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ac3faee4 | 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 | **************************************************************************/ | |
4966b266 | 15 | |
ac3faee4 | 16 | /* $Id$ */ |
17 | ||
18 | /////////////////////////////////////////////////////////////////////////////// | |
4966b266 | 19 | // |
20 | // AliGenAfterBurnerFlow is a After Burner event generator applying flow. | |
21 | // The generator changes Phi coordinate of the particle momentum. | |
22 | // Flow (directed and elliptical) can be defined on particle type level | |
23 | // | |
24 | // For examples, parameters and testing macros refer to: | |
25 | // http:/home.cern.ch/radomski | |
26 | // | |
27 | // Author: | |
28 | // Sylwester Radomski, | |
29 | // GSI, April 2002 | |
30 | // | |
31 | // S.Radomski@gsi.de | |
32 | // | |
ac3faee4 | 33 | ////////////////////////////////////////////////////////////////////////////// |
4966b266 | 34 | |
b2ab503d | 35 | #include <Riostream.h> |
4966b266 | 36 | #include "TParticle.h" |
37 | #include "TLorentzVector.h" | |
38 | #include "AliStack.h" | |
39 | #include "AliGenAfterBurnerFlow.h" | |
3e2e3ece | 40 | #include "AliMC.h" |
4966b266 | 41 | #include "AliGenCocktailAfterBurner.h" |
42 | ||
cc41459d | 43 | // emanuele ---------------------------------------------------------------( |
44 | #include <TList.h> | |
45 | #include "AliCollisionGeometry.h" | |
46 | #include "AliGenCocktailEntry.h" | |
47 | #include "TRandom.h" | |
48 | // emanuele ---------------------------------------------------------------) | |
49 | ||
4966b266 | 50 | ClassImp(AliGenAfterBurnerFlow) |
51 | ||
52 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
53 | ||
1c56e311 | 54 | AliGenAfterBurnerFlow::AliGenAfterBurnerFlow(): |
55 | fReactionPlane(0), | |
56 | fCounter(0) | |
57 | { | |
58 | // | |
59 | // Default Construction | |
60 | // | |
4966b266 | 61 | } |
62 | ||
63 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
64 | ||
1c56e311 | 65 | AliGenAfterBurnerFlow::AliGenAfterBurnerFlow(Float_t reactionPlane): |
66 | fReactionPlane(reactionPlane), | |
67 | fCounter(0) | |
68 | { | |
7e4131fc | 69 | // |
4966b266 | 70 | // Standard Construction |
71 | // | |
cc41459d | 72 | // reactionPlane - Reaction Plane Angle given in Deg [0-360] |
73 | // but stored and applied in radiants (standard for TParticle & AliCollisionGeometry) | |
74 | ||
75 | // emanuele ---------------------------------------------------------------( | |
76 | ||
77 | if(reactionPlane == 0) { Info("AliGenAfterBurnerFlow", "Using a random R.P. Angle event by event ( ! not the same used by Hijing ! ) ") ; } | |
78 | else if(reactionPlane < 0) { Info("AliGenAfterBurnerFlow", "Using the Hijing R.P. Angle event by event ") ; } | |
79 | else if(reactionPlane > 0) { Info("AliGenAfterBurnerFlow", "Using a fixed R.P. Angle ( psi = %d deg.) for every event ", reactionPlane) ; } | |
80 | ||
81 | // it was // if(reactionPlane < 0 || reactionPlane > 360) Error("AliGenAfterBurnerFlow", "Reaction Plane Angle - %d - out of bounds [0-360]", reactionPlane); // | |
4966b266 | 82 | |
