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25 // 25 //
26 // G4TauLeptonicDecayChannel class implementat <<
27 // 26 //
28 // Author: H.Kurashige, 30 May 1997 << 27 // $Id: G4TauLeptonicDecayChannel.cc,v 1.5 2006/06/29 19:26:18 gunter Exp $
29 // ------------------------------------------- << 28 // GEANT4 tag $Name: geant4-08-03-patch-01 $
30 << 29 //
31 #include "G4TauLeptonicDecayChannel.hh" << 30 //
>> 31 // ------------------------------------------------------------
>> 32 // GEANT 4 class header file
>> 33 //
>> 34 // History: first implementation, based on object model of
>> 35 // 30 May 1997 H.Kurashige
>> 36 //
>> 37 // Fix bug in calcuration of electron energy in DecayIt 28 Feb. 01 H.Kurashige
>> 38 // ------------------------------------------------------------
32 39
33 #include "G4DecayProducts.hh" <<
34 #include "G4LorentzRotation.hh" <<
35 #include "G4LorentzVector.hh" <<
36 #include "G4ParticleDefinition.hh" 40 #include "G4ParticleDefinition.hh"
37 #include "G4PhysicalConstants.hh" << 41 #include "G4DecayProducts.hh"
38 #include "G4SystemOfUnits.hh" <<
39 #include "G4VDecayChannel.hh" 42 #include "G4VDecayChannel.hh"
>> 43 #include "G4TauLeptonicDecayChannel.hh"
40 #include "Randomize.hh" 44 #include "Randomize.hh"
>> 45 #include "G4LorentzVector.hh"
>> 46 #include "G4LorentzRotation.hh"
41 47
42 G4TauLeptonicDecayChannel::G4TauLeptonicDecayC << 48
43 << 49 G4TauLeptonicDecayChannel::G4TauLeptonicDecayChannel(
44 : G4VDecayChannel("Tau Leptonic Decay", 1) << 50 const G4String& theParentName,
>> 51 G4double theBR,
>> 52 const G4String& theLeptonName)
>> 53 :G4VDecayChannel("Tau Leptonic Decay",1)
45 { 54 {
46 // set names for daughter particles 55 // set names for daughter particles
47 if (theParentName == "tau+") { 56 if (theParentName == "tau+") {
48 SetBR(theBR); 57 SetBR(theBR);
49 SetParent("tau+"); 58 SetParent("tau+");
50 SetNumberOfDaughters(3); 59 SetNumberOfDaughters(3);
51 if ((theLeptonName == "e-" || theLeptonNam << 60 if ((theLeptonName=="e-"||theLeptonName=="e+")){
52 SetDaughter(0, "e+"); 61 SetDaughter(0, "e+");
53 SetDaughter(1, "nu_e"); 62 SetDaughter(1, "nu_e");
54 SetDaughter(2, "anti_nu_tau"); 63 SetDaughter(2, "anti_nu_tau");
55 } << 64 } else {
56 else { <<
57 SetDaughter(0, "mu+"); 65 SetDaughter(0, "mu+");
58 SetDaughter(1, "nu_mu"); 66 SetDaughter(1, "nu_mu");
59 SetDaughter(2, "anti_nu_tau"); 67 SetDaughter(2, "anti_nu_tau");
60 } << 68 }
61 } << 69 } else if (theParentName == "tau-") {
62 else if (theParentName == "tau-") { <<
63 SetBR(theBR); 70 SetBR(theBR);
64 SetParent("tau-"); 71 SetParent("tau-");
65 SetNumberOfDaughters(3); 72 SetNumberOfDaughters(3);
66 if ((theLeptonName == "e-" || theLeptonNam << 73 if ((theLeptonName=="e-"||theLeptonName=="e+")){
67 SetDaughter(0, "e-"); 74 SetDaughter(0, "e-");
68 SetDaughter(1, "anti_nu_e"); 75 SetDaughter(1, "anti_nu_e");
69 SetDaughter(2, "nu_tau"); 76 SetDaughter(2, "nu_tau");
70 } << 77 } else {
71 else { <<
72 SetDaughter(0, "mu-"); 78 SetDaughter(0, "mu-");
