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25 //
26
27 // G4 Low energy model: n-p scattering
28 // F.W. Jones, L.G. Greeniaus, H.P. Wellisch
29
30 // 11-OCT-2007 F.W. Jones: removed erroneous code for identity
31 // exchange of particles.
32 // FWJ 27-AUG-2010: extended to 5 GeV by Tony Kwan TRIUMF
33 // 06-Aug-15 A.Ribon migrating to G4Pow
34
35 #include "G4LEHadronProtonElastic.hh"
36 #include "G4PhysicalConstants.hh"
37 #include "G4SystemOfUnits.hh"
38 #include "Randomize.hh"
39 #include "G4ios.hh"
40 #include "G4Pow.hh"
41 #include "G4PhysicsModelCatalog.hh"
42
43
44 G4LEHadronProtonElastic::G4LEHadronProtonElastic():
45 G4HadronElastic("G4LEHadronProtonElastic")
46 {
47 secID = G4PhysicsModelCatalog::GetModelID( "model_" + GetModelName() );
48 SetMinEnergy(0.);
49 SetMaxEnergy(20.*MeV);
50 }
51
52 G4LEHadronProtonElastic::~G4LEHadronProtonElastic()
53 {
54 theParticleChange.Clear();
55 }
56
57 G4HadFinalState*
58 G4LEHadronProtonElastic::ApplyYourself(const G4HadProjectile& aTrack,
59 G4Nucleus& targetNucleus)
60 {
61 theParticleChange.Clear();
62 const G4HadProjectile* aParticle = &aTrack;
63
64 G4double P = aParticle->GetTotalMomentum();
65 G4double Px = aParticle->Get4Momentum().x();
66 G4double Py = aParticle->Get4Momentum().y();
67 G4double Pz = aParticle->Get4Momentum().z();
68 G4double ek = aParticle->GetKineticEnergy();
69 G4ThreeVector theInitial = aParticle->Get4Momentum().vect();
70
71 if (verboseLevel > 1)
72 {
73 G4double E = aParticle->GetTotalEnergy();
74 G4double E0 = aParticle->GetDefinition()->GetPDGMass();
75 G4double Q = aParticle->GetDefinition()->GetPDGCharge();
76 G4int A = targetNucleus.GetA_asInt();
77 G4int Z = targetNucleus.GetZ_asInt();
78 G4cout << "G4LEHadronProtonElastic:ApplyYourself: incident particle: "
79 << aParticle->GetDefinition()->GetParticleName() << G4endl;
80 G4cout << "P = " << P/GeV << " GeV/c"
81 << ", Px = " << Px/GeV << " GeV/c"
82 << ", Py = " << Py/GeV << " GeV/c"
83 << ", Pz = " << Pz/GeV << " GeV/c" << G4endl;
84 G4cout << "E = " << E/GeV << " GeV"
85 << ", kinetic energy = " << ek/GeV << " GeV"
86 << ", mass = " << E0/GeV << " GeV"
87 << ", charge = " << Q << G4endl;
88 G4cout << "G4LEHadronProtonElastic:ApplyYourself: material:" << G4endl;
89 G4cout << "A = " << A
90 << ", Z = " << Z
91 << ", atomic mass "
92 << G4Proton::Proton()->GetPDGMass()/GeV << "GeV"
93 << G4endl;
94 //
95 // GHEISHA ADD operation to get total energy, mass, charge
96 //
97 E += proton_mass_c2;
98 G4double E02 = E*E - P*P;
99 E0 = std::sqrt(std::abs(E02));
100 if (E02 < 0)E0 *= -1;
101 Q += Z;
102 G4cout << "G4LEHadronProtonElastic:ApplyYourself: total:" << G4endl;
103 G4cout << "E = " << E/GeV << " GeV"
104 << ", mass = " << E0/GeV << " GeV"
105 << ", charge = " << Q << G4endl;
106 }
107
108 G4double theta = (0.5)*pi/180.;
109
110 // Get the target particle
111
112 G4DynamicParticle* targetParticle = targetNucleus.ReturnTargetParticle();
113
114 G4double E1 = aParticle->GetTotalEnergy();
115 G4double M1 = aParticle->GetDefinition()->GetPDGMass();
