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Adaption to new fluka common blocks (E. Futo)
[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$Log$
116cbefd 18Revision 1.12 2002/11/21 20:05:22 alibrary
19Removing AliMC and AliMCProcess
20
832f1922 21Revision 1.11 2001/11/11 17:27:50 hristov
22Minor corrections
23
0ff3ad02 24Revision 1.10 2001/09/26 16:00:47 coppedis
25Minor change
26
f3f777b8 27Revision 1.8 2001/04/20 10:10:25 coppedis
28Minor changes
29
c4c7fa06 30Revision 1.7 2001/03/15 16:13:28 coppedis
31Code review
32
5a881c97 33Revision 1.6 2000/11/30 17:16:14 coppedis
34Changes suggested by fca
35
1de555dc 36Revision 1.5 2000/11/22 11:30:12 coppedis
37Major code revision
38
866ab5a2 39Revision 1.4 2000/10/05 08:02:47 fca
40Correction of the generator direction
41
699b37ac 42Revision 1.3 2000/10/02 21:28:20 fca
43Removal of useless dependecies via forward declarations
44
94de3818 45Revision 1.2 2000/07/11 11:12:34 fca
46Some syntax corrections for non standard HP aCC
47
c0ceba4c 48Revision 1.1 2000/07/10 13:58:01 fca
49New version of ZDC from E.Scomparin & C.Oppedisano
50
68ca986e 51Revision 1.7 2000/01/19 17:17:40 fca
52
53Revision 1.6 1999/09/29 09:24:35 fca
54Introduction of the Copyright and cvs Log
55
56*/
94de3818 57#include <assert.h>
58
116cbefd 59#include <TDatabasePDG.h>
68ca986e 60#include <TLorentzVector.h>
116cbefd 61#include <TMCProcess.h>
62#include <TPDGCode.h>
63#include <TRandom.h>
68ca986e 64#include <TVector3.h>
65
68ca986e 66#include "AliConst.h"
116cbefd 67#include "AliGenZDC.h"
68ca986e 68#include "AliRun.h"
69
70ClassImp(AliGenZDC)
71
72//_____________________________________________________________________________
73AliGenZDC::AliGenZDC()
74 :AliGenerator()
75{
76 //
77 // Default constructor
78 //
79 fIpart = 0;
80}
81
82//_____________________________________________________________________________
83AliGenZDC::AliGenZDC(Int_t npart)
84 :AliGenerator(npart)
85{
86 //
87 // Standard constructor
88 //
89 fName = "AliGenZDC";
90 fTitle = "Generation of Test Particles for ZDCs";
91 fIpart = kNeutron;
92 fCosx = 0.;
93 fCosy = 0.;
94 fCosz = 1.;
95 fPseudoRapidity = 0.;
5a881c97 96
68ca986e 97 fFermiflag = 1;
98 // LHC values for beam divergence and crossing angle
99 fBeamDiv = 0.000032;
100 fBeamCrossAngle = 0.0001;
101 fBeamCrossPlane = 2;
5a881c97 102
103 Int_t i, j;
104 for(i=0; i<201; i++){
105 fProbintp[i] = 0;
106 fProbintn[i] = 0;
107 }
108 for(j=0; j<3; j++){
109 fPp[i] = 0;
110 }
111 fDebugOpt = 0;
68ca986e 112}
113
114//_____________________________________________________________________________
115void AliGenZDC::Init()
116{
5a881c97 117 printf("\n\n AliGenZDC initialized with:\n");
866ab5a2 118 printf(" Fermi flag = %d, Beam Divergence = %f, Crossing Angle "
68ca986e 119 "= %f, Crossing Plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
120 fBeamCrossPlane);
5a881c97 121
68ca986e 122 //Initialize Fermi momentum distributions for Pb-Pb
123 FermiTwoGaussian(207.,82.,fPp,fProbintp,fProbintn);
124}
125
126//_____________________________________________________________________________
127void AliGenZDC::Generate()
128{
129 //
130 // Generate one trigger (n or p)
131 //
c0ceba4c 132 Int_t i;
133
5a881c97 134 Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3];
135 Float_t fPTrack[3], ptot = fPMin;
68ca986e 136 Int_t nt;
137
866ab5a2 138 if(fPseudoRapidity==0.){
68ca986e 139 pLab[0] = ptot*fCosx;
140 pLab[1] = ptot*fCosy;
141 pLab[2] = ptot*fCosz;
142 }
143 else{
144 Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
145 pLab[0] = -ptot*TMath::Sin(scang);
