DetectorConstruction.cc

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/// \file B2/B2b/src/DetectorConstruction.cc
/// \brief Implementation of the B2b::DetectorConstruction class
 
#include "DetectorConstruction.hh"
#include "DetectorMessenger.hh"
#include "ChamberParameterisation.hh"
#include "TrackerSD.hh"
 
#include "G4Material.hh"
#include "G4NistManager.hh"
#include "G4SDManager.hh"
 
#include "G4Box.hh"
#include "G4Tubs.hh"
#include "G4LogicalVolume.hh"
#include "G4PVPlacement.hh"
#include "G4PVParameterised.hh"
#include "G4GlobalMagFieldMessenger.hh"
#include "G4AutoDelete.hh"
 
#include "G4GeometryTolerance.hh"
#include "G4GeometryManager.hh"
 
#include "G4UserLimits.hh"
 
#include "G4VisAttributes.hh"
#include "G4Colour.hh"
 
#include "G4SystemOfUnits.hh"
 
using namespace B2;
 
namespace B2b
{
 
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G4ThreadLocal
G4GlobalMagFieldMessenger* DetectorConstruction::fMagFieldMessenger = nullptr;
 
DetectorConstruction::DetectorConstruction()
{
  fMessenger = new DetectorMessenger(this);
}
 
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DetectorConstruction::~DetectorConstruction()
{
  delete fStepLimit;
  delete fMessenger;
}
 
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G4VPhysicalVolume* DetectorConstruction::Construct()
{
  // Define materials
  DefineMaterials();
 
  // Define volumes
  return DefineVolumes();
}
 
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void DetectorConstruction::DefineMaterials()
{
  // Material definition
 
  G4NistManager* nistManager = G4NistManager::Instance();
 
  // Air defined using NIST Manager
  nistManager->FindOrBuildMaterial("G4_AIR");
 
  // Lead defined using NIST Manager
  fTargetMaterial  = nistManager->FindOrBuildMaterial("G4_Pb");
 
  // Xenon gas defined using NIST Manager
  fChamberMaterial = nistManager->FindOrBuildMaterial("G4_Xe");
 
  // Print materials
  G4cout << *(G4Material::GetMaterialTable()) << G4endl;
}
 
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G4VPhysicalVolume* DetectorConstruction::DefineVolumes()
{
  G4Material* air  = G4Material::GetMaterial("G4_AIR");
 
  // Sizes of the principal geometrical components (solids)
 
  G4int NbOfChambers = 5;
  G4double chamberSpacing = 80*cm; // from chamber center to center!
 
  G4double chamberWidth = 20.0*cm; // width of the chambers
  G4double targetLength =  5.0*cm; // full length of Target
 
  G4double trackerLength = (NbOfChambers+1)*chamberSpacing;
 
  G4double worldLength = 1.2 * (2*targetLength + trackerLength);
 
  G4double targetRadius  = 0.5*targetLength;   // Radius of Target
  targetLength = 0.5*targetLength;             // Half length of the Target
  G4double trackerSize   = 0.5*trackerLength;  // Half length of the Tracker
 
  // Definitions of Solids, Logical Volumes, Physical Volumes
 
  // World
 
  G4GeometryManager::GetInstance()->SetWorldMaximumExtent(worldLength);
 
  G4cout << "Computed tolerance = "
         << G4GeometryTolerance::GetInstance()->GetSurfaceTolerance()/mm
         << " mm" << G4endl;
 
  auto worldS = new G4Box("world",                       // its name
    worldLength / 2, worldLength / 2, worldLength / 2);  // its size
  auto worldLV = new G4LogicalVolume(worldS,             // its solid
    air,                                                 // its material
    "World");                                            // its name
 
  //  Must place the World Physical volume unrotated at (0,0,0).
  //
  auto worldPV = new G4PVPlacement(nullptr,  // no rotation
    G4ThreeVector(),                         // at (0,0,0)
    worldLV,                                 // its logical volume
    "World",                                 // its name
    nullptr,                                 // its mother  volume
    false,                                   // no boolean operations
    0,                                       // copy number
    fCheckOverlaps);                         // checking overlaps
 
  // Target
 
  G4ThreeVector positionTarget = G4ThreeVector(0,0,-(targetLength+trackerSize));
 
  auto targetS = new G4Tubs("target", 0., targetRadius, targetLength, 0. * deg, 360. * deg);
  fLogicTarget = new G4LogicalVolume(targetS, fTargetMaterial, "Target", nullptr, nullptr, nullptr);
  new G4PVPlacement(nullptr,  // no rotation
    positionTarget,           // at (x,y,z)
    fLogicTarget,             // its logical volume
    "Target",                 // its name
    worldLV,                  // its mother volume
    false,                    // no boolean operations
    0,                        // copy number
    fCheckOverlaps);          // checking overlaps
 
  G4cout << "Target is " << 2*targetLength/cm << " cm of "
         << fTargetMaterial->GetName() << G4endl;
 
  // Tracker
 
  G4ThreeVector positionTracker = G4ThreeVector(0,0,0);
 
  auto trackerS = new G4Tubs("tracker", 0, trackerSize, trackerSize, 0. * deg, 360. * deg);
  auto trackerLV = new G4LogicalVolume(trackerS, air, "Tracker", nullptr, nullptr, nullptr);
  new G4PVPlacement(nullptr,  // no rotation
    positionTracker,          // at (x,y,z)
    trackerLV,                // its logical volume
    "Tracker",                // its name
    worldLV,                  // its mother  volume
    false,                    // no boolean operations
    0,                        // copy number
    fCheckOverlaps);          // checking overlaps
 
