Gabriele Cosmo
277 lines
7.8 KiB
C++
277 lines
7.8 KiB
C++
// This code implementation is the intellectual property of
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// the GEANT4 collaboration.
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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 statement,
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// and all its terms.
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//
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//
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// --------------------------------------------------------------
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// GEANT 4 class implementation file --- Copyright CERN 1998
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// CERN Geneva Switzerland
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//
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// For information related to this code contact:
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// CERN, CN Division, ASD group
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// History: first implementation, based on object model of
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// 2nd December 1995, G.Cosmo
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// ------------ G4MuonMinusCaptureAtRest physics process --------
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// by Vladimir Ivanchenko
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// E-mail: Vladimir.Ivantchenko@cern.ch
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// April 2000
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// **************************************************************
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//-----------------------------------------------------------------------------
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#include "G4MuMinusCaptureCascade.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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// constructor
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G4MuMinusCaptureCascade::G4MuMinusCaptureCascade()
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{
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theElectron = G4Electron::Electron();
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theGamma = G4Gamma::Gamma();
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Emass = theElectron->GetPDGMass();
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MuMass = G4MuonMinus::MuonMinus()->GetPDGMass();
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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// destructor
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G4MuMinusCaptureCascade::~G4MuMinusCaptureCascade()
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{ }
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuMinusCaptureCascade::GetKShellEnergy(G4double Z)
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{
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// Calculate the Energy of K Mesoatom Level for this Element using
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// the Energy of Hydrogen Atom taken into account finite size of the
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// nucleus (V.Ivanchenko)
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const size_t ListK = 27;
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static G4double ListZK[ListK] = {
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2., 4., 6., 8., 11., 14., 17., 18., 21., 24.,
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26., 29., 32., 38., 40., 41., 44., 49., 53., 55.,
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60., 65., 70., 75., 81., 85., 92.};
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static G4double ListKEnergy[ListK] = {
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0.011, 0.043, 0.098, 0.173, 0.326,
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0.524, 0.765, 0.853, 1.146, 1.472,
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1.708, 2.081, 2.475, 3.323, 3.627,
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3.779, 4.237, 5.016, 5.647, 5.966,
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6.793, 7.602, 8.421, 9.249, 10.222,
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10.923,11.984};
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// Energy with finit size corrections
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G4double KEnergy = GetLinApprox(ListK,ListZK,ListKEnergy,Z);
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return KEnergy;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4MuMinusCaptureCascade::GetLinApprox(const size_t N,
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const G4double X[],
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const G4double Y[],
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G4double Xuser)
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{
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G4double Yuser = 0.0;
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G4int i;
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if(N < 1) return Yuser;
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else if(Xuser < X[0]) Yuser = Y[0];
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else if(Xuser > X[N-1]) Yuser = Y[N-1];
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else {
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for (i = 1; i < N - 1; i++){
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if(Xuser < X[i]) {break;}
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}
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Yuser = X[i] - X[i-1];
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if(Yuser != 0.0){
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Yuser = Y[i-1] + (Y[i] - Y[i-1]) * (Xuser - X[i-1]) / Yuser;
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}
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}
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return Yuser;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4ThreeVector G4MuMinusCaptureCascade::GetRandomVec()
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{
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//
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// generate uniform vector
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//
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G4double Theta = (2.0 * G4UniformRand() - 1.0) * pi ;
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G4double Phi = twopi * G4UniformRand() ;
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G4double sinTheta = sin(Theta);
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G4double dirx = sinTheta * cos(Phi);
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G4double diry = sinTheta * sin(Phi);
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G4double dirz = cos(Theta);
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return G4ThreeVector(dirx, diry, dirz);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4MuMinusCaptureCascade::AddNewParticle(G4ParticleDefinition* aParticle,
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G4ThreeVector Momentum,
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G4double mass,
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G4int* nParticle,
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G4GHEKinematicsVector* Cascade)
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{
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// Store particle in the HEK vector and increment counter
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Cascade[*nParticle].SetZero();
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Cascade[*nParticle].SetMass( mass );
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Cascade[*nParticle].SetMomentumAndUpdate(Momentum.x(), Momentum.y(), Momentum.z());
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Cascade[*nParticle].SetParticleDef( aParticle );
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(*nParticle)++;
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return;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4int G4MuMinusCaptureCascade::DoCascade(const G4double Z, const G4double massA,
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G4GHEKinematicsVector* Cascade)
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{
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// Inicialization - cascade start from 14th level
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// N.C.Mukhopadhyay Phy. Rep. 30 (1977) 1.
