G4PreCompoundProton.cc

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// $Id$
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4PreCompoundProton
//
// Author:         V.Lara
//
// Modified:  
// 21.08.2008 J. M. Quesada added external choice of inverse cross section option
// 21.08.2008 J. M. Quesada added external choice for superimposed Coulomb 
//                          barrier (if useSICB=true) 
// 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
//                         use int Z and A and cleanup
//

#include "G4PreCompoundProton.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Proton.hh"

G4PreCompoundProton::G4PreCompoundProton()
  : G4PreCompoundNucleon(G4Proton::Proton(), &theProtonCoulombBarrier)
{
  ResidualA = GetRestA();
  ResidualZ = GetRestZ(); 
  theA = GetA();
  theZ = GetZ();
  ResidualAthrd = ResidualA13();
  FragmentAthrd = ResidualAthrd;
  FragmentA = theA + ResidualA;
}

G4PreCompoundProton::~G4PreCompoundProton()
{}

G4double G4PreCompoundProton::GetRj(G4int nParticles, G4int nCharged)
{
  G4double rj = 0.0;
  if(nParticles > 0) { 
    rj = static_cast<G4double>(nCharged)/static_cast<G4double>(nParticles);
  }
  return rj;
}

//J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections 
//OPT=0 Dostrovski's parameterization
//OPT=1 Chatterjee's paramaterization 
//OPT=2,4 Wellisch's parametarization
//OPT=3 Kalbach's parameterization 
// 
G4double G4PreCompoundProton::CrossSection(G4double K)
{
  ResidualA = GetRestA();
  ResidualZ = GetRestZ(); 
  theA = GetA();
  theZ = GetZ();
  ResidualAthrd = ResidualA13();
  FragmentA = theA + ResidualA;
  FragmentAthrd = g4pow->Z13(FragmentA);

  if (OPTxs==0) { return GetOpt0(K); }
  else if( OPTxs==1) { return GetOpt1(K); }
  else if( OPTxs==2|| OPTxs==4) { return GetOpt2(K); }
  else if (OPTxs==3)  { return GetOpt3(K); }
  else{
    std::ostringstream errOs;
    errOs << "BAD PROTON CROSS SECTION OPTION !!"  <<G4endl;
    throw G4HadronicException(__FILE__, __LINE__, errOs.str());
    return 0.;
  }
}

G4double G4PreCompoundProton::GetAlpha()
{
  G4int aZ = ResidualZ;
  G4double C = 0.0;
  if (aZ >= 70) 
    {
      C = 0.10;
    } 
  else 
    {
      C = ((((0.15417e-06*aZ) - 0.29875e-04)*aZ + 0.21071e-02)*aZ - 0.66612e-01)*aZ + 0.98375;
    }
  return 1.0 + C;
}

G4double G4PreCompoundProton::GetBeta() 
{
  return -GetCoulombBarrier();
}
  
//********************* OPT=1 : Chatterjee's cross section *********************
//(fitting to cross section from Bechetti & Greenles OM potential)

G4double G4PreCompoundProton::GetOpt1(G4double K)
{
  G4double Kc=K; 

  // JMQ  xsec is set constat above limit of validity
  if (K > 50*MeV) { Kc = 50*MeV; }

  G4double landa, landa0, landa1, mu, mm0, mu1,nu, nu0, nu1, nu2,xs;
  G4double p, p0, p1, p2,Ec,delta,q,r,ji;
  
  p0 = 15.72;
  p1 = 9.65;
  p2 = -449.0;
  landa0 = 0.00437;
  landa1 = -16.58;
  mm0 = 244.7;
  mu1 = 0.503;
  nu0 = 273.1;
  nu1 = -182.4;
  nu2 = -1.872;  
  delta=0.;  

  Ec = 1.44*theZ*ResidualZ/(1.5*ResidualAthrd+delta);
  p = p0 + p1/Ec + p2/(Ec*Ec);
  landa = landa0*ResidualA + landa1;

  G4double resmu1 = g4pow->powZ(ResidualA,mu1); 
  mu = mm0*resmu1;
  nu = resmu1*(nu0 + nu1*Ec + nu2*(Ec*Ec));
  q = landa - nu/(Ec*Ec) - 2*p*Ec;
  r = mu + 2*nu/Ec + p*(Ec*Ec);

  ji=std::max(Kc,Ec);
  if(Kc < Ec) { xs = p*Kc*Kc + q*Kc + r;}
  else {xs = p*(Kc - ji)*(Kc - ji) + landa*Kc + mu + nu*(2 - Kc/ji)/ji ;}
  if (xs <0.0) {xs=0.0;}

  return xs; 
}

//************* OPT=2 : Welisch's proton reaction cross section ***************

G4double G4PreCompoundProton::GetOpt2(G4double K)
{

  G4double eekin,ekin,ff1,ff2,ff3,r0,fac,fac1,fac2,b0,xine_th(0);
 
