G4KalbachCrossSection Class Reference

#include <G4KalbachCrossSection.hh>

Static Public Member Functions
static G4double	ComputePowerParameter (G4int resA, G4int idx)
static G4double	ComputeCrossSection (G4double K, G4double cb, G4double resA13, G4double amu1, G4int idx, G4int Z, G4int A, G4int resA)

Detailed Description

Definition at line 40 of file G4KalbachCrossSection.hh.

Member Function Documentation

ComputeCrossSection()

G4double G4KalbachCrossSection::ComputeCrossSection ( G4double K, G4double cb, G4double resA13, G4double amu1, G4int idx, G4int Z, G4int A, G4int resA )

static

Definition at line 75 of file G4KalbachCrossSection.cc.

{
  G4double sig = 0.0;
  G4double signor = 1.0; 
  G4double lambda, mu, nu;
  G4double ec = std::min(4.0, 100./(G4double)resA);  // in MeV
  if(0 < Z) { ec = cb; }
 
  G4double ecsq = ec*ec;
  G4double elab = K * (A + resA) / G4double(resA);    
    
  if(idx == 0) { // parameterization for neutron
 
    if(resA < 40)       { signor =0.7 + resA*0.0075; }
    else if(resA > 210) { signor = 1. + (resA-210)*0.004; }
    lambda = paramK[idx][3]/resA13 + paramK[idx][4];
    mu = (paramK[idx][5] + paramK[idx][6]*resA13)*resA13;
    // JMQ 20.11.2008 very low energy behaviour corrected 
    //                (problem for A (apprx.)>60) fix for avoiding  
    //                neutron xs going to zero at very low energies
    nu = std::abs((paramK[idx][7]*resA + paramK[idx][8]*resA13)*resA13 
          + paramK[idx][9]);
 
  } else { // parameterization for charged 
    // proton correction
    if(idx == 1) {
      if (resA <= 60)      { signor = 0.92; }
      else if (resA < 100) { signor = 0.8 + resA*0.002; }
    }
    lambda = paramK[idx][3]*resA + paramK[idx][4];
    mu = paramK[idx][5]*amu1;
    nu = amu1* (paramK[idx][7] + paramK[idx][8]*ec + paramK[idx][9]*ecsq);
  }
  /*
    G4cout << "## idx=" << idx << " K=" << K << " elab=" << elab 
           << " ec=" << ec << " lambda=" << lambda << " mu=" << mu 
           << "  nu=" << nu << G4endl; 
  */
  // threashold cross section
  if(elab < ec) {
    G4double p = paramK[idx][0];
    if(0 < Z) { p += paramK[idx][1]/ec + paramK[idx][2]/ecsq; }
    G4double a = -2*p*ec + lambda - nu/ecsq;
    G4double b = p*ecsq + mu + 2*nu/ec;
    G4double det = a*a - 4*p*b;
    G4double ecut = (det > 0.0) ? (std::sqrt(det) - a)/(2*p) : -a/(2*p);
 
    //G4cout << "  elab= " << elab << " ecut= " << ecut << " sig= " << sig
    //       << "  sig1= " << (p*elab*elab + a*elab + b)*signor << G4endl;
    // If ecut>0, sig=0 at elab=ecut
    if(0 == idx) {
      sig = (lambda*ec + mu + nu/ec)*signor*std::sqrt(elab/ec);
    } else if(elab >= ecut) { 
      sig = (p*elab*elab + a*elab + b)*signor; 
 
      // extra proton correction
      if(1 == idx) {
    // c and w are for global correction factor for 
    // they are scaled down for light targets where ec is low.
    G4double cc = std::min(3.15, ec*0.5);
    G4double signor2 = (ec - elab - cc) *3.15/ (0.7*cc);
    sig /= (1. + G4Exp(signor2));
      }
    }
    //G4cout << "       ecut= " << ecut << " a= " << a << "  b= " << b 
    //     <<  " signor= " << signor << " sig= " << sig << G4endl;  
 
    // high energy cross section
  } else {
    // etest is the energy above which the rxn cross section is
    // compared with the geometrical limit and the max taken.
 
    // neutron parameters
    G4double etest  = 32.;
    G4double xnulam = 1.0;
 
    // parameters for charged
    static const G4double flow = 1.e-18;
    static const G4double spill= 1.e+18;
    if(0 < Z) {
      etest = 0.0;
      xnulam = nu / lambda;
      xnulam = std::min(xnulam, spill); 
      if (xnulam >= flow) { 
    if(1 == idx) { etest = std::sqrt(xnulam) + 7.; }
    else         { etest = 1.2 *std::sqrt(xnulam); }
      }
    }
    // ** For xnulam.gt.0, sig reaches a maximum at sqrt(xnulam).
    sig = (lambda*elab + mu + nu/elab)*signor;
    if (xnulam >= flow && elab >= etest) {
      G4double geom = std::sqrt(A*K);
      geom = 1.23*resA13 + paramK[idx][10] + 4.573/geom;
      geom = 31.416 * geom * geom;
      sig = std::max(sig, geom);
    }
  }
  sig = std::max(sig, 0.0);
  //G4cout << "  ---- sig= " << sig << G4endl;
  return sig;
}

Referenced by G4EvaporationProbability::CrossSection(), and G4PreCompoundFragment::CrossSection().

ComputePowerParameter()

G4double G4KalbachCrossSection::ComputePowerParameter ( G4int resA, G4int idx )

static

Definition at line 69 of file G4KalbachCrossSection.cc.

{
  return G4Pow::GetInstance()->powZ(resA, paramK[idx][6]);
}

Referenced by G4PreCompoundFragment::CalcEmissionProbability(), and G4EvaporationProbability::CrossSection().

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The documentation for this class was generated from the following files:

• G4KalbachCrossSection.hh
• G4KalbachCrossSection.cc