Add class to access simulation parameters, AliEMCALSimParam, to be set in configurati...
[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
88cb7938 16/* $Id$ */
116cbefd 17
8a2624cc 18//////////////////////////////////////////////////////////////////////
19// // //
20// Generator of spectator nucleons (either protons or neutrons)//
21// computes beam crossing and divergence and Fermi momentum //
22// //
23/////////////////////////////////////////////////////////////////////
24
94de3818 25#include <assert.h>
26
116cbefd 27#include <TDatabasePDG.h>
68ca986e 28#include <TLorentzVector.h>
116cbefd 29#include <TMCProcess.h>
30#include <TPDGCode.h>
31#include <TRandom.h>
68ca986e 32#include <TVector3.h>
33
68ca986e 34#include "AliConst.h"
116cbefd 35#include "AliGenZDC.h"
68ca986e 36#include "AliRun.h"
5d12ce38 37#include "AliMC.h"
68ca986e 38
39ClassImp(AliGenZDC)
40
41//_____________________________________________________________________________
42AliGenZDC::AliGenZDC()
a718c993 43 :AliGenerator(),
44 fIpart(0),
45 fCosx(0),
46 fCosy(0),
47 fCosz(0),
48 fPseudoRapidity(0),
49 fFermiflag(0),
50 fBeamDiv(0),
51 fBeamCrossAngle(0),
52 fBeamCrossPlane(0),
53 fDebugOpt(0)
68ca986e 54{
55 //
56 // Default constructor
57 //
68ca986e 58}
59
60//_____________________________________________________________________________
61AliGenZDC::AliGenZDC(Int_t npart)
a718c993 62 :AliGenerator(npart),
63 fIpart(kNeutron),
64 fCosx(0.),
65 fCosy(0.),
66 fCosz(1.),
67 fPseudoRapidity(0.),
68 fFermiflag(1),
69 fBeamDiv(0.000032),
70 fBeamCrossAngle(0.0001),
71 fBeamCrossPlane(2),
72 fDebugOpt(0)
68ca986e 73{
74 //
75 // Standard constructor
76 //
77 fName = "AliGenZDC";
78 fTitle = "Generation of Test Particles for ZDCs";
5a881c97 79
80 Int_t i, j;
81 for(i=0; i<201; i++){
82 fProbintp[i] = 0;
83 fProbintn[i] = 0;
84 }
c294be39 85 for(j=0; j<3; j++) fPp[i] = 0;
68ca986e 86}
87
88//_____________________________________________________________________________
89void AliGenZDC::Init()
90{
8a2624cc 91 //Initialize Fermi momentum distributions for Pb-Pb
92 //
c294be39 93 printf("\n\n AliGenZDC initialization:\n");
94 printf(" Particle: %d, Track cosines: x = %f, y = %f, z = %f \n",
95 fIpart,fCosx,fCosy,fCosz);
96 printf(" Fermi flag = %d, Beam divergence = %f, Crossing angle "
97 "= %f, Crossing plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
68ca986e 98 fBeamCrossPlane);
5a881c97 99
fd9afd60 100 FermiTwoGaussian(208.);
68ca986e 101}
102
103//_____________________________________________________________________________
104void AliGenZDC::Generate()
105{
106 //
107 // Generate one trigger (n or p)
108 //
c0ceba4c 109 Int_t i;
110
8a2624cc 111 Double_t mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3];
5a881c97 112 Float_t fPTrack[3], ptot = fPMin;
68ca986e 113 Int_t nt;
114
866ab5a2 115 if(fPseudoRapidity==0.){
68ca986e 116 pLab[0] = ptot*fCosx;
117 pLab[1] = ptot*fCosy;
118 pLab[2] = ptot*fCosz;
119 }
120 else{
121 Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity)));
122 pLab[0] = -ptot*TMath::Sin(scang);
123 pLab[1] = 0.;
124 pLab[2] = ptot*TMath::Cos(scang);
125 }
c294be39 126 for(i=0; i<=2; i++) fP[i] = pLab[i];
127 if(fDebugOpt == 1){
128 printf("\n\n Particle momentum before divergence and crossing\n");
129 for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]);
68ca986e 130 }
131
132 // Beam divergence and crossing angle
866ab5a2 133 if(fBeamCrossAngle!=0.) {
92339a90 134 BeamDivCross(1, pLab);
c294be39 135 for(i=0; i<=2; i++) fP[i] = pLab[i];
866ab5a2 136 }
137 if(fBeamDiv!=0.) {
92339a90 138 BeamDivCross(0, pLab);
