1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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8 * documentation strictly for non-commercial purposes is hereby granted *
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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 **************************************************************************/
18 Revision 1.18 2002/12/11 11:58:11 morsch
19 Bug in formula for pi0 energy for decay corrected.
21 Revision 1.17 2002/12/10 17:44:57 morsch
22 Correct mother child relation for pi0.
24 Revision 1.16 2002/11/28 11:46:15 morsch
25 Don't track pi0 if already decayed.
27 Revision 1.15 2002/11/28 11:38:53 morsch
30 Revision 1.14 2002/11/26 17:12:36 morsch
31 Decay pi0 if requested.
33 Revision 1.13 2002/10/14 14:55:35 hristov
34 Merging the VirtualMC branch to the main development branch (HEAD)
36 Revision 1.11.4.1 2002/07/24 08:56:28 alibrary
37 Updating EVGEN on TVirtulaMC
39 Revision 1.12 2002/06/19 06:56:34 hristov
42 Revision 1.11 2002/03/20 10:21:13 hristov
43 Set fPtMax to 15 GeV in order to avoid some numerical problems
45 Revision 1.10 2001/10/15 16:44:46 morsch
46 - Possibility for vertex distribution truncation.
47 - Write mc header with vertex position.
49 Revision 1.9 2001/07/27 17:09:36 morsch
50 Use local SetTrack, KeepTrack and SetHighWaterMark methods
51 to delegate either to local stack or to stack owned by AliRun.
52 (Piotr Skowronski, A.M.)
54 Revision 1.8 2001/07/20 11:03:58 morsch
55 Issue warning message if used outside allowed eta range (-8 to 8).
57 Revision 1.7 2001/07/17 12:41:01 morsch
58 - Calculation of fraction of event corresponding to selected pt-range corrected
60 - Parent weight corrected.
62 Revision 1.6 2001/05/16 14:57:10 alibrary
63 New files for folders and Stack
65 Revision 1.5 2000/12/21 16:24:06 morsch
66 Coding convention clean-up
68 Revision 1.4 2000/11/30 07:12:50 alibrary
69 Introducing new Rndm and QA classes
71 Revision 1.3 2000/10/02 21:28:06 fca
72 Removal of useless dependecies via forward declarations
74 Revision 1.2 2000/07/11 18:24:55 fca
75 Coding convention corrections + few minor bug fixes
77 Revision 1.1 2000/06/09 20:20:30 morsch
78 Same class as previously in AliSimpleGen.cxx
79 All coding rule violations except RS3 corrected (AM)
83 // Parameterisation of pi and K, eta and pt distributions
84 // used for the ALICE TDRs.
85 // eta: according to HIJING (shadowing + quenching)
86 // pT : according to CDF measurement at 1.8 TeV
87 // Author: andreas.morsch@cern.ch
92 <img src="picts/AliGeneratorClass.gif">
95 <font size=+2 color=red>
96 <p>The responsible person for this module is
97 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
103 ///////////////////////////////////////////////////////////////////
106 #include <TClonesArray.h>
107 #include <TDatabasePDG.h>
109 #include <TParticle.h>
110 #include <TPDGCode.h>
112 #include "AliConst.h"
113 #include "AliDecayer.h"
114 #include "AliDecayerPythia.h"
115 #include "AliGenEventHeader.h"
116 #include "AliGenHIJINGpara.h"
119 ClassImp(AliGenHIJINGpara)
121 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
126 //_____________________________________________________________________________
127 static Double_t ptpi(Double_t *px, Double_t *)
130 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
131 // POWER LAW FOR PT > 500 MEV
132 // MT SCALING BELOW (T=160 MEV)
134 const Double_t kp0 = 1.3;
135 const Double_t kxn = 8.28;
136 const Double_t kxlim=0.5;
137 const Double_t kt=0.160;
138 const Double_t kxmpi=0.139;
139 const Double_t kb=1.;
140 Double_t y, y1, xmpi2, ynorm, a;
143 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
145 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
148 y=a*TMath::Power(kp0/(kp0+x),kxn);
150 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
154 //_____________________________________________________________________________
155 static Double_t ptscal(Double_t pt, Int_t np)
157 // SCALING EN MASSE PAR RAPPORT A PTPI
158 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
159 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
160 // VALUE MESON/PI AT 5 GEV
161 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
163 Double_t f5=TMath::Power(((
164 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
165 Double_t fmax2=f5/kfmax[np];
167 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
168 Double_t fmtscal=TMath::Power(((
169 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
171 return fmtscal*ptpion;
174 //_____________________________________________________________________________
175 static Double_t ptka( Double_t *px, Double_t *)
178 // pt parametrisation for k
180 return ptscal(*px,2);
184 //_____________________________________________________________________________
185 static Double_t etapic( Double_t *py, Double_t *)
188 // eta parametrisation for pi
190 const Double_t ka1 = 4913.;
191 const Double_t ka2 = 1819.;
192 const Double_t keta1 = 0.22;
193 const Double_t keta2 = 3.66;
194 const Double_t kdeta1 = 1.47;
195 const Double_t kdeta2 = 1.51;
196 Double_t y=TMath::Abs(*py);
198 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
199 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
200 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
203 //_____________________________________________________________________________
204 static Double_t etakac( Double_t *py, Double_t *)
207 // eta parametrisation for ka
209 const Double_t ka1 = 497.6;
210 const Double_t ka2 = 215.6;
211 const Double_t keta1 = 0.79;
212 const Double_t keta2 = 4.09;
213 const Double_t kdeta1 = 1.54;
214 const Double_t kdeta2 = 1.40;
