Gabriele Cosmo
240 lines
8.0 KiB
C++
240 lines
8.0 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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// $Id: G4NeutronBetaDecayChannel.cc 91896 2015-08-10 09:54:06Z gcosmo $
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// GEANT4 tag $Name: geant4-09-04-ref-00 $
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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: first implementation, based on object model of
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// 18 Sep 2001 H.Kurashige
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//---
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// Fix energy of proton and neutrino May 2011 H.Kurashige
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// Fix direction of proton and neutrino Nov 2013 H.Kurashige
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// ------------------------------------------------------------
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#include "G4ParticleDefinition.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "G4DecayProducts.hh"
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#include "G4VDecayChannel.hh"
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#include "G4NeutronBetaDecayChannel.hh"
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#include "Randomize.hh"
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#include "G4RotationMatrix.hh"
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#include "G4LorentzVector.hh"
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#include "G4LorentzRotation.hh"
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G4NeutronBetaDecayChannel::G4NeutronBetaDecayChannel()
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:G4VDecayChannel(),
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aENuCorr(-0.102)
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{
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}
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G4NeutronBetaDecayChannel::G4NeutronBetaDecayChannel(
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const G4String& theParentName,
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G4double theBR)
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:G4VDecayChannel("Neutron Decay"),
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aENuCorr(-0.102)
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{
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// set names for daughter particles
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if (theParentName == "neutron") {
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SetBR(theBR);
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SetParent("neutron");
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SetNumberOfDaughters(3);
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SetDaughter(0, "e-");
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SetDaughter(1, "anti_nu_e");
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SetDaughter(2, "proton");
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} else if (theParentName == "anti_neutron") {
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SetBR(theBR);
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SetParent("anti_neutron");
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SetNumberOfDaughters(3);
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SetDaughter(0, "e+");
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SetDaughter(1, "nu_e");
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SetDaughter(2, "anti_proton");
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} else {
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>0) {
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G4cout << "G4NeutronBetaDecayChannel:: constructor :";
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G4cout << " parent particle is not neutron 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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}
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G4NeutronBetaDecayChannel::~G4NeutronBetaDecayChannel()
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{
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}
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G4NeutronBetaDecayChannel::G4NeutronBetaDecayChannel(const G4NeutronBetaDecayChannel &right)
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: G4VDecayChannel(right),
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aENuCorr(-0.102)
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{
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}
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G4NeutronBetaDecayChannel & G4NeutronBetaDecayChannel::operator=(const G4NeutronBetaDecayChannel & 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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}
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return *this;
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}
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G4DecayProducts *G4NeutronBetaDecayChannel::DecayIt(G4double)
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{
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// This class describes free neutron beta decay kinemtics.
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// This version neglects neutron/electron polarization
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// without Coulomb effect
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>1) G4cout << "G4NeutronBetaDecayChannel::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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//daughters'mass
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G4double daughtermass[3];
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G4double sumofdaughtermass = 0.0;
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for (G4int index=0; index<3; 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 xmax = parentmass-sumofdaughtermass;
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//create parent G4DynamicParticle at rest
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G4ThreeVector dummy;
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G4DynamicParticle * parentparticle = 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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// calculate daughter momentum
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G4double daughtermomentum[3];
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// calcurate electron energy
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G4double x; // Ee
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G4double p; // Pe
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G4double dm = daughtermass[0]; //Me
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G4double w; // cosine of e-nu angle
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G4double r;
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G4double r0;
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const size_t MAX_LOOP=10000;
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for (size_t loop_counter=0; loop_counter <MAX_LOOP; ++loop_counter){
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x = xmax*G4UniformRand();
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p = std::sqrt(x*(x+2.0*dm));
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w = 1.0-2.0*G4UniformRand();
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r = p*(x+dm)*(xmax-x)*(xmax-x)*(1.0+aENuCorr*p/(x+dm)*w);
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r0 = G4UniformRand()*(xmax+dm)*(xmax+dm)*xmax*xmax*(1.0+aENuCorr);
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if (r > r0) break;
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}
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//create daughter G4DynamicParticle
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// rotation materix to lab frame
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G4double costheta = 2.*G4UniformRand()-1.0;
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G4double theta = std::acos(costheta)*rad;
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G4double phi = twopi*G4UniformRand()*rad;
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G4RotationMatrix rm;
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rm.rotateY(theta);
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rm.rotateZ(phi);
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// daughter 0 (electron) in Z direction
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daughtermomentum[0] = p;
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G4ThreeVector direction0(0.0, 0.0, 1.0);
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direction0 = rm * direction0;
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G4DynamicParticle * daughterparticle0
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= new G4DynamicParticle( G4MT_daughters[0], direction0*daughtermomentum[0]);
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products->PushProducts(daughterparticle0);
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// daughter 1 (nutrino) in XZ plane
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G4double eNu; // Enu
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eNu = (parentmass-daughtermass[2])*(parentmass+daughtermass[2])+(dm*dm)-2.*parentmass*(x+dm);
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eNu /= 2.*(parentmass+p*w-(x+dm));
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G4double cosn = w;
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G4double phin = twopi*G4UniformRand()*rad;
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G4double sinn = std::sqrt((1.0-cosn)*(1.0+cosn));
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G4ThreeVector direction1(sinn*std::cos(phin), sinn*std::sin(phin), cosn);
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direction1 = rm * direction1;
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G4DynamicParticle * daughterparticle1
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= new G4DynamicParticle( G4MT_daughters[1], direction1*eNu);
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products->PushProducts(daughterparticle1);
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// daughter 2 (proton) at REST
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G4double eP; // Eproton
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eP = parentmass-eNu-(x+dm)-daughtermass[2];
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G4double pPx = -eNu*sinn;
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G4double pPz = -p-eNu*cosn;
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G4double pP = std::sqrt(eP*(eP+2.*daughtermass[2]));
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G4ThreeVector direction2(pPx/pP*std::cos(phin), pPx/pP*std::sin(phin), pPz/pP);
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G4DynamicParticle * daughterparticle2
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= new G4DynamicParticle( G4MT_daughters[2], direction2);
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products->PushProducts(daughterparticle2);
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// output message
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#ifdef G4VERBOSE
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if (GetVerboseLevel()>1) {
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G4cout << "G4NeutronBetaDecayChannel::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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