Field.cc

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/*
   Authors: Haiwang Yu
*/
#include "Field.h"

#include <phfield/PHField.h>

#include <TVector3.h>                   // for TVector3

#include <CLHEP/Units/SystemOfUnits.h>

#include <cassert>
#include <limits>

namespace genfit
{
Field::Field(const PHField* field)
  : field_(field)
{
  assert(field_);
}

//
//bool Field::initialize(std::string inname)
//{
//  field_map_r_ = new TH2D("field_map_r_", "B_{r} [kGauss]; z [cm]; r [cm]", 401, -401, 401, 151, -1, 301);
//  field_map_r_->SetDirectory(0);
//  field_map_z_ = new TH2D("field_map_z_", "B_{z} [kGauss]; z [cm]; r [cm]", 401, -401, 401, 151, -1, 301);
//  field_map_z_->SetDirectory(0);
//  TFile* fin = TFile::Open(inname.data(), "READ");
//  if (!fin)
//  {
//    LogERROR("Input TFile is invalid!");
//    return false;
//  }
//  TNtuple* T = (TNtuple*) fin->Get("fieldmap");
//  if (!T)
//  {
//    LogERROR("Input filed map NTuple not found!");
//    ;
//    return false;
//  }
//
//  Float_t r;
//  Float_t z;
//  Float_t br;
//  Float_t bz;
//  T->SetBranchAddress("r", &r);
//  T->SetBranchAddress("z", &z);
//  T->SetBranchAddress("br", &br);
//  T->SetBranchAddress("bz", &bz);
//
//  for (long ientry = 0; ientry < T->GetEntries(); ientry++)
//  {
//    //if (T->GetEntry(ientry) < 0) continue;
//    T->GetEntry(ientry);
//    //std::cout<<r <<" ,"<<z <<" ,"<<br<<" ,"<<bz<<"\n";
//    field_map_r_->SetBinContent(
//        field_map_r_->GetXaxis()->FindBin(z),
//        field_map_r_->GetYaxis()->FindBin(r),
//        br * 10);
//    field_map_z_->SetBinContent(
//        field_map_z_->GetXaxis()->FindBin(z),
//        field_map_z_->GetYaxis()->FindBin(r),
//        bz * 10);
//  }
//  fin->Close();
//
//  //field_map_z_->Print("all");
//
//  return true;
//}

//void Field::plot(std::string option){
//
//      TH2D *hbr = new TH2D("hbr","|B_{r}| [kGauss]; z [cm]; r [cm]",300, -350, 350, 200, 0, 290);
//      TH2D *hbz = new TH2D("hbz","|B_{z}| [kGauss]; z [cm]; r [cm]",300, -350, 350, 200, 0, 290);
//      for (double r = 0; r < 300; r+=1)
//              for (double z = 400; z > -400; z-=1) {
//                      double bx;
//                      double by;
//                      double bz;
//                      get(r, 0, z, bx, by, bz);
//
//
//                      //std::cout <<"DEBUG: "<<__LINE__<<":"<< r << " ," << z << " ," << br << " ," << bz << "\n";
//
//                      hbr->SetBinContent(
//                                      hbr->GetXaxis()->FindBin(z),
//                                      hbr->GetYaxis()->FindBin(r),
//                                      bz*10);
//                      hbz->SetBinContent(
//                                      hbz->GetXaxis()->FindBin(z),
//                                      hbz->GetYaxis()->FindBin(r),
//                                      bz*10);
//              }
//
//      TCanvas *c0 = new TCanvas("c0","c0");
//      c0->Divide(1,2);
//      c0->cd(1);
//      hbr->SetStats(0);
//      hbr->Draw("colz");
//      c0->cd(2);
//      hbz->SetStats(0);
//      hbz->Draw("colz");
//      c0->Update();
//
//      c0->SaveAs("Field_plot.root");
//      c0->SaveAs("Field_plot.pdf");
//
//      delete c0;
//      delete hbr;
//      delete hbz;
//
//      return;
//}

TVector3 Field::get(const TVector3& v) const
{
  double x = v.x();
  double y = v.y();
  double z = v.z();
  double Bx;
  double By;
  double Bz;
  get(x, y, z, Bx, By, Bz);
  return TVector3(Bx, By, Bz);
}

void Field::get(const double& x, const double& y, const double& z, double& Bx, double& By, double& Bz) const
{
  assert(field_);

  const double Point[] = {x * CLHEP::cm, y * CLHEP::cm, z * CLHEP::cm, 0};
  double Bfield[] = {std::numeric_limits<double>::signaling_NaN(),
                     std::numeric_limits<double>::signaling_NaN(),
                     std::numeric_limits<double>::signaling_NaN(),
                     std::numeric_limits<double>::signaling_NaN(),
                     std::numeric_limits<double>::signaling_NaN(),
                     std::numeric_limits<double>::signaling_NaN()};

  field_->GetFieldValue(Point, Bfield);

  Bx = Bfield[0] / CLHEP::kilogauss;
  By = Bfield[1] / CLHEP::kilogauss;
  Bz = Bfield[2] / CLHEP::kilogauss;

  //  double r = sqrt(x * x + y * y);
  //
  //  if (fabs(r) > 300 || fabs(z) > 400)
  //  {
  //    Bx = 0;
  //    By = 0;
  //    Bz = 0;
  //    return;
  //  }
  //
  //  int bin_z = field_map_r_->GetXaxis()->FindBin(z);
  //  int bin_r = field_map_r_->GetYaxis()->FindBin(r);
  //
  //  Bz = field_map_z_->GetBinContent(bin_z, bin_r);
  //  double Br = field_map_r_->GetBinContent(bin_z, bin_r);
  //
  //  Bx = x / r * Br;
  //  By = y / r * Br;
  //
  //  if (r == 0)
  //  {
  //    Bx = 0;
  //    By = 0;
  //  }

  //std::cout<<"DEBUG: "<<__LINE__<<": "<<z<<","<<r<<","<<bin_z<<","<<bin_r<<": "<<Br<<","<<Bz<<"\n";
}

} /* End of namespace genfit */