Gabriele Cosmo
524 lines
18 KiB
C++
524 lines
18 KiB
C++
// This code implementation is the intellectual property of
|
|
// the GEANT4 collaboration.
|
|
//
|
|
// By copying, distributing or modifying the Program (or any work
|
|
// based on the Program) you indicate your acceptance of this statement,
|
|
// and all its terms.
|
|
//
|
|
// $Id: G4LEAntiNeutronInelastic.cc,v 1.2 1999/12/15 14:53:07 gunter Exp $
|
|
// GEANT4 tag $Name: geant4-03-01 $
|
|
//
|
|
// Hadronic Process: AntiNeutron Inelastic Process
|
|
// J.L. Chuma, TRIUMF, 18-Feb-1997
|
|
// Last modified: 27-Mar-1997
|
|
// J.P.Wellisch: 23-Apr-97: Added theNucleus.SetParameters call
|
|
// J.P. Wellisch: 23-Apr-97: nm = np+1; in line 392
|
|
// Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta
|
|
|
|
#include "G4LEAntiNeutronInelastic.hh"
|
|
#include "Randomize.hh"
|
|
|
|
G4VParticleChange *
|
|
G4LEAntiNeutronInelastic::ApplyYourself( const G4Track &aTrack,
|
|
G4Nucleus &targetNucleus )
|
|
{
|
|
theParticleChange.Initialize( aTrack );
|
|
|
|
const G4DynamicParticle *originalIncident = aTrack.GetDynamicParticle();
|
|
//
|
|
// create the target particle
|
|
//
|
|
G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
|
|
|
|
if( verboseLevel > 1 )
|
|
{
|
|
G4Material *targetMaterial = aTrack.GetMaterial();
|
|
G4cout << "G4LEAntiNeutronInelastic::ApplyYourself called" << G4endl;
|
|
G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
|
|
G4cout << "target material = " << targetMaterial->GetName() << ", ";
|
|
G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
|
|
<< G4endl;
|
|
}
|
|
//
|
|
// Fermi motion and evaporation
|
|
// As of Geant3, the Fermi energy calculation had not been Done
|
|
//
|
|
G4double ek = originalIncident->GetKineticEnergy()/MeV;
|
|
G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
|
|
G4ReactionProduct modifiedOriginal;
|
|
modifiedOriginal = *originalIncident;
|
|
|
|
G4double tkin = targetNucleus.Cinema( ek );
|
|
ek += tkin;
|
|
modifiedOriginal.SetKineticEnergy( ek*MeV );
|
|
G4double et = ek + amas;
|
|
G4double p = sqrt( abs((et-amas)*(et+amas)) );
|
|
G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
|
|
if( pp > 0.0 )
|
|
{
|
|
G4ThreeVector momentum = modifiedOriginal.GetMomentum();
|
|
modifiedOriginal.SetMomentum( momentum * (p/pp) );
|
|
}
|
|
//
|
|
// calculate black track energies
|
|
//
|
|
tkin = targetNucleus.EvaporationEffects( ek );
|
|
ek -= tkin;
|
|
modifiedOriginal.SetKineticEnergy( ek*MeV );
|
|
et = ek + amas;
|
|
p = sqrt( abs((et-amas)*(et+amas)) );
|
|
pp = modifiedOriginal.GetMomentum().mag()/MeV;
|
|
if( pp > 0.0 )
|
|
{
|
|
G4ThreeVector momentum = modifiedOriginal.GetMomentum();
|
|
modifiedOriginal.SetMomentum( momentum * (p/pp) );
|
|
}
|
|
|
|
G4ReactionProduct currentParticle = modifiedOriginal;
|
|
G4ReactionProduct targetParticle;
|
|
targetParticle = *originalTarget;
|
|
currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
|
|
targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
|
|
G4bool incidentHasChanged = false;
|
|
G4bool targetHasChanged = false;
|
|
G4bool quasiElastic = false;
|