146 pLab[1] = 0.;
147 pLab[2] = ptot*TMath::Cos(scang);
148 }
c0ceba4c 149 for(i=0; i<=2; i++){
68ca986e 150 fP[i] = pLab[i];
151 }
152
5a881c97 153
68ca986e 154 // Beam divergence and crossing angle
866ab5a2 155 if(fBeamCrossAngle!=0.) {
156 BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
157 for(i=0; i<=2; i++){
158 fP[i] = pLab[i];
159 }
160 }
161 if(fBeamDiv!=0.) {
162 BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
163 for(i=0; i<=2; i++){
164 fP[i] = pLab[i];
165 }
166 }
167
68ca986e 168 // If required apply the Fermi momentum
169 if(fFermiflag==1){
170 if((fIpart==kProton) || (fIpart==kNeutron)){
171 ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp);
172 }
5a881c97 173 Mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass();
174 fP0 = TMath::Sqrt(fP[0]*fP[0]+fP[1]*fP[1]+fP[2]*fP[2]+Mass*Mass);
c0ceba4c 175 for(i=0; i<=2; i++){
68ca986e 176 dddp[i] = ddp[i];
177 }
5a881c97 178 dddp0 = TMath::Sqrt(dddp[0]*dddp[0]+dddp[1]*dddp[1]+dddp[2]*dddp[2]+Mass*Mass);
68ca986e 179
866ab5a2 180 TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
68ca986e 181 TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);
182
68ca986e 183 pFermi.Boost(b);
c0ceba4c 184 for(i=0; i<=2; i++){
68ca986e 185 fBoostP[i] = pFermi[i];
866ab5a2 186 fP[i] = pFermi[i];
68ca986e 187 }
188
189 }
866ab5a2 190
191 for(i=0; i<=2; i++){
192 fPTrack[i] = fP[i];
193 }
194
68ca986e 195 Float_t polar[3] = {0,0,0};
866ab5a2 196 gAlice->SetTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
1de555dc 197 kPPrimary,nt);
5a881c97 198 if(fDebugOpt == 1){
199 printf("\n\n Track momentum:\n");
200 printf("\n fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
201 }
68ca986e 202}
203
204//_____________________________________________________________________________
5a881c97 205void AliGenZDC::FermiTwoGaussian(Float_t A, Float_t Z, Double_t *fPp,
206 Double_t *fProbintp, Double_t *fProbintn)
68ca986e 207{
208//
209// Momenta distributions according to the "double-gaussian"
210// distribution (Ilinov) - equal for protons and neutrons
211//
5a881c97 212
68ca986e 213 fProbintp[0] = 0;
214 fProbintn[0] = 0;
215 Double_t sig1 = 0.113;
216 Double_t sig2 = 0.250;
217 Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
218 Double_t xk = (2*k2PI)/((1.+alfa)*(TMath::Power(k2PI,1.5)));
219
220 for(Int_t i=1; i<=200; i++){
221 Double_t p = i*0.005;
222 fPp[i] = p;
68ca986e 223 Double_t e1 = (p*p)/(2.*sig1*sig1);
224 Double_t e2 = (p*p)/(2.*sig2*sig2);
225 Double_t f1 = TMath::Exp(-(e1));
226 Double_t f2 = TMath::Exp(-(e2));
227 Double_t probp = xk*p*p*(f1/(TMath::Power(sig1,3.))+
228 alfa*f2/(TMath::Power(sig2,3.)))*0.005;
68ca986e 229 fProbintp[i] = fProbintp[i-1] + probp;
230 fProbintn[i] = fProbintp[i];
5a881c97 231 }
232 if(fDebugOpt == 1){
233 printf("\n\n Initialization of Fermi momenta distribution \n");
234 for(Int_t i=0; i<=200; i++){
235 printf(" fProbintp[%d] = %f, fProbintn[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
236 }
68ca986e 237 }
238}
239//_____________________________________________________________________________
5a881c97 240void AliGenZDC::ExtractFermi(Int_t id, Double_t *fPp, Double_t *fProbintp,
241 Double_t *fProbintn, Double_t *ddp)
68ca986e 242{
243//
244// Compute Fermi momentum for spectator nucleons
245//
5a881c97 246
68ca986e 247 Int_t i;
248 Float_t xx = gRandom->Rndm();
699b37ac 249 assert ( id==kProton || id==kNeutron );
68ca986e 250 if(id==kProton){
0ff3ad02 251 for(i=1; i<=200; i++){
68ca986e 252 if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
253 }
254 }
94de3818 255 else {
