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Question Problem in pion absorption cross section in Bertini cascade model 

Forum: Hadronic Processes
Date: 16 Oct, 2008
From: Katsuki Hiraide <Katsuki Hiraide>

Hi,

I am using Bertini cascade model to simulate interaction of positive pions (~150 MeV kinetic energy) on carbon. I realize that the simulated pion absorption cross section is only 20-30% of experimental data (for example, Ashery et al., Phys. Rev. C23, 2173 (1981)).

In a function where it calculates absorption cross section in the Bertini cascade model which is implemented in Geant4, there is an overall normalization factor (corr_fac) which is set to 0.2 now (see below).

I am not sure what the factor (0.2) means, but if I change the factor to 1, the simulation reproduces experimental data very well at least for carbon. So, I am wondering if this factor should be 1, instead of 0.2.

Could someone check this? Any help/insight would be greatly appreciated.

Thanks,

Katsuki

-----------------------------------------------------------------------------

/geant4.9.1/source/processes/hadronic/models/cascade/cascade/src/G4CascadSpecialFunctions.cc

G4double G4CascadSpecialFunctions::absorptionCrosSection(G4double e,
                                                         G4int type) {
  ...

  const G4double corr_fac = 0.2;

  if (e < 0.3) {
    csec = 0.1106/std::sqrt(e)-0.8+0.08/((e-0.123)*(e-0.123)+0.0056);
  } else if (e < 1.0) {
    csec = 3.6735*(1.0-e)*(1.0-e);
  };
  if (csec < 0.0) csec = 0.0;

  ...

  return corr_fac * csec;
}

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1 None: Re: Problem in pion absorption cross section in Bertini cascade model   (Dennis H. Wright - 17 Oct, 2008)
(_ None: Re: Problem in pion absorption cross section in Bertini cascade model   (Katsuki Hiraide - 17 Oct, 2008)
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