# How to simulate a beam of particles?

Hi,

As the title suggests, I’m looking for a way to simulate a beam going through a proportional counter. Based on what I know about Garfield so far, it seems like the only way to do this is by calling NewTrack() as many times as you need. Is there a more efficient way to do this?

Hi,
calling `NewTrack` multiple times is indeed the way to go.

Hi @hschindl ,

I have a follow-up question. At the moment, this is how I am simulating a track from the incident beam:

``````  TrackHeed track;
track.SetSensor(&sensor);
track.SetParticle("proton");
track.SetKineticEnergy(20.e6);

double xc = 0., yc = 0., zc = 0., tc = 0., ec = 0., extra = 0.;
int nc = 0;
std::vector<double> electrons;
double xe = 0., ye = 0., ze = 0., te = 0., ee = 0.;
double dx = 0., dy = 0., dz = 0.;
int left=0, right = 0;
int NofProton = 100;
for (int i = 0; i < NofProton; i++) {
// Simulate a track
track.NewTrack(-x, 1.0, -x, 100., 1., 0., 1.); //45 degrees
while (track.GetCluster(xc, yc, zc, tc, nc, ec, extra)) {
for (int k = 0; k < nc; ++k) {
track.GetElectron(k, xe, ye, ze, te, ee, dx, dy, dz);
electrons.push_back(xe);
electrons.push_back(ye);
electrons.push_back(ze);
electrons.push_back(te);
}
}
}
``````

When NofProton = 1, I get a rather straight track, like below:

However, when NofProton = 100, the track becomes this

Can you please explain to me why this is happening?

Note: each tick mark corresponds to 1 cm.

Hi,
nice plot! I think it’s just statistical fluctuations and the little sprigs you see on the plot are the secondaries created by delta electrons.

Hi,

That makes sense! Thanks.

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