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Gabriele Cosmo
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//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * *
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// * Parts of this code which have been developed by QinetiQ Ltd *
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// * under contract to the European Space Agency (ESA) are the *
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// * intellectual property of ESA. Rights to use, copy, modify and *
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// * redistribute this software for general public use are granted *
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// * in compliance with any licensing, distribution and development *
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// * policy adopted by the Geant4 Collaboration. This code has been *
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// * written by QinetiQ Ltd for the European Space Agency, under ESA *
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// * contract 17191/03/NL/LvH (Aurora Programme). *
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// * *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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//
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// MODULE: G4EMDissociationCrossSection.cc
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//
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// Version: B.1
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// Date: 15/04/04
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// Author: P R Truscott
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// Organisation: QinetiQ Ltd, UK
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// Customer: ESA/ESTEC, NOORDWIJK
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// Contract: 17191/03/NL/LvH
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//
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// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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//
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// CHANGE HISTORY
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// --------------
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//
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// 17 October 2003, P R Truscott, QinetiQ Ltd, UK
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// Created.
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//
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// 15 March 2004, P R Truscott, QinetiQ Ltd, UK
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// Beta release
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//
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// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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////////////////////////////////////////////////////////////////////////////////
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//
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#include "G4EMDissociationCrossSection.hh"
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#include "G4PhysicsFreeVector.hh"
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#include "G4ParticleTable.hh"
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#include "G4IonTable.hh"
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#include "globals.hh"
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////////////////////////////////////////////////////////////////////////////////
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//
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G4EMDissociationCrossSection::G4EMDissociationCrossSection ()
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{
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//
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//
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// This function makes use of the class which can sample the virtual photon
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// spectrum, G4EMDissociationSpectrum.
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//
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thePhotonSpectrum = new G4EMDissociationSpectrum();
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//
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//
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// Define other constants.
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//
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r0 = 1.18 * fermi;
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J = 36.8 * MeV;
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Qprime = 17.0 * MeV;
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epsilon = 0.0768;
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xd = 0.25;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4EMDissociationCrossSection::~G4EMDissociationCrossSection()
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{
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delete thePhotonSpectrum;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4bool G4EMDissociationCrossSection::IsApplicable
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(const G4DynamicParticle *theDynamicParticle, const G4Element* theElement)
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{
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//
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//
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// The condition for the applicability of this class is that the projectile
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// must be an ion and the target must have more than one nucleon. In reality
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// the value of A for either the projectile or target could be much higher,
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// since for cases where both he projectile and target are medium to small
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// Z, the probability of the EMD process is, I think, VERY small.
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//
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if (G4ParticleTable::GetParticleTable()->GetIonTable()->
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IsIon(theDynamicParticle->GetDefinition()) && theElement->GetN() > 1.0)
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return true;
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else
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return false;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4double G4EMDissociationCrossSection::GetCrossSection
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(const G4DynamicParticle *theDynamicParticle, const G4Element* theElement,
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G4double )
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{
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//
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//
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// Get relevant information about the projectile and target (A, Z) and
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// velocity of the projectile.
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//
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G4ParticleDefinition *definitionP = theDynamicParticle->GetDefinition();
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G4double AP = definitionP->GetBaryonNumber();
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G4double ZP = definitionP->GetPDGCharge();
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G4double b = theDynamicParticle->Get4Momentum().beta();
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// G4double bsq = b * b;
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G4double AT = theElement->GetN();
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G4double ZT = theElement->GetZ();
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G4double bmin = thePhotonSpectrum->GetClosestApproach(AP, ZP, AT, ZT, b);
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//
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//
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// Calculate the cross-section for the projectile and then the target. The
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// information is returned in a G4PhysicsFreeVector, which separates out the
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// cross-sections for the E1 and E2 moments of the virtual photon field, and
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// the energies (GDR and GQR).
