[819] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // |
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| 27 | // |
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| 28 | // ------------------------------------------------------------ |
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| 29 | // GEANT 4 class header file |
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| 30 | // |
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| 31 | // ---------------- G4SampleResonance ---------------- |
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| 32 | // by Henning Weber, March 2001. |
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| 33 | // helper class for sampling resonance masses |
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| 34 | // ------------------------------------------------------------ |
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| 35 | |
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| 36 | |
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| 37 | #include "globals.hh" |
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| 38 | #include <iostream> |
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| 39 | #include "G4SampleResonance.hh" |
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| 40 | #include "G4DecayTable.hh" |
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| 41 | #include "Randomize.hh" |
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| 42 | #include "G4HadronicException.hh" |
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| 43 | |
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| 44 | G4SampleResonance::minMassMapType G4SampleResonance::minMassCache; |
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| 45 | |
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| 46 | G4double G4SampleResonance::GetMinimumMass(const G4ParticleDefinition* p) const |
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| 47 | { |
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| 48 | |
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| 49 | G4double minResonanceMass = DBL_MAX; |
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| 50 | |
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| 51 | if ( p->IsShortLived() ) |
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| 52 | { |
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| 53 | minMassMapIterator i = minMassCache.find(p); |
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| 54 | if ( i!=minMassCache.end() ) |
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| 55 | { |
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| 56 | minResonanceMass = (*i).second; |
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| 57 | } |
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| 58 | else |
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| 59 | { |
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| 60 | // G4cout << "--> request for " << p->GetParticleName() << G4endl; |
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| 61 | |
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| 62 | const G4DecayTable* theDecays = const_cast<G4ParticleDefinition*>(p)->GetDecayTable(); |
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| 63 | const G4int nDecays = theDecays->entries(); |
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| 64 | |
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| 65 | for (G4int i=0; i<nDecays; i++) |
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| 66 | { |
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| 67 | const G4VDecayChannel* aDecay = theDecays->GetDecayChannel(i); |
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| 68 | const G4int nDaughters = aDecay->GetNumberOfDaughters(); |
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| 69 | |
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| 70 | G4double minChannelMass = 0; |
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| 71 | |
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| 72 | for (G4int j=0; j<nDaughters; j++) |
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| 73 | { |
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| 74 | const G4ParticleDefinition* aDaughter = const_cast<G4VDecayChannel*>(aDecay)->GetDaughter(j); |
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| 75 | G4double minMass = GetMinimumMass(aDaughter); |
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| 76 | if (!minMass) minMass = DBL_MAX; // exclude gamma channel; |
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| 77 | minChannelMass+=minMass; |
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| 78 | } |
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| 79 | // G4cout << "channel mass for the above is " << minChannelMass/MeV << G4endl; |
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| 80 | if (minChannelMass < minResonanceMass) minResonanceMass = minChannelMass; |
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| 81 | |
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| 82 | } |
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| 83 | // replace this as soon as the compiler supports mutable!! |
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| 84 | G4SampleResonance* self = const_cast<G4SampleResonance*>(this); |
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| 85 | (self->minMassCache)[p] = minResonanceMass; |
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| 86 | |
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| 87 | } |
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| 88 | } |
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| 89 | else |
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| 90 | { |
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| 91 | |
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| 92 | minResonanceMass = p->GetPDGMass(); |
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| 93 | |
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| 94 | } |
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| 95 | // G4cout << "minimal mass for " << p->GetParticleName() << " is " << minResonanceMass/MeV << G4endl; |
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| 96 | |
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| 97 | return minResonanceMass; |
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| 98 | } |
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| 99 | |
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| 100 | |
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| 101 | |
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| 102 | G4double G4SampleResonance::SampleMass(const G4ParticleDefinition* p, const G4double maxMass) const |
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| 103 | { |
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| 104 | return SampleMass(p->GetPDGMass(), p->GetPDGWidth(), GetMinimumMass(p), maxMass); |
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| 105 | } |
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| 106 | |
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| 107 | |
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| 108 | G4double G4SampleResonance::SampleMass(const G4double poleMass, |
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| 109 | const G4double gamma, |
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| 110 | const G4double minMass, |
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| 111 | const G4double maxMass) const |
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| 112 | { |
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| 113 | // Chooses a mass randomly between minMass and maxMass |
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| 114 | // according to a Breit-Wigner function with constant |
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| 115 | // width gamma and pole poleMass |
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| 116 | |
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| 117 | if ( minMass > maxMass ) |
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| 118 | { |
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| 119 | throw G4HadronicException(__FILE__, __LINE__, |
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| 120 | "SampleResonanceMass: mass range negative (minMass>maxMass)"); |
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| 121 | } |
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| 122 | |
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| 123 | G4double returnMass; |
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| 124 | |
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| 125 | if ( gamma < DBL_EPSILON ) |
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| 126 | { |
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| 127 | returnMass = std::max(minMass, std::min(maxMass, poleMass)); |
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| 128 | } |
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| 129 | else |
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| 130 | { |
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| 131 | double fmin = BrWigInt0(minMass, gamma, poleMass); |
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| 132 | double fmax = BrWigInt0(maxMass, gamma, poleMass); |
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| 133 | double f = fmin + (fmax-fmin)*G4UniformRand(); |
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| 134 | returnMass = BrWigInv(f, gamma, poleMass); |
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| 135 | } |
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| 136 | |
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| 137 | return returnMass; |
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| 138 | } |
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| 139 | |
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| 140 | |
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| 141 | |
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| 142 | |
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