Hello,experts!
Recently I came across some code that made me confused, especially regarding DriftLineRKF(), AvalancheMicroscopic(), and AvalancheMC(). Here are the code and my questions.
void HeedModel::SetTracking(){
if(driftRKF){
fDriftRKF = new Garfield::DriftLineRKF();
fDriftRKF->SetSensor(fSensor);
fDriftRKF->EnableDebugging();
}
else if(trackMicro){
fAvalanche = new Garfield::AvalancheMicroscopic();
fAvalanche->SetSensor(fSensor);
fAvalanche->EnableSignalCalculation();
}
else{
fDrift = new Garfield::AvalancheMC();
fDrift->SetSensor(fSensor);
fDrift->EnableSignalCalculation();
fDrift->SetDistanceSteps(2.e-3);
if(createAval) fDrift->EnableAttachment();
else fDrift->DisableAttachment();
}
fTrackHeed = new Garfield::TrackHeed();
fTrackHeed->SetSensor(fSensor);
fTrackHeed->SetParticle(“e-”);
fTrackHeed->EnableDeltaElectronTransport();
}
I’m wondering what are the differences between AvalancheMicroscopic() and AvalancheMC().
In what situations should each of these three methods be used?
3.AvalancheMC() consider EnableAttachment() or DisableAttachment()? When should i consider the attachment，Why the other two methods don 't need to consider attachment?
DriftLineRKF calculates the path of an electron or ion by numerical integration of the drift velocity vector. In the absence of a magnetic field, the drift lines will follow the electric field lines. The method is well adapted to fields that are smooth, such as analytic potentials. The avalanche growth along a drift line is calculated by integrating the effective Townsend coefficient α - η; or the average gain and shape of the gain distribution can be set explicitly by the user.
AvalancheMicroscopic simulates electron trajectories using a “microscopic” Monte Carlo simulation based on the electron-atom/molecule scattering cross-sections. You would use it if you need an accurate simulation of event-by-event fluctuations of the electron signal.
AvalancheMC, similarly as DriftLineRKF, uses the macroscopic drift velocity as function of the electric field for calculating electron or ion drift lines but adds a random diffusion component to each drift line step. It simulates all electrons in an avalanche individually.
By default, attachment is switched on (enabled) in AvalancheMC. You would normally only switch it off for testing purposes. AvalancheMicroscopic does consider attachment (you cannot switch it off). DriftLineRKF also uses the attachment coefficient for calculating the induced signal and the average effective gain along a drift line.