  // This is redundant when the Coulomb  barrier is overimposed to all 
  // cross sections 
  // It should be kept when Coulomb barrier only imposed at OPTxs=2

  if(!useSICB && K<=theCoulombBarrier) { return 0.0; }

  eekin=K;
  G4int rnneu=ResidualA-ResidualZ;
  ekin=eekin/1000;
  r0=1.36*1.e-15;
  fac=pi*r0*r0;
  b0=2.247-0.915*(1.-1./ResidualAthrd);
  fac1=b0*(1.-1./ResidualAthrd);
  fac2=1.;
  if(rnneu > 1.5) { fac2 = g4pow->logZ(rnneu); }
  xine_th= 1.e+31*fac*fac2*(1.+ResidualAthrd-fac1);
  xine_th=(1.-0.15*std::exp(-ekin))*xine_th/(1.00-0.0007*ResidualA);    
  ff1=0.70-0.0020*ResidualA;
  ff2=1.00+1/G4double(ResidualA);
  ff3=0.8+18/G4double(ResidualA)-0.002*ResidualA;
  fac=1.-(1./(1.+std::exp(-8.*ff1*(std::log10(ekin)+1.37*ff2))));
  xine_th=xine_th*(1.+ff3*fac);
  ff1=1.-1/G4double(ResidualA)-0.001*ResidualA;
  ff2=1.17-2.7/G4double(ResidualA)-0.0014*ResidualA;
  fac=-8.*ff1*(std::log10(ekin)+2.0*ff2);
  fac=1./(1.+std::exp(fac));
  xine_th=xine_th*fac;            
  if (xine_th < 0.0){
    std::ostringstream errOs;
    G4cout<<"WARNING:  negative Wellisch cross section "<<G4endl; 
    errOs << "RESIDUAL: A=" << ResidualA << " Z=" << ResidualZ <<G4endl;
    errOs <<"  xsec("<<ekin<<" MeV) ="<<xine_th <<G4endl;
    throw G4HadronicException(__FILE__, __LINE__, errOs.str());
  }
  return xine_th;
}

// *********** OPT=3 : Kalbach's cross sections (from PRECO code)*************
G4double G4PreCompoundProton::GetOpt3(const  G4double K)
{
  //     ** p from  becchetti and greenlees (but modified with sub-barrier
  //     ** correction function and xp2 changed from -449)

  G4double landa, landa0, landa1, mu, mm0, mu1,nu, nu0, nu1, nu2;
  G4double p, p0, p1, p2;
  p0 = 15.72;
  p1 = 9.65;
  p2 = -300.;
  landa0 = 0.00437;
  landa1 = -16.58;
  mm0 = 244.7;
  mu1 = 0.503;
  nu0 = 273.1;
  nu1 = -182.4;
  nu2 = -1.872;
  
  // parameters for  proton cross section refinement 
  /*
  G4double afit,bfit,a2,b2;
  afit=-0.0785656;
  bfit=5.10789;
  a2= -0.00089076;
  b2= 0.0231597;  
  */

  G4double ec,ecsq,xnulam,etest(0.),ra(0.),a,w,c,signor(1.),signor2,sig; 
  G4double b,ecut,cut,ecut2,geom,elab;
    
  G4double      flow = 1.e-18;
  G4double       spill= 1.e+18; 
   
  if (ResidualA <= 60)      { signor = 0.92; }
  else if (ResidualA < 100) { signor = 0.8 + ResidualA*0.002; }
  
  ec = 1.44 * theZ * ResidualZ / (1.5*ResidualAthrd+ra);
  ecsq = ec * ec;
  p = p0 + p1/ec + p2/ecsq;
  landa = landa0*ResidualA + landa1;
  a = g4pow->powZ(ResidualA,mu1);
  mu = mm0 * a;
  nu = a* (nu0+nu1*ec+nu2*ecsq);
  
  c =std::min(3.15,ec*0.5);
  w = 0.7 * c / 3.15; 
  
  xnulam = nu / landa;
  if (xnulam > spill) { xnulam=0.; }
  if (xnulam >= flow) { etest =std::sqrt(xnulam) + 7.; }
  
  a = -2.*p*ec + landa - nu/ecsq;
  b = p*ecsq + mu + 2.*nu/ec;
  ecut = 0.;
  cut = a*a - 4.*p*b;
  if (cut > 0.) { ecut = std::sqrt(cut); }
  ecut = (ecut-a) / (p+p);
  ecut2 = ecut;
  //JMQ 290310 for avoiding unphysical increase below minimum (at ecut)
  // ecut<0 means that there is no cut with energy axis, i.e. xs is set 
  // to 0 bellow minimum
  //  if (cut < 0.) ecut2 = ecut - 2.;
  if (cut < 0.) { ecut2 = ecut; }
  elab = K * FragmentA /G4double(ResidualA);
  sig = 0.;
  if (elab <= ec) { //start for E<Ec 
    if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; }
    
    signor2 = (ec-elab-c) / w;
    signor2 = 1. + std::exp(signor2);
    sig = sig / signor2;
  }              //end for E<=Ec
  else{           //start for  E>Ec
    sig = (landa*elab+mu+nu/elab) * signor;
    geom = 0.;
    
    if (xnulam < flow || elab < etest) 
      {
        if (sig <0.0) {sig=0.0;}
        return sig;
      }
    geom = std::sqrt(theA*K);
    geom = 1.23*ResidualAthrd + ra + 4.573/geom;
    geom = 31.416 * geom * geom;
    sig = std::max(geom,sig);
    
  }   //end for E>Ec
  return sig;
}

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