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Wrong BFIR positioning removed.
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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// Parameterisation of pi and K, eta and pt distributions
19// used for the ALICE TDRs.
20// eta: according to HIJING (shadowing + quenching)
21// pT : according to CDF measurement at 1.8 TeV
22// Author: andreas.morsch@cern.ch
23
24
25//Begin_Html
26/*
27<img src="picts/AliGeneratorClass.gif">
28</pre>
29<br clear=left>
30<font size=+2 color=red>
31<p>The responsible person for this module is
32<a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
33</font>
34<pre>
35*/
36//End_Html
37// //
38///////////////////////////////////////////////////////////////////
39
40#include <TArrayF.h>
41#include <TClonesArray.h>
42#include <TDatabasePDG.h>
43#include <TF1.h>
44#include <TParticle.h>
45#include <TPDGCode.h>
46#include <TVirtualMC.h>
47
48#include "AliConst.h"
49#include "AliDecayer.h"
50#include "AliGenEventHeader.h"
51#include "AliGenHIJINGpara.h"
52#include "AliRun.h"
53
54ClassImp(AliGenHIJINGpara)
55
56
57AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para):
58 AliGenerator(para)
59{
60// Copy constructor
61 para.Copy(*this);
62}
63
64//_____________________________________________________________________________
65static Double_t ptpi(Double_t *px, Double_t *)
66{
67 //
68 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
69 // POWER LAW FOR PT > 500 MEV
70 // MT SCALING BELOW (T=160 MEV)
71 //
72 const Double_t kp0 = 1.3;
73 const Double_t kxn = 8.28;
74 const Double_t kxlim=0.5;
75 const Double_t kt=0.160;
76 const Double_t kxmpi=0.139;
77 const Double_t kb=1.;
78 Double_t y, y1, xmpi2, ynorm, a;
79 Double_t x=*px;
80 //
81 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
82 xmpi2=kxmpi*kxmpi;
83 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
84 a=ynorm/y1;
85 if (x > kxlim)
86 y=a*TMath::Power(kp0/(kp0+x),kxn);
87 else
88 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
89 return y*x;
90}
91
92//_____________________________________________________________________________
93static Double_t ptscal(Double_t pt, Int_t np)
94{
95 // SCALING EN MASSE PAR RAPPORT A PTPI
96 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
97 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
98 // VALUE MESON/PI AT 5 GEV
99 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
100 np--;
101 Double_t f5=TMath::Power(((
102 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
103 Double_t fmax2=f5/kfmax[np];
104 // PIONS
105 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
106 Double_t fmtscal=TMath::Power(((
107 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
108 fmax2;
109 return fmtscal*ptpion;
110}
111
112//_____________________________________________________________________________
113static Double_t ptka( Double_t *px, Double_t *)
114{
115 //
116 // pt parametrisation for k
117 //
118 return ptscal(*px,2);
119}
120
121
122//_____________________________________________________________________________
123static Double_t etapic( Double_t *py, Double_t *)
124{
125 //
126 // eta parametrisation for pi
127 //
128 const Double_t ka1 = 4913.;
129 const Double_t ka2 = 1819.;
130 const Double_t keta1 = 0.22;
131 const Double_t keta2 = 3.66;
132 const Double_t kdeta1 = 1.47;
133 const Double_t kdeta2 = 1.51;
134 Double_t y=TMath::Abs(*py);
135 //
136 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
137 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
138 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
139}
140
141//_____________________________________________________________________________
142static Double_t etakac( Double_t *py, Double_t *)
143{
144 //
145 // eta parametrisation for ka
146 //
147 const Double_t ka1 = 497.6;
