来不及解释了，“几何边界的信息抽取”加班加点写给大家。
目 录
1.事件示范step信息
2.几何边界的判断
a) 抽取track的nextvolume
b) 抽取PostStepPoint的所属volume
c) 抽取Pre/PostStepPoint的status
1. 事件示范step信息
图1. 1MeV gamma入射到1cm3 BGO闪烁体的step信息
图2. 1 MeV gamma入射事件的几何记录信息
2. 几何边界的判断
以伽玛在Boundary2处做讲解分析。首先判断PreStepPoint所在的physicalvolume是否为”phybgo”，然后通过以下三种方式给出Boundary2的定义：
a) 抽取当前step所属track的nextvolume
代码语言：javascript复制void B1SteppingAction::UserSteppingAction(const G4Step* step)
{ /* const*/ G4StepPoint* prePoint = step->GetPreStepPoint();
/* const*/ G4StepPoint* endPoint = step->GetPostStepPoint();
G4String nowvolumename= prePoint->GetTouchableHandle()->GetVolume()->GetName();
G4Track *aTrack = step->GetTrack();
G4VPhysicalVolume* nextpv=aTrack->GetNextVolume();
if (nextpv!=NULL)
{
G4String nextvolumename = nextpv->GetName();
if(nowvolumename=="phybgo"&&nextvolumename=="World")
{G4double E=aTrack->GetKineticEnergy();
G4cout<<"boundaryenergy is "<< E<<G4endl;
}
}
}b) 抽取当前step的PostStepPoint的所属volume
代码语言：javascript复制void B1SteppingAction::UserSteppingAction(const G4Step* step)
{ /* const*/ G4StepPoint* prePoint = step->GetPreStepPoint();
/* const*/ G4StepPoint* endPoint = step->GetPostStepPoint();
G4Track *aTrack = step->GetTrack();
G4String nowvolumename= prePoint->GetTouchableHandle()->GetVolume()->GetName();
G4VPhysicalVolume* nextpv= endPoint ->GetTouchableHandle()->GetVolume();
if (nextpv!=NULL)
{
G4String nextvolumename = nextpv->GetName();
if(nowvolumename=="phybgo"&&nextvolumename=="World")
{G4double E=aTrack->GetKineticEnergy();
G4cout<<"boundaryenergy is "<< E<<G4endl;
}
}
}c) 抽取当前step的PreStepPoint或PostStepPoint的status
代码语言：javascript复制void B1SteppingAction::UserSteppingAction(const G4Step* step)
{ /* const*/ G4StepPoint* prePoint = step->GetPreStepPoint();
/* const*/ G4StepPoint* endPoint = step->GetPostStepPoint();
G4Track *aTrack = step->GetTrack();
G4String nowvolumename= prePoint->GetTouchableHandle()->GetVolume()->GetName();
if ( nowvolumename=="phybgo"&&endPoint->GetStepStatus() == fGeomBoundary)
{G4double E=aTrack->GetKineticEnergy();
G4cout<<"boundary energy is "<<E<<G4endl;
}
}
图3. 三种方法均能给出gamma逃出BGO时的判断
下一篇将给出step的信息抽取代码示范，特别给出Segmentationfault (core dumped)段错误的常见情况分析。
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