lars/geant4
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
a8e9364ceaa10b8535e82c376966c9f1eccf3be3
geant4/source/processes/electromagnetic/standard/src/G4CoulombScatteringModel.cc
T
Gabriele Cosmo a8e9364cea Import Geant4 9.0.0 source tree
2016-06-09 15:16:48 +02:00

226 lines
8.0 KiB
C++
Raw Blame History

//
// ********************************************************************
// * License and Disclaimer *
// * *
// * The Geant4 software is copyright of the Copyright Holders of *
// * the Geant4 Collaboration. It is provided under the terms and *
// * conditions of the Geant4 Software License, included in the file *
// * LICENSE and available at http://cern.ch/geant4/license . These *
// * include a list of copyright holders. *
// * *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work make any representation or warranty, express or implied, *
// * regarding this software system or assume any liability for its *
// * use. Please see the license in the file LICENSE and URL above *
// * for the full disclaimer and the limitation of liability. *
// * *
// * This code implementation is the result of the scientific and *
// * technical work of the GEANT4 collaboration. *
// * By using, copying, modifying or distributing the software (or *
// * any work based on the software) you agree to acknowledge its *
// * use in resulting scientific publications, and indicate your *
// * acceptance of all terms of the Geant4 Software license. *
// ********************************************************************
//
// $Id: G4CoulombScatteringModel.cc,v 1.8 2007/05/22 17:34:36 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-00 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name: G4CoulombScatteringModel
//
// Author: Vladimir Ivanchenko
//
// Creation date: 22.08.2005
//
// Modifications:
// 01.08.06 V.Ivanchenko extend upper limit of table to TeV and review the
// logic of building - only elements from G4ElementTable
// 08.08.06 V.Ivanchenko build internal table in ekin scale, introduce faclim
// 19.10.06 V.Ivanchenko use inheritance from G4eCoulombScatteringModel
//
// Class Description:
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
#include "G4CoulombScatteringModel.hh"
#include "Randomize.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4NistManager.hh"
#include "G4ParticleTable.hh"
#include "G4IonTable.hh"
#include "G4Proton.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
using namespace std;
G4CoulombScatteringModel::G4CoulombScatteringModel(
G4double thetaMin, G4double thetaMax, G4bool build,
G4double tlim, const G4String& nam)
: G4eCoulombScatteringModel(thetaMin,thetaMax,build,tlim,nam)
{
theMatManager = G4NistManager::Instance();
theParticleTable = G4ParticleTable::GetParticleTable();
theProton = G4Proton::Proton();
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4CoulombScatteringModel::~G4CoulombScatteringModel()
{}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4CoulombScatteringModel::CalculateCrossSectionPerAtom(
const G4ParticleDefinition* p,
G4double kinEnergy,
G4double Z)
{
G4double cross= 0.0;
G4int iz = G4int(Z);
G4double m = p->GetPDGMass();
G4double mom2 = kinEnergy*(kinEnergy + 2.0*m);
G4double mass2= m*m;
G4double m1 = theMatManager->GetAtomicMassAmu(iz)*amu_c2;
G4double etot = kinEnergy + m + m1;
G4double ptot = sqrt(mom2);
G4double bet = ptot/etot;
G4double gam = 1.0/sqrt((1.0 - bet)*(1.0 + bet));
G4double momCM = gam*(ptot - bet*etot);
G4double momCM2 = momCM*momCM;
G4double costm = std::max(cosThetaMax, 1.0 - 0.5*q2Limit/momCM2);
if(1 == iz && p == theProton) costm = std::max(0.0, costm);