|
G4FastVector<G4ReactionProduct,128> vec; // vec will contain the secondary particles
|
|
G4int vecLen = 0;
|
|
vec.Initialize( 0 );
|
|
|
|
const G4double cutOff = 0.1*MeV;
|
|
const G4double anni = G4std::min( 1.3*currentParticle.GetTotalMomentum()/GeV, 0.4 );
|
|
|
|
if( (currentParticle.GetKineticEnergy()/MeV > cutOff) ||
|
|
(G4UniformRand() > anni) )
|
|
Cascade( vec, vecLen,
|
|
originalIncident, currentParticle, targetParticle,
|
|
incidentHasChanged, targetHasChanged, quasiElastic );
|
|
else
|
|
quasiElastic = true;
|
|
|
|
CalculateMomenta( vec, vecLen,
|
|
originalIncident, originalTarget, modifiedOriginal,
|
|
targetNucleus, currentParticle, targetParticle,
|
|
incidentHasChanged, targetHasChanged, quasiElastic );
|
|
|
|
SetUpChange( vec, vecLen,
|
|
currentParticle, targetParticle,
|
|
incidentHasChanged );
|
|
|
|
delete originalTarget;
|
|
return &theParticleChange;
|
|
}
|
|
|
|
void
|
|
G4LEAntiNeutronInelastic::Cascade(
|
|
G4FastVector<G4ReactionProduct,128> &vec,
|
|
G4int& vecLen,
|
|
const G4DynamicParticle *originalIncident,
|
|
G4ReactionProduct ¤tParticle,
|
|
G4ReactionProduct &targetParticle,
|
|
G4bool &incidentHasChanged,
|
|
G4bool &targetHasChanged,
|
|
G4bool &quasiElastic )
|
|
{
|
|
// derived from original FORTRAN code CASNB by H. Fesefeldt (13-Sep-1987)
|
|
//
|
|
// AntiNeutron undergoes interaction with nucleon within a nucleus. Check if it is
|
|
// energetically possible to produce pions/kaons. In not, assume nuclear excitation
|
|
// occurs and input particle is degraded in energy. No other particles are produced.
|
|
// If reaction is possible, find the correct number of pions/protons/neutrons
|
|
// produced using an interpolation to multiplicity data. Replace some pions or
|
|
// protons/neutrons by kaons or strange baryons according to the average
|
|
// multiplicity per Inelastic reaction.
|
|
//
|
|
const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
|
|
const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
|
|
const G4double pOriginal = originalIncident->GetTotalMomentum()/MeV;
|
|
const G4double targetMass = targetParticle.GetMass()/MeV;
|
|
G4double centerofmassEnergy = sqrt( mOriginal*mOriginal +
|
|
targetMass*targetMass +
|
|
2.0*targetMass*etOriginal );
|
|
G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
|
|
|
|
static G4bool first = true;
|
|
const G4int numMul = 1200;
|
|
const G4int numMulA = 400;
|
|
const G4int numSec = 60;
|
|
static G4double protmul[numMul], protnorm[numSec]; // proton constants
|
|
static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
|
|
static G4double protmulA[numMulA], protnormA[numSec]; // proton constants
|
|
static G4double neutmulA[numMulA], neutnormA[numSec]; // neutron constants
|
|
// np = number of pi+, nm = number of pi-, nz = number of pi0
|
|
G4int counter, nt=0, np=0, nm=0, nz=0;
|
|
G4double test;
|
|
const G4double c = 1.25;
|
|
const G4double b[] = { 0.70, 0.70 };
|
|
if( first ) // compute normalization constants, this will only be Done once
|
|
{
|
|
first = false;
|
|
G4int i;
|
|
for( i=0; i<numMul; ++i )protmul[i] = 0.0;
|
|
