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Question Re: Problems with Radioactive Decay: no decay lines 

Forum: Hadronic Processes
Re: Question Problems with Radioactive Decay: no decay lines (Kseniia Rezynkina)
Re: None Re: Problems with Radioactive Decay: no decay lines (michel maire)
Date: 16 Jun, 2014
From: Kseniia Rezynkina <Kseniia Rezynkina>

Thanks for you response. In fact, that's not exactly what I meant.

I'm trying to simulate the decay of an isomer in 210Ra to radon (not the full chain) and get the response of the detectors to the particles from the decay.

I coded in the simplified version of the detector (only the silicon double-sided strip detector for the moment) and a gun that generates my decaying nuclei in the volume of the detector. 
I have tested my code with a simpler gun (shooting the alpha-particles of a given energy of 7016. keV) 
   G4int nofParticles = 1;
    fParticleGun  = new G4ParticleGun(nofParticles);

    // Define particle properties
    G4String particleName = "alpha";
    G4ThreeVector position(0, 0, -5.*um);
    G4ThreeVector momentum(0, 0, 0.*keV);

    // Default particle kinematics
    G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
    G4ParticleDefinition* particle
    = particleTable->FindParticle(particleName);
    fParticleGun->SetParticleDefinition(particle);
    fParticleGun->SetParticleMomentum(momentum);
    fParticleGun->SetParticlePosition(position);

   //randomized position
    G4double x= 0.*cm, d_x= 20.*cm;
    G4double y= 0.*cm, d_y= 20.*cm;
    x += d_x*(G4UniformRand()-0.5)*2;
    y += d_y*(G4UniformRand()-0.5)*2;
    G4ThreeVector position(x, y, -2.*um);           //implantation depth
    fParticleGun->SetParticlePosition(position);

    // randomized direction
    G4double dtheta = 360.*deg;
    G4double dphi = 360*deg;
    G4double theta = G4UniformRand()*dtheta;
    G4double phi = G4UniformRand()*dphi;
    fParticleGun->SetParticleMomentumDirection(G4ThreeVector(sin(theta)*sin(phi),
                                                             sin(theta)*cos(phi),
                                                             cos(theta)));
    fParticleGun->SetParticleEnergy(7016.*keV);
    fParticleGun->GeneratePrimaryVertex(event);

The response of my "detector" is exactly what I expect it to be - a 7016 line and some not-full-energy-deposing particles:
 http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/06/16/08.03-28433-4-06-16_at_5.03.14_PM.png

But with the Radioactive decay gun (defined as in my first post) I do not get any full-energy alpha peak:

http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/06/05/02.02-8651--06-05_at_11.00.10_AM.png

For sure, this has to be wrong, so I guess that I'm not implementing either the gun, or something else related to the radioactive decay correctly.

Could you please help me out with this one?

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1 None: Re: Problems with Radioactive Decay: no decay lines   (michel maire - 17 Jun, 2014)
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