FastY90 positron spectrum issue about gate HOT 6 CLOSED

I suspect the problem is in the analysis. How are you extracting the energy spectra? Are you using an actor that filters on primary particles generated? That you have an identical number of entries in both spectra is suspicious. At the very least, there should be far fewer positrons (~32 per million decays) than brem photons (~6 % of the number of decays).

from gate.

I'm using the code you provided in plot.C:

...
// open the output file 
TFile* f2 =new TFile (" fastY90Pos.root"); 
// and print the content
f2->ls();

// retrieve the energy spectrum histogram 
TH1F * h2 = (TH1F*)f2->Get("energySpectrum");
h2->SetLineColor(kRed);
// set title and the axis legend
h2->SetTitle("fastY90 positron kinetic energy");
h2->GetXaxis()->SetTitle("Energy (MeV)");
h2->GetYaxis()->SetTitle("Counts");
h2->GetXaxis()->SetRangeUser(0. ,1);

// statistic type ( (1) write mean value, number of entries and RMS)
h2->SetStats(1);

// draw histogram using point (P) associated with error bar (E) or HIST for histogramm
c1->cd(2);
h2->Draw("HIST");
...

and the output was generated with the unmodified output.mac:

...
/gate/actor/addActor EnergySpectrumActor pos_actor
/gate/actor/pos_actor/attachTo MainBox
/gate/actor/pos_actor/addFilter    particleFilter
/gate/actor/pos_actor/particleFilter/addParticle  e+
/gate/actor/pos_actor/save output/fastY90Pos.root
/gate/actor/pos_actor/energySpectrum/setEmin 0 eV
/gate/actor/pos_actor/energySpectrum/setEmax 1 MeV
/gate/actor/pos_actor/energySpectrum/setNumberOfBins 100

I agree with your point on the suspicious numbers of particles being exactly the same. Even inspecting the fastY90Pos.root file directly yields the duplicate data:

from gate.

I really don't understand. I created the example plot using the code that's in the example directory, and rereading, everything appears to be in order.

One thing I do notice is that the total number of entries in your output (6504827) is exactly equal to the sum of the brem and positron entries (6501704 and 3123 respectively) that I got when I created the example. It seems like the particle filter of the actor is doing nothing and both of your outputs contain both the gammas and the positrons. The number of positrons is small, so the peak isn't visible in the plot.

from gate.

Hello,
any progress on that issue ? Should we still consider it as open ?

from gate.

I tried to reproduce this behavior on multiple machines with the same configuration (Ubuntu 16.04 LTS, Geant4.10.02.p02, Root 5.34.36) and I could not get the plots provided, i.e. the correct positron kinetic energy. Maybe someone else can try and confirm this issue?

from gate.

I re-evaluated this issue with Gate 8.0, Geant4 10.3.1 and root 6.10/00 and I cannot reproduce it any more.
With the versions mentioned it works as intended. I consider this issue closed.

from gate.