cc41459d | 83 | // emanuele ---------------------------------------------------------------( |
4966b266 | 84 | |
cc41459d | 85 | fReactionPlane = 2 * TMath::Pi() * (reactionPlane/360) ; // r.p. given in degrees (Radomski's way) but stored and applied in radiants (TParticle's way) |
4966b266 | 86 | fCounter = 0; |
87 | } | |
88 | ||
89 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
90 | ||
91 | AliGenAfterBurnerFlow::~AliGenAfterBurnerFlow() { | |
92 | // Standard Destructor | |
93 | ||
94 | } | |
95 | ||
96 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
97 | ||
7e4131fc | 98 | void AliGenAfterBurnerFlow::SetDirectedSimple(Int_t pdg, Float_t v1) { |
99 | // | |
100 | // Set Directed Flow | |
101 | // The same directed flow is applied to all specified particles | |
102 | // independently on transverse momentum or rapidity | |
103 | // | |
104 | // PDG - particle type to apply directed flow | |
105 | // if (PDG == 0) use as default | |
106 | // | |
107 | ||
108 | SetFlowParameters(pdg, 1, 0, v1, 0, 0, 0); | |
109 | } | |
110 | ||
111 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
112 | ||
113 | void AliGenAfterBurnerFlow::SetDirectedParam | |
114 | (Int_t pdg, Float_t v11, Float_t v12, Float_t v13, Float_t v14) { | |
115 | // | |
116 | // Set Directed Flow | |
117 | // Directed flow is parameterised as follows | |
4966b266 | 118 | // |
4966b266 | 119 | // V1(Pt,Y) = (V11 + V12*Pt) * sign(Y) * (V13 + V14 * Y^3) |
120 | // | |
121 | // where sign = 1 for Y > 0 and -1 for Y < 0 | |
122 | // | |
123 | // Defaults values | |
124 | // v12 = v14 = 0 | |
125 | // v13 = 1 | |
7e4131fc | 126 | // |
127 | // PDG - particle type to apply directed flow | |
128 | // if (PDG == 0) use as default | |
129 | // | |
130 | ||
131 | SetFlowParameters(pdg, 1, 1, v11, v12, v13, v14); | |
4966b266 | 132 | } |
133 | ||
134 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
135 | ||
7e4131fc | 136 | void AliGenAfterBurnerFlow::SetEllipticSimple(Int_t pdg, Float_t v2) { |
4966b266 | 137 | // |
7e4131fc | 138 | // Set Elliptic Flow |
139 | // The same Elliptic flow is applied to all specified particles | |
140 | // independently on transverse momentum or rapidity | |
4966b266 | 141 | // |
7e4131fc | 142 | // PDG - particle type to apply directed flow |
143 | // if (PDG == 0) use as default | |
4966b266 | 144 | // |
7e4131fc | 145 | // V2 - flow coefficient |
146 | // | |
147 | // NOTE: for starting playing with FLOW | |
148 | // start with this function and values 0.05 - 0.1 | |
4966b266 | 149 | // |
150 | ||
7e4131fc | 151 | SetFlowParameters(pdg, 2, 0, v2, 0, 0, 0); |
4966b266 | 152 | } |
153 | ||
154 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
155 | ||
7e4131fc | 156 | void AliGenAfterBurnerFlow::SetEllipticParamPion |
157 | (Int_t pdg, Float_t v21, Float_t pTmax, Float_t v22) { | |
158 | // | |
159 | // Set Elliptic Flow | |
160 | // | |
161 | // Elliptic flow is parametrised to reproduce | |
162 | // V2 of Pions at RHIC energies and is given by: | |
4966b266 | 163 | // |
7e4131fc | 164 | // V2 = v21 * (pT/pTMax ) * exp (-v22 * y^2) where pT <= pTmax |
