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Forum: Hadronic Processes
Re: Question Simulation of an AmBe-neutron source (Martin Kirchner)
Re: None Re: Simulation of an AmBe-neutron source (Artem Zontikov)
Date: 23 May, 2016
From: Martin Kirchner <Martin Kirchner>

Thank you very much for your response!

ad 1.: I found that AmO2 is in use with Be, but no further information on the chemical compostion. Do you (or someone else?) know chemical compostion of an AmBe n-source?

ad 2.: Is there another library I could use, or a way to include the cross section for this process?

ad 3.: Indeed, I found it interessting, but not yet satisfying. I added the suggested fixes as well as the following lines to the physics list to use G4ParticleHPInelastic model for the alphas:

void Cresst::PhysicsList::ConstructProcess() {
  .
  .
  .
  G4ProcessManager* pManagerA = G4Alpha::Alpha()->GetProcessManager();
  // Elastic
  G4HadronElasticProcess* pElastProc = new G4HadronElasticProcess();
  G4ParticleHPElastic* pElastModel = new G4ParticleHPElastic();
  pElastProc->RegisterMe(pElastModel);
  pManagerA->AddDiscreteProcess(pElastProc);
  // Inelastic
  G4AlphaInelasticProcess* inelProcess = new G4AlphaInelasticProcess();
  G4ParticleHPInelastic* thepIneModel = new G4ParticleHPInelastic(G4Alpha::Alpha());
  G4ParticleHPInelasticData* thepIneData = new G4ParticleHPInelasticData(G4Alpha::Alpha());
  thepIneData->SetMinKinEnergy(0.0);
  thepIneData->SetMaxKinEnergy(20.*MeV);
  inelProcess->RegisterMe(thepIneModel);
  inelProcess->AddDataSet(thepIneData);
  pManagerA->AddDiscreteProcess(inelProcess);
}

Which occasionally (~once per 250k runs) gives the following error while running :

.
.
2016-05-20 08:03:43> G4IonTable::GetIon() : illegal atomic number/mass Z =0  A = 1  E = 0
[2016-05-20 08:03:43> G4IonTable::GetIon() : illegal atomic number/mass Z =0  A = 1  E = 0
[2016-05-20 08:03:43>
-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : Warning
      issued by : G4ParticleHPEnAngCorrelation::Sample
Too many trials were done. Exiting current loop by force. You may have Probably, the result violating (baryon number) conservation law will be obtained.
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

This happens with and without Watt's Fix, and also when removing all other registered models for Alpha particles. Any idea how to fix this new problem?

I did run the sim (24Mio runs) with this problem to see if the spectrum improves, but didn't find this to be the case (attached).

Best regards, Martin

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      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2016/05/23/08.21-85979-est_run0520_outofcube.jpg

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1 None: Re: Simulation of an AmBe-neutron source   (Artem Zontikov - 25 May, 2016)
(_ None: Re: Simulation of an AmBe-neutron source   (Martin Kirchner - 14 Jun, 2016)
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