Gabriele Cosmo
501 lines
14 KiB
C++
501 lines
14 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 implementation file
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//
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// ---------------- G4Fancy3DNucleus ----------------
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// by Gunter Folger, May 1998.
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// class for a 3D nucleus, arranging nucleons in space and momentum.
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// ------------------------------------------------------------
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// 20110805 M. Kelsey -- Remove C-style array (pointer) of G4Nucleons,
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// make vector a container of objects. Move Helper class
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// to .hh. Move testSums, places, momentum and fermiM to
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// class data members for reuse.
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#include <algorithm>
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#include "G4Fancy3DNucleus.hh"
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#include "G4Fancy3DNucleusHelper.hh"
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#include "G4NuclearFermiDensity.hh"
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#include "G4NuclearShellModelDensity.hh"
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#include "G4NucleiProperties.hh"
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#include "G4Nucleon.hh"
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#include "G4SystemOfUnits.hh"
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#include "Randomize.hh"
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#include "G4ios.hh"
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#include "G4HadronicException.hh"
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G4Fancy3DNucleus::G4Fancy3DNucleus()
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: myA(0), myZ(0), theNucleons(250), currentNucleon(-1), theDensity(0),
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nucleondistance(0.8*fermi),excitationEnergy(0.),
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places(250), momentum(250), fermiM(250), testSums(250)
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{
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//G4cout <<"G4Fancy3DNucleus::G4Fancy3DNucleus()"<<G4endl;
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}
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G4Fancy3DNucleus::~G4Fancy3DNucleus()
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{
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if(theDensity) delete theDensity;
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}
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#if defined(NON_INTEGER_A_Z)
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void G4Fancy3DNucleus::Init(G4double theA, G4double theZ)
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{
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G4int intZ = G4int(theZ);
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G4int intA= ( G4UniformRand()>theA-G4int(theA) ) ? G4int(theA) : G4int(theA)+1;
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// forward to integer Init()
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Init(intA, intZ);
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}
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#endif
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void G4Fancy3DNucleus::Init(G4int theA, G4int theZ)
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{
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// G4cout << "G4Fancy3DNucleus::Init(theA, theZ) called"<<G4endl;
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currentNucleon=-1;
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theNucleons.clear();
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myZ = theZ;
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myA= theA;
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excitationEnergy=0;
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theNucleons.resize(myA); // Pre-loads vector with empty elements
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// G4cout << "myA, myZ" << myA << ", " << myZ << G4endl;
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if(theDensity) delete theDensity;
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if ( myA < 17 ) {
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theDensity = new G4NuclearShellModelDensity(myA, myZ);
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} else {
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theDensity = new G4NuclearFermiDensity(myA, myZ);
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}
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theFermi.Init(myA, myZ);
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ChooseNucleons();
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ChoosePositions();
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// CenterNucleons(); // This would introduce a bias
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ChooseFermiMomenta();
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G4double Ebinding= BindingEnergy()/myA;
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for (G4int aNucleon=0; aNucleon < myA; aNucleon++)
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{
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theNucleons[aNucleon].SetBindingEnergy(Ebinding);
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}
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return;
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}
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G4bool G4Fancy3DNucleus::StartLoop()
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{
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currentNucleon=0;
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return (theNucleons.size()>0);
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}
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// Returns by pointer; null pointer indicates end of loop
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G4Nucleon * G4Fancy3DNucleus::GetNextNucleon()
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{
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return ( (currentNucleon>=0 && currentNucleon<myA) ?
