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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" | |
40 | #include "AliGenCocktailAfterBurner.h" | |
41 | ||
42 | ClassImp(AliGenAfterBurnerFlow) | |
43 | ||
44 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
45 | ||
46 | AliGenAfterBurnerFlow::AliGenAfterBurnerFlow() { | |
7e4131fc | 47 | // |
4966b266 | 48 | // Deafult Construction |
7e4131fc | 49 | // |
50 | ||
4966b266 | 51 | fReactionPlane = 0; |
52 | fCounter = 0; | |
53 | } | |
54 | ||
55 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
56 | ||
57 | AliGenAfterBurnerFlow::AliGenAfterBurnerFlow(Float_t reactionPlane) { | |
7e4131fc | 58 | // |
4966b266 | 59 | // Standard Construction |
60 | // | |
7e4131fc | 61 | // reactionPlane - Reaction Plane Angle in Deg [0-360] |
62 | // | |
4966b266 | 63 | |
64 | if (reactionPlane < 0 || reactionPlane > 360) | |
65 | Error("AliGenAfterBurnerFlow", | |
66 | "Reaction Plane Angle - %d - ot of bounds [0-360]", reactionPlane); | |
67 | ||
68 | fReactionPlane = reactionPlane; | |
69 | fCounter = 0; | |
70 | } | |
71 | ||
72 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
73 | ||
74 | AliGenAfterBurnerFlow::~AliGenAfterBurnerFlow() { | |
75 | // Standard Destructor | |
76 | ||
77 | } | |
78 | ||
79 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
80 | ||
7e4131fc | 81 | void AliGenAfterBurnerFlow::SetDirectedSimple(Int_t pdg, Float_t v1) { |
82 | // | |
83 | // Set Directed Flow | |
84 | // The same directed flow is applied to all specified particles | |
85 | // independently on transverse momentum or rapidity | |
86 | // | |
87 | // PDG - particle type to apply directed flow | |
88 | // if (PDG == 0) use as default | |
89 | // | |
90 | ||
91 | SetFlowParameters(pdg, 1, 0, v1, 0, 0, 0); | |
92 | } | |
93 | ||
94 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
95 | ||
96 | void AliGenAfterBurnerFlow::SetDirectedParam | |
97 | (Int_t pdg, Float_t v11, Float_t v12, Float_t v13, Float_t v14) { | |
98 | // | |
99 | // Set Directed Flow | |
100 | // Directed flow is parameterised as follows | |
4966b266 | 101 | // |
4966b266 | 102 | // V1(Pt,Y) = (V11 + V12*Pt) * sign(Y) * (V13 + V14 * Y^3) |
103 | // | |
104 | // where sign = 1 for Y > 0 and -1 for Y < 0 | |
105 | // | |
106 | // Defaults values | |
107 | // v12 = v14 = 0 | |
108 | // v13 = 1 | |
7e4131fc | 109 | // |
110 | // PDG - particle type to apply directed flow | |
111 | // if (PDG == 0) use as default | |
112 | // | |
113 | ||
114 | SetFlowParameters(pdg, 1, 1, v11, v12, v13, v14); | |
4966b266 | 115 | } |
116 | ||
117 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
118 | ||
7e4131fc | 119 | void AliGenAfterBurnerFlow::SetEllipticSimple(Int_t pdg, Float_t v2) { |
4966b266 | 120 | // |
7e4131fc | 121 | // Set Elliptic Flow |
122 | // The same Elliptic flow is applied to all specified particles | |
123 | // independently on transverse momentum or rapidity | |
4966b266 | 124 | // |
7e4131fc | 125 | // PDG - particle type to apply directed flow |
126 | // if (PDG == 0) use as default | |
4966b266 | 127 | // |
7e4131fc | 128 | // V2 - flow coefficient |
129 | // | |
130 | // NOTE: for starting playing with FLOW | |
131 | // start with this function and values 0.05 - 0.1 | |
4966b266 | 132 | // |
133 | ||
7e4131fc | 134 | SetFlowParameters(pdg, 2, 0, v2, 0, 0, 0); |
4966b266 | 135 | } |
136 | ||
137 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
138 | ||
