Gabriele Cosmo
190 lines
5.9 KiB
C++
190 lines
5.9 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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// File name: G4PiMinusStopMaterial
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//
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// Author: Maria Grazia Pia (pia@genova.infn.it)
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//
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// Creation date: 8 May 1998
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//
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// -------------------------------------------------------------------
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#include "G4ios.hh"
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#include "G4PiMinusStopMaterial.hh"
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#include <vector>
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#include "globals.hh"
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#include "Randomize.hh"
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#include "G4Proton.hh"
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#include "G4Neutron.hh"
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#include "G4PionMinus.hh"
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#include "G4ParticleTypes.hh"
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#include "G4ReactionKinematics.hh"
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#include "G4DynamicParticleVector.hh"
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#include "G4LorentzVector.hh"
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#include "G4PiMinusStopMaterial.hh"
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#include "G4DistributionGenerator.hh"
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// Constructor
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G4PiMinusStopMaterial::G4PiMinusStopMaterial()
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{
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_definitions = 0;
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_momenta = 0;
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_distributionE = 0;
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_distributionAngle = 0;
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theR = 0.5;
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}
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// Destructor
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G4PiMinusStopMaterial::~G4PiMinusStopMaterial()
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{
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if (_definitions != 0) delete _definitions;
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_definitions = 0;
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for (unsigned int i=0; i<_momenta->size(); i++) delete(*_momenta)[i];
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if (_momenta != 0) delete _momenta;
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delete _distributionE;
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delete _distributionAngle;
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}
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std::vector<G4ParticleDefinition*>* G4PiMinusStopMaterial::DefinitionVector()
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{
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_definitions->push_back(G4Neutron::Neutron());
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G4double ranflat = G4UniformRand();
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if (ranflat < theR)
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{ _definitions->push_back(G4Proton::Proton()); }
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else
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{ _definitions->push_back(G4Neutron::Neutron()); }
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return _definitions;
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}
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std::vector<G4LorentzVector*>*
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G4PiMinusStopMaterial::P4Vector(const G4double binding,
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const G4double massNucleus)
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{
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// Generate energy of direct absorption products according to experimental
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// data. The energy distribution of the two nucleons is assumed to be the
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// same for protons and neutrons.
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G4double eKin1;
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G4double eKin2;
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G4double eRecoil;
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// Assume absorption on two nucleons
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G4int nNucleons = 2;
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G4double availableE = G4PionMinus::PionMinus()->GetPDGMass() - nNucleons * binding;
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G4LorentzVector p1;
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G4LorentzVector p2;
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do
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{
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G4double ranflat;
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G4double p;
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G4double energy;
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G4double mass;
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ranflat = G4UniformRand();
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eKin1 = _distributionE->Generate(ranflat);
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mass = (*_definitions)[0]->GetPDGMass();
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energy = eKin1 + mass;
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p = std::sqrt(energy*energy - mass*mass);
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G4double theta1 = pi*G4UniformRand();
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G4double phi1 = GenerateAngle(2.*pi);
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p1 = MakeP4(p,theta1,phi1,energy);
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ranflat = G4UniformRand();
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eKin2 = _distributionE->Generate(ranflat);
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mass = (*_definitions)[1]->GetPDGMass();
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energy = eKin2 + mass;
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p = std::sqrt(energy*energy - mass*mass);
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ranflat = G4UniformRand();
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G4double opAngle = _distributionAngle->Generate(ranflat);
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G4double theta2 = theta1 + opAngle;
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G4double phi2 = phi1 + opAngle;
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p2 = MakeP4(p,theta2,phi2,energy);
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G4double pNucleus = (p1.vect() + p2.vect()).mag();
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eRecoil = std::sqrt(pNucleus*pNucleus + massNucleus*massNucleus) - massNucleus;
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// ---- Debug
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// G4cout << " ---- binding = " << binding << ", nucleus mass = " << massNucleus
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// << ", p nucleus = " << pNucleus << G4endl;
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// G4cout << "eKin1,2 " << eKin1 << " " << eKin2 << " eRecoil " << eRecoil
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// << " availableE " << availableE << G4endl;
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// ----
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} while ((eKin1 + eKin2 + eRecoil) > availableE);
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_momenta->push_back(new G4LorentzVector(p1));
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_momenta->push_back(new G4LorentzVector(p2));
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return _momenta;
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}
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G4double G4PiMinusStopMaterial::GenerateAngle(G4double x)
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{
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G4double ranflat = G4UniformRand();
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G4double value = ranflat * x;
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return value;
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}
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G4LorentzVector G4PiMinusStopMaterial::MakeP4(G4double p, G4double theta, G4double phi, G4double e)
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{
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// G4LorentzVector p4;
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G4double px = p * std::sin(theta) * std::cos(phi);
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G4double py = p * std::sin(theta) * std::sin(phi);
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G4double pz = p * std::cos(theta);
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G4LorentzVector p4(px,py,pz,e);
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return p4;
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}
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G4double G4PiMinusStopMaterial::RecoilEnergy(const G4double mass)
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{
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G4ThreeVector p(0.,0.,0.);
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for (unsigned int i = 0; i< _momenta->size(); i++)
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{
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p = p + (*_momenta)[i]->vect();
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}
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G4double pNucleus = p.mag();
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G4double eNucleus = std::sqrt(pNucleus*pNucleus + mass*mass);
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return eNucleus;
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}
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