// Cross section in CM system
if(costm < cosThetaMin) {
G4double q = p->GetPDGCharge()/eplus;
G4double q2 = q*q;
G4double invbeta2 = 1.0 + mass2/momCM2;
G4double A = ScreeningParameter(Z, q2, momCM2, invbeta2);
G4double a = 2.0*A + 1.0;
G4double f = q * m1 /(m + m1);
cross = coeff*f*f*Z*(Z + 1.0)*invbeta2*(cosThetaMin - costm)/
((a - cosThetaMin)*(a - costm)*momCM2);
}
//G4cout << "p= " << mom << " momCM= " << momCM << " Z= " << Z << " A= " << A
//<< " cross= " << cross << " m1(GeV)= " << m1/GeV <<G4endl;
return cross;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double G4CoulombScatteringModel::SelectIsotope(const G4Element* elm)
{
G4double N = elm->GetN();
G4int ni = elm->GetNumberOfIsotopes();
if(ni > 0) {
G4double* ab = elm->GetRelativeAbundanceVector();
G4double x = G4UniformRand();
G4int idx;
for(idx=0; idx<ni; idx++) {
x -= ab[idx];
if (x <= 0.0) break;
}
if(idx >= ni) {
G4cout << "G4CoulombScatteringModel::SelectIsotope WARNING: "
<< "abandance vector for"
<< elm->GetName() << " is not normalised to unit" << G4endl;
} else {
N = G4double(elm->GetIsotope(idx)->GetN());
}
}
return N;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4CoulombScatteringModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
const G4MaterialCutsCouple* couple,
const G4DynamicParticle* dp,
G4double,
G4double)
{
const G4Material* aMaterial = couple->GetMaterial();
const G4ParticleDefinition* p = dp->GetDefinition();
const G4Element* elm =
SelectRandomAtom(aMaterial, p, dp->GetKineticEnergy());
G4double Z = elm->GetZ();
G4double N = SelectIsotope(elm);
G4int iz = G4int(Z);
G4int in = G4int(N + 0.5);
G4double m2 = theParticleTable->GetIonTable()->GetNucleusMass(iz, in);
G4double m1 = dp->GetMass();
G4double q = p->GetPDGCharge()/eplus;
G4double q2 = q*q;
// Transformation to CM system
G4LorentzVector lv1 = dp->Get4Momentum();
G4ThreeVector dir = dp->GetMomentumDirection();
G4LorentzVector lv2(0.0,0.0,0.0,m2);
G4LorentzVector lv = lv1 + lv2;
G4ThreeVector bst = lv.boostVector();
lv1.boost(-bst);
lv2.boost(-bst);
G4ThreeVector p1 = lv1.vect();
G4double momCM2 = p1.mag2();
G4double invbeta2 = 1.0 + m1*m1/momCM2;
G4double A = ScreeningParameter(Z, q2, momCM2, invbeta2);
G4double a = 2.0*A + 1.0;
G4double costm = std::max(cosThetaMax, 1.0 - 0.5*q2Limit/momCM2);
if(1 == iz && p == theProton) costm = std::max(0.0, costm);
if(costm > cosThetaMin) return;
G4double x = G4UniformRand();
G4double y = (a + 1.0 - cosThetaMin)/(cosThetaMin - costm);
G4double st2 = 0.5*(y*(1.0 - costm) - a*x)/(y + x);
if(st2 < 0.0 || st2 > 1.0) {
G4cout << "G4CoulombScatteringModel::SampleSecondaries WARNING st2= "
<< st2 << G4endl;
st2 = 0.0;
}
G4double tet = 2.0*asin(sqrt(st2));
G4double cost= cos(tet);
G4double sint= sin(tet);
G4double phi = twopi * G4UniformRand();
G4ThreeVector v1(cos(phi)*sint,sin(phi)*sint,cost);
G4double p1tot = sqrt(momCM2);
// v1.rotateUz(p1);
G4LorentzVector lfv1(v1.x()*p1tot,v1.y()*p1tot,v1.z(),lv1.e());
lfv1.boost(bst);
G4LorentzVector lfv2 = lv - lfv1;
G4ThreeVector newdir = lfv1.vect().unit();
fParticleChange->ProposeMomentumDirection(newdir);
G4double ekin = lfv1.e() - m1;
if(ekin < 0.0) ekin = 0.0;
fParticleChange->SetProposedKineticEnergy(ekin);
ekin = lfv2.e() - m2;
if(ekin > Z*aMaterial->GetIonisation()->GetMeanExcitationEnergy()) {
G4ParticleDefinition* ion = theParticleTable->GetIon(iz, in, 0.0);
G4DynamicParticle* newdp = new G4DynamicParticle(ion, lfv2);
fvect->push_back(newdp);
} else if(ekin > 0.0) {
fParticleChange->ProposeLocalEnergyDeposit(ekin);
}
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
Reference in New Issue View Git Blame Copy Permalink