73 SetDaughter(1, "anti_nu_mu"); 79 SetDaughter(1, "anti_nu_mu");
74 SetDaughter(2, "nu_tau"); 80 SetDaughter(2, "nu_tau");
75 } << 81 }
76 } << 82 } else {
77 else { <<
78 #ifdef G4VERBOSE 83 #ifdef G4VERBOSE
79 if (GetVerboseLevel() > 0) { << 84 if (GetVerboseLevel()>0) {
80 G4cout << "G4TauLeptonicDecayChannel:: c 85 G4cout << "G4TauLeptonicDecayChannel:: constructor :";
81 G4cout << " parent particle is not tau b 86 G4cout << " parent particle is not tau but ";
82 G4cout << theParentName << G4endl; 87 G4cout << theParentName << G4endl;
83 } 88 }
84 #endif 89 #endif
85 } 90 }
86 } 91 }
87 92
88 G4TauLeptonicDecayChannel& << 93 G4TauLeptonicDecayChannel::~G4TauLeptonicDecayChannel()
89 G4TauLeptonicDecayChannel::operator=(const G4T <<
90 { 94 {
91 if (this != &right) { <<
92 kinematics_name = right.kinematics_name; <<
93 verboseLevel = right.verboseLevel; <<
94 rbranch = right.rbranch; <<
95 <<
96 // copy parent name <<
97 parent_name = new G4String(*right.parent_n <<
98 <<
99 // clear daughters_name array <<
100 ClearDaughtersName(); <<
101 <<
102 // recreate array <<
103 numberOfDaughters = right.numberOfDaughter <<
104 if (numberOfDaughters > 0) { <<
105 if (daughters_name != nullptr) ClearDaug <<
106 daughters_name = new G4String*[numberOfD <<
107 // copy daughters name <<
108 for (G4int index = 0; index < numberOfDa <<
109 daughters_name[index] = new G4String(* <<
110 } <<
111 } <<
112 } <<
113 return *this; <<
114 } 95 }
115 96
116 G4DecayProducts* G4TauLeptonicDecayChannel::De << 97 G4DecayProducts *G4TauLeptonicDecayChannel::DecayIt(G4double)
117 { 98 {
118 // this version neglects muon polarization << 99 // this version neglects muon polarization
119 // assumes the pure V-A couplin 100 // assumes the pure V-A coupling
120 // gives incorrect energy spect 101 // gives incorrect energy spectrum for neutrinos
121 <<
122 #ifdef G4VERBOSE 102 #ifdef G4VERBOSE
123 if (GetVerboseLevel() > 1) G4cout << "G4TauL << 103 if (GetVerboseLevel()>1) G4cout << "G4TauLeptonicDecayChannel::DecayIt ";
124 #endif 104 #endif
125 105
126 CheckAndFillParent(); << 106 if (parent == 0) FillParent();
127 CheckAndFillDaughters(); << 107 if (daughters == 0) FillDaughters();
128 << 108
129 // parent mass 109 // parent mass
130 G4double parentmass = G4MT_parent->GetPDGMas << 110 G4double parentmass = parent->GetPDGMass();
131 111
132 // daughters'mass << 112 //daughters'mass
133 const G4int N_DAUGHTER = 3; << 113 G4double daughtermass[3];
134 G4double daughtermass[N_DAUGHTER]; << 114 for (G4int index=0; index<3; index++){
135 for (G4int index = 0; index < N_DAUGHTER; ++ << 115 daughtermass[index] = daughters[index]->GetPDGMass();
136 daughtermass[index] = G4MT_daughters[index <<
137 } 116 }
138 117
139 // create parent G4DynamicParticle at rest << 118 //create parent G4DynamicParticle at rest
140 G4ThreeVector dummy; 119 G4ThreeVector dummy;
141 auto parentparticle = new G4DynamicParticle( << 120 G4DynamicParticle * parentparticle = new G4DynamicParticle( parent, dummy, 0.0);
