Changes to add AliZDCFragment class
[u/mrichter/AliRoot.git] / ZDC / AliGenZDC.cxx
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68ca986e 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
16/*
17$Log$
c4c7fa06 18Revision 1.7 2001/03/15 16:13:28 coppedis
19Code review
20
5a881c97 21Revision 1.6 2000/11/30 17:16:14 coppedis
22Changes suggested by fca
23
1de555dc 24Revision 1.5 2000/11/22 11:30:12 coppedis
25Major code revision
26
866ab5a2 27Revision 1.4 2000/10/05 08:02:47 fca
28Correction of the generator direction
29
699b37ac 30Revision 1.3 2000/10/02 21:28:20 fca
31Removal of useless dependecies via forward declarations
32
94de3818 33Revision 1.2 2000/07/11 11:12:34 fca
34Some syntax corrections for non standard HP aCC
35
c0ceba4c 36Revision 1.1 2000/07/10 13:58:01 fca
37New version of ZDC from E.Scomparin & C.Oppedisano
38
68ca986e 39Revision 1.7 2000/01/19 17:17:40 fca
40
41Revision 1.6 1999/09/29 09:24:35 fca
42Introduction of the Copyright and cvs Log
43
44*/
94de3818 45#include <assert.h>
46
68ca986e 47#include <TRandom.h>
48#include <TLorentzVector.h>
49#include <TVector3.h>
94de3818 50#include "TDatabasePDG.h"
68ca986e 51
52#include "AliGenZDC.h"
53#include "AliConst.h"
54#include "AliPDG.h"
55#include "AliRun.h"
1de555dc 56#include "AliMCProcess.h"
68ca986e 57
58ClassImp(AliGenZDC)
59
60//_____________________________________________________________________________
61AliGenZDC::AliGenZDC()
62 :AliGenerator()
63{
64 //
65 // Default constructor
66 //
67 fIpart = 0;
68}
69
70//_____________________________________________________________________________
71AliGenZDC::AliGenZDC(Int_t npart)
72 :AliGenerator(npart)
73{
74 //
75 // Standard constructor
76 //
77 fName = "AliGenZDC";
78 fTitle = "Generation of Test Particles for ZDCs";
79 fIpart = kNeutron;
80 fCosx = 0.;
81 fCosy = 0.;
82 fCosz = 1.;
83 fPseudoRapidity = 0.;
5a881c97 84
68ca986e 85 fFermiflag = 1;
86 // LHC values for beam divergence and crossing angle
87 fBeamDiv = 0.000032;
88 fBeamCrossAngle = 0.0001;
89 fBeamCrossPlane = 2;
5a881c97 90
91 Int_t i, j;
92 for(i=0; i<201; i++){
93 fProbintp[i] = 0;
94 fProbintn[i] = 0;
95 }
96 for(j=0; j<3; j++){
97 fPp[i] = 0;
98 }
99 fDebugOpt = 0;
68ca986e 100}
101
102//_____________________________________________________________________________
103void AliGenZDC::Init()
104{
5a881c97 105 printf("\n\n AliGenZDC initialized with:\n");
866ab5a2 106 printf(" Fermi flag = %d, Beam Divergence = %f, Crossing Angle "
68ca986e 107 "= %f, Crossing Plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
108 fBeamCrossPlane);
5a881c97 109
68ca986e 110 //Initialize Fermi momentum distributions for Pb-Pb
111 FermiTwoGaussian(207.,82.,fPp,fProbintp,fProbintn);
112}
113
114//_____________________________________________________________________________
115void AliGenZDC::Generate()
116{
117 //
118 // Generate one trigger (n or p)
119 //
c0ceba4c 120 Int_t i;
121
5a881c97 122 Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3];
123 Float_t fPTrack[3], ptot = fPMin;
68ca986e 124 Int_t nt;
125
866ab5a2 126 if(fPseudoRapidity==0.){
68ca986e 127 pLab[0] = ptot*fCosx;
128 pLab[1] = ptot*fCosy;
129 pLab[2] = ptot*fCosz;
130 }
131 else{
132 Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
133 pLab[0] = -ptot*TMath::Sin(scang);
134 pLab[1] = 0.;
135 pLab[2] = ptot*TMath::Cos(scang);
136 }
c0ceba4c 137 for(i=0; i<=2; i++){
68ca986e 138 fP[i] = pLab[i];
139 }
140
5a881c97 141
68ca986e 142 // Beam divergence and crossing angle