7e4131fc | 139 | void AliGenAfterBurnerFlow::SetEllipticParamPion |
140 | (Int_t pdg, Float_t v21, Float_t pTmax, Float_t v22) { | |
141 | // | |
142 | // Set Elliptic Flow | |
143 | // | |
144 | // Elliptic flow is parametrised to reproduce | |
145 | // V2 of Pions at RHIC energies and is given by: | |
4966b266 | 146 | // |
7e4131fc | 147 | // V2 = v21 * (pT/pTMax ) * exp (-v22 * y^2) where pT <= pTmax |
148 | // v21 * exp (-v22 * y^2) where pT > pTmax | |
4966b266 | 149 | // |
7e4131fc | 150 | // v21 - value at saturation |
151 | // pTmax - saturation transverse momentum | |
152 | // v22 - rapidity decrising | |
4966b266 | 153 | // |
154 | ||
7e4131fc | 155 | SetFlowParameters(pdg, 2, 1, v21, pTmax, v22, 0); |
4966b266 | 156 | } |
157 | ||
158 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
159 | ||
7e4131fc | 160 | void AliGenAfterBurnerFlow::SetEllipticParamOld |
161 | (Int_t pdg, Float_t v21, Float_t v22, Float_t v23) { | |
162 | // | |
163 | // Set Elliptic Flow | |
4966b266 | 164 | // |
7e4131fc | 165 | // Elliptic flow is parameterised using |
166 | // old MevSim parameterisation | |
167 | // | |
168 | // V2 = (V21 + V22 pT^2) * exp (-v22 * y^2) | |
4966b266 | 169 | // |
170 | ||
7e4131fc | 171 | SetFlowParameters(pdg, 2, 2, v21, v22, v23, 0); |
4966b266 | 172 | } |
173 | ||
174 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
175 | ||
176 | void AliGenAfterBurnerFlow::SetFlowParameters | |
7e4131fc | 177 | (Int_t pdg, Int_t order, Int_t type, Float_t v1, Float_t v2,Float_t v3,Float_t v4) { |
4966b266 | 178 | // |
179 | // private function | |
180 | // | |
181 | ||
182 | Int_t index = 0; | |
7e4131fc | 183 | Bool_t newEntry = kTRUE; |
4966b266 | 184 | |
185 | // Defaults | |
186 | ||
187 | if (pdg == 0) { | |
0af12c00 | 188 | index = fgkN - order; |
7e4131fc | 189 | newEntry = kFALSE; |
4966b266 | 190 | } |
191 | ||
192 | // try to find existing entry | |
193 | for (Int_t i=0; i<fCounter; i++) { | |
194 | if (pdg == (Int_t)fParams[i][0] && | |
195 | order == (Int_t)fParams[i][1]) { | |
196 | ||
197 | index = i; | |
7e4131fc | 198 | newEntry = kFALSE; |
4966b266 | 199 | } |
200 | } | |
201 | ||
202 | // check fCounter | |
203 | ||
0af12c00 | 204 | if (newEntry && (fCounter > fgkN-3)) { |
4966b266 | 205 | Error("AliAfterBurnerFlow","Overflow"); |
206 | return; | |
207 | } | |
208 | ||
209 | if (newEntry) { | |
210 | index = fCounter; | |
211 | fCounter++; | |
212 | } | |
213 | ||
214 | // Set new particle type | |
215 | ||
216 | fParams[index][0] = pdg; | |
217 | fParams[index][1] = order; | |
7e4131fc | 218 | fParams[index][2] = type; |
219 | fParams[index][3] = v1; | |
220 | fParams[index][4] = v2; | |
221 | fParams[index][5] = v3; | |
222 | fParams[index][6] = v4; | |
4966b266 | 223 | } |
224 | ||
225 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
226 | ||
227 | void AliGenAfterBurnerFlow::Init() { | |
228 | // | |
229 | // Standard AliGenerator Initializer | |
230 | // | |
231 | ||
232 | } | |
233 | ||
234 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
235 | ||
7e4131fc | 236 | Float_t AliGenAfterBurnerFlow::GetCoefficient |
4966b266 | 237 | (Int_t pdg, Int_t n, Float_t Pt, Float_t Y) { |
238 | // | |
239 | // private function | |
240 | // Return Flow Coefficient for a given particle type flow order | |
241 | // and particle momentum (Pt, Y) | |
242 | // | |
243 | ||
0af12c00 | 244 | Int_t index = fgkN - n; // default index |
4966b266 | 245 | Float_t v = 0; |
246 | ||
247 | // try to find specific parametrs | |