148 const Double_t ka2 = 215.6;
149 const Double_t keta1 = 0.79;
150 const Double_t keta2 = 4.09;
151 const Double_t kdeta1 = 1.54;
152 const Double_t kdeta2 = 1.40;
153 Double_t y=TMath::Abs(*py);
154 //
155 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
156 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
157 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
158}
159
160//_____________________________________________________________________________
161AliGenHIJINGpara::AliGenHIJINGpara()
162 :AliGenerator()
163{
164 //
165 // Default constructor
166 //
167 fPtpi = 0;
168 fPtka = 0;
169 fETApic = 0;
170 fETAkac = 0;
171 fDecayer = 0;
172 fNt = -1;
173 SetCutVertexZ();
174 SetPtRange();
175 SetPi0Decays();
176}
177
178//_____________________________________________________________________________
179AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
180 :AliGenerator(npart)
181{
182 //
183 // Standard constructor
184 //
185 fName="HIJINGpara";
186 fTitle="HIJING Parametrisation Particle Generator";
187 fPtpi = 0;
188 fPtka = 0;
189 fETApic = 0;
190 fETAkac = 0;
191 fDecayer = 0;
192 fNt = -1;
193 SetCutVertexZ();
194 SetPtRange();
195 SetPi0Decays();
196}
197
198//_____________________________________________________________________________
199AliGenHIJINGpara::~AliGenHIJINGpara()
200{
201 //
202 // Standard destructor
203 //
204 delete fPtpi;
205 delete fPtka;
206 delete fETApic;
207 delete fETAkac;
208}
209
210//_____________________________________________________________________________
211void AliGenHIJINGpara::Init()
212{
213 //
214 // Initialise the HIJING parametrisation
215 //
216 Float_t etaMin =-TMath::Log(TMath::Tan(
217 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
218 Float_t etaMax = -TMath::Log(TMath::Tan(
219 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
220 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
221 fPtka = new TF1("ptka",&ptka,0,20,0);
222 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
223 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
224
225 TF1 etaPic0("etapic",&etapic,-7,7,0);
226 TF1 etaKac0("etakac",&etakac,-7,7,0);
227
228 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
229 TF1 ptKac0("ptka",&ptka,0.,15.,0);
230
231 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
232 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
233 Float_t scalePi = 7316/(intETApi/1.5);
234 Float_t scaleKa = 684/(intETAka/2.0);
235
236// Fraction of events corresponding to the selected pt-range
237 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
238 0.123*ptKac0.Integral(0, 15));
239 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
240 0.123*ptKac0.Integral(fPtMin, fPtMax));
241 Float_t ptFrac = intPtSel/intPt;
242
243// Fraction of events corresponding to the selected eta-range
244 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
245 scaleKa*etaKac0.Integral(etaMin, etaMax));
246// Fraction of events corresponding to the selected phi-range
247 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
248
249
250 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
251
252 if (fAnalog != 0) {
253 fPtWgtPi = (fPtMax - fPtMin) / fPtpi->Integral(0., 20.);
254 fPtWgtKa = (fPtMax - fPtMin) / fPtka->Integral(0., 20.);
255 fParentWeight = Float_t(fNpart)/(intETASel*phiFrac);
256 }
257
258
259 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
260 ClassName(),100.*fParentWeight);
261
262// Issue warning message if etaMin or etaMax are outside the alowed range
263// of the parametrization
264 if (etaMin < -8.001 || etaMax > 8.001) {
265 printf("\n \n WARNING FROM AliGenHIJINGPara !");
266 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
267 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
268 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
269 }