165 | // v21 * exp (-v22 * y^2) where pT > pTmax | |
4966b266 | 166 | // |
7e4131fc | 167 | // v21 - value at saturation |
168 | // pTmax - saturation transverse momentum | |
169 | // v22 - rapidity decrising | |
4966b266 | 170 | // |
171 | ||
7e4131fc | 172 | SetFlowParameters(pdg, 2, 1, v21, pTmax, v22, 0); |
4966b266 | 173 | } |
174 | ||
175 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
176 | ||
7e4131fc | 177 | void AliGenAfterBurnerFlow::SetEllipticParamOld |
178 | (Int_t pdg, Float_t v21, Float_t v22, Float_t v23) { | |
179 | // | |
180 | // Set Elliptic Flow | |
4966b266 | 181 | // |
7e4131fc | 182 | // Elliptic flow is parameterised using |
183 | // old MevSim parameterisation | |
184 | // | |
185 | // V2 = (V21 + V22 pT^2) * exp (-v22 * y^2) | |
4966b266 | 186 | // |
187 | ||
7e4131fc | 188 | SetFlowParameters(pdg, 2, 2, v21, v22, v23, 0); |
4966b266 | 189 | } |
190 | ||
191 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
192 | ||
193 | void AliGenAfterBurnerFlow::SetFlowParameters | |
7e4131fc | 194 | (Int_t pdg, Int_t order, Int_t type, Float_t v1, Float_t v2,Float_t v3,Float_t v4) { |
4966b266 | 195 | // |
196 | // private function | |
197 | // | |
198 | ||
199 | Int_t index = 0; | |
7e4131fc | 200 | Bool_t newEntry = kTRUE; |
4966b266 | 201 | |
202 | // Defaults | |
203 | ||
204 | if (pdg == 0) { | |
0af12c00 | 205 | index = fgkN - order; |
7e4131fc | 206 | newEntry = kFALSE; |
4966b266 | 207 | } |
208 | ||
209 | // try to find existing entry | |
210 | for (Int_t i=0; i<fCounter; i++) { | |
211 | if (pdg == (Int_t)fParams[i][0] && | |
212 | order == (Int_t)fParams[i][1]) { | |
213 | ||
214 | index = i; | |
7e4131fc | 215 | newEntry = kFALSE; |
4966b266 | 216 | } |
217 | } | |
218 | ||
219 | // check fCounter | |
220 | ||
0af12c00 | 221 | if (newEntry && (fCounter > fgkN-3)) { |
4966b266 | 222 | Error("AliAfterBurnerFlow","Overflow"); |
223 | return; | |
224 | } | |
225 | ||
226 | if (newEntry) { | |
227 | index = fCounter; | |
228 | fCounter++; | |
229 | } | |
230 | ||
231 | // Set new particle type | |
232 | ||
233 | fParams[index][0] = pdg; | |
234 | fParams[index][1] = order; | |
7e4131fc | 235 | fParams[index][2] = type; |
236 | fParams[index][3] = v1; | |
237 | fParams[index][4] = v2; | |
238 | fParams[index][5] = v3; | |
239 | fParams[index][6] = v4; | |
4966b266 | 240 | } |
241 | ||
242 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
243 | ||
244 | void AliGenAfterBurnerFlow::Init() { | |
245 | // | |
246 | // Standard AliGenerator Initializer | |
247 | // | |
248 | ||
249 | } | |
250 | ||
251 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
252 | ||
7e4131fc | 253 | Float_t AliGenAfterBurnerFlow::GetCoefficient |
4966b266 | 254 | (Int_t pdg, Int_t n, Float_t Pt, Float_t Y) { |
255 | // | |
256 | // private function | |
257 | // Return Flow Coefficient for a given particle type flow order | |
258 | // and particle momentum (Pt, Y) | |
259 | // | |
260 | ||
0af12c00 | 261 | Int_t index = fgkN - n; // default index |
4966b266 | 262 | Float_t v = 0; |
263 | ||
264 | // try to find specific parametrs | |
265 | ||