248 | ||
249 | for (Int_t i=0; i<fCounter; i++) { | |
250 | ||
251 | if ((Int_t)fParams[i][0] == pdg && | |
252 | (Int_t)fParams[i][1] == n) { | |
253 | ||
254 | index = i; | |
255 | break; | |
256 | } | |
257 | } | |
258 | ||
259 | // calculate v | |
260 | ||
7e4131fc | 261 | Int_t type = (Int_t)fParams[index][2]; |
262 | ||
4966b266 | 263 | if ((Int_t)fParams[index][1] == 1) { // Directed |
7e4131fc | 264 | |
265 | if (type == 0 ) | |
266 | v = fParams[index][3]; | |
267 | else | |
268 | v = (fParams[index][3] + fParams[index][4] * Pt) * TMath::Sign((Float_t)1.,Y) * | |
269 | (fParams[index][5] + fParams[index][6] * TMath::Abs(Y*Y*Y) ); | |
4966b266 | 270 | |
271 | } else { // Elliptic | |
272 | ||
7e4131fc | 273 | if (type == 0) v = fParams[index][3]; |
274 | ||
275 | // Pion parameterisation | |
276 | ||
277 | if (type == 1) { | |
278 | if (Pt < fParams[index][4]) | |
279 | v = fParams[index][3] * (Pt / fParams[index][4]) ; | |
280 | else | |
281 | v = fParams[index][3]; | |
282 | ||
283 | v *= TMath::Exp( - fParams[index][5] * Y * Y); | |
284 | } | |
285 | ||
286 | // Old parameterisation | |
287 | ||
288 | if (type == 2) | |
289 | v = (fParams[index][3] + fParams[index][4] * Pt * Pt) * | |
290 | TMath::Exp( - fParams[index][5] * Y * Y); | |
4966b266 | 291 | } |
292 | ||
293 | return v; | |
294 | } | |
295 | ||
296 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
297 | ||
298 | void AliGenAfterBurnerFlow::Generate() { | |
299 | // | |
300 | // AliGenerator generate function doing actual job. | |
301 | // Algorythm: | |
302 | // | |
303 | // 1. loop over particles on the stack | |
304 | // 2. find direct and elliptical flow coefficients for | |
305 | // a particle type ore use defaults | |
306 | // 3. calculate delta phi | |
307 | // 4. change phi in orginal particle | |
308 | // | |
309 | // Algorythm based on: | |
310 | // A.M. Poskanzer, S.A. Voloshin | |
311 | // "Methods of analysisng anisotropic flow in relativistic nuclear collisions" | |
312 | // PRC 58, 1671 (September 1998) | |
313 | // | |
314 | ||
315 | AliGenCocktailAfterBurner *gen; | |
316 | AliStack *stack; | |
317 | TParticle *particle; | |
318 | TLorentzVector momentum; | |
319 | ||
320 | Int_t pdg; | |
321 | Float_t phi, dPhi; | |
322 | Float_t pt, y; | |
323 | ||
324 | // Get Stack of the first Generator | |
325 | gen = (AliGenCocktailAfterBurner *)gAlice->Generator(); | |
326 | stack = gen->GetStack(0); | |
327 | ||
328 | // Loop over particles | |
329 | ||
330 | for (Int_t i=0; i<stack->GetNtrack(); i++) { | |
331 | ||
332 | particle = stack->Particle(i); | |
333 | ||
334 | particle->Momentum(momentum); | |
335 | pdg = particle->GetPdgCode(); | |
336 | phi = particle->Phi(); | |
337 | ||
338 | // get Pt, Y | |
339 | ||
340 | pt = momentum.Pt(); | |
341 | y = momentum.Rapidity(); | |
342 | ||
343 | // Calculate Delta Phi for Directed and Elliptic Flow | |
344 | ||
7e4131fc | 345 | dPhi = -2 * GetCoefficient(pdg, 1, pt, y) * TMath::Sin( phi - fReactionPlane ); |
346 | dPhi -= GetCoefficient(pdg, 2, pt, y) * TMath::Sin( 2 * (phi - fReactionPlane)); | |
4966b266 | 347 | |
4966b266 | 348 | // Set new phi |
349 | ||
350 | phi += dPhi; | |
351 | momentum.SetPhi(phi); | |
352 | particle->SetMomentum(momentum); | |
353 | } | |
354 | ||
7e4131fc | 355 | Info("Generate","Flow After Burner: DONE"); |
4966b266 | 356 | } |
357 | ||
358 | //////////////////////////////////////////////////////////////////////////////////////////////////// | |
359 |