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4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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14 **************************************************************************/
18 Revision 1.15 2002/11/28 11:38:53 morsch
21 Revision 1.14 2002/11/26 17:12:36 morsch
22 Decay pi0 if requested.
24 Revision 1.13 2002/10/14 14:55:35 hristov
25 Merging the VirtualMC branch to the main development branch (HEAD)
27 Revision 1.11.4.1 2002/07/24 08:56:28 alibrary
28 Updating EVGEN on TVirtulaMC
30 Revision 1.12 2002/06/19 06:56:34 hristov
33 Revision 1.11 2002/03/20 10:21:13 hristov
34 Set fPtMax to 15 GeV in order to avoid some numerical problems
36 Revision 1.10 2001/10/15 16:44:46 morsch
37 - Possibility for vertex distribution truncation.
38 - Write mc header with vertex position.
40 Revision 1.9 2001/07/27 17:09:36 morsch
41 Use local SetTrack, KeepTrack and SetHighWaterMark methods
42 to delegate either to local stack or to stack owned by AliRun.
43 (Piotr Skowronski, A.M.)
45 Revision 1.8 2001/07/20 11:03:58 morsch
46 Issue warning message if used outside allowed eta range (-8 to 8).
48 Revision 1.7 2001/07/17 12:41:01 morsch
49 - Calculation of fraction of event corresponding to selected pt-range corrected
51 - Parent weight corrected.
53 Revision 1.6 2001/05/16 14:57:10 alibrary
54 New files for folders and Stack
56 Revision 1.5 2000/12/21 16:24:06 morsch
57 Coding convention clean-up
59 Revision 1.4 2000/11/30 07:12:50 alibrary
60 Introducing new Rndm and QA classes
62 Revision 1.3 2000/10/02 21:28:06 fca
63 Removal of useless dependecies via forward declarations
65 Revision 1.2 2000/07/11 18:24:55 fca
66 Coding convention corrections + few minor bug fixes
68 Revision 1.1 2000/06/09 20:20:30 morsch
69 Same class as previously in AliSimpleGen.cxx
70 All coding rule violations except RS3 corrected (AM)
74 // Parameterisation of pi and K, eta and pt distributions
75 // used for the ALICE TDRs.
76 // eta: according to HIJING (shadowing + quenching)
77 // pT : according to CDF measurement at 1.8 TeV
78 // Author: andreas.morsch@cern.ch
83 <img src="picts/AliGeneratorClass.gif">
86 <font size=+2 color=red>
87 <p>The responsible person for this module is
88 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
94 ///////////////////////////////////////////////////////////////////
96 #include "AliGenHIJINGpara.h"
97 #include "AliGenEventHeader.h"
100 #include "AliDecayer.h"
101 #include "AliDecayerPythia.h"
106 #include <TDatabasePDG.h>
107 #include <TClonesArray.h>
108 #include <TParticle.h>
110 ClassImp(AliGenHIJINGpara)
112 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
117 //_____________________________________________________________________________
118 static Double_t ptpi(Double_t *px, Double_t *)
121 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
122 // POWER LAW FOR PT > 500 MEV
123 // MT SCALING BELOW (T=160 MEV)
125 const Double_t kp0 = 1.3;
126 const Double_t kxn = 8.28;
127 const Double_t kxlim=0.5;
128 const Double_t kt=0.160;
129 const Double_t kxmpi=0.139;
130 const Double_t kb=1.;
131 Double_t y, y1, xmpi2, ynorm, a;
134 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
136 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
139 y=a*TMath::Power(kp0/(kp0+x),kxn);
141 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
145 //_____________________________________________________________________________
146 static Double_t ptscal(Double_t pt, Int_t np)
148 // SCALING EN MASSE PAR RAPPORT A PTPI
149 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
150 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
151 // VALUE MESON/PI AT 5 GEV
152 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
154 Double_t f5=TMath::Power(((
155 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
156 Double_t fmax2=f5/kfmax[np];
158 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
159 Double_t fmtscal=TMath::Power(((
160 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
162 return fmtscal*ptpion;
165 //_____________________________________________________________________________
166 static Double_t ptka( Double_t *px, Double_t *)
169 // pt parametrisation for k
171 return ptscal(*px,2);
175 //_____________________________________________________________________________
176 static Double_t etapic( Double_t *py, Double_t *)
179 // eta parametrisation for pi
181 const Double_t ka1 = 4913.;
182 const Double_t ka2 = 1819.;
183 const Double_t keta1 = 0.22;
184 const Double_t keta2 = 3.66;
185 const Double_t kdeta1 = 1.47;
186 const Double_t kdeta2 = 1.51;
187 Double_t y=TMath::Abs(*py);
189 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
190 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
191 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
194 //_____________________________________________________________________________
195 static Double_t etakac( Double_t *py, Double_t *)
198 // eta parametrisation for ka
200 const Double_t ka1 = 497.6;
201 const Double_t ka2 = 215.6;
202 const Double_t keta1 = 0.79;
203 const Double_t keta2 = 4.09;
204 const Double_t kdeta1 = 1.54;
205 const Double_t kdeta2 = 1.40;
206 Double_t y=TMath::Abs(*py);
208 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
209 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
210 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
213 //_____________________________________________________________________________