116 G4double E2 = targetParticle->GetTotalEnergy();
117 G4double M2 = targetParticle->GetDefinition()->GetPDGMass();
118 G4double totalEnergy = E1 + E2;
119 G4double pseudoMass = std::sqrt(totalEnergy*totalEnergy - P*P);
120
121 // Transform into centre of mass system
122
123 G4double px = (M2/pseudoMass)*Px;
124 G4double py = (M2/pseudoMass)*Py;
125 G4double pz = (M2/pseudoMass)*Pz;
126 G4double p = std::sqrt(px*px + py*py + pz*pz);
127
128 if (verboseLevel > 1) {
129 G4cout << " E1, M1 (GeV) " << E1/GeV << " " << M1/GeV << G4endl;
130 G4cout << " E2, M2 (GeV) " << E2/GeV << " " << M2/GeV << G4endl;
131 G4cout << " particle 1 momentum in CM " << px/GeV << " " << py/GeV << " "
132 << pz/GeV << " " << p/GeV << G4endl;
133 }
134
135 // First scatter w.r.t. Z axis
136 G4double phi = G4UniformRand()*twopi;
137 G4double pxnew = p*std::sin(theta)*std::cos(phi);
138 G4double pynew = p*std::sin(theta)*std::sin(phi);
139 G4double pznew = p*std::cos(theta);
140
141 // Rotate according to the direction of the incident particle
142 if (px*px + py*py > 0)
143 {
144 G4double cost, sint, ph, cosp, sinp;
145 cost = pz/p;
146 sint = (std::sqrt(std::fabs((1-cost)*(1+cost)))
147 + std::sqrt(px*px+py*py)/p)/2;
148 py < 0 ? ph = 3*halfpi : ph = halfpi;
149 if (std::abs(px) > 0.000001*GeV) ph = std::atan2(py,px);
150 cosp = std::cos(ph);
151 sinp = std::sin(ph);
152 px = (cost*cosp*pxnew - sinp*pynew + sint*cosp*pznew);
153 py = (cost*sinp*pxnew + cosp*pynew + sint*sinp*pznew);
154 pz = (-sint*pxnew + cost*pznew);
155 }
156 else {
157 px = pxnew;
158 py = pynew;
159 pz = pznew;
160 }
161
162 if (verboseLevel > 1) {
163 G4cout << " AFTER SCATTER..." << G4endl;
164 G4cout << " particle 1 momentum in CM " << px/GeV
165 << " " << py/GeV << " " << pz/GeV << " " << p/GeV
166 << G4endl;
167 }
168
169 // Transform to lab system
170
171 G4double E1pM2 = E1 + M2;
172 G4double betaCM = P/E1pM2;
173 G4double betaCMx = Px/E1pM2;
174 G4double betaCMy = Py/E1pM2;
175 G4double betaCMz = Pz/E1pM2;
176 G4double gammaCM = E1pM2/std::sqrt(E1pM2*E1pM2 - P*P);
177
178 if (verboseLevel > 1) {
179 G4cout << " betaCM " << betaCMx << " " << betaCMy << " "
180 << betaCMz << " " << betaCM << G4endl;
181 G4cout << " gammaCM " << gammaCM << G4endl;
182 }
183
184 // Now following GLOREN...
185
186 G4double BETA[5], PA[5], PB[5];
187 BETA[1] = -betaCMx;
188 BETA[2] = -betaCMy;
189 BETA[3] = -betaCMz;
190 BETA[4] = gammaCM;
191
192 //The incident particle...
193
194 PA[1] = px;
195 PA[2] = py;
196 PA[3] = pz;
197 PA[4] = std::sqrt(M1*M1 + p*p);
198
199 G4double BETPA = BETA[1]*PA[1] + BETA[2]*PA[2] + BETA[3]*PA[3];
200 G4double BPGAM = (BETPA * BETA[4]/(BETA[4] + 1.) - PA[4]) * BETA[4];
201
202 PB[1] = PA[1] + BPGAM * BETA[1];
203 PB[2] = PA[2] + BPGAM * BETA[2];
204 PB[3] = PA[3] + BPGAM * BETA[3];
205 PB[4] = (PA[4] - BETPA) * BETA[4];
206
207 G4DynamicParticle* newP = new G4DynamicParticle;
208 newP->SetDefinition(aParticle->GetDefinition());
209 newP->SetMomentum(G4ThreeVector(PB[1], PB[2], PB[3]));
210
211 //The target particle...
