Gabriele Cosmo
280 lines
8.3 KiB
C++
280 lines
8.3 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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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. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// ------------------------------------------------------------
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// GEANT 4 class header file
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//
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// History:
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// 01 August 2007 P.Gumplinger
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// Reference: TRIUMF PIENU Technote:
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// M. Blecher - "Inclusion of pi->enug in MC "
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// Rate is for gammas > 100keV
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//
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// ------------------------------------------------------------
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//
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//
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//
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#include "G4PionRadiativeDecayChannel.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "Randomize.hh"
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#include "G4DecayProducts.hh"
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#include "G4LorentzVector.hh"
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G4PionRadiativeDecayChannel::G4PionRadiativeDecayChannel()
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: G4VDecayChannel(),
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beta(0.),cib(0.),csdp(0.),csdm(0.),cif(0.),cig(0.),
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xl(0.), yl(0.), xu(0.), yu(0.), d2wmax(0.)
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{
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}
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G4PionRadiativeDecayChannel::
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G4PionRadiativeDecayChannel(const G4String& theParentName,
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G4double theBR)
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: G4VDecayChannel("Radiative Pion Decay",1)
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{
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// set names for daughter particles
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if (theParentName == "pi+") {
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SetBR(theBR);
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SetParent("pi+");
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SetNumberOfDaughters(3);
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SetDaughter(0, "e+");
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SetDaughter(1, "gamma");
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SetDaughter(2, "nu_e");
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} else if (theParentName == "pi-") {
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SetBR(theBR);
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SetParent("pi-");
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SetNumberOfDaughters(3);
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SetDaughter(0, "e-");
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SetDaughter(1, "gamma");
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SetDaughter(2, "anti_nu_e");
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} else {
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>0) {
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G4cout << "G4RadiativePionDecayChannel:: constructor :";
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G4cout << " parent particle is not charged pion but ";
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G4cout << theParentName << G4endl;
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}
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#endif
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}
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beta = 3.6612e-03;
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cib = 1.16141e-03;
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csdp = 3.45055e-02;
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csdm = 5.14122e-03;
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cif = 4.63543e-05;
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cig = 1.78928e-05;
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xl = 2.*0.1*MeV/139.57*MeV;
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yl = ((1.-xl) + std::sqrt((1-xl)*(1-xl)+4*beta*beta))/2.;
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xu = 1. - (yl - std::sqrt(yl*yl-4.*beta*beta))/2.;
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yu = 1. + beta*beta;
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d2wmax = D2W(xl,yl);
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}
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G4PionRadiativeDecayChannel::~G4PionRadiativeDecayChannel()
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{
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}
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G4PionRadiativeDecayChannel::G4PionRadiativeDecayChannel(const G4PionRadiativeDecayChannel &right)
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:G4VDecayChannel(right),
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beta(right.beta),cib(right.cib),csdp(right.csdp),
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csdm(right.csdm),cif(right.cif),cig(right.cig),
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xl(right.xl), yl(right.yl), xu(right.xu), yu(right.yu),
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d2wmax(right.d2wmax)
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{
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}
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G4PionRadiativeDecayChannel & G4PionRadiativeDecayChannel::operator=(const G4PionRadiativeDecayChannel & right)
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{
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if (this != &right) {
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kinematics_name = right.kinematics_name;
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verboseLevel = right.verboseLevel;
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rbranch = right.rbranch;
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// copy parent name
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parent_name = new G4String(*right.parent_name);
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// clear daughters_name array
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ClearDaughtersName();
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// recreate array
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numberOfDaughters = right.numberOfDaughters;
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if ( numberOfDaughters >0 ) {
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if (daughters_name !=0) ClearDaughtersName();
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daughters_name = new G4String*[numberOfDaughters];
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//copy daughters name
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for (G4int index=0; index < numberOfDaughters; index++) {
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daughters_name[index] = new G4String(*right.daughters_name[index]);
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}
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}
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beta = right.beta;
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cib = right.cib;
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csdp = right.csdp;
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csdm = right.csdm;
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cif = right.cif;
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cig = right.cig;
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xl = right.xl;