for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
|
|
counter = -1;
|
|
for( np=0; np<(numSec/3); ++np )
|
|
{
|
|
for( nm=G4std::max(0,np-2); nm<=np; ++nm )
|
|
{
|
|
for( nz=0; nz<numSec/3; ++nz )
|
|
{
|
|
if( ++counter < numMul )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( nt>0 && nt<=numSec )
|
|
{
|
|
protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
|
|
protnorm[nt-1] += protmul[counter];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
|
|
for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
|
|
counter = -1;
|
|
for( np=0; np<numSec/3; ++np )
|
|
{
|
|
for( nm=G4std::max(0,np-1); nm<=(np+1); ++nm )
|
|
{
|
|
for( nz=0; nz<numSec/3; ++nz )
|
|
{
|
|
if( ++counter < numMul )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( (nt>0) && (nt<=numSec) )
|
|
{
|
|
neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
|
|
neutnorm[nt-1] += neutmul[counter];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
for( i=0; i<numSec; ++i )
|
|
{
|
|
if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
|
|
if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
|
|
}
|
|
//
|
|
// do the same for annihilation channels
|
|
//
|
|
for( i=0; i<numMulA; ++i )protmulA[i] = 0.0;
|
|
for( i=0; i<numSec; ++i )protnormA[i] = 0.0;
|
|
counter = -1;
|
|
for( np=1; np<(numSec/3); ++np )
|
|
{
|
|
nm = np-1;
|
|
for( nz=0; nz<numSec/3; ++nz )
|
|
{
|
|
if( ++counter < numMulA )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( nt>1 && nt<=numSec )
|
|
{
|
|
protmulA[counter] = Pmltpc(np,nm,nz,nt,b[0],c);
|
|
protnormA[nt-1] += protmulA[counter];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
for( i=0; i<numMulA; ++i )neutmulA[i] = 0.0;
|
|
for( i=0; i<numSec; ++i )neutnormA[i] = 0.0;
|
|
counter = -1;
|
|
for( np=0; np<numSec/3; ++np )
|
|
{
|
|
nm = np;
|
|
for( nz=0; nz<numSec/3; ++nz )
|
|
{
|
|
if( ++counter < numMulA )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( nt>1 && nt<=numSec )
|
|
{
|
|
neutmulA[counter] = Pmltpc(np,nm,nz,nt,b[1],c);
|
|
neutnormA[nt-1] += neutmulA[counter];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
for( i=0; i<numSec; ++i )
|
|
{
|
|
if( protnormA[i] > 0.0 )protnormA[i] = 1.0/protnormA[i];
|
|
if( neutnormA[i] > 0.0 )neutnormA[i] = 1.0/neutnormA[i];
|
|
}
|
|
} // end of initialization
|
|
const G4double expxu = 82.; // upper bound for arg. of exp
|
|
const G4double expxl = -expxu; // lower bound for arg. of exp
|
|
G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
|
|
G4ParticleDefinition *aProton = G4Proton::Proton();
|
|
G4ParticleDefinition *anAntiProton = G4AntiProton::AntiProton();
|
|
G4ParticleDefinition *aPiPlus = G4PionPlus::PionPlus();
|
|
G4ParticleDefinition *aPiMinus = G4PionMinus::PionMinus();
|
|
G4ParticleDefinition *aPiZero = G4PionZero::PionZero();
|
|
|
|
// energetically possible to produce pion(s) --> inelastic scattering
|
|
// otherwise quasi-elastic scattering
|
|
|
|
const G4double anhl[] = {1.00,1.00,1.00,1.00,1.00,1.00,1.00,1.00,0.97,0.88,
|
|
0.85,0.81,0.75,0.64,0.64,0.55,0.55,0.45,0.47,0.40,
|
|
0.39,0.36,0.33,0.10,0.01};
|
|
G4int iplab = G4int( pOriginal/GeV*10.0 );