215 Double_t y=TMath::Abs(*py);
217 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
218 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
219 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
222 //_____________________________________________________________________________
223 AliGenHIJINGpara::AliGenHIJINGpara()
227 // Default constructor
240 //_____________________________________________________________________________
241 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
245 // Standard constructor
248 fTitle="HIJING Parametrisation Particle Generator";
260 //_____________________________________________________________________________
261 AliGenHIJINGpara::~AliGenHIJINGpara()
264 // Standard destructor
272 //_____________________________________________________________________________
273 void AliGenHIJINGpara::Init()
276 // Initialise the HIJING parametrisation
278 Float_t etaMin =-TMath::Log(TMath::Tan(
279 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
280 Float_t etaMax = -TMath::Log(TMath::Tan(
281 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
282 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
283 fPtka = new TF1("ptka",&ptka,0,20,0);
284 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
285 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
287 TF1 etaPic0("etapic",&etapic,-7,7,0);
288 TF1 etaKac0("etakac",&etakac,-7,7,0);
290 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
291 TF1 ptKac0("ptka",&ptka,0.,15.,0);
293 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
294 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
295 Float_t scalePi = 7316/(intETApi/1.5);
296 Float_t scaleKa = 684/(intETAka/2.0);
298 // Fraction of events corresponding to the selected pt-range
299 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
300 0.123*ptKac0.Integral(0, 15));
301 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
302 0.123*ptKac0.Integral(fPtMin, fPtMax));
303 Float_t ptFrac = intPtSel/intPt;
305 // Fraction of events corresponding to the selected eta-range
306 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
307 scaleKa*etaKac0.Integral(etaMin, etaMax));
308 // Fraction of events corresponding to the selected phi-range
309 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
311 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
313 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
314 ClassName(),100.*fParentWeight);
316 // Issue warning message if etaMin or etaMax are outside the alowed range
317 // of the parametrization
318 if (etaMin < -8.001 || etaMax > 8.001) {
319 printf("\n \n WARNING FROM AliGenHIJINGPara !");
320 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
321 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
322 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
326 if (fPi0Decays) fDecayer = new AliDecayerPythia();
330 //_____________________________________________________________________________
331 void AliGenHIJINGpara::Generate()
334 // Generate one trigger
338 const Float_t kRaKpic=0.14;
339 const Float_t kBorne=1/(1+kRaKpic);
340 Float_t polar[3]= {0,0,0};
342 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
343 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
346 Float_t pt, pl, ptot;
356 for (j=0;j<3;j++) origin[j]=fOrigin[j];
358 if(fVertexSmear == kPerEvent) {
361 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
363 for (j=0; j < 3; j++) {
364 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
365 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
368 for (j=0; j < 3; j++) origin[j] += dv[j];
372 eventVertex[0] = origin[0];
373 eventVertex[1] = origin[1];
374 eventVertex[2] = origin[2];
376 for(i=0;i<fNpart;i++) {
379 if(random[0]<kBorne) {
380 part=kPions[Int_t (random[1]*3)];
384 part=kKaons[Int_t (random[1]*4)];
388 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
389 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
390 if(theta<fThetaMin || theta>fThetaMax) continue;
392 pl=pt/TMath::Tan(theta);
393 ptot=TMath::Sqrt(pt*pt+pl*pl);
394 if(ptot<fPMin || ptot>fPMax) continue;
395 p[0]=pt*TMath::Cos(phi);
396 p[1]=pt*TMath::Sin(phi);
398 if(fVertexSmear==kPerTrack) {
401 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
402 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
405 if (part == kPi0 && fPi0Decays){
407 // Decay pi0 if requested
408 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
412 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
418 SetHighWaterMark(fNt);
423 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
425 header->SetPrimaryVertex(eventVertex);
426 gAlice->SetGenEventHeader(header);
429 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
431 // Assignment operator
435 void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
436 AliGenerator::SetPtRange(ptmin, ptmax);
439 void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
443 // and put decay products on the stack
445 static TClonesArray *particles;
446 if(!particles) particles = new TClonesArray("TParticle",1000);
448 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
449 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
452 TLorentzVector pmom(p[0], p[1], p[2], e);
453 fDecayer->Decay(kPi0, &pmom);
456 // Put decay particles on the stack
458 Float_t polar[3] = {0., 0., 0.};
459 Int_t np = fDecayer->ImportParticles(particles);
461 for (Int_t i = 1; i < np; i++)
463 TParticle* iParticle = (TParticle *) particles->At(i);
464 p[0] = iParticle->Px();
465 p[1] = iParticle->Py();
466 p[2] = iParticle->Pz();
467 Int_t part = iParticle->GetPdgCode();
469 SetTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);