68ca986e 256 for(i=0; i<=200; i++){
257 if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
258 }
259 }
260 Float_t pext = fPp[i]+0.001;
261 Float_t phi = k2PI*(gRandom->Rndm());
262 Float_t cost = (1.-2.*(gRandom->Rndm()));
263 Float_t tet = TMath::ACos(cost);
264 ddp[0] = pext*TMath::Sin(tet)*TMath::Cos(phi);
265 ddp[1] = pext*TMath::Sin(tet)*TMath::Sin(phi);
266 ddp[2] = pext*cost;
5a881c97 267
268 if(fDebugOpt == 1){
269 printf("\n\n Extraction of Fermi momentum\n");
270 printf("\n pxFermi = %f pyFermi = %f pzFermi = %f \n",ddp[0],ddp[1],ddp[2]);
271 }
68ca986e 272}
273
274//_____________________________________________________________________________
275void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle,
5a881c97 276 Int_t fBeamCrossPlane, Double_t *pLab)
68ca986e 277{
866ab5a2 278 Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
68ca986e 279 Double_t rvec;
c0ceba4c 280
281 Int_t i;
68ca986e 282 Double_t pmq = 0.;
c0ceba4c 283 for(i=0; i<=2; i++){
68ca986e 284 pmq = pmq+pLab[i]*pLab[i];
285 }
286 Double_t pmod = TMath::Sqrt(pmq);
68ca986e 287
68ca986e 288 if(icross==0){
289 rvec = gRandom->Gaus(0.0,1.0);
290 tetdiv = fBeamDiv * TMath::Abs(rvec);
291 fidiv = (gRandom->Rndm())*k2PI;
292 }
293 else if(icross==1){
294 if(fBeamCrossPlane==0.){
295 tetdiv = 0.;
296 fidiv = 0.;
297 }
298 else if(fBeamCrossPlane==1.){
299 tetdiv = fBeamCrossAngle;
300 fidiv = 0.;
301 }
302 else if(fBeamCrossPlane==2.){
303 tetdiv = fBeamCrossAngle;
736c9b58 304 fidiv = k2PI/4.;
68ca986e 305 }
306 }
866ab5a2 307
308 tetpart = TMath::ATan(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1])/pLab[2]);
309 if(pLab[1]!=0. || pLab[0]!=0.){
310 fipart = TMath::ATan2(pLab[1],pLab[0]);
68ca986e 311 }
312 else{
313 fipart = 0.;
314 }
315 if(fipart<0.) {fipart = fipart+k2PI;}
68ca986e 316 tetdiv = tetdiv*kRaddeg;
317 fidiv = fidiv*kRaddeg;
318 tetpart = tetpart*kRaddeg;
319 fipart = fipart*kRaddeg;
320 AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
321 tetsum = angleSum[0];
322 fisum = angleSum[1];
68ca986e 323 tetsum = tetsum*kDegrad;
324 fisum = fisum*kDegrad;
325 pLab[0] = pmod*TMath::Sin(tetsum)*TMath::Cos(fisum);
326 pLab[1] = pmod*TMath::Sin(tetsum)*TMath::Sin(fisum);
327 pLab[2] = pmod*TMath::Cos(tetsum);
5a881c97 328 if(fDebugOpt == 1){
329 printf("\n\n Beam divergence and crossing angle\n");
330 for(i=0; i<=2; i++){
331 printf(" pLab[%d] = %f\n",i,pLab[i]);
332 }
68ca986e 333 }
334}
335
336//_____________________________________________________________________________
337void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
5a881c97 338 Double_t phi2, Double_t *angleSum)
68ca986e 339{
340 Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
341 Double_t rtetsum, tetsum, fisum;
342
343 temp = -1.;
344 conv = 180./TMath::ACos(temp);
345
346 ct1 = TMath::Cos(theta1/conv);
347 st1 = TMath::Sin(theta1/conv);
348 cp1 = TMath::Cos(phi1/conv);
349 sp1 = TMath::Sin(phi1/conv);
350 ct2 = TMath::Cos(theta2/conv);
351 st2 = TMath::Sin(theta2/conv);
352 cp2 = TMath::Cos(phi2/conv);
353 sp2 = TMath::Sin(phi2/conv);
354 cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2;
355 cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2;
356 cz = ct1*ct2-st1*st2*cp2;
357
358 rtetsum = TMath::ACos(cz);
359 tetsum = conv*rtetsum;
360 if(tetsum==0. || tetsum==180.){
361 fisum = 0.;
362 return;
363 }
364 temp = cx/TMath::Sin(rtetsum);
365 if(temp>1.) temp=1.;
366 if(temp<-1.) temp=-1.;
367 fisum = conv*TMath::ACos(temp);
368 if(cy<0) {fisum = 360.-fisum;}
68ca986e 369 angleSum[0] = tetsum;
370 angleSum[1] = fisum;
371}
372