142 // create G4Decayproducts << 121 //create G4Decayproducts
143 auto products = new G4DecayProducts(*parentp << 122 G4DecayProducts *products = new G4DecayProducts(*parentparticle);
144 delete parentparticle; 123 delete parentparticle;
145 124
146 // calculate daughter momentum 125 // calculate daughter momentum
147 G4double daughtermomentum[N_DAUGHTER]; << 126 G4double daughtermomentum[3];
>> 127 G4double energy;
148 128
149 // calculate lepton momentum << 129 // calcurate lepton momentum
150 G4double pmax = (parentmass * parentmass - d << 130 G4double pmax = (parentmass*parentmass-daughtermass[0]*daughtermass[0])/2./parentmass;
151 G4double p, e; 131 G4double p, e;
152 G4double r; 132 G4double r;
153 const std::size_t MAX_LOOP = 10000; << 133 do {
154 for (std::size_t loop_counter = 0; loop_coun <<
155 // determine momentum/energy 134 // determine momentum/energy
156 r = G4UniformRand(); 135 r = G4UniformRand();
157 p = pmax * G4UniformRand(); << 136 p = pmax*G4UniformRand();
158 e = std::sqrt(p * p + daughtermass[0] * da << 137 e = std::sqrt(p*p + daughtermass[0]*daughtermass[0]);
159 if (r < spectrum(p, e, parentmass, daughte << 138 } while (r > spectrum(p,e,parentmass,daughtermass[0]) );
160 } << 139 energy = e- daughtermass[0];
161 140
162 // create daughter G4DynamicParticle << 141 //create daughter G4DynamicParticle
163 // daughter 0 (lepton) 142 // daughter 0 (lepton)
164 daughtermomentum[0] = p; 143 daughtermomentum[0] = p;
165 G4double costheta, sintheta, phi, sinphi, co << 144 G4double costheta, sintheta, phi, sinphi, cosphi;
166 costheta = 2. * G4UniformRand() - 1.0; << 145 costheta = 2.*G4UniformRand()-1.0;
167 sintheta = std::sqrt((1.0 - costheta) * (1.0 << 146 sintheta = std::sqrt((1.0-costheta)*(1.0+costheta));
168 phi = twopi * G4UniformRand() * rad; << 147 phi = twopi*G4UniformRand()*rad;
169 sinphi = std::sin(phi); 148 sinphi = std::sin(phi);
170 cosphi = std::cos(phi); 149 cosphi = std::cos(phi);
171 G4ThreeVector direction0(sintheta * cosphi, << 150 G4ThreeVector direction0(sintheta*cosphi,sintheta*sinphi,costheta);
172 auto daughterparticle = << 151 G4DynamicParticle * daughterparticle
173 new G4DynamicParticle(G4MT_daughters[0], d << 152 = new G4DynamicParticle( daughters[0], direction0*daughtermomentum[0]);
174 products->PushProducts(daughterparticle); 153 products->PushProducts(daughterparticle);
175 154
176 // daughter 1 ,2 (nutrinos) 155 // daughter 1 ,2 (nutrinos)
177 // create neutrinos in the C.M frame of two 156 // create neutrinos in the C.M frame of two neutrinos
178 G4double energy2 = parentmass - e; << 157 G4double energy2 = parentmass-e;
179 G4double vmass = std::sqrt((energy2 - daught << 158 G4double vmass = std::sqrt((energy2-daughtermomentum[0])*(energy2+daughtermomentum[0]));
180 G4double beta = -1.0 * daughtermomentum[0] / << 159 G4double beta = -1.0*daughtermomentum[0]/energy2;
181 G4double costhetan = 2. * G4UniformRand() - << 160 G4double costhetan = 2.*G4UniformRand()-1.0;
