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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 | 18 | Revision 1.7 2001/03/15 16:13:28 coppedis |
19 | Code review | |
20 | ||
5a881c97 | 21 | Revision 1.6 2000/11/30 17:16:14 coppedis |
22 | Changes suggested by fca | |
23 | ||
1de555dc | 24 | Revision 1.5 2000/11/22 11:30:12 coppedis |
25 | Major code revision | |
26 | ||
866ab5a2 | 27 | Revision 1.4 2000/10/05 08:02:47 fca |
28 | Correction of the generator direction | |
29 | ||
699b37ac | 30 | Revision 1.3 2000/10/02 21:28:20 fca |
31 | Removal of useless dependecies via forward declarations | |
32 | ||
94de3818 | 33 | Revision 1.2 2000/07/11 11:12:34 fca |
34 | Some syntax corrections for non standard HP aCC | |
35 | ||
c0ceba4c | 36 | Revision 1.1 2000/07/10 13:58:01 fca |
37 | New version of ZDC from E.Scomparin & C.Oppedisano | |
38 | ||
68ca986e | 39 | Revision 1.7 2000/01/19 17:17:40 fca |
40 | ||
41 | Revision 1.6 1999/09/29 09:24:35 fca | |
42 | Introduction 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 | |
58 | ClassImp(AliGenZDC) | |
59 | ||
60 | //_____________________________________________________________________________ | |
61 | AliGenZDC::AliGenZDC() | |
62 | :AliGenerator() | |
63 | { | |
64 | // | |
65 | // Default constructor | |
66 | // | |
67 | fIpart = 0; | |
68 | } | |
69 | ||
70 | //_____________________________________________________________________________ | |
71 | AliGenZDC::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 | //_____________________________________________________________________________ | |
103 | void 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 | //_____________________________________________________________________________ | |
115 | void 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 | 193 | void 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 | 228 | void 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 | //_____________________________________________________________________________ | |
263 | void 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 | //_____________________________________________________________________________ | |
325 | void 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 |