G4InuclParamAngDst.cc

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// $Id$
// Author:  Michael Kelsey (SLAC)
// Date:    22 April 2013
//
// Description: intermediate base class for INUCL parametrizations of
//              three-body angular distributions in Bertini-style cascade
//
// 20130308  M. Kelsey -- Move PQ,PR calculation to G4InuclSpecialFunctions.

#include "G4InuclParamAngDst.hh"
#include "G4InuclSpecialFunctions.hh"
#include "G4InuclParticleNames.hh"
using namespace G4InuclSpecialFunctions;
using namespace G4InuclParticleNames;


// Use coefficients in power expansion of random fraction

G4double G4InuclParamAngDst::GetCosTheta(G4int ptype, G4double ekin) const {
  if (verboseLevel>3) {
    G4cout << theName << "::GetCosTheta: ptype " << ptype << " ekin " << ekin
           << G4endl;
  }

  G4int J = (ptype==pro || ptype==neu) ? 0 : 1;         // nucleon vs. other
  if (verboseLevel > 3) G4cout << " J " << J << G4endl;

  const G4int itry_max = 100;   // Parametrizations aren't properly bounded

  G4double Spow = -999.;
  G4int itry = 0;
  while ((Spow < 0. || Spow > 1.) && itry < itry_max) {
    itry++;
    Spow = randomInuclPowers(ekin, coeffAB[J]);
  }

  if (itry == itry_max) {       // No success, just throw flat distribution
    if (verboseLevel > 2) {
      G4cout << theName << "::GetCosTheta -> itry = itry_max " << itry
             << G4endl;
    }

    Spow = inuclRndm();
  }

  return 2.0*Spow - 1.0;        // Convert generated [0..1] to [-1..1]
}