muenchen,
   Authors: Christian Hoeppner & Sebastian Neubert & Johannes Rauch
 
   This file is part of GENFIT.
 
   GENFIT is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   GENFIT is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.
 
   You should have received a copy of the GNU Lesser General Public License
   along with GENFIT.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "BellField.h"
#include "math.h"
#include <iostream>
using std::cout;
using std::endl;
Double_t kilogauss = 1.;
Double_t tesla     = 10*kilogauss;
Double_t cm  = 1;       // cm
Double_t meter   = 100*cm;  //  m
Double_t mm  = 0.1*cm;  //  mm
 
// implementation of Bellshape field for Ship
namespace genfit {
 
  BellField::BellField()
    : AbsBField(),
      fMiddle(0),fPeak(0)
  { ; }
  BellField::BellField(double Peak, double Middle,int orientation, double Btube )
    : AbsBField(),
      fMiddle(Middle),fPeak(Peak),fOrient(orientation),fBtube(Btube)
  { ; }
 
TVector3 BellField::get(const TVector3& pos) const {
  Double_t bx,by,bz; 
  get(pos.X(),pos.Y(),pos.Z(),bx,by,bz);
  TVector3 field_(bx,by,bz);
  return field_;
}
 
void BellField::get(const double& x, const double& y, const double& z, double& Bx, double& By, double& Bz) const {
  Double_t zlocal=fabs((z-fMiddle)/100.);
  Bz = 0.;
  By = 0.;
  Bx = 0.;
  if (fOrient==1){ By = fPeak/(1.+pow(fabs(zlocal)/2.1,6.));}
  if (fOrient==2){
   //new field based on simulation of Davide Tommasini (22/1/2015)
 
    //field in box 20 cm larger than inner tube.
    if ( (fabs(x)<2.7*meter) && (fabs(y)<fBtube+0.2*meter) )  {
      if (zlocal<3.8) {
        Bx=0.14361*exp( -0.5 * pow((zlocal-0.45479E-01)/2.5046,2.));
      }else if (zlocal<11.9) {
        Bx=0.19532-0.61512E-01*zlocal+0.68447E-02*pow(zlocal,2.)-0.25672E-03*pow(zlocal,3.);
      }
      Bx=((fPeak/tesla)/0.14361)*Bx*tesla;
    }
  // cout << "genfit Bell " << x << ", " << y << ", " << z << ", Bx= " << Bx << endl;
  }
}
} /* End of namespace genfit */