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G4int nPart = 0;
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G4double EnergyLevel[14];
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G4double mass = MuMass * massA / (MuMass + massA) ;
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const G4double KEnergy = 13.6 * eV * Z * Z * mass/ electron_mass_c2;
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EnergyLevel[0] = GetKShellEnergy(Z);
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for( G4int i = 2; i < 15; i++ ) {
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EnergyLevel[i-1] = KEnergy / (i*i) ;
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}
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G4int nElec = G4int(Z);
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G4int nAuger = 1;
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G4int nLevel = 13;
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G4double DeltaE;
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G4double pGamma = Z*Z*Z*Z;
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// Capture on 14-th level
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G4double ptot = sqrt(EnergyLevel[13]*(EnergyLevel[13] + 2.0*Emass));
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G4ThreeVector moment = ptot * GetRandomVec();
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AddNewParticle(theElectron,moment,Emass,&nPart,Cascade);
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// Emit new photon or electron
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// Simplified model for probabilities
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// N.C.Mukhopadhyay Phy. Rep. 30 (1977) 1.
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do {
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// case of Auger electrons
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if((nAuger < nElec) && ((pGamma + 10000.0) * G4UniformRand() < 10000.0) ) {
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nAuger++;
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DeltaE = EnergyLevel[nLevel-1] - EnergyLevel[nLevel];
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nLevel--;
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ptot = sqrt(DeltaE * (DeltaE + 2.0*Emass));
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moment = ptot * GetRandomVec();
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AddNewParticle(theElectron, moment, Emass, &nPart, Cascade);
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} else {
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// Case of photon cascade, probabilities from
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// C.S.Wu and L.Wilets, Ann. Rev. Nuclear Sci. 19 (1969) 527.
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G4double var = (10.0 + G4double(nLevel - 1) ) * G4UniformRand();
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G4int iLevel = nLevel - 1 ;
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if(var > 10.0) iLevel -= G4int(var-10.0) + 1;
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if( iLevel < 0 ) iLevel = 0;
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DeltaE = EnergyLevel[iLevel] - EnergyLevel[nLevel];
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nLevel = iLevel;
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moment = DeltaE * GetRandomVec();
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AddNewParticle(theGamma, moment, 0.0, &nPart, Cascade);
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}
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} while( nLevel > 0 );
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return nPart;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4MuMinusCaptureCascade::DoBoundMuonMinusDecay(G4double Z, G4double massA,
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G4int* nCascade,
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G4GHEKinematicsVector* Cascade)
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{
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// Simulation on Decay of mu- on a K-shell of the muonic atom
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G4double Energy, r, x;
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G4double xmax = ( 1.0 + Emass*Emass/ (MuMass*MuMass) );
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G4double KEnergy = GetKShellEnergy(Z);
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// Calculate electron energy
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do {
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do {
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x = xmax*G4UniformRand();
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} while (G4UniformRand() < (3.0 - 2.0*x)*x*x );
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Energy = x*MuMass*0.5 - Emass - KEnergy;
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} while (Energy < 0.0);
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//
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// generate uniform vector
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//
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G4double ptot = sqrt(Energy * (Energy + 2.0*Emass));
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G4ThreeVector moment = ptot * GetRandomVec();
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AddNewParticle(theElectron, moment, Emass, nCascade, Cascade);
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// Calculate rest frame parameters of 2 neutrinos
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G4double E = MuMass*( 1.0 - x*0.5 );
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G4double P = sqrt( MuMass*MuMass*x*x*0.25 - Emass*Emass );
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if(P >= E) {P = E;}
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G4double ecm = 0.5 * sqrt( E*E - P*P );
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//
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// generate uniform vector
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//
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moment *= -P / (ptot * E);
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G4ThreeVector p1 = ecm * GetRandomVec();
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// Create Neutrinos
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G4LorentzVector N1 = G4LorentzVector(p1,ecm);
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N1.boost(moment);
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AddNewParticle(G4AntiNeutrinoE::AntiNeutrinoE(),G4ThreeVector(N1),0.0,nCascade,Cascade);
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G4LorentzVector N2 = G4LorentzVector(-p1,ecm);
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N2.boost(moment);
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AddNewParticle(G4NeutrinoMu::NeutrinoMu(),G4ThreeVector(N2),0.0,nCascade,Cascade);
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return;
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}
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