Gabriele Cosmo
188 lines
6.5 KiB
C++
188 lines
6.5 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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// Multibody "phase space" generator, which provides multiple algorithms
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// for sampling. Momentum vectors are generated in the center-of-mass
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// frame of the decay, and returned in a user-supplied buffer. A sampling
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// algorithm is specified via constructor argument.
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//
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// Author: Michael Kelsey (SLAC) <kelsey@slac.stanford.edu>
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#include "G4HadDecayGenerator.hh"
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#include "G4VHadDecayAlgorithm.hh"
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#include "G4HadPhaseSpaceKopylov.hh"
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#include "G4HadPhaseSpaceGenbod.hh"
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#include "G4HadPhaseSpaceNBodyAsai.hh"
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#include "G4HadronicException.hh"
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#include "G4LorentzVector.hh"
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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 "G4ThreeVector.hh"
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#include "Randomize.hh"
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#include <vector>
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#include <algorithm>
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#include <numeric>
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#include <iterator>
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#include <iostream>
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// Constructors and destructor
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G4HadDecayGenerator::G4HadDecayGenerator(Algorithm alg, G4int verbose)
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: verboseLevel(verbose), theAlgorithm(0) {
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switch (alg) {
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case Kopylov: theAlgorithm = new G4HadPhaseSpaceKopylov(verboseLevel); break;
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case GENBOD: theAlgorithm = new G4HadPhaseSpaceGenbod(verboseLevel); break;
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case NBody: theAlgorithm = new G4HadPhaseSpaceNBodyAsai(verboseLevel); break;
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case NONE: theAlgorithm = 0; break; // User may explicitly set no algorithm
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default: ReportInvalidAlgorithm(alg);
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}
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if (verboseLevel) {
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G4cout << " >>> G4HadDecayGenerator";
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if (theAlgorithm) G4cout << " using " << theAlgorithm->GetName();
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G4cout << G4endl;
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}
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}
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G4HadDecayGenerator::G4HadDecayGenerator(G4VHadDecayAlgorithm* alg,
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G4int verbose)
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: verboseLevel(verbose), theAlgorithm(alg) {
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if (verboseLevel) {
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G4cout << " >>> G4HadDecayGenerator";
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if (theAlgorithm) G4cout << " using " << theAlgorithm->GetName();
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G4cout << G4endl;
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}
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}
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G4HadDecayGenerator::~G4HadDecayGenerator() {
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delete theAlgorithm;
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theAlgorithm = 0;
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}
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// Sanity checks -- throws exception if no algorithm chosen
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void G4HadDecayGenerator::ReportInvalidAlgorithm(Algorithm alg) const {
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if (verboseLevel)
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G4cerr << "G4HadDecayGenerator: bad algorithm code " << alg << G4endl;
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throw G4HadronicException(__FILE__, __LINE__, "Invalid algorithm code");
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}
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void G4HadDecayGenerator::ReportMissingAlgorithm() const {
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if (verboseLevel)
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G4cerr << "G4HadDecayGenerator: no algorithm specified" << G4endl;
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throw G4HadronicException(__FILE__, __LINE__, "Null algorithm pointer");
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}
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// Enable (or disable if 0) diagnostic messages
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void G4HadDecayGenerator::SetVerboseLevel(G4int verbose) {
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verboseLevel = verbose;
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if (theAlgorithm) theAlgorithm->SetVerboseLevel(verbose);
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}
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const G4String& G4HadDecayGenerator::GetAlgorithmName() const {
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static const G4String& none = "NONE";
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return (theAlgorithm ? theAlgorithm->GetName() : none);
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}
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// Initial state (rest mass) and list of final masses
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G4bool
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G4HadDecayGenerator::Generate(G4double initialMass,
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const std::vector<G4double>& masses,
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std::vector<G4LorentzVector>& finalState) {
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if (verboseLevel)
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G4cout << " >>> G4HadDecayGenerator::Generate (mass)" << G4endl;
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if (!theAlgorithm) ReportMissingAlgorithm();
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if (masses.size() == 1U)
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return GenerateOneBody(initialMass, masses, finalState);
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theAlgorithm->Generate(initialMass, masses, finalState);
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return !finalState.empty(); // Generator failure returns empty state
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}
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// Initial state particle and list of final masses
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G4bool
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G4HadDecayGenerator::Generate(const G4ParticleDefinition* initialPD,
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const std::vector<G4double>& masses,
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std::vector<G4LorentzVector>& finalState) {
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if (verboseLevel)
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G4cout << " >>> G4HadDecayGenerator::Generate (particle)" << G4endl;
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return (initialPD && Generate(initialPD->GetPDGMass(), masses, finalState));
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}
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// Final state particles will be boosted to initial-state frame
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G4bool
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G4HadDecayGenerator::Generate(const G4LorentzVector& initialState,
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const std::vector<G4double>& masses,
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std::vector<G4LorentzVector>& finalState) {
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if (verboseLevel)
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G4cout << " >>> G4HadDecayGenerator::Generate (frame)" << G4endl;
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G4bool good = Generate(initialState.m(), masses, finalState);
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if (good) {
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G4ThreeVector bv = initialState.boostVector();
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for (size_t i=0; i<finalState.size(); i++) {
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finalState[i].boost(bv);
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}
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}
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return good;
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}
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// Handle special case of "one body decay" (used for kaon mixing)
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G4bool G4HadDecayGenerator::
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GenerateOneBody(G4double initialMass,
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const std::vector<G4double>& masses,
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std::vector<G4LorentzVector>& finalState) const {
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if (verboseLevel>1)
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G4cout << " >>> G4HadDecayGenerator::GenerateOneBody" << G4endl;
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// Initialization and sanity checks
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finalState.clear();
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if (masses.size() != 1U) return false; // Should not have been called
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if (std::fabs(initialMass-masses[0]) > eV) return false;
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if (verboseLevel>2) G4cout << " finalState mass = " << masses[0] << G4endl;
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finalState.push_back(G4LorentzVector(0.,0.,0.,masses[0]));
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return true;
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}
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