866ab5a2 143 if(fBeamCrossAngle!=0.) {
144 BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
145 for(i=0; i<=2; i++){
146 fP[i] = pLab[i];
147 }
148 }
149 if(fBeamDiv!=0.) {
150 BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
151 for(i=0; i<=2; i++){
152 fP[i] = pLab[i];
153 }
154 }
155
68ca986e 156 // If required apply the Fermi momentum
157 if(fFermiflag==1){
158 if((fIpart==kProton) || (fIpart==kNeutron)){
159 ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp);
160 }
5a881c97 161 Mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass();
162 fP0 = TMath::Sqrt(fP[0]*fP[0]+fP[1]*fP[1]+fP[2]*fP[2]+Mass*Mass);
c0ceba4c 163 for(i=0; i<=2; i++){
68ca986e 164 dddp[i] = ddp[i];
165 }
5a881c97 166 dddp0 = TMath::Sqrt(dddp[0]*dddp[0]+dddp[1]*dddp[1]+dddp[2]*dddp[2]+Mass*Mass);
68ca986e 167
866ab5a2 168 TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
68ca986e 169 TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);
170
68ca986e 171 pFermi.Boost(b);
c0ceba4c 172 for(i=0; i<=2; i++){
68ca986e 173 fBoostP[i] = pFermi[i];
866ab5a2 174 fP[i] = pFermi[i];
68ca986e 175 }
176
177 }
866ab5a2 178
179 for(i=0; i<=2; i++){
180 fPTrack[i] = fP[i];
181 }
182
68ca986e 183 Float_t polar[3] = {0,0,0};
866ab5a2 184 gAlice->SetTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
1de555dc 185 kPPrimary,nt);
5a881c97 186 if(fDebugOpt == 1){
187 printf("\n\n Track momentum:\n");
188 printf("\n fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
189 }
68ca986e 190}
191
192//_____________________________________________________________________________
5a881c97 193void AliGenZDC::FermiTwoGaussian(Float_t A, Float_t Z, Double_t *fPp,
194 Double_t *fProbintp, Double_t *fProbintn)
68ca986e 195{
196//
197// Momenta distributions according to the "double-gaussian"
198// distribution (Ilinov) - equal for protons and neutrons
199//
5a881c97 200
68ca986e 201 fProbintp[0] = 0;
202 fProbintn[0] = 0;
203 Double_t sig1 = 0.113;
204 Double_t sig2 = 0.250;
205 Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
206 Double_t xk = (2*k2PI)/((1.+alfa)*(TMath::Power(k2PI,1.5)));
207
208 for(Int_t i=1; i<=200; i++){
209 Double_t p = i*0.005;
210 fPp[i] = p;
68ca986e 211 Double_t e1 = (p*p)/(2.*sig1*sig1);
212 Double_t e2 = (p*p)/(2.*sig2*sig2);
213 Double_t f1 = TMath::Exp(-(e1));
214 Double_t f2 = TMath::Exp(-(e2));
215 Double_t probp = xk*p*p*(f1/(TMath::Power(sig1,3.))+
216 alfa*f2/(TMath::Power(sig2,3.)))*0.005;
68ca986e 217 fProbintp[i] = fProbintp[i-1] + probp;
218 fProbintn[i] = fProbintp[i];
5a881c97 219 }
220 if(fDebugOpt == 1){
221 printf("\n\n Initialization of Fermi momenta distribution \n");
222 for(Int_t i=0; i<=200; i++){
223 printf(" fProbintp[%d] = %f, fProbintn[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
224 }
68ca986e 225 }
226}
227//_____________________________________________________________________________
5a881c97 228void AliGenZDC::ExtractFermi(Int_t id, Double_t *fPp, Double_t *fProbintp,
229 Double_t *fProbintn, Double_t *ddp)
68ca986e 230{
231//
232// Compute Fermi momentum for spectator nucleons
233//
5a881c97 234
68ca986e 235 Int_t i;
236 Float_t xx = gRandom->Rndm();
699b37ac 237 assert ( id==kProton || id==kNeutron );
68ca986e 238 if(id==kProton){
239 for(i=0; i<=200; i++){
240 if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
241 }
242 }
94de3818 243 else {
68ca986e 244 for(i=0; i<=200; i++){
245 if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