212
213 PA[1] = -px;
214 PA[2] = -py;
215 PA[3] = -pz;
216 PA[4] = std::sqrt(M2*M2 + p*p);
217
218 BETPA = BETA[1]*PA[1] + BETA[2]*PA[2] + BETA[3]*PA[3];
219 BPGAM = (BETPA * BETA[4]/(BETA[4] + 1.) - PA[4]) * BETA[4];
220
221 PB[1] = PA[1] + BPGAM * BETA[1];
222 PB[2] = PA[2] + BPGAM * BETA[2];
223 PB[3] = PA[3] + BPGAM * BETA[3];
224 PB[4] = (PA[4] - BETPA) * BETA[4];
225
226 targetParticle->SetMomentum(G4ThreeVector(PB[1], PB[2], PB[3]));
227
228 if (verboseLevel > 1) {
229 G4cout << " particle 1 momentum in LAB "
230 << newP->GetMomentum()*(1./GeV)
231 << " " << newP->GetTotalMomentum()/GeV << G4endl;
232 G4cout << " particle 2 momentum in LAB "
233 << targetParticle->GetMomentum()*(1./GeV)
234 << " " << targetParticle->GetTotalMomentum()/GeV << G4endl;
235 G4cout << " TOTAL momentum in LAB "
236 << (newP->GetMomentum()+targetParticle->GetMomentum())*(1./GeV)
237 << " "
238 << (newP->GetMomentum()+targetParticle->GetMomentum()).mag()/GeV
239 << G4endl;
240 }
241
242 theParticleChange.SetMomentumChange(newP->GetMomentumDirection());
243 theParticleChange.SetEnergyChange(newP->GetKineticEnergy());
244 delete newP;
245 theParticleChange.AddSecondary(targetParticle, secID);
246
247 return &theParticleChange;
248 }
249
250 ////////////////////////////////////////////////////////////////////
251 //
252 // sample momentum transfer using Lab. momentum
253
254 G4double
255 G4LEHadronProtonElastic::SampleInvariantT(const G4ParticleDefinition* p,
256 G4double plab, G4int , G4int )
257 {
258 G4double hMass = p->GetPDGMass();
259 G4double pCMS = 0.5*plab;
260 // pCMS *= 50;
261 G4double hEcms = std::sqrt(pCMS*pCMS+hMass*hMass);
262 // G4double gamma = hEcms/hMass;
263 // gamma *= 15;
264 G4double beta = pCMS/hEcms; // std::sqrt(1-1./gamma/gamma); //
265 // beta /= 0.8; // 0.95; // 1.0; // 1.1 // 0.5*pi; // pi; twopi;
266 G4double cosDipole = RandCosThetaDipPen();
267 G4double cosTheta = cosDipole + beta;
268 cosTheta /= 1. + cosDipole*beta;
269 G4double t = 2.*pCMS*pCMS*(1.-cosTheta);
270 return t;
271
272 }
273
274 ///////////////////////////////////////////////////////////////
275 //
276 // 1 + cos^2(theta) random distribution in the projectile rest frame, Penelope algorithm
277
278 G4double G4LEHadronProtonElastic::RandCosThetaDipPen()
279 {
280 G4double x, cosTheta, signX, modX, power = 1./3.;
281
282 if( G4UniformRand() > 0.25)
283 {
284 cosTheta = 2.*G4UniformRand()-1.;
285 }
286 else
287 {
288 x = 2.*G4UniformRand()-1.;
289
290 if ( x < 0. )
291 {
292 modX = -x;
293 signX = -1.;
294 }
295 else
296 {
297 modX = x;
298 signX = 1.;
299 }
300 cosTheta = signX*G4Pow::GetInstance()->powA(modX,power);
301 }
302 return cosTheta;
303 }
304
305 // end of file
306