266 | for (Int_t i=0; i<fCounter; i++) { | |
267 | ||
268 | if ((Int_t)fParams[i][0] == pdg && | |
269 | (Int_t)fParams[i][1] == n) { | |
270 | ||
271 | index = i; | |
272 | break; | |
273 | } | |
274 | } | |
275 | ||
276 | // calculate v | |
277 | ||
7e4131fc | 278 | Int_t type = (Int_t)fParams[index][2]; |
279 | ||
4966b266 | 280 | if ((Int_t)fParams[index][1] == 1) { // Directed |
7e4131fc | 281 | |
282 | if (type == 0 ) | |
283 | v = fParams[index][3]; | |
284 | else | |
285 | v = (fParams[index][3] + fParams[index][4] * Pt) * TMath::Sign((Float_t)1.,Y) * | |
286 | (fParams[index][5] + fParams[index][6] * TMath::Abs(Y*Y*Y) ); | |
4966b266 | 287 | |
288 | } else { // Elliptic | |
289 | ||
7e4131fc | 290 | if (type == 0) v = fParams[index][3]; |
291 | ||
292 | // Pion parameterisation | |
293 | ||
294 | if (type == 1) { | |
295 | if (Pt < fParams[index][4]) | |
296 | v = fParams[index][3] * (Pt / fParams[index][4]) ; | |
297 | else | |
298 | v = fParams[index][3]; | |
299 | ||
300 | v *= TMath::Exp( - fParams[index][5] * Y * Y); | |
301 | } | |
302 | ||
303 | // Old parameterisation | |
304 | ||
305 | if (type == 2) | |
306 | v = (fParams[index][3] + fParams[index][4] * Pt * Pt) * | |
307 | TMath::Exp( - fParams[index][5] * Y * Y); | |
4966b266 | 308 | } |
309 | ||
310 | return v; | |
311 | } | |
312 | ||
313 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
314 | ||
315 | void AliGenAfterBurnerFlow::Generate() { | |
316 | // | |
317 | // AliGenerator generate function doing actual job. | |
318 | // Algorythm: | |
319 | // | |
320 | // 1. loop over particles on the stack | |
321 | // 2. find direct and elliptical flow coefficients for | |
322 | // a particle type ore use defaults | |
323 | // 3. calculate delta phi | |
324 | // 4. change phi in orginal particle | |
325 | // | |
326 | // Algorythm based on: | |
327 | // A.M. Poskanzer, S.A. Voloshin | |
328 | // "Methods of analysisng anisotropic flow in relativistic nuclear collisions" | |
329 | // PRC 58, 1671 (September 1998) | |
330 | // | |
331 | ||
332 | AliGenCocktailAfterBurner *gen; | |
333 | AliStack *stack; | |
334 | TParticle *particle; | |
335 | TLorentzVector momentum; | |
336 | ||
337 | Int_t pdg; | |
338 | Float_t phi, dPhi; | |
339 | Float_t pt, y; | |
340 | ||
341 | // Get Stack of the first Generator | |
3e2e3ece | 342 | gen = (AliGenCocktailAfterBurner *)gAlice->GetMCApp()->Generator(); |
4966b266 | 343 | |
cc41459d | 344 | // emanuele ---------------------------------------------------------------( |
345 | ||
346 | AliGenerator* genHijing = 0 ; | |
347 | AliCollisionGeometry* geom = 0 ; | |
348 | AliGenCocktailEntry* entry = 0 ; | |
349 | TList* fEntries = 0 ; | |
350 | ||
351 | TRandom* rand = new TRandom(0) ; | |
352 | Float_t fHow = fReactionPlane ; // this is a temp. solution not to add a new data member in the .h | |
353 | ||
354 | for(Int_t ns=0;ns<gen->GetNumberOfEvents();ns++) | |
355 | { | |
356 | gen->SetActiveEventNumber(ns) ; | |
357 | stack = gen->GetStack(ns); // it was 0. | |
358 | fEntries = gen->Entries() ; | |
359 | ||
360 | TIter next(fEntries) ; | |
361 | while((entry = (AliGenCocktailEntry*)next())) | |