270//
271//
272 if (fPi0Decays && gMC)
273 fDecayer = gMC->GetDecayer();
274}
275
276
277//_____________________________________________________________________________
278void AliGenHIJINGpara::Generate()
279{
280 //
281 // Generate one trigger
282 //
283
284
285 const Float_t kRaKpic=0.14;
286 const Float_t kBorne=1/(1+kRaKpic);
287 Float_t polar[3]= {0,0,0};
288 //
289 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
290 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
291 //
292 Float_t origin[3];
293 Float_t pt, pl, ptot, wgt;
294 Float_t phi, theta;
295 Float_t p[3];
296 Int_t i, part, j;
297 //
298 TF1 *ptf;
299 TF1 *etaf;
300 //
301 Float_t random[6];
302 //
303 for (j=0;j<3;j++) origin[j]=fOrigin[j];
304
305 if(fVertexSmear == kPerEvent) {
306 Vertex();
307 for (j=0; j < 3; j++) origin[j] = fVertex[j];
308 } // if kPerEvent
309 TArrayF eventVertex;
310 eventVertex.Set(3);
311 eventVertex[0] = origin[0];
312 eventVertex[1] = origin[1];
313 eventVertex[2] = origin[2];
314
315 for(i=0;i<fNpart;i++) {
316 while(1) {
317 Rndm(random,4);
318 if(random[0]<kBorne) {
319 part=kPions[Int_t (random[1]*3)];
320 ptf=fPtpi;
321 etaf=fETApic;
322 wgt = fPtWgtPi;
323 } else {
324 part=kKaons[Int_t (random[1]*4)];
325 ptf=fPtka;
326 etaf=fETAkac;
327 wgt = fPtWgtKa;
328 }
329 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
330 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
331 if(theta<fThetaMin || theta>fThetaMax) continue;
332
333 if (fAnalog == 0) {
334 pt = ptf->GetRandom();
335 } else {
336 pt = fPtMin + random[3] * (fPtMax - fPtMin);
337 }
338
339
340 pl=pt/TMath::Tan(theta);
341 ptot=TMath::Sqrt(pt*pt+pl*pl);
342 if(ptot<fPMin || ptot>fPMax) continue;
343 p[0]=pt*TMath::Cos(phi);
344 p[1]=pt*TMath::Sin(phi);
345 p[2]=pl;
346 if(fVertexSmear==kPerTrack) {
347 Rndm(random,6);
348 for (j=0;j<3;j++) {
349 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
350 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
351 }
352 }
353
354 if (fAnalog == 0) {
355 wgt = fParentWeight;
356 } else {
357 wgt *= (fParentWeight * ptf->Eval(pt));
358 }
359
360
361 if (part == kPi0 && fPi0Decays){
362//
363// Decay pi0 if requested
364 PushTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
365 KeepTrack(fNt);
366 DecayPi0(origin, p);
367 } else {
368 PushTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
369 KeepTrack(fNt);
370 }
371
372 break;
373 }
374 SetHighWaterMark(fNt);
375 }
376//
377
378// Header
379 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
380// Event Vertex
381 header->SetPrimaryVertex(eventVertex);
382 gAlice->SetGenEventHeader(header);
383}
384
385void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
386 AliGenerator::SetPtRange(ptmin, ptmax);
387}
388
389void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
390{
391//
392// Decay the pi0
393// and put decay products on the stack
394//
395 static TClonesArray *particles;
396 if(!particles) particles = new TClonesArray("TParticle",1000);
397//
398 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
399 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
400//
401// Decay the pi0
402 TLorentzVector pmom(p[0], p[1], p[2], e);
403 fDecayer->Decay(kPi0, &pmom);
404
405//
406// Put decay particles on the stack
407//
408 Float_t polar[3] = {0., 0., 0.};
409 Int_t np = fDecayer->ImportParticles(particles);
410 Int_t nt;
411 for (Int_t i = 1; i < np; i++)
412 {
413 TParticle* iParticle = (TParticle *) particles->At(i);
414 p[0] = iParticle->Px();
415 p[1] = iParticle->Py();
416 p[2] = iParticle->Pz();
417 Int_t part = iParticle->GetPdgCode();
418
419 PushTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);
420 KeepTrack(nt);
421 }
422 fNt = nt;
423}
424
425void AliGenHIJINGpara::Copy(AliGenHIJINGpara &) const
426{
427 Fatal("Copy","Not implemented!\n");
428}