182 G4double sinthetan = std::sqrt((1.0 - costhe << 161 G4double sinthetan = std::sqrt((1.0-costhetan)*(1.0+costhetan));
183 G4double phin = twopi * G4UniformRand() * ra << 162 G4double phin = twopi*G4UniformRand()*rad;
184 G4double sinphin = std::sin(phin); 163 G4double sinphin = std::sin(phin);
185 G4double cosphin = std::cos(phin); 164 G4double cosphin = std::cos(phin);
186 165
187 G4ThreeVector direction1(sinthetan * cosphin << 166 G4ThreeVector direction1(sinthetan*cosphin,sinthetan*sinphin,costhetan);
188 auto daughterparticle1 = new G4DynamicPartic << 167 G4DynamicParticle * daughterparticle1
189 auto daughterparticle2 = << 168 = new G4DynamicParticle( daughters[1], direction1*(vmass/2.));
190 new G4DynamicParticle(G4MT_daughters[2], d << 169 G4DynamicParticle * daughterparticle2
>> 170 = new G4DynamicParticle( daughters[2], direction1*(-1.0*vmass/2.));
191 171
192 // boost to the muon rest frame 172 // boost to the muon rest frame
193 G4LorentzVector p4; 173 G4LorentzVector p4;
194 p4 = daughterparticle1->Get4Momentum(); 174 p4 = daughterparticle1->Get4Momentum();
195 p4.boost(direction0.x() * beta, direction0.y << 175 p4.boost( direction0.x()*beta, direction0.y()*beta, direction0.z()*beta);
196 daughterparticle1->Set4Momentum(p4); 176 daughterparticle1->Set4Momentum(p4);
197 p4 = daughterparticle2->Get4Momentum(); 177 p4 = daughterparticle2->Get4Momentum();
198 p4.boost(direction0.x() * beta, direction0.y << 178 p4.boost( direction0.x()*beta, direction0.y()*beta, direction0.z()*beta);
199 daughterparticle2->Set4Momentum(p4); 179 daughterparticle2->Set4Momentum(p4);
200 products->PushProducts(daughterparticle1); 180 products->PushProducts(daughterparticle1);
201 products->PushProducts(daughterparticle2); 181 products->PushProducts(daughterparticle2);
202 daughtermomentum[1] = daughterparticle1->Get 182 daughtermomentum[1] = daughterparticle1->GetTotalMomentum();
203 daughtermomentum[2] = daughterparticle2->Get 183 daughtermomentum[2] = daughterparticle2->GetTotalMomentum();
204 184
205 // output message << 185
>> 186 // output message
206 #ifdef G4VERBOSE 187 #ifdef G4VERBOSE
207 if (GetVerboseLevel() > 1) { << 188 if (GetVerboseLevel()>1) {
208 G4cout << "G4TauLeptonicDecayChannel::Deca 189 G4cout << "G4TauLeptonicDecayChannel::DecayIt ";
209 G4cout << " create decay products in rest << 190 G4cout << " create decay products in rest frame " <<G4endl;
210 products->DumpInfo(); 191 products->DumpInfo();
211 } 192 }
212 #endif 193 #endif
213 return products; 194 return products;
214 } 195 }
215 196
216 G4double G4TauLeptonicDecayChannel::spectrum(G << 197
>> 198
>> 199
>> 200 G4double G4TauLeptonicDecayChannel::spectrum(G4double p,
>> 201 G4double e,
>> 202 G4double mtau,
>> 203 G4double ml)
217 { 204 {
218 G4double f1; 205 G4double f1;
219 f1 = 3.0 * e * (mtau * mtau + ml * ml) - 4.0 << 206 f1 = 3.0*e*(mtau*mtau+ml*ml)-4.0*mtau*e*e-2.0*mtau*ml*ml;
220 return p * (f1) / (mtau * mtau * mtau * mtau << 207 return p*(f1)/(mtau*mtau*mtau*mtau)/(0.6);
221 } 208 }
>> 209
>> 210
>> 211
222 212