source: trunk/source/processes/hadronic/models/coherent_elastic/src/G4LEnp.cc @ 1315

Last change on this file since 1315 was 819, checked in by garnier, 16 years ago

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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
33#include "G4LEnp.hh"
34#include "Randomize.hh"
35#include "G4ios.hh"
36
37// Initialization of static data arrays:
38#include "G4LEnpData.hh"
39#include "Randomize.hh"
40
41
42G4LEnp::G4LEnp():G4HadronicInteraction("G4LEnp")
43{
44  //    theParticleChange.SetNumberOfSecondaries(1);
45 
46  //    SetMinEnergy(10.*MeV);
47  //    SetMaxEnergy(1200.*MeV);
48  SetMinEnergy(0.);
49  SetMaxEnergy(1200.*GeV);
50}
51
52G4LEnp::~G4LEnp()
53{
54      theParticleChange.Clear();
55}
56
57G4HadFinalState*
58G4LEnp::ApplyYourself(const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
59{
60    theParticleChange.Clear();
61    const G4HadProjectile* aParticle = &aTrack;
62
63    G4double P = aParticle->GetTotalMomentum();
64    G4double Px = aParticle->Get4Momentum().x();
65    G4double Py = aParticle->Get4Momentum().y();
66    G4double Pz = aParticle->Get4Momentum().z();
67    G4double ek = aParticle->GetKineticEnergy();
68    G4ThreeVector theInitial = aParticle->Get4Momentum().vect();
69
70    if (verboseLevel > 1) {
71      G4double E = aParticle->GetTotalEnergy();
72      G4double E0 = aParticle->GetDefinition()->GetPDGMass();
73      G4double Q = aParticle->GetDefinition()->GetPDGCharge();
74      G4double N = targetNucleus.GetN();
75      G4double Z = targetNucleus.GetZ();
76      G4cout << "G4LEnp:ApplyYourself: incident particle: "
77             << aParticle->GetDefinition()->GetParticleName() << G4endl;
78      G4cout << "P = " << P/GeV << " GeV/c"
79             << ", Px = " << Px/GeV << " GeV/c"
80             << ", Py = " << Py/GeV << " GeV/c"
81             << ", Pz = " << Pz/GeV << " GeV/c" << G4endl;
82      G4cout << "E = " << E/GeV << " GeV"
83             << ", kinetic energy = " << ek/GeV << " GeV"
84             << ", mass = " << E0/GeV << " GeV"
85             << ", charge = " << Q << G4endl;
86      G4cout << "G4LEnp:ApplyYourself: material:" << G4endl;
87      G4cout << "A = " << N
88             << ", Z = " << Z
89             << ", atomic mass " 
90             <<  G4Proton::Proton()->GetPDGMass()/GeV << "GeV" 
91             << G4endl;
92      //
93      // GHEISHA ADD operation to get total energy, mass, charge
94      //
95      E += G4Proton::Proton()->GetPDGMass();
96      G4double E02 = E*E - P*P;
97      E0 = std::sqrt(std::abs(E02));
98      if (E02 < 0)E0 *= -1;
99      Q += Z;
100      G4cout << "G4LEnp:ApplyYourself: total:" << G4endl;
101      G4cout << "E = " << E/GeV << " GeV"
102             << ", mass = " << E0/GeV << " GeV"
103             << ", charge = " << Q << G4endl;
104    }
105
106    // Find energy bin
107
108    G4int je1 = 0;
109    G4int je2 = NENERGY - 1;
110    ek = ek/GeV;
111    do {
112      G4int midBin = (je1 + je2)/2;
113      if (ek < elab[midBin])
114        je2 = midBin;
115      else
116        je1 = midBin;
117    } while (je2 - je1 > 1); 
118    //    G4int j;
119    //std::abs(ek-elab[je1]) < std::abs(ek-elab[je2]) ? j = je1 : j = je2;
120    G4double delab = elab[je2] - elab[je1];
121
122    // Sample the angle
123
124    G4float sample = G4UniformRand();
125    G4int ke1 = 0;
126    G4int ke2 = NANGLE - 1;
127    G4double dsig = sig[je2][0] - sig[je1][0];
128    G4double rc = dsig/delab;
129    G4double b = sig[je1][0] - rc*elab[je1];
130    G4double sigint1 = rc*ek + b;
131    G4double sigint2 = 0.;
132
133    if (verboseLevel > 1) G4cout << "sample=" << sample << G4endl
134                                 << ke1 << " " << ke2 << " " 
135                                 << sigint1 << " " << sigint2 << G4endl;
136
137    do {
138      G4int midBin = (ke1 + ke2)/2;
139      dsig = sig[je2][midBin] - sig[je1][midBin];
140      rc = dsig/delab;
141      b = sig[je1][midBin] - rc*elab[je1];
142      G4double sigint = rc*ek + b;
143      if (sample < sigint) {
144        ke2 = midBin;
145        sigint2 = sigint;
146      }
147      else {
148        ke1 = midBin;
149        sigint1 = sigint;
150      }
