Energy Spectrum

Particles, Track, Event, Run and Biasing
1

Hi everyone,
I would like to know if I can download the energy spectrum of a particular particle inside a code in G4 and how I can do this. Can I also put together , in the same run , the spectra of more particles ? And is there an example doing this ?
Thank you in advance.

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2

I am interesting . I also donā€™t know how to extract energy spectrum

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3

Youā€™ll need to modify steppingaction.cc. Basically what I did in the TestEM7 example was, when crossing a boundary, I record the energy, position and momenta for each particle and write it in a CSV file. This resultant csv I run through a matlab script which analyses the spectra. Gimme a shout if youā€™d like me to send you the modified file.
image

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4

Hi, may I ask you how do you implement the condition at the boundary? With getstepstatus() I still get all the particles and not only the ones crossing the boundary.
Thank you so much.

5

//My modification. Spits out the energy of the particle as it enters the absorber.

G4StepPoint* prePoint = step->GetPreStepPoint();

G4StepPoint* postPoint = step->GetPostStepPoint();

G4VPhysicalVolume* prePhysVol = prePoint->GetPhysicalVolume();

G4VPhysicalVolume* postPhysVol = postPoint->GetPhysicalVolume();

if (prePhysVol != postPhysVol)

{

G4double KE = track->GetKineticEnergy();

//G4ThreeVector Position = track->GetPosition();    

//G4ThreeVector Momentum = track->GetMomentum();

if (KE > 1.0)

{

  G4String postPhysVolName = postPhysVol->GetName();

  if (postPhysVolName == "Absorber")

  {

    if (writefile)

    {

      G4ThreeVector Position = track->GetPosition();    

      G4ThreeVector Momentum = track->GetMomentum();

      // Not a mistype. Beam is rotated in the macro file and enters on the x axis so x = z and vice versa. 

      writefile << Position.z() << "," << Momentum.z() << "," << Position.y() << "," << Momentum.y() << "," << Position.x() << "," << Momentum.x() << "," << KE << G4endl;

    }

  }

}

}

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6

Thank you , but Iā€™d like to know if I can download an energy spectrum of a particle on Geant4 and use it for primary generator . I also would like to know if I can use more tha one particle in a single run . Thank you so much

7

I have done this but the code isnā€™t too flash Iā€™m afraid. Again it takes modification of the code. That code would read a csv file generated in my above reply and inject that beam at the position at which the csv file recorded the beam.

By one particle I assume you mean one species of particle? If this is the case I have only done it for protons.

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8

Ok thank you so much , sorry, for ā€˜ā€™ more particlesā€™ā€™ I meaned more than one specie , protons with neutrons or others . But Thank you

9

Off-hand, I think you might be able to.

In my code posted above you have ā€œG4ThreeVector Position = track->GetPosition();ā€. From track you might be able to determine the particle species. See if thereā€™s a member function that allows you to do this. If there is you can either a) add an additional column in the csv file and sort it out later or b) write several files. One for each species.

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10

track->GetParticleDefinition() gets you the const G4ParticleDefinition* pointer.
From G4PD, you can either use GetParticleName() and store a string into your N-tuple, or you can use GetPDGEncoding() to get the numeric code for the particle.

Please look at $G4INCUDE/G4Track.hh to see all of the information you can retrieve for the track, and $G4INCLUDE/G4ParticleDefinition.hh for all the particle type information thatā€™s available.

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11

Thank you, so this is for having the same script for differents species, but I wanted in a one script more species together . thank you

12

Thank you , Iā€™ll try this suggestion.