c294be39 139 for(i=0; i<=2; i++) fP[i] = pLab[i];
866ab5a2 140 }
141
68ca986e 142 // If required apply the Fermi momentum
143 if(fFermiflag==1){
c294be39 144 if((fIpart==kProton) || (fIpart==kNeutron))
92339a90 145 ExtractFermi(fIpart, ddp);
fc22e8ec 146 mass=TDatabasePDG::Instance()->GetParticle(fIpart)->Mass();
8a2624cc 147 fP0 = TMath::Sqrt(fP[0]*fP[0]+fP[1]*fP[1]+fP[2]*fP[2]+mass*mass);
c294be39 148 for(i=0; i<=2; i++) dddp[i] = ddp[i];
8a2624cc 149 dddp0 = TMath::Sqrt(dddp[0]*dddp[0]+dddp[1]*dddp[1]+dddp[2]*dddp[2]+mass*mass);
68ca986e 150
866ab5a2 151 TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0);
68ca986e 152 TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0);
153
68ca986e 154 pFermi.Boost(b);
c0ceba4c 155 for(i=0; i<=2; i++){
68ca986e 156 fBoostP[i] = pFermi[i];
866ab5a2 157 fP[i] = pFermi[i];
68ca986e 158 }
159
160 }
866ab5a2 161
c294be39 162 for(i=0; i<=2; i++) fPTrack[i] = fP[i];
866ab5a2 163
68ca986e 164 Float_t polar[3] = {0,0,0};
5d12ce38 165 gAlice->GetMCApp()->PushTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0,
1de555dc 166 kPPrimary,nt);
03cc1ceb 167 // -----------------------------------------------------------------------
5a881c97 168 if(fDebugOpt == 1){
169 printf("\n\n Track momentum:\n");
170 printf("\n fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
171 }
03cc1ceb 172 else if(fDebugOpt == 2){
173 FILE *file;
174 if((file = fopen("SpectMomentum.dat","a")) == NULL){
175 printf("Cannot open file SpectMomentum.dat\n");
176 return;
177 }
178 fprintf(file," %f \t %f \t %f \n",fPTrack[0],fPTrack[1],fPTrack[2]);
179 fclose(file);
180 }
181
68ca986e 182}
183
184//_____________________________________________________________________________
92339a90 185void AliGenZDC::FermiTwoGaussian(Float_t A)
68ca986e 186{
187//
188// Momenta distributions according to the "double-gaussian"
189// distribution (Ilinov) - equal for protons and neutrons
190//
5a881c97 191
68ca986e 192 Double_t sig1 = 0.113;
193 Double_t sig2 = 0.250;
194 Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3));
195 Double_t xk = (2*k2PI)/((1.+alfa)*(TMath::Power(k2PI,1.5)));
196
197 for(Int_t i=1; i<=200; i++){
198 Double_t p = i*0.005;
199 fPp[i] = p;
68ca986e 200 Double_t e1 = (p*p)/(2.*sig1*sig1);
201 Double_t e2 = (p*p)/(2.*sig2*sig2);
202 Double_t f1 = TMath::Exp(-(e1));
203 Double_t f2 = TMath::Exp(-(e2));
204 Double_t probp = xk*p*p*(f1/(TMath::Power(sig1,3.))+
205 alfa*f2/(TMath::Power(sig2,3.)))*0.005;
68ca986e 206 fProbintp[i] = fProbintp[i-1] + probp;
207 fProbintn[i] = fProbintp[i];
5a881c97 208 }
209 if(fDebugOpt == 1){
210 printf("\n\n Initialization of Fermi momenta distribution \n");
c294be39 211 //for(Int_t i=0; i<=200; i++)
212 // printf(" fProbintp[%d] = %f, fProbintn[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]);
68ca986e 213 }
214}
215//_____________________________________________________________________________
92339a90 216void AliGenZDC::ExtractFermi(Int_t id, Double_t *ddp)
68ca986e 217{
218//
219// Compute Fermi momentum for spectator nucleons
220//
5a881c97 221
68ca986e 222 Int_t i;
223 Float_t xx = gRandom->Rndm();
699b37ac 224 assert ( id==kProton || id==kNeutron );
68ca986e 225 if(id==kProton){
0ff3ad02 226 for(i=1; i<=200; i++){
68ca986e 227 if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
228 }
229 }
94de3818 230 else {
68ca986e 231 for(i=0; i<=200; i++){
232 if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
233 }
234 }
235 Float_t pext = fPp[i]+0.001;
236 Float_t phi = k2PI*(gRandom->Rndm());
237 Float_t cost = (1.-2.*(gRandom->Rndm()));
238 Float_t tet = TMath::ACos(cost);
