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