  // Tracker segments
 
  // An example of Parameterised volumes
  // Dummy values for G4Tubs -- modified by parameterised volume
 
  auto chamberS = new G4Tubs("tracker", 0, 100 * cm, 100 * cm, 0. * deg, 360. * deg);
  fLogicChamber =
    new G4LogicalVolume(chamberS, fChamberMaterial, "Chamber", nullptr, nullptr, nullptr);
 
  G4double firstPosition = -trackerSize + chamberSpacing;
  G4double firstLength   = trackerLength/10;
  G4double lastLength    = trackerLength;
 
  G4VPVParameterisation* chamberParam =
    new ChamberParameterisation(
                                  NbOfChambers,   // NoChambers
                                  firstPosition,  // Z of center of first
                                  chamberSpacing, // Z spacing of centers
                                  chamberWidth,  // chamber width
                                  firstLength,    // initial length
                                  lastLength);    // final length
 
  // dummy value : kZAxis -- modified by parameterised volume
 
  new G4PVParameterised("Chamber",       // their name
                        fLogicChamber,   // their logical volume
                        trackerLV,       // Mother logical volume
                        kZAxis,          // Are placed along this axis
                        NbOfChambers,    // Number of chambers
                        chamberParam,    // The parametrisation
                        fCheckOverlaps); // checking overlaps
 
  G4cout << "There are " << NbOfChambers << " chambers in the tracker region. "
         << G4endl
         << "The chambers are " << chamberWidth/cm << " cm of "
         << fChamberMaterial->GetName() << G4endl
         << "The distance between chamber is " << chamberSpacing/cm << " cm"
         << G4endl;
 
  // Visualization attributes
 
  G4VisAttributes boxVisAtt(G4Colour::White());
 
  worldLV   ->SetVisAttributes(boxVisAtt);
  fLogicTarget ->SetVisAttributes(boxVisAtt);
  trackerLV ->SetVisAttributes(boxVisAtt);
 
  G4VisAttributes chamberVisAtt(G4Colour::Yellow());
  fLogicChamber->SetVisAttributes(chamberVisAtt);
 
  // Example of User Limits
  //
  // Below is an example of how to set tracking constraints in a given
  // logical volume
  //
  // Sets a max step length in the tracker region, with G4StepLimiter
 
  G4double maxStep = 0.5*chamberWidth;
  fStepLimit = new G4UserLimits(maxStep);
  trackerLV->SetUserLimits(fStepLimit);
 
  /// Set additional contraints on the track, with G4UserSpecialCuts
  ///
  /// G4double maxLength = 2*trackerLength, maxTime = 0.1*ns, minEkin = 10*MeV;
  /// trackerLV->SetUserLimits(new G4UserLimits(maxStep,
  ///                                           maxLength,
  ///                                           maxTime,
  ///                                           minEkin));
 
  // Always return the physical world
 
  return worldPV;
}
 
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void DetectorConstruction::ConstructSDandField()
{
  // Sensitive detectors
 
  G4String trackerChamberSDname = "B2/TrackerChamberSD";
  auto aTrackerSD = new TrackerSD(trackerChamberSDname, "TrackerHitsCollection");
  G4SDManager::GetSDMpointer()->AddNewDetector(aTrackerSD);
  SetSensitiveDetector( fLogicChamber,  aTrackerSD );
 
  // Create global magnetic field messenger.
  // Uniform magnetic field is then created automatically if
  // the field value is not zero.
  G4ThreeVector fieldValue = G4ThreeVector();
  fMagFieldMessenger = new G4GlobalMagFieldMessenger(fieldValue);
  fMagFieldMessenger->SetVerboseLevel(1);
 
  // Register the field messenger for deleting
  G4AutoDelete::Register(fMagFieldMessenger);
}
 
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void DetectorConstruction::SetTargetMaterial(G4String materialName)
{
  G4NistManager* nistManager = G4NistManager::Instance();
 
  G4Material* pttoMaterial =
              nistManager->FindOrBuildMaterial(materialName);
 
  if (fTargetMaterial != pttoMaterial) {
     if ( pttoMaterial ) {
        fTargetMaterial = pttoMaterial;
        if (fLogicTarget) fLogicTarget->SetMaterial(fTargetMaterial);
        G4cout
          << G4endl
          << "----> The target is made of " << materialName << G4endl;
     } else {
        G4cout
          << G4endl
          << "-->  WARNING from SetTargetMaterial : "
          << materialName << " not found" << G4endl;
     }
  }
}
 
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void DetectorConstruction::SetChamberMaterial(G4String materialName)
{
  G4NistManager* nistManager = G4NistManager::Instance();
 
  G4Material* pttoMaterial =
              nistManager->FindOrBuildMaterial(materialName);
 
  if (fChamberMaterial != pttoMaterial) {
     if ( pttoMaterial ) {
        fChamberMaterial = pttoMaterial;
        if (fLogicChamber) fLogicChamber->SetMaterial(fChamberMaterial);
        G4cout
          << G4endl
          << "----> The chambers are made of " << materialName << G4endl;
     } else {
        G4cout
          << G4endl
          << "-->  WARNING from SetChamberMaterial : "
          << materialName << " not found" << G4endl;
     }
  }
}
 
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void DetectorConstruction::SetMaxStep(G4double maxStep)
{
  if ((fStepLimit)&&(maxStep>0.)) fStepLimit->SetMaxAllowedStep(maxStep);
}
 
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}