214 AliGenHIJINGpara::AliGenHIJINGpara()
218 // Default constructor
230 //_____________________________________________________________________________
231 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
235 // Standard constructor
238 fTitle="HIJING Parametrisation Particle Generator";
249 //_____________________________________________________________________________
250 AliGenHIJINGpara::~AliGenHIJINGpara()
253 // Standard destructor
261 //_____________________________________________________________________________
262 void AliGenHIJINGpara::Init()
265 // Initialise the HIJING parametrisation
267 Float_t etaMin =-TMath::Log(TMath::Tan(
268 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
269 Float_t etaMax = -TMath::Log(TMath::Tan(
270 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
271 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
272 fPtka = new TF1("ptka",&ptka,0,20,0);
273 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
274 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
276 TF1 etaPic0("etapic",&etapic,-7,7,0);
277 TF1 etaKac0("etakac",&etakac,-7,7,0);
279 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
280 TF1 ptKac0("ptka",&ptka,0.,15.,0);
282 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
283 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
284 Float_t scalePi = 7316/(intETApi/1.5);
285 Float_t scaleKa = 684/(intETAka/2.0);
287 // Fraction of events corresponding to the selected pt-range
288 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
289 0.123*ptKac0.Integral(0, 15));
290 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
291 0.123*ptKac0.Integral(fPtMin, fPtMax));
292 Float_t ptFrac = intPtSel/intPt;
294 // Fraction of events corresponding to the selected eta-range
295 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
296 scaleKa*etaKac0.Integral(etaMin, etaMax));
297 // Fraction of events corresponding to the selected phi-range
298 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
300 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
302 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
303 ClassName(),100.*fParentWeight);
305 // Issue warning message if etaMin or etaMax are outside the alowed range
306 // of the parametrization
307 if (etaMin < -8.001 || etaMax > 8.001) {
308 printf("\n \n WARNING FROM AliGenHIJINGPara !");
309 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
310 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
311 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
315 if (fPi0Decays) fDecayer = new AliDecayerPythia();
319 //_____________________________________________________________________________
320 void AliGenHIJINGpara::Generate()
323 // Generate one trigger
327 const Float_t kRaKpic=0.14;
328 const Float_t kBorne=1/(1+kRaKpic);
329 Float_t polar[3]= {0,0,0};
331 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
332 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
335 Float_t pt, pl, ptot;
338 Int_t i, part, nt, j;
345 for (j=0;j<3;j++) origin[j]=fOrigin[j];
347 if(fVertexSmear == kPerEvent) {
350 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
352 for (j=0; j < 3; j++) {
353 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
354 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
357 for (j=0; j < 3; j++) origin[j] += dv[j];
361 eventVertex[0] = origin[0];
362 eventVertex[1] = origin[1];
363 eventVertex[2] = origin[2];
365 for(i=0;i<fNpart;i++) {
368 if(random[0]<kBorne) {
369 part=kPions[Int_t (random[1]*3)];
373 part=kKaons[Int_t (random[1]*4)];
377 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
378 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
379 if(theta<fThetaMin || theta>fThetaMax) continue;
381 pl=pt/TMath::Tan(theta);
382 ptot=TMath::Sqrt(pt*pt+pl*pl);
383 if(ptot<fPMin || ptot>fPMax) continue;
384 p[0]=pt*TMath::Cos(phi);
385 p[1]=pt*TMath::Sin(phi);
387 if(fVertexSmear==kPerTrack) {
390 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
391 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
394 if (part == kPi0 && fPi0Decays){
396 // Decay pi0 if requested
397 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
400 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
407 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
409 header->SetPrimaryVertex(eventVertex);
410 gAlice->SetGenEventHeader(header);
413 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
415 // Assignment operator
419 void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
420 AliGenerator::SetPtRange(ptmin, ptmax);
423 void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
427 // and put decay products on the stack
429 static TClonesArray *particles;
430 if(!particles) particles = new TClonesArray("TParticle",1000);
432 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
433 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] +p[2] * p[2] * kMass * kMass);
436 TLorentzVector pmom(p[0], p[1], p[2], e);
437 fDecayer->Decay(kPi0, &pmom);
439 // Put decay particles on the stack
442 Float_t polar[3] = {0., 0., 0.};
443 Int_t np = fDecayer->ImportParticles(particles);
445 for (Int_t i = 1; i < np; i++)
447 TParticle* iParticle = (TParticle *) particles->At(i);
448 p[0] = iParticle->Px();
449 p[1] = iParticle->Py();
450 p[2] = iParticle->Pz();
451 Int_t part = iParticle->GetPdgCode();
452 SetTrack(fTrackIt, 0, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);