246 }
247 }
248 Float_t pext = fPp[i]+0.001;
249 Float_t phi = k2PI*(gRandom->Rndm());
250 Float_t cost = (1.-2.*(gRandom->Rndm()));
251 Float_t tet = TMath::ACos(cost);
252 ddp[0] = pext*TMath::Sin(tet)*TMath::Cos(phi);
253 ddp[1] = pext*TMath::Sin(tet)*TMath::Sin(phi);
254 ddp[2] = pext*cost;
5a881c97 255
256 if(fDebugOpt == 1){
257 printf("\n\n Extraction of Fermi momentum\n");
258 printf("\n pxFermi = %f pyFermi = %f pzFermi = %f \n",ddp[0],ddp[1],ddp[2]);
259 }
68ca986e 260}
261
262//_____________________________________________________________________________
263void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle,
5a881c97 264 Int_t fBeamCrossPlane, Double_t *pLab)
68ca986e 265{
866ab5a2 266 Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
68ca986e 267 Double_t rvec;
c0ceba4c 268
269 Int_t i;
68ca986e 270 Double_t pmq = 0.;
c0ceba4c 271 for(i=0; i<=2; i++){
68ca986e 272 pmq = pmq+pLab[i]*pLab[i];
273 }
274 Double_t pmod = TMath::Sqrt(pmq);
68ca986e 275
68ca986e 276 if(icross==0){
277 rvec = gRandom->Gaus(0.0,1.0);
278 tetdiv = fBeamDiv * TMath::Abs(rvec);
279 fidiv = (gRandom->Rndm())*k2PI;
280 }
281 else if(icross==1){
282 if(fBeamCrossPlane==0.){
283 tetdiv = 0.;
284 fidiv = 0.;
285 }
286 else if(fBeamCrossPlane==1.){
287 tetdiv = fBeamCrossAngle;
288 fidiv = 0.;
289 }
290 else if(fBeamCrossPlane==2.){
291 tetdiv = fBeamCrossAngle;
292 fidiv = k2PI/4.;
293 }
294 }
866ab5a2 295
296 tetpart = TMath::ATan(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1])/pLab[2]);
297 if(pLab[1]!=0. || pLab[0]!=0.){
298 fipart = TMath::ATan2(pLab[1],pLab[0]);
68ca986e 299 }
300 else{
301 fipart = 0.;
302 }
303 if(fipart<0.) {fipart = fipart+k2PI;}
68ca986e 304 tetdiv = tetdiv*kRaddeg;
305 fidiv = fidiv*kRaddeg;
306 tetpart = tetpart*kRaddeg;
307 fipart = fipart*kRaddeg;
308 AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
309 tetsum = angleSum[0];
310 fisum = angleSum[1];
68ca986e 311 tetsum = tetsum*kDegrad;
312 fisum = fisum*kDegrad;
313 pLab[0] = pmod*TMath::Sin(tetsum)*TMath::Cos(fisum);
314 pLab[1] = pmod*TMath::Sin(tetsum)*TMath::Sin(fisum);
315 pLab[2] = pmod*TMath::Cos(tetsum);
5a881c97 316 if(fDebugOpt == 1){
317 printf("\n\n Beam divergence and crossing angle\n");
318 for(i=0; i<=2; i++){
319 printf(" pLab[%d] = %f\n",i,pLab[i]);
320 }
68ca986e 321 }
322}
323
324//_____________________________________________________________________________
325void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
5a881c97 326 Double_t phi2, Double_t *angleSum)
68ca986e 327{
328 Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
329 Double_t rtetsum, tetsum, fisum;
330
331 temp = -1.;
332 conv = 180./TMath::ACos(temp);
333
334 ct1 = TMath::Cos(theta1/conv);
335 st1 = TMath::Sin(theta1/conv);
336 cp1 = TMath::Cos(phi1/conv);
337 sp1 = TMath::Sin(phi1/conv);
338 ct2 = TMath::Cos(theta2/conv);
339 st2 = TMath::Sin(theta2/conv);
340 cp2 = TMath::Cos(phi2/conv);
341 sp2 = TMath::Sin(phi2/conv);
342 cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2;
343 cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2;
344 cz = ct1*ct2-st1*st2*cp2;
345
346 rtetsum = TMath::ACos(cz);
347 tetsum = conv*rtetsum;
348 if(tetsum==0. || tetsum==180.){
349 fisum = 0.;
350 return;
351 }
352 temp = cx/TMath::Sin(rtetsum);
353 if(temp>1.) temp=1.;
354 if(temp<-1.) temp=-1.;
355 fisum = conv*TMath::ACos(temp);
356 if(cy<0) {fisum = 360.-fisum;}
68ca986e 357 angleSum[0] = tetsum;
358 angleSum[1] = fisum;
359}
360