362 | { | |
363 | if(fHow == 0) // hijing R.P. | |
364 | { | |
365 | Info("Generate (e)","Using R.P. from HIJING ... "); | |
366 | genHijing = entry->Generator() ; // cout <<" * GENERATOR IS "<< genHijing << " : " << genHijing->GetName() << endl; | |
367 | if(genHijing->ProvidesCollisionGeometry()) | |
368 | { | |
369 | geom = gen->GetCollisionGeometry(ns) ; // cout << " * GEOMETRY YES * " << endl ; | |
370 | fReactionPlane = geom->ReactionPlaneAngle() ; | |
371 | } | |
372 | else | |
373 | { | |
374 | Error("Generate (e)", "NO CollisionGeometry !!! - using fixed R.P. angle = 0. ") ; | |
375 | fReactionPlane = 0. ; | |
376 | } | |
377 | } | |
378 | else if(fHow < 0) // random R.P. | |
379 | { | |
380 | Info("Generate (e)","Using random R.P.s ... "); | |
381 | fReactionPlane = 2 * TMath::Pi() * rand->Rndm() ; | |
382 | } | |
383 | else // if constant R.P. -> do nothing (fReactionPlane already setted) | |
384 | { | |
385 | Info("Generate (e)","Using a fixed R.P. psi = %d rad.",fReactionPlane); | |
386 | } | |
387 | cout << " * Reaction Plane Angle (event " << ns << ") = " << fReactionPlane << " rad. ( = " << (360*fReactionPlane/(2*TMath::Pi())) << " deg.) * " << endl ; | |
388 | } | |
389 | ||
390 | // emanuele ---------------------------------------------------------------) | |
391 | ||
392 | // Loop over particles | |
393 | ||
394 | for (Int_t i=0; i<stack->GetNtrack(); i++) | |
395 | { | |
396 | particle = stack->Particle(i); | |
397 | ||
398 | particle->Momentum(momentum); | |
399 | pdg = particle->GetPdgCode(); | |
400 | phi = particle->Phi(); | |
401 | ||
402 | // get Pt, Y | |
403 | ||
404 | pt = momentum.Pt() ; | |
405 | //y = momentum.Rapidity() ; | |
406 | ||
407 | // emanuele ---------------------------------------------------------------( | |
408 | ||
409 | if(TMath::Abs(momentum.Z()) != TMath::Abs(momentum.T())) { y = momentum.Rapidity() ; } | |
410 | else { y = 0. ; } | |
411 | // cout << " * Lorentz Vector (momentum) = " << momentum.X() << " , " << momentum.Y() << " , " << momentum.Z() << " , " << momentum.T() << " . * " << endl ; | |
412 | // cout << " * pt = " << momentum.Pt() << " . * " << endl ; | |
413 | // cout << " * Y = " << y << " . * " << endl ; | |
414 | ||
415 | // emanuele ---------------------------------------------------------------) | |
416 | ||
417 | // Calculate Delta Phi for Directed and Elliptic Flow | |
418 | ||
419 | dPhi = -2 * GetCoefficient(pdg, 1, pt, y) * TMath::Sin( phi - fReactionPlane ); | |
420 | dPhi -= GetCoefficient(pdg, 2, pt, y) * TMath::Sin( 2 * (phi - fReactionPlane)); | |
421 | ||
422 | // Set new phi | |
423 | ||
424 | phi += dPhi; | |
425 | momentum.SetPhi(phi); | |
426 | particle->SetMomentum(momentum); | |
427 | } | |
428 | ||
429 | // emanuele ---------------------------------------------------------------( | |
4966b266 | 430 | } |
cc41459d | 431 | // emanuele ---------------------------------------------------------------) |
4966b266 | 432 | |
7e4131fc | 433 | Info("Generate","Flow After Burner: DONE"); |
4966b266 | 434 | } |
435 | ||
436 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
437 |