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&theNucleons[currentNucleon++] : 0 );
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}
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const std::vector<G4Nucleon> & G4Fancy3DNucleus::GetNucleons()
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{
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return theNucleons;
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}
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// Class-scope function to sort nucleons by Z coordinate
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bool G4Fancy3DNucleusHelperForSortInZ(const G4Nucleon& nuc1, const G4Nucleon& nuc2)
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{
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return nuc1.GetPosition().z() < nuc2.GetPosition().z();
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}
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void G4Fancy3DNucleus::SortNucleonsIncZ() // on increased Z-coordinates Uzhi 29.08.08
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{
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if (theNucleons.size() < 2 ) return; // Avoid unnecesary work
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std::sort(theNucleons.begin(), theNucleons.end(),
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G4Fancy3DNucleusHelperForSortInZ);
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}
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void G4Fancy3DNucleus::SortNucleonsDecZ() // on decreased Z-coordinates Uzhi 29.08.08
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{
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if (theNucleons.size() < 2 ) return; // Avoid unnecessary work
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SortNucleonsIncZ();
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std::reverse(theNucleons.begin(), theNucleons.end());
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}
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G4double G4Fancy3DNucleus::BindingEnergy()
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{
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return G4NucleiProperties::GetBindingEnergy(myA,myZ);
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}
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G4double G4Fancy3DNucleus::GetNuclearRadius()
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{
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return GetNuclearRadius(0.5);
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}
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G4double G4Fancy3DNucleus::GetNuclearRadius(const G4double maxRelativeDensity)
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{
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return theDensity->GetRadius(maxRelativeDensity);
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}
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G4double G4Fancy3DNucleus::GetOuterRadius()
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{
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G4double maxradius2=0;
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for (int i=0; i<myA; i++)
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{
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if ( theNucleons[i].GetPosition().mag2() > maxradius2 )
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{
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maxradius2=theNucleons[i].GetPosition().mag2();
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}
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}
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return std::sqrt(maxradius2)+nucleondistance;
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}
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G4double G4Fancy3DNucleus::GetMass()
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{
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return myZ*G4Proton::Proton()->GetPDGMass() +
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(myA-myZ)*G4Neutron::Neutron()->GetPDGMass() -
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BindingEnergy();
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}
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void G4Fancy3DNucleus::DoLorentzBoost(const G4LorentzVector & theBoost)
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{
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for (G4int i=0; i<myA; i++){
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theNucleons[i].Boost(theBoost);
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}
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}
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void G4Fancy3DNucleus::DoLorentzBoost(const G4ThreeVector & theBeta)
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{
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for (G4int i=0; i<myA; i++){
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theNucleons[i].Boost(theBeta);
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}
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}
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void G4Fancy3DNucleus::DoLorentzContraction(const G4ThreeVector & theBeta)
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{
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G4double beta2=theBeta.mag2();
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if (beta2 > 0) {
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G4double factor=(1-std::sqrt(1-beta2))/beta2; // (gamma-1)/gamma/beta**2
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G4ThreeVector rprime;
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for (G4int i=0; i< myA; i++) {
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rprime = theNucleons[i].GetPosition() -
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factor * (theBeta*theNucleons[i].GetPosition()) * theBeta;
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theNucleons[i].SetPosition(rprime);
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}
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}
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}
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void G4Fancy3DNucleus::DoLorentzContraction(const G4LorentzVector & theBoost)
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{
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if (theBoost.e() !=0 ) {
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G4ThreeVector beta = theBoost.vect()/theBoost.e();
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DoLorentzContraction(beta);
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}
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}
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void G4Fancy3DNucleus::CenterNucleons()
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{
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G4ThreeVector center;
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for (G4int i=0; i<myA; i++ )
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{
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center+=theNucleons[i].GetPosition();
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}
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center /= -myA;
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DoTranslation(center);
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}
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void G4Fancy3DNucleus::DoTranslation(const G4ThreeVector & theShift)
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{
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G4ThreeVector tempV;
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for (G4int i=0; i<myA; i++ )
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{
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tempV = theNucleons[i].GetPosition() + theShift;
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theNucleons[i].SetPosition(tempV);
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}
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}
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const G4VNuclearDensity * G4Fancy3DNucleus::GetNuclearDensity() const
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{
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return theDensity;
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}
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//----------------------- private Implementation Methods-------------
