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