151      if (verboseLevel > 1)G4cout << ke1 << " " << ke2 << " " 
152                                  << sigint1 << " " << sigint2 << G4endl;
153    } while (ke2 - ke1 > 1); 
154
155    // sigint1 and sigint2 should be recoverable from above loop
156
157    //    G4double dsig = sig[je2][ke1] - sig[je1][ke1];
158    //    G4double rc = dsig/delab;
159    //    G4double b = sig[je1][ke1] - rc*elab[je1];
160    //    G4double sigint1 = rc*ek + b;
161
162    //    G4double dsig = sig[je2][ke2] - sig[je1][ke2];
163    //    G4double rc = dsig/delab;
164    //    G4double b = sig[je1][ke2] - rc*elab[je1];
165    //    G4double sigint2 = rc*ek + b;
166
167    dsig = sigint2 - sigint1;
168    rc = 1./dsig;
169    b = ke1 - rc*sigint1;
170    G4double kint = rc*sample + b;
171    G4double theta = (0.5 + kint)*pi/180.;
172
173    //    G4int k;
174    //std::abs(sample-sig[j][ke1]) < std::abs(sample-sig[j][ke2]) ? k = ke1 : k = ke2;
175    //    G4double theta = (0.5 + k)*pi/180.;
176
177    if (verboseLevel > 1) {
178      G4cout << "   energy bin " << je1 << " energy=" << elab[je1] << G4endl;
179      G4cout << "   angle bin " << kint << " angle=" << theta/degree << G4endl;
180    }
181
182
183    // Get the target particle
184
185    G4DynamicParticle* targetParticle = targetNucleus.ReturnTargetParticle();
186
187    G4double E1 = aParticle->GetTotalEnergy();
188    G4double M1 = aParticle->GetDefinition()->GetPDGMass();
189    G4double E2 = targetParticle->GetTotalEnergy();
190    G4double M2 = targetParticle->GetDefinition()->GetPDGMass();
191    G4double totalEnergy = E1 + E2;
192    G4double pseudoMass = std::sqrt(totalEnergy*totalEnergy - P*P);
193    // pseudoMass also = std::sqrt(M1*M1 + M2*M2 + 2*M2*E1)
194
195    // Transform into centre of mass system
196
197    G4double px = (M2/pseudoMass)*Px;
198    G4double py = (M2/pseudoMass)*Py;
199    G4double pz = (M2/pseudoMass)*Pz;
200    G4double p = std::sqrt(px*px + py*py + pz*pz);
201
202    if (verboseLevel > 1) {
203      G4cout << "  E1, M1 (GeV) " << E1/GeV << " " << M1/GeV << G4endl;
204      G4cout << "  E2, M2 (GeV) " << E2/GeV << " " << M2/GeV << G4endl;
205      G4cout << "  particle  1 momentum in CM " << px/GeV << " " << py/GeV << " "
206           << pz/GeV << " " << p/GeV << G4endl;
207    }
208
209    // First scatter w.r.t. Z axis
210    G4double phi = G4UniformRand()*twopi;
211    G4double pxnew = p*std::sin(theta)*std::cos(phi);
212    G4double pynew = p*std::sin(theta)*std::sin(phi);
213    G4double pznew = p*std::cos(theta);
214
215    // Rotate according to the direction of the incident particle
216    if (px*px + py*py > 0) {
217      G4double cost, sint, ph, cosp, sinp;
218      cost = pz/p;
219      sint = (std::sqrt(std::abs((1-cost)*(1+cost))) + std::sqrt(px*px+py*py)/p)/2;
220      py < 0 ? ph = 3*halfpi : ph = halfpi;
221      if (std::abs(px) > 0.000001*GeV) ph = std::atan2(py,px);
222      cosp = std::cos(ph);
223      sinp = std::sin(ph);
224      px = (cost*cosp*pxnew - sinp*pynew + sint*cosp*pznew);
225      py = (cost*sinp*pxnew + cosp*pynew + sint*sinp*pznew);
226      pz = (-sint*pxnew                  + cost*pznew);
227      //      G4ThreeVector it(a,b,c);
228      //      p0->SetMomentum(it);
229      //      G4ThreeVector aTargetMom = theInitial - it;
230      //      targetParticle->SetMomentum(aTargetMom);
231    }
232    else {
233      px = pxnew;
234      py = pynew;
235      pz = pznew;
236    }
237
238    if (verboseLevel > 1) {
239      G4cout << "  AFTER SCATTER..." << G4endl;
240      G4cout << "  particle 1 momentum in CM " << px/GeV << " " << py/GeV << " "
241           << pz/GeV << " " << p/GeV << G4endl;
242    }
243
244    // Transform to lab system
245
246    G4double E1pM2 = E1 + M2;
247    G4double betaCM  = P/E1pM2;
248    G4double betaCMx = Px/E1pM2;
249    G4double betaCMy = Py/E1pM2;
250    G4double betaCMz = Pz/E1pM2;
251    G4double gammaCM = E1pM2/std::sqrt(E1pM2*E1pM2 - P*P);
252
253    if (verboseLevel > 1) {
254      G4cout << "  betaCM " << betaCMx << " " << betaCMy << " "
255             << betaCMz << " " << betaCM << G4endl;
256      G4cout << "  gammaCM " << gammaCM << G4endl;
257    }
258
259    // Now following GLOREN...