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//
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G4PhysicsFreeVector *theProjectileCrossSections =
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GetCrossSectionForProjectile (AP, ZP, AT, ZT, b, bmin);
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G4double crossSection =
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(*theProjectileCrossSections)[0]+(*theProjectileCrossSections)[1];
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delete theProjectileCrossSections;
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G4PhysicsFreeVector *theTargetCrossSections =
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GetCrossSectionForTarget (AP, ZP, AT, ZT, b, bmin);
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crossSection +=
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(*theTargetCrossSections)[0]+(*theTargetCrossSections)[1];
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delete theTargetCrossSections;
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return crossSection;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4PhysicsFreeVector *
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G4EMDissociationCrossSection::GetCrossSectionForProjectile (G4double AP,
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G4double ZP, G4double AT, G4double ZT, G4double b, G4double bmin)
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{
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//
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//
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// Use Wilson et al's approach to calculate the cross-sections due to the E1
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// and E2 moments of the field at the giant dipole and quadrupole resonances
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// respectively, Note that the algorithm is traditionally applied to the
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// EMD break-up of the projectile in the field of the target, as is implemented
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// here.
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//
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// Initialise variables and calculate the energies for the GDR and GQR.
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//
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G4double AProot3 = pow(AP,1.0/3.0);
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G4double u = 3.0 * J / Qprime / AProot3;
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G4double R0 = r0 * AProot3;
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G4double E_GDR = hbarc / sqrt(0.7*amu_c2*R0*R0/8.0/J*
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(1.0 + u - (1.0 + epsilon + 3.0*u)/(1.0 + epsilon + u)*epsilon));
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G4double E_GQR = 63.0 * MeV / AProot3;
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//
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//
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// Determine the virtual photon spectra at these energies.
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//
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G4double ZTsq = ZT * ZT;
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G4double nE1 = ZTsq *
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thePhotonSpectrum->GetGeneralE1Spectrum(E_GDR, b, bmin);
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G4double nE2 = ZTsq *
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thePhotonSpectrum->GetGeneralE2Spectrum(E_GQR, b, bmin);
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//
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//
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// Now calculate the cross-section of the projectile for interaction with the
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// E1 and E2 fields.
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//
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G4double sE1 = 60.0 * millibarn * MeV * (AP-ZP)*ZP/AP;
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G4double sE2 = 0.22 * microbarn / MeV * ZP * AProot3 * AProot3;
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if (AP > 100.0) sE2 *= 0.9;
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else if (AP > 40.0) sE2 *= 0.6;
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else sE2 *= 0.3;
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//
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//
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// ... and multiply with the intensity of the virtual photon spectra to get
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// the probability of interaction.
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//
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G4PhysicsFreeVector *theCrossSectionVector = new G4PhysicsFreeVector(2);
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theCrossSectionVector->PutValue(0, E_GDR, sE1*nE1);
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theCrossSectionVector->PutValue(1, E_GQR, sE2*nE2*E_GQR*E_GQR);
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return theCrossSectionVector;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4PhysicsFreeVector *
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G4EMDissociationCrossSection::GetCrossSectionForTarget (G4double AP,
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G4double ZP, G4double AT, G4double ZT, G4double b, G4double bmin)
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{
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//
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//
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// This is a cheaky little member function to calculate the probability of
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// EMD for the target in the field of the projectile ... just by reversing the
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// A and Z's for the participants.
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//
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return GetCrossSectionForProjectile (AT, ZT, AP, ZP, b, bmin);
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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G4double
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G4EMDissociationCrossSection::GetWilsonProbabilityForProtonDissociation
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(G4double A, G4double Z)
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{
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//
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//
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// This is a simple algorithm to choose whether a proton or neutron is ejected
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// from the nucleus in the EMD interaction.
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//
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G4double p = 0.0;
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if (Z < 6.0)
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p = 0.5;
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else if (Z < 8.0)
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p = 0.6;
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else if (Z < 14.0)
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p = 0.7;
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else
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{
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G4double p1 = (G4double) Z / (G4double) A;
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G4double p2 = 1.95*exp(-0.075*Z);
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if (p1 < p2) p = p1;
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else p = p2;
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}
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return p;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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