G4EMDissociationCrossSection Class Reference

#include <G4EMDissociationCrossSection.hh>

Inheritance diagram for G4EMDissociationCrossSection:

G4VCrossSectionDataSet

Public Member Functions

 G4EMDissociationCrossSection ()
 ~G4EMDissociationCrossSection ()
virtual G4bool IsElementApplicable (const G4DynamicParticle *, G4int Z, const G4Material *)
virtual G4double GetElementCrossSection (const G4DynamicParticle *, G4int Z, const G4Material *)
G4PhysicsFreeVectorGetCrossSectionForProjectile (G4double, G4double, G4double, G4double, G4double, G4double)
G4PhysicsFreeVectorGetCrossSectionForTarget (G4double, G4double, G4double, G4double, G4double, G4double)
G4double GetWilsonProbabilityForProtonDissociation (G4double, G4double)

Detailed Description

Definition at line 79 of file G4EMDissociationCrossSection.hh.


Constructor & Destructor Documentation

G4EMDissociationCrossSection::G4EMDissociationCrossSection (  ) 

Definition at line 79 of file G4EMDissociationCrossSection.cc.

00080  : G4VCrossSectionDataSet("Electromagnetic dissociation")
00081 {
00082   // This function makes use of the class which can sample the virtual photon
00083   // spectrum, G4EMDissociationSpectrum.
00084 
00085   thePhotonSpectrum = new G4EMDissociationSpectrum();
00086 
00087   // Define other constants.
00088 
00089   r0      = 1.18 * fermi;
00090   J       = 36.8 * MeV;
00091   Qprime  = 17.0 * MeV;
00092   epsilon = 0.0768;
00093   xd      = 0.25;
00094 }

G4EMDissociationCrossSection::~G4EMDissociationCrossSection (  ) 

Definition at line 98 of file G4EMDissociationCrossSection.cc.

00099 {
00100   delete thePhotonSpectrum;
00101 }


Member Function Documentation

G4PhysicsFreeVector * G4EMDissociationCrossSection::GetCrossSectionForProjectile ( G4double  ,
G4double  ,
G4double  ,
G4double  ,
G4double  ,
G4double   
)

Definition at line 165 of file G4EMDissociationCrossSection.cc.

References G4EMDissociationSpectrum::GetGeneralE1Spectrum(), G4EMDissociationSpectrum::GetGeneralE2Spectrum(), and G4PhysicsFreeVector::PutValue().

Referenced by GetCrossSectionForTarget().

00167 {
00168 //
00169 //
00170 // Use Wilson et al's approach to calculate the cross-sections due to the E1
00171 // and E2 moments of the field at the giant dipole and quadrupole resonances
00172 // respectively,  Note that the algorithm is traditionally applied to the
00173 // EMD break-up of the projectile in the field of the target, as is implemented
00174 // here.
00175 //
00176 // Initialise variables and calculate the energies for the GDR and GQR.
00177 //
00178   G4double AProot3 = std::pow(AP,1.0/3.0);
00179   G4double u       = 3.0 * J / Qprime / AProot3;
00180   G4double R0      = r0 * AProot3;
00181   G4double E_GDR  = hbarc / std::sqrt(0.7*amu_c2*R0*R0/8.0/J*
00182     (1.0 + u - (1.0 + epsilon + 3.0*u)/(1.0 + epsilon + u)*epsilon));
00183   G4double E_GQR  = 63.0 * MeV / AProot3;
00184 //
00185 //
00186 // Determine the virtual photon spectra at these energies.
00187 //
00188   G4double ZTsq = ZT * ZT;
00189   G4double nE1 = ZTsq *
00190     thePhotonSpectrum->GetGeneralE1Spectrum(E_GDR, b, bmin);
00191   G4double nE2 = ZTsq *
00192     thePhotonSpectrum->GetGeneralE2Spectrum(E_GQR, b, bmin);
00193 //
00194 //
00195 // Now calculate the cross-section of the projectile for interaction with the
00196 // E1 and E2 fields.
00197 //
00198   G4double sE1 = 60.0 * millibarn * MeV * (AP-ZP)*ZP/AP;
00199   G4double sE2 = 0.22 * microbarn / MeV * ZP * AProot3 * AProot3;
00200   if (AP > 100.0)     sE2 *= 0.9;
00201   else if (AP > 40.0) sE2 *= 0.6;
00202   else                sE2 *= 0.3;
00203 //
00204 //
00205 // ... and multiply with the intensity of the virtual photon spectra to get
00206 // the probability of interaction.
00207 //
00208   G4PhysicsFreeVector *theCrossSectionVector = new G4PhysicsFreeVector(2);
00209   theCrossSectionVector->PutValue(0, E_GDR, sE1*nE1);
00210   theCrossSectionVector->PutValue(1, E_GQR, sE2*nE2*E_GQR*E_GQR);
00211 
00212   return theCrossSectionVector;
00213 }

G4PhysicsFreeVector * G4EMDissociationCrossSection::GetCrossSectionForTarget ( G4double  ,
G4double  ,
G4double  ,
G4double  ,
G4double  ,
G4double   
)

Definition at line 218 of file G4EMDissociationCrossSection.cc.