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yl = right.yl;
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xu = right.xu;
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yu = right.yu;
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d2wmax = right.d2wmax;
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}
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return *this;
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}
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G4DecayProducts *G4PionRadiativeDecayChannel::DecayIt(G4double)
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{
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>1)
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G4cout << "G4PionRadiativeDecayChannel::DecayIt ";
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#endif
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if (G4MT_parent == 0) FillParent();
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if (G4MT_daughters == 0) FillDaughters();
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// parent mass
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G4double parentmass = G4MT_parent->GetPDGMass();
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G4double EMPI = parentmass;
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//daughters'mass
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const G4int N_DAUGHTER=3;
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G4double daughtermass[N_DAUGHTER];
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G4double sumofdaughtermass = 0.0;
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for (G4int index=0; index<N_DAUGHTER; index++){
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daughtermass[index] = G4MT_daughters[index]->GetPDGMass();
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sumofdaughtermass += daughtermass[index];
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}
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G4double EMASS = daughtermass[0];
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//create parent G4DynamicParticle at rest
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G4ThreeVector dummy;
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G4DynamicParticle * parentparticle =
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new G4DynamicParticle( G4MT_parent, dummy, 0.0);
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//create G4Decayproducts
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G4DecayProducts *products = new G4DecayProducts(*parentparticle);
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delete parentparticle;
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G4double x, y;
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const size_t MAX_LOOP=1000;
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for (size_t loop_counter1=0; loop_counter1<MAX_LOOP; ++loop_counter1){
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for (size_t loop_counter2=0; loop_counter2<MAX_LOOP; ++loop_counter2){
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x = xl + G4UniformRand()*(xu-xl);
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y = yl + G4UniformRand()*(yu-yl);
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if (x+y > 1.) break;
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}
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G4double d2w = D2W(x,y);
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if (d2w > G4UniformRand()*d2wmax) break;
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}
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//-----------------------------------------------------------------------
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//
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// Calculate the angle between positron and photon (cosine)
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//
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G4double cthetaGE = (y*(x-2.)+2.*(1.-x+beta*beta)) /
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(x*std::sqrt(y*y-4.*beta*beta));
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//
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//-----------------------------------------------------------------------
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//
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G4double G = x * EMPI/2.;
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G4double E = y * EMPI/2.;
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//
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//-----------------------------------------------------------------------
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//
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if (E < EMASS) E = EMASS;
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// calculate daughter momentum
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G4double daughtermomentum[2];
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daughtermomentum[0] = std::sqrt(E*E - EMASS*EMASS);
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G4double cthetaE = 2.*G4UniformRand()-1.;
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G4double sthetaE = std::sqrt(1.-cthetaE*cthetaE);
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G4double phiE = twopi*G4UniformRand()*rad;
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G4double cphiE = std::cos(phiE);
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G4double sphiE = std::sin(phiE);
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//Coordinates of the decay positron
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G4double px = sthetaE*cphiE;
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G4double py = sthetaE*sphiE;
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G4double pz = cthetaE;
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G4ThreeVector direction0(px,py,pz);
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G4DynamicParticle * daughterparticle0
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= new G4DynamicParticle( G4MT_daughters[0], daughtermomentum[0]*direction0);
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products->PushProducts(daughterparticle0);
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daughtermomentum[1] = G;
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G4double sthetaGE = std::sqrt(1.-cthetaGE*cthetaGE);
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G4double phiGE = twopi*G4UniformRand()*rad;
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G4double cphiGE = std::cos(phiGE);
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G4double sphiGE = std::sin(phiGE);
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//Coordinates of the decay gamma with respect to the decay positron
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px = sthetaGE*cphiGE;
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py = sthetaGE*sphiGE;
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pz = cthetaGE;
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G4ThreeVector direction1(px,py,pz);
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direction1.rotateUz(direction0);
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G4DynamicParticle * daughterparticle1
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= new G4DynamicParticle( G4MT_daughters[1], daughtermomentum[1]*direction1);
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products->PushProducts(daughterparticle1);
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// output message
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>1) {
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G4cout << "G4PionRadiativeDecayChannel::DecayIt ";
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G4cout << " create decay products in rest frame " <<G4endl;
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products->DumpInfo();
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}
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#endif
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return products;
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}
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