260
261    G4double BETA[5], PA[5], PB[5];
262    BETA[1] = -betaCMx;
263    BETA[2] = -betaCMy;
264    BETA[3] = -betaCMz;
265    BETA[4] = gammaCM;
266
267    //The incident particle...
268
269    PA[1] = px;
270    PA[2] = py;
271    PA[3] = pz;
272    PA[4] = std::sqrt(M1*M1 + p*p);
273
274    G4double BETPA  = BETA[1]*PA[1] + BETA[2]*PA[2] + BETA[3]*PA[3];
275    G4double BPGAM  = (BETPA * BETA[4]/(BETA[4] + 1.) - PA[4]) * BETA[4];
276
277    PB[1] = PA[1] + BPGAM  * BETA[1];
278    PB[2] = PA[2] + BPGAM  * BETA[2];
279    PB[3] = PA[3] + BPGAM  * BETA[3];
280    PB[4] = (PA[4] - BETPA) * BETA[4];
281
282    G4DynamicParticle* newP = new G4DynamicParticle;
283    newP->SetDefinition(const_cast<G4ParticleDefinition *>(aParticle->GetDefinition()));
284    newP->SetMomentum(G4ThreeVector(PB[1], PB[2], PB[3]));
285
286    //The target particle...
287
288    PA[1] = -px;
289    PA[2] = -py;
290    PA[3] = -pz;
291    PA[4] = std::sqrt(M2*M2 + p*p);
292
293    BETPA  = BETA[1]*PA[1] + BETA[2]*PA[2] + BETA[3]*PA[3];
294    BPGAM  = (BETPA * BETA[4]/(BETA[4] + 1.) - PA[4]) * BETA[4];
295
296    PB[1] = PA[1] + BPGAM  * BETA[1];
297    PB[2] = PA[2] + BPGAM  * BETA[2];
298    PB[3] = PA[3] + BPGAM  * BETA[3];
299    PB[4] = (PA[4] - BETPA) * BETA[4];
300
301    targetParticle->SetMomentum(G4ThreeVector(PB[1], PB[2], PB[3]));
302
303    if (verboseLevel > 1) {
304      G4cout << "  particle 1 momentum in LAB " 
305           << newP->GetMomentum()*(1./GeV) 
306           << " " << newP->GetTotalMomentum()/GeV << G4endl;
307      G4cout << "  particle 2 momentum in LAB " 
308           << targetParticle->GetMomentum()*(1./GeV) 
309           << " " << targetParticle->GetTotalMomentum()/GeV << G4endl;
310      G4cout << "  TOTAL momentum in LAB " 
311           << (newP->GetMomentum()+targetParticle->GetMomentum())*(1./GeV) 
312           << " " 
313           << (newP->GetMomentum()+targetParticle->GetMomentum()).mag()/GeV
314           << G4endl;
315    }
316
317    theParticleChange.SetMomentumChange(newP->GetMomentumDirection());
318    theParticleChange.SetEnergyChange(newP->GetKineticEnergy());
319    delete newP;
320    G4DynamicParticle* p1 = new G4DynamicParticle;
321    p1->SetDefinition(targetParticle->GetDefinition());
322    p1->SetMomentum(targetParticle->GetMomentum());
323    theParticleChange.AddSecondary(p1);   
324
325    return &theParticleChange;
326}
327
328 // end of file
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