References GetCrossSectionForProjectile().

00220 {
00221 //
00222 // This is a cheaky little member function to calculate the probability of
00223 // EMD for the target in the field of the projectile ... just by reversing the
00224 // A and Z's for the participants.
00225 //
00226   return GetCrossSectionForProjectile (AT, ZT, AP, ZP, b, bmin);
00227 }

G4double G4EMDissociationCrossSection::GetElementCrossSection ( const G4DynamicParticle ,
G4int  Z,
const G4Material  
) [virtual]

Reimplemented from G4VCrossSectionDataSet.

Definition at line 125 of file G4EMDissociationCrossSection.cc.

References G4DynamicParticle::Get4Momentum(), G4NistManager::GetAtomicMassAmu(), G4ParticleDefinition::GetBaryonNumber(), G4DynamicParticle::GetDefinition(), G4ParticleDefinition::GetPDGCharge(), and G4NistManager::Instance().

00127 {
00128   // VI protection for Hydrogen
00129   if(1 >= Z) { return 0.0; }
00130      
00131   //
00132   // Get relevant information about the projectile and target (A, Z) and
00133   // velocity of the projectile.
00134   //
00135   G4ParticleDefinition *definitionP = theDynamicParticle->GetDefinition();
00136   G4double AP   = definitionP->GetBaryonNumber();
00137   G4double ZP   = definitionP->GetPDGCharge();
00138   G4double b    = theDynamicParticle->Get4Momentum().beta();
00139   
00140   G4double AT   = G4NistManager::Instance()->GetAtomicMassAmu(Z);
00141   G4double ZT   = (G4double)Z;
00142   G4double bmin = thePhotonSpectrum->GetClosestApproach(AP, ZP, AT, ZT, b);
00143   //
00144   //
00145   // Calculate the cross-section for the projectile and then the target.  The
00146   // information is returned in a G4PhysicsFreeVector, which separates out the
00147   // cross-sections for the E1 and E2 moments of the virtual photon field, and
00148   // the energies (GDR and GQR).
00149   //
00150   G4PhysicsFreeVector *theProjectileCrossSections =
00151     GetCrossSectionForProjectile (AP, ZP, AT, ZT, b, bmin);
00152   G4double crossSection =
00153     (*theProjectileCrossSections)[0]+(*theProjectileCrossSections)[1];
00154   delete theProjectileCrossSections;
00155   G4PhysicsFreeVector *theTargetCrossSections =
00156     GetCrossSectionForTarget (AP, ZP, AT, ZT, b, bmin);
00157   crossSection +=
00158     (*theTargetCrossSections)[0]+(*theTargetCrossSections)[1];
00159   delete theTargetCrossSections;
00160   return crossSection;
00161 }

G4double G4EMDissociationCrossSection::GetWilsonProbabilityForProtonDissociation ( G4double  ,
G4double   
)

Definition at line 232 of file G4EMDissociationCrossSection.cc.

00234 {
00235 //
00236 // This is a simple algorithm to choose whether a proton or neutron is ejected
00237 // from the nucleus in the EMD interaction.
00238 //
00239   G4double p = 0.0;
00240   if (Z < 6.0)
00241     p = 0.5;
00242   else if (Z < 8.0)
00243     p = 0.6;
00244   else if (Z < 14.0)
00245     p = 0.7;
00246   else
00247   {
00248     G4double p1 = (G4double) Z / (G4double) A;
00249     G4double p2 = 1.95*std::exp(-0.075*Z);
00250     if (p1 < p2) p = p1;
00251     else         p = p2;
00252   }
00253 
00254   return p;
00255 }

G4bool G4EMDissociationCrossSection::IsElementApplicable ( const G4DynamicParticle ,
G4int  Z,
const G4Material  
) [virtual]

Reimplemented from G4VCrossSectionDataSet.

Definition at line 105 of file G4EMDissociationCrossSection.cc.

References G4DynamicParticle::GetDefinition(), and G4ParticleTable::GetParticleTable().

00107 {
00108 //
00109 // The condition for the applicability of this class is that the projectile
00110 // must be an ion and the target must have more than one nucleon.  In reality
00111 // the value of A for either the projectile or target could be much higher,
00112 // since for cases where both he projectile and target are medium to small
00113 // Z, the probability of the EMD process is, I think, VERY small.
00114 //
00115   if (G4ParticleTable::GetParticleTable()->GetIonTable()->IsIon(part->GetDefinition())) {
00116     return true;
00117   } else {
00118     return false;
00119   }
00120 }


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