|
|
if( iplab > 9 )iplab = G4int( (pOriginal/GeV- 1.0)*5.0 ) + 10;
|
|
if( iplab > 14 )iplab = G4int( pOriginal/GeV- 2.0 ) + 15;
|
|
if( iplab > 22 )iplab = G4int( (pOriginal/GeV-10.0)/10.0 ) + 23;
|
|
if( iplab > 24 )iplab = 24;
|
|
if( G4UniformRand() > anhl[iplab] )
|
|
{
|
|
if( availableEnergy <= aPiPlus->GetPDGMass()/MeV )
|
|
{
|
|
quasiElastic = true;
|
|
return;
|
|
}
|
|
G4int ieab = availableEnergy*5.0/GeV;
|
|
const G4double supp[] = {0.,0.4,0.55,0.65,0.75,0.82,0.86,0.90,0.94,0.98};
|
|
G4double w0, wp, wt, wm;
|
|
if( (availableEnergy < 2.0*GeV) && (G4UniformRand() >= supp[ieab]) )
|
|
{
|
|
// suppress high multiplicity events at low momentum
|
|
// only one pion will be produced
|
|
//
|
|
np = nm = nz = 0;
|
|
if( targetParticle.GetDefinition() == aProton )
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(1.0+b[0])*(1.0+b[0])/(2.0*c*c) ) ) );
|
|
w0 = test;
|
|
wp = test;
|
|
if( G4UniformRand() < w0/(w0+wp) )
|
|
nz = 1;
|
|
else
|
|
np = 1;
|
|
}
|
|
else // target is a neutron
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(1.0+b[1])*(1.0+b[1])/(2.0*c*c) ) ) );
|
|
w0 = test;
|
|
wp = test;
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(-1.0+b[1])*(-1.0+b[1])/(2.0*c*c) ) ) );
|
|
wm = test;
|
|
wt = w0+wp+wm;
|
|
wp += w0;
|
|
G4double ran = G4UniformRand();
|
|
if( ran < w0/wt )
|
|
nz = 1;
|
|
else if( ran < wp/wt )
|
|
np = 1;
|
|
else
|
|
nm = 1;
|
|
}
|
|
}
|
|
else // (availableEnergy >= 2.0*GeV) || (random number < supp[ieab])
|
|
{
|
|
G4double n, anpn;
|
|
GetNormalizationConstant( availableEnergy, n, anpn );
|
|
G4double ran = G4UniformRand();
|
|
G4double dum, excs = 0.0;
|
|
if( targetParticle.GetDefinition() == aProton )
|
|
{
|
|
counter = -1;
|
|
for( np=0; np<numSec/3 && ran>=excs; ++np )
|
|
{
|
|
for( nm=G4std::max(0,np-2); nm<=np && ran>=excs; ++nm )
|
|
{
|
|
for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
|
|
{
|
|
if( ++counter < numMul )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( nt > 0 )
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
|
|
dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
|
|
if( fabs(dum) < 1.0 )
|
|
{
|
|
if( test >= 1.0e-10 )excs += dum*test;
|
|
}
|
|
else
|
|
excs += dum*test;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if( ran >= excs ) // 3 previous loops continued to the end
|
|
{
|
|
quasiElastic = true;
|
|
return;
|
|
}
|
|
np--; nm--; nz--;
|
|
}
|
|
else // target must be a neutron
|
|
{
|
|
counter = -1;
|
|
for( np=0; np<numSec/3 && ran>=excs; ++np )
|
|
{
|
|
for( nm=G4std::max(0,np-1); nm<=(np+1) && ran>=excs; ++nm )
|
|
{
|
|
for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
|
|
{
|
|
if( ++counter < numMul )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( (nt>=1) && (nt<=numSec) )
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
|
|
dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
|
|
if( fabs(dum) < 1.0 )
|
|
{
|
|
if( test >= 1.0e-10 )excs += dum*test;
|
|
}
|
|
else
|
|
excs += dum*test;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if( ran >= excs ) // 3 previous loops continued to the end
