G4_Piston.C

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#ifndef MACRO_G4PISTON_C
#define MACRO_G4PISTON_C

#include <GlobalVariables.C>

#include <G4_Pipe.C>

#include <g4detectors/PHG4ConeSubsystem.h>
#include <g4detectors/PHG4CylinderSubsystem.h>

#include <g4main/PHG4Reco.h>

R__LOAD_LIBRARY(libg4detectors.so)

namespace Enable
{
  bool PISTON = false;
  bool PISTON_ABSORBER = false;
  bool PISTON_OVERLAPCHECK = false;
  int PISTON_VERBOSITY = 0;
}  // namespace Enable

namespace G4PISTON
{
  double zpos1 = 305. - 20.;                       // front of forward ECal/MPC
  double zpos2 = 335.9 - 10.2 / 2.;                // front of the forward field endcap
  double calorimeter_hole_diameter = 9.92331 * 2;  // side length of the middle hole of MPC that
}  // namespace G4PISTON

void PistonInit()
{
  BlackHoleGeometry::max_radius = std::max(BlackHoleGeometry::max_radius, G4PISTON::calorimeter_hole_diameter / 2.);
  BlackHoleGeometry::max_z = std::max(BlackHoleGeometry::max_z, ((G4PISTON::zpos2 + G4PISTON::zpos1) / 2. + (G4PISTON::zpos2 - G4PISTON::zpos1) / 2.));
}

void Piston(PHG4Reco *g4Reco,
            const int absorberactive = 0)
{
  bool AbsorberActive = Enable::ABSORBER || Enable::PISTON_ABSORBER || absorberactive;
  bool OverlapCheck = Enable::OVERLAPCHECK || Enable::PISTON_OVERLAPCHECK;
  int verbosity = std::max(Enable::VERBOSITY, Enable::PISTON_VERBOSITY);

  string name = "magpiston";
  const double zpos0 = G4PIPE::al_pipe_length + G4PIPE::be_pipe_length * 0.5;  // first large GEM station

  const double beampipe_radius = G4PIPE::be_pipe_radius;

  // teeth cone section specific
  const double number_of_wteeth = 100;
  const double teeth_thickness = 0.3504 * 2;  //2 X0
  const double eta_inner = -log(tan(atan((beampipe_radius + 0.1) / zpos0) / 2));
  const double eta_outter = 4.2;
  const double eta_teeth_outter = 4.05;
  double pos = zpos0 + (G4PISTON::zpos1 - zpos0) / 2;
  //  cout << "MAGNETIC PISTON:" << eta_inner << " " << eta_outter << " " << pos
  //      << endl;

  PHG4ConeSubsystem *magpiston = new PHG4ConeSubsystem("Piston", 0);
  magpiston->SetZlength((G4PISTON::zpos1 - zpos0) / 2);
  magpiston->SetPlaceZ((G4PISTON::zpos1 + zpos0) / 2);
  magpiston->SetR1(beampipe_radius,
                   tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_outter)) * zpos0);
  magpiston->SetR2(beampipe_radius,
                   tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_outter)) * G4PISTON::zpos1);
  magpiston->SetMaterial("G4_Fe");
  magpiston->OverlapCheck(OverlapCheck);
  g4Reco->registerSubsystem(magpiston);

  //  PHG4ConeSubsystem *magpiston = new PHG4ConeSubsystem(name, 1);
  //  magpiston->SetZlength((G4PISTON::zpos1 - zpos0) / 2);
  //  magpiston->SetPlaceZ(pos);
  //  magpiston->Set_eta_range(eta_outter, eta_inner);
  //  magpiston->SetMaterial("G4_Fe");
  //  magpiston->SuperDetector(name);
  //  magpiston->SetActive(false);
  //  g4Reco->registerSubsystem(magpiston);

  pos = zpos0 + 1.0 + teeth_thickness / 2;
  for (int i = 0; i < number_of_wteeth; i++)
  {
    stringstream s;
    s << name;
    s << "_teeth_";
    s << i;

    magpiston = new PHG4ConeSubsystem(s.str(), i);
    magpiston->SuperDetector(name);
    magpiston->SetZlength(teeth_thickness / 2);
    magpiston->SetPlaceZ(pos);
    magpiston->SetR1(
        //
        tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_outter - .01)) * (pos - teeth_thickness / 2),  //
        tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_teeth_outter)) * (pos - teeth_thickness / 2)   //
    );
    magpiston->SetR2(
        //
        tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_outter - .01)) * (pos + teeth_thickness / 2),      //
        tan(PHG4Sector::Sector_Geometry::eta_to_polar_angle(eta_outter - .01)) * (pos + teeth_thickness / 2) + .1  //
    );
    magpiston->SetMaterial("G4_W");
    magpiston->SuperDetector(name);
    if (AbsorberActive) magpiston->SetActive();
    magpiston->OverlapCheck(OverlapCheck);
    g4Reco->registerSubsystem(magpiston);
    pos += ((G4PISTON::zpos1 - zpos0 - 10) / number_of_wteeth);
  }

  // last piece connect to the field return
  PHG4CylinderSubsystem *magpiston2 = new PHG4CylinderSubsystem("Piston_EndSection", 0);
  magpiston2->set_double_param("length", G4PISTON::zpos2 - G4PISTON::zpos1);
  magpiston2->set_double_param("place_z", (G4PISTON::zpos2 + G4PISTON::zpos1) / 2.);
  magpiston2->set_double_param("radius", beampipe_radius);
  magpiston2->set_double_param("thickness", G4PISTON::calorimeter_hole_diameter / 2. - beampipe_radius);
  magpiston2->set_string_param("material", "G4_Fe");
  magpiston2->SuperDetector(name);
  if (AbsorberActive) magpiston2->SetActive();
  magpiston2->OverlapCheck(OverlapCheck);
  g4Reco->registerSubsystem(magpiston2);

  return;
}
#endif