Hello, I am a beginner of Garfield++ and want to get information about avalanche electrons in a parallel plate chamber with a space charge effect.
I’m trying to use the AvalancheMicroscopic class to obtain the avalanche electrons’ information and the AvalancheGridSpaceCharge class to perform the gas avalanche process, but I don’t know how to make it work.
Is it possible to process the above?
I attached my source code.
This program was written with reference to Example/Gem/gem.C and Example/RPCSpaceCharge/rpc_space_charge.cc, which attempts to get energy of avalanche electrons and fill it in a histogram.
Thanks for your question. It is not entirely clear to me what you want to achieve. However, if you would like to know how the electron density evolves with time, you can export the grids, which hold information about the electrons, ions and field-strengths. To achieve this you can, following your code, evolve the electron using the AvalancheMicroscopic class for a few nanoseconds, import the electrons onto the grid and evolve it in time-steps with the AvalancheGridSpaceCharge while exporting the grids at each time-step.
// Avalanche electron
aval.SetTimeWindow(0., 0.5.); // set the time window integration (in ns) for AvalancheMicroscopic
aval.AvalancheElectron(xi, yi, zi, ti, ei, 0., 0., 0.);
avalsc.ImportElectronsFromAvalancheMicroscopic(&aval); // import the electrons
double dt = 0.5; // time step in ns
for (int k = 0; k < 20.; k++) {
avalsc.StartGridAvalanche(dt); // evolve the electrons on the grid with time step dt
avalsc.ExportGrid("my_grid_at_time_" + std::to_string((k + 1) * dt)); // export the grids
}
Unfortunately, in the grid-based approaches you cannot extract the energy of the electrons.
If you have further question feel free to reach out again.
Specifically, what I wanted to do was get the energy of each electron at its endpoint after the avalanche process.
I was not trying to get information in time-steps.
For example, in the framework of the AvalancheMicroscopic class, the following code should do it.
AvalancheMicroscopic aval;
aval.AvalancheElectron(xi, yi, zi, ti, ei, 0., 0., 0.);
for(const auto &electron : aval.GetElectron()) {
const auto &p = electron.path[1];
hist->Fill(p.energy);
}
or
for(unsigned int i = 0; i < aval.GetElectrons().size(); i++) {
aval.GetElectronEndpoint(i, x0, y0, z0, t0, e0, x1, y1, z1, t1, e1 status);
hist->Fill(e1);
}
I wanted to ask if there is a way to access each avalanche electron’s information in the AvalancheGridSpaceCharge framework, like aval.GetElectron() and aval.GetElectronEndpoint() in the example code above.
Within the grid-based approaches (AvalancheGrid and AvalancheGridSpaceCharge) the algorithms do not track individual electrons but evolves them in bundles (sometimes called “Superparticles”). Therefore and unfortunately, it is not possible to retrieve information about the individual electrons.