|
|
{
|
|
quasiElastic = true;
|
|
return;
|
|
}
|
|
np--; nm--; nz--;
|
|
}
|
|
}
|
|
if( targetParticle.GetDefinition() == aProton )
|
|
{
|
|
switch( np-nm )
|
|
{
|
|
case 1:
|
|
if( G4UniformRand() < 0.5 )
|
|
{
|
|
currentParticle.SetDefinitionAndUpdateE( anAntiProton );
|
|
incidentHasChanged = true;
|
|
}
|
|
else
|
|
{
|
|
targetParticle.SetDefinitionAndUpdateE( aNeutron );
|
|
targetHasChanged = true;
|
|
}
|
|
break;
|
|
case 2:
|
|
currentParticle.SetDefinitionAndUpdateE( anAntiProton );
|
|
targetParticle.SetDefinitionAndUpdateE( aNeutron );
|
|
incidentHasChanged = true;
|
|
targetHasChanged = true;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
else // target must be a neutron
|
|
{
|
|
switch( np-nm )
|
|
{
|
|
case 0:
|
|
if( G4UniformRand() < 0.33 )
|
|
{
|
|
currentParticle.SetDefinitionAndUpdateE( anAntiProton );
|
|
targetParticle.SetDefinitionAndUpdateE( aProton );
|
|
incidentHasChanged = true;
|
|
targetHasChanged = true;
|
|
}
|
|
break;
|
|
case 1:
|
|
currentParticle.SetDefinitionAndUpdateE( anAntiProton );
|
|
incidentHasChanged = true;
|
|
break;
|
|
default:
|
|
targetParticle.SetDefinitionAndUpdateE( aProton );
|
|
targetHasChanged = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
else // random number <= anhl[iplab]
|
|
{
|
|
if( centerofmassEnergy <= 2*aPiPlus->GetPDGMass()/MeV )
|
|
{
|
|
quasiElastic = true;
|
|
return;
|
|
}
|
|
//
|
|
// annihilation channels
|
|
//
|
|
G4double n, anpn;
|
|
GetNormalizationConstant( -centerofmassEnergy, n, anpn );
|
|
G4double ran = G4UniformRand();
|
|
G4double dum, excs = 0.0;
|
|
if( targetParticle.GetDefinition() == aProton )
|
|
{
|
|
counter = -1;
|
|
for( np=1; (np<numSec/3) && (ran>=excs); ++np )
|
|
{
|
|
nm = np-1;
|
|
for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz )
|
|
{
|
|
if( ++counter < numMulA )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( nt>1 && nt<=numSec )
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
|
|
dum = (pi/anpn)*nt*protmulA[counter]*protnormA[nt-1]/(2.0*n*n);
|
|
if( fabs(dum) < 1.0 )
|
|
{
|
|
if( test >= 1.0e-10 )excs += dum*test;
|
|
}
|
|
else
|
|
excs += dum*test;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else // target must be a neutron
|
|
{
|
|
counter = -1;
|
|
for( np=0; (np<numSec/3) && (ran>=excs); ++np )
|
|
{
|
|
nm = np;
|
|
for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz )
|
|
{
|
|
if( ++counter < numMulA )
|
|
{
|
|
nt = np+nm+nz;
|
|
if( (nt>1) && (nt<=numSec) )
|
|
{
|
|
test = exp( G4std::min( expxu, G4std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
|
|
dum = (pi/anpn)*nt*neutmulA[counter]*neutnormA[nt-1]/(2.0*n*n);
|
|
if( fabs(dum) < 1.0 )
|
|
{
|
|
if( test >= 1.0e-10 )excs += dum*test;
|
|
}
|
|
else
|
|
excs += dum*test;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if( ran >= excs ) // 3 previous loops continued to the end
|
|
{
|
|
quasiElastic = true;
|
|
return;
|
|
}
|
|
np--; nz--;
|
|
currentParticle.SetMass( 0.0 );
|
|
targetParticle.SetMass( 0.0 );
|
|
}
|
|
SetUpPions( np, nm, nz, vec, vecLen );
|
|
return;
|
|
}
|
|
|
|
/* end of file */
|
|
|