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void G4Fancy3DNucleus::ChooseNucleons()
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{
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G4int protons=0,nucleons=0;
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while (nucleons < myA )
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{
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if ( protons < myZ && G4UniformRand() < (G4double)(myZ-protons)/(G4double)(myA-nucleons) )
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{
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protons++;
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theNucleons[nucleons++].SetParticleType(G4Proton::Proton());
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}
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else if ( (nucleons-protons) < (myA-myZ) )
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{
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theNucleons[nucleons++].SetParticleType(G4Neutron::Neutron());
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}
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else G4cout << "G4Fancy3DNucleus::ChooseNucleons not efficient" << G4endl;
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}
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return;
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}
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void G4Fancy3DNucleus::ChoosePositions()
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{
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G4int i=0;
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G4ThreeVector aPos, delta;
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G4bool freeplace;
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static G4ThreadLocal G4double *nd2_G4MT_TLS_ = 0 ; if (!nd2_G4MT_TLS_) {nd2_G4MT_TLS_ = new G4double ; *nd2_G4MT_TLS_= sqr(nucleondistance) ; } G4double &nd2 = *nd2_G4MT_TLS_;
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G4double maxR=GetNuclearRadius(0.001); // there are no nucleons at a
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// relative Density of 0.01
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G4int jr=0;
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G4int jx,jy;
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G4double arand[600];
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G4double *prand=arand;
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places.clear(); // Reset data buffer
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while ( i < myA )
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{
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do
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{
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if ( jr < 3 )
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{
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jr=std::min(600,9*(myA - i));
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G4RandFlat::shootArray(jr,prand);
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//CLHEP::RandFlat::shootArray(jr, prand );
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}
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jx=--jr;
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jy=--jr;
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aPos.set((2*arand[jx]-1.), (2*arand[jy]-1.), (2*arand[--jr]-1.));
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} while (aPos.mag2() > 1. );
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aPos *=maxR;
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G4double density=theDensity->GetRelativeDensity(aPos);
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if (G4UniformRand() < density)
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{
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freeplace= true;
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std::vector<G4ThreeVector>::iterator iplace;
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for( iplace=places.begin(); iplace!=places.end() && freeplace;++iplace)
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{
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delta = *iplace - aPos;
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freeplace= delta.mag2() > nd2;
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}
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if ( freeplace )
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{
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G4double pFermi=theFermi.GetFermiMomentum(theDensity->GetDensity(aPos));
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// protons must at least have binding energy of CoulombBarrier, so
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// assuming the Fermi energy corresponds to a potential, we must place these such
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// that the Fermi Energy > CoulombBarrier
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if (theNucleons[i].GetDefinition() == G4Proton::Proton())
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{
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G4double nucMass = theNucleons[i].GetDefinition()->GetPDGMass();
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G4double eFermi= std::sqrt( sqr(pFermi) + sqr(nucMass) )
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- nucMass;
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if (eFermi <= CoulombBarrier() ) freeplace=false;
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}
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}
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if ( freeplace )
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{
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theNucleons[i].SetPosition(aPos);
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places.push_back(aPos);
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++i;
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}
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}
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}
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}
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void G4Fancy3DNucleus::ChooseFermiMomenta()
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{
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G4int i;
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G4double density;
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// Pre-allocate buffers for filling by index
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momentum.resize(myA, G4ThreeVector(0.,0.,0.));
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fermiM.resize(myA, 0.*GeV);
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for (G4int ntry=0; ntry<1 ; ntry ++ )
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{
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for (i=0; i < myA; i++ ) // momenta for all, including last, in case we swap nucleons
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{
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density = theDensity->GetDensity(theNucleons[i].GetPosition());
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fermiM[i] = theFermi.GetFermiMomentum(density);
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G4ThreeVector mom=theFermi.GetMomentum(density);
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if (theNucleons[i].GetDefinition() == G4Proton::Proton())
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{
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G4double eMax = std::sqrt(sqr(fermiM[i]) +sqr(theNucleons[i].GetDefinition()->GetPDGMass()) )
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- CoulombBarrier();
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if ( eMax > theNucleons[i].GetDefinition()->GetPDGMass() )
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{
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G4double pmax2= sqr(eMax) - sqr(theNucleons[i].GetDefinition()->GetPDGMass());
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fermiM[i] = std::sqrt(pmax2);
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while ( mom.mag2() > pmax2 )
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{
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mom=theFermi.GetMomentum(density, fermiM[i]);
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}
