geant4如何获取粒子打在闪烁体上的脉冲波形，用G4Scintillation

在 Geant4 中，可以使用 G4Scintillation 类来模拟闪烁体中的光子产生和传播，并使用 G4SensitiveDetector 类来模拟击中命中的响应。以下是一个简单的示例程序，展示了如何在 Geant4 中使用 G4Scintillation 和 G4SensitiveDetector 获取击中命中的电荷脉冲和光子脉冲：

#include "MySD.hh"
#include "MyHit.hh"
#include "G4Scintillation.hh"
#include "G4SDManager.hh"

void MyDetectorConstruction::Construct() {
  // 创建闪烁体
  G4Material* scintillator = new G4Material("Scintillator", 1.032*g/cm3, 2);
  scintillator->AddElement(G4Element::GetElement("C"), 9);
  scintillator->AddElement(G4Element::GetElement("H"), 10);
  G4MaterialPropertiesTable* mpt = new G4MaterialPropertiesTable();
  mpt->AddProperty("FASTCOMPONENT", scint_energy, scint_spectrum, nEntries);
  mpt->AddProperty("RINDEX", photon_energy, rindex, nEntries);
  mpt->AddProperty("ABSLENGTH", photon_energy, abs_length, nEntries);
  scintillator->SetMaterialPropertiesTable(mpt);

  // 创建闪烁体逻辑体和物理体
  G4Box* scint_box = new G4Box("Scintillator", 50*mm, 50*mm, 5*mm);
  G4LogicalVolume* scint_log = new G4LogicalVolume(scint_box, scintillator, "Scintillator");
  G4VPhysicalVolume* scint_phys = new G4PVPlacement(0, G4ThreeVector(), scint_log, "Scintillator", world_log, false, 0);

  // 注册闪烁体敏感探测器
  G4SDManager* SDman = G4SDManager::GetSDMpointer();
  MySD* scint_SD = new MySD("Scintillator");
  SDman->AddNewDetector(scint_SD);
  scint_log->SetSensitiveDetector(scint_SD);
}

void MyRunAction::BeginOfRunAction(const G4Run* aRun) {
  // 获取闪烁体敏感探测器的 ID
  G4SDManager* SDman = G4SDManager::GetSDMpointer();
  scint_SD_ID = SDman->GetCollectionID("Scintillator/HitCollection");
}

void MyEventAction::EndOfEventAction(const G4Event* aEvent) {
  // 获取闪烁体的击中命中
  G4HCofThisEvent* HCE = aEvent->GetHCofThisEvent();
  MyHitsCollection* scint_hits = nullptr;
  if (HCE) {
    scint_hits = static_cast<MyHitsCollection*>(HCE->GetHC(scint_SD_ID));
  }

  // 处理击中命中的电荷脉冲和光子脉冲
  if (scint_hits) {
    for (int i = 0; i < scint_hits->entries(); ++i) {
      MyHit* hit = (*scint_hits)[i];
      G4double time = hit->GetTime();
      G4double charge = hit->GetCharge();
      G4int nphotons = hit->GetNPhotons();
      // 处理电荷脉冲和光子脉冲
      // ...
    }
  }
}

void MyPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent) {
  // 创建一个光子源
  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4ParticleDefinition* particle = particleTable->FindParticle("gamma");
  G4PrimaryParticle* gamma = new G4PrimaryParticle(particle);
  gamma->SetMomentumDirection(G4ThreeVector(0, 0, 1));
  gamma->SetKineticEnergy(1*MeV);

  // 在闪烁体中发射光子
  G4Scintillation scint;
  G4Step step;
  G4Track track(gamma, 0, G4ThreeVector());
  scint.DoIt(track, step);
  G4double time = step.GetPostStepPoint()->GetGlobalTime();
  G4double energy = step.GetPostStepPoint()->GetKineticEnergy();
  G4int nphotons = scint.GetNumPhotons();
  // 注册光子击中命中
  MyHit* hit = new MyHit();
  hit->SetCharge(0);
  hit->SetNPhotons(nphotons);
  hit->SetTime(time);
  G4HCofThisEvent* HCE = anEvent->GetHCofThisEvent();
  MyHitsCollection* scint_hits = nullptr;
  if (!HCE) {
    HCE = new G4HCofThisEvent();
    anEvent->SetHCofThisEvent(HCE);
  }
  scint_hits = static_cast<MyHitsCollection*>(HCE->GetHC(scint_SD_ID));
  if (!scint_hits) {
    scint_hits = new MyHitsCollection("Scintillator/HitCollection");
    HCE->AddHitsCollection(scint_SD_ID, scint_hits);
  }
  scint_hits->insert(hit);
}

这段代码展示了如何在 Geant4 中创建一个闪烁体，使用 G4Scintillation 和 G4SensitiveDetector 获取击中命中的电荷脉冲和光子脉冲，以及如何在 MyPrimaryGeneratorAction::GeneratePrimaries() 中发射光子和注册光子击中命中。请注意，此代码仅用于演示目的，实际应用中需要根据具体要求进行修改。