239 ddp[0] = pext*TMath::Sin(tet)*TMath::Cos(phi);
240 ddp[1] = pext*TMath::Sin(tet)*TMath::Sin(phi);
241 ddp[2] = pext*cost;
5a881c97 242
243 if(fDebugOpt == 1){
244 printf("\n\n Extraction of Fermi momentum\n");
245 printf("\n pxFermi = %f pyFermi = %f pzFermi = %f \n",ddp[0],ddp[1],ddp[2]);
246 }
68ca986e 247}
248
249//_____________________________________________________________________________
92339a90 250void AliGenZDC::BeamDivCross(Int_t icross, Double_t *pLab)
68ca986e 251{
8a2624cc 252 // Applying beam divergence and crossing angle
253 //
866ab5a2 254 Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
68ca986e 255 Double_t rvec;
c0ceba4c 256
68ca986e 257 Double_t pmq = 0.;
c294be39 258 Int_t i;
259 for(i=0; i<=2; i++) pmq = pmq+pLab[i]*pLab[i];
68ca986e 260 Double_t pmod = TMath::Sqrt(pmq);
68ca986e 261
03cc1ceb 262 if(icross==0){ // ##### Beam divergence
68ca986e 263 rvec = gRandom->Gaus(0.0,1.0);
264 tetdiv = fBeamDiv * TMath::Abs(rvec);
265 fidiv = (gRandom->Rndm())*k2PI;
266 }
03cc1ceb 267 else if(icross==1){ // ##### Crossing angle
92339a90 268 if(fBeamCrossPlane==0){
68ca986e 269 tetdiv = 0.;
270 fidiv = 0.;
271 }
92339a90 272 else if(fBeamCrossPlane==1){ // Horizontal crossing plane
68ca986e 273 tetdiv = fBeamCrossAngle;
274 fidiv = 0.;
275 }
92339a90 276 else if(fBeamCrossPlane==2){ // Vertical crossing plane
68ca986e 277 tetdiv = fBeamCrossAngle;
736c9b58 278 fidiv = k2PI/4.;
68ca986e 279 }
280 }
866ab5a2 281
03cc1ceb 282 tetpart = TMath::ATan2(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1]),pLab[2]);
c294be39 283 if(pLab[1]!=0. || pLab[0]!=0.) fipart = TMath::ATan2(pLab[1],pLab[0]);
284 else fipart = 0.;
68ca986e 285 if(fipart<0.) {fipart = fipart+k2PI;}
68ca986e 286 tetdiv = tetdiv*kRaddeg;
287 fidiv = fidiv*kRaddeg;
288 tetpart = tetpart*kRaddeg;
289 fipart = fipart*kRaddeg;
290 AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
291 tetsum = angleSum[0];
292 fisum = angleSum[1];
68ca986e 293 tetsum = tetsum*kDegrad;
294 fisum = fisum*kDegrad;
295 pLab[0] = pmod*TMath::Sin(tetsum)*TMath::Cos(fisum);
296 pLab[1] = pmod*TMath::Sin(tetsum)*TMath::Sin(fisum);
03cc1ceb 297 pLab[2] = pmod*TMath::Cos(tetsum);
5a881c97 298 if(fDebugOpt == 1){
03cc1ceb 299 if(icross==0) printf("\n\n Beam divergence \n");
300 else printf("\n\n Beam crossing \n");
c294be39 301 for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]);
68ca986e 302 }
303}
304
305//_____________________________________________________________________________
306void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
5a881c97 307 Double_t phi2, Double_t *angleSum)
8a2624cc 308{
309 // Calculating the sum of 2 angles
68ca986e 310 Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
311 Double_t rtetsum, tetsum, fisum;
312
313 temp = -1.;
314 conv = 180./TMath::ACos(temp);
315
316 ct1 = TMath::Cos(theta1/conv);
317 st1 = TMath::Sin(theta1/conv);
318 cp1 = TMath::Cos(phi1/conv);
319 sp1 = TMath::Sin(phi1/conv);
320 ct2 = TMath::Cos(theta2/conv);
321 st2 = TMath::Sin(theta2/conv);
322 cp2 = TMath::Cos(phi2/conv);
323 sp2 = TMath::Sin(phi2/conv);
324 cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2;
325 cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2;
326 cz = ct1*ct2-st1*st2*cp2;
327
328 rtetsum = TMath::ACos(cz);
329 tetsum = conv*rtetsum;
330 if(tetsum==0. || tetsum==180.){
331 fisum = 0.;
332 return;
333 }
334 temp = cx/TMath::Sin(rtetsum);
335 if(temp>1.) temp=1.;
336 if(temp<-1.) temp=-1.;
337 fisum = conv*TMath::ACos(temp);
338 if(cy<0) {fisum = 360.-fisum;}
68ca986e 339 angleSum[0] = tetsum;
340 angleSum[1] = fisum;
341}
342