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} else
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{
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G4cerr << "G4Fancy3DNucleus: difficulty finding proton momentum" << G4endl;
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mom=G4ThreeVector(0,0,0);
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}
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}
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momentum[i]= mom;
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}
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if ( ReduceSum() ) break;
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// G4cout <<" G4FancyNucleus: iterating to find momenta: "<< ntry<< G4endl;
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}
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// G4ThreeVector sum;
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// for (G4int index=0; index<myA;sum+=momentum[index++])
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// ;
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// G4cout << "final sum / mag() " << sum << " / " << sum.mag() << G4endl;
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G4double energy;
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for ( i=0; i< myA ; i++ )
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{
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energy = theNucleons[i].GetParticleType()->GetPDGMass()
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- BindingEnergy()/myA;
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G4LorentzVector tempV(momentum[i],energy);
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theNucleons[i].SetMomentum(tempV);
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// GF 11-05-2011: set BindingEnergy to be T of Nucleon with p , ~ p**2/2m
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//theNucleons[i].SetBindingEnergy(
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// 0.5*sqr(fermiM[i])/theNucleons[i].GetParticleType()->GetPDGMass());
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}
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}
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G4bool G4Fancy3DNucleus::ReduceSum()
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{
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G4ThreeVector sum;
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G4double PFermi=fermiM[myA-1];
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for (G4int i=0; i < myA-1 ; i++ )
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{ sum+=momentum[i]; }
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// check if have to do anything at all..
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if ( sum.mag() <= PFermi )
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{
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momentum[myA-1]=-sum;
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return true;
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}
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// find all possible changes in momentum, changing only the component parallel to sum
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G4ThreeVector testDir=sum.unit();
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testSums.clear();
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testSums.resize(myA-1); // Allocate block for filling below
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G4ThreeVector delta;
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for (G4int aNucleon=0; aNucleon < myA-1; aNucleon++) {
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delta = 2.*((momentum[aNucleon]*testDir)*testDir);
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testSums[aNucleon].Fill(delta, delta.mag(), aNucleon);
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}
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std::sort(testSums.begin(), testSums.end());
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// reduce Momentum Sum until the next would be allowed.
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G4int index=testSums.size();
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while ( (sum-testSums[--index].Vector).mag()>PFermi && index>0)
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{
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// Only take one which improve, ie. don't change sign and overshoot...
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if ( sum.mag() > (sum-testSums[index].Vector).mag() ) {
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momentum[testSums[index].Index]-=testSums[index].Vector;
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sum-=testSums[index].Vector;
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}
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}
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if ( (sum-testSums[index].Vector).mag() <= PFermi )
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{
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G4int best=-1;
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G4double pBest=2*PFermi; // anything larger than PFermi
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for ( G4int aNucleon=0; aNucleon<=index; aNucleon++)
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{
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// find the momentum closest to choosen momentum for last Nucleon.
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G4double pTry=(testSums[aNucleon].Vector-sum).mag();
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if ( pTry < PFermi
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&& std::abs(momentum[myA-1].mag() - pTry ) < pBest )
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{
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pBest=std::abs(momentum[myA-1].mag() - pTry );
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best=aNucleon;
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}
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}
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if ( best < 0 )
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{
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G4String text = "G4Fancy3DNucleus.cc: Logic error in ReduceSum()";
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throw G4HadronicException(__FILE__, __LINE__, text);
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}
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momentum[testSums[best].Index]-=testSums[best].Vector;
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momentum[myA-1]=testSums[best].Vector-sum;
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return true;
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}
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// try to compensate momentum using another Nucleon....
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G4int swapit=-1;
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while (swapit<myA-1)
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{
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if ( fermiM[++swapit] > PFermi ) break;
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}
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if (swapit == myA-1 ) return false;
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// Now we have a nucleon with a bigger Fermi Momentum.
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// Exchange with last nucleon.. and iterate.
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std::swap(theNucleons[swapit], theNucleons[myA-1]);
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std::swap(momentum[swapit], momentum[myA-1]);
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std::swap(fermiM[swapit], fermiM[myA-1]);
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return ReduceSum();
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}
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|
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G4double G4Fancy3DNucleus::CoulombBarrier()
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{
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G4double coulombBarrier = (1.44/1.14) * MeV * myZ / (1.0 + std::pow(G4double(myA),1./3.));
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return coulombBarrier;
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}
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