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4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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18 Revision 1.11 2002/03/20 10:21:13 hristov
19 Set fPtMax to 15 GeV in order to avoid some numerical problems
21 Revision 1.10 2001/10/15 16:44:46 morsch
22 - Possibility for vertex distribution truncation.
23 - Write mc header with vertex position.
25 Revision 1.9 2001/07/27 17:09:36 morsch
26 Use local SetTrack, KeepTrack and SetHighWaterMark methods
27 to delegate either to local stack or to stack owned by AliRun.
28 (Piotr Skowronski, A.M.)
30 Revision 1.8 2001/07/20 11:03:58 morsch
31 Issue warning message if used outside allowed eta range (-8 to 8).
33 Revision 1.7 2001/07/17 12:41:01 morsch
34 - Calculation of fraction of event corresponding to selected pt-range corrected
36 - Parent weight corrected.
38 Revision 1.6 2001/05/16 14:57:10 alibrary
39 New files for folders and Stack
41 Revision 1.5 2000/12/21 16:24:06 morsch
42 Coding convention clean-up
44 Revision 1.4 2000/11/30 07:12:50 alibrary
45 Introducing new Rndm and QA classes
47 Revision 1.3 2000/10/02 21:28:06 fca
48 Removal of useless dependecies via forward declarations
50 Revision 1.2 2000/07/11 18:24:55 fca
51 Coding convention corrections + few minor bug fixes
53 Revision 1.1 2000/06/09 20:20:30 morsch
54 Same class as previously in AliSimpleGen.cxx
55 All coding rule violations except RS3 corrected (AM)
59 // Parameterisation of pi and K, eta and pt distributions
60 // used for the ALICE TDRs.
61 // eta: according to HIJING (shadowing + quenching)
62 // pT : according to CDF measurement at 1.8 TeV
63 // Author: andreas.morsch@cern.ch
68 <img src="picts/AliGeneratorClass.gif">
71 <font size=+2 color=red>
72 <p>The responsible person for this module is
73 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
79 ///////////////////////////////////////////////////////////////////
81 #include "AliGenHIJINGpara.h"
82 #include "AliGenEventHeader.h"
90 ClassImp(AliGenHIJINGpara)
92 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
97 //_____________________________________________________________________________
98 static Double_t ptpi(Double_t *px, Double_t *)
101 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
102 // POWER LAW FOR PT > 500 MEV
103 // MT SCALING BELOW (T=160 MEV)
105 const Double_t kp0 = 1.3;
106 const Double_t kxn = 8.28;
107 const Double_t kxlim=0.5;
108 const Double_t kt=0.160;
109 const Double_t kxmpi=0.139;
110 const Double_t kb=1.;
111 Double_t y, y1, xmpi2, ynorm, a;
114 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
116 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
119 y=a*TMath::Power(kp0/(kp0+x),kxn);
121 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
125 //_____________________________________________________________________________
126 static Double_t ptscal(Double_t pt, Int_t np)
128 // SCALING EN MASSE PAR RAPPORT A PTPI
129 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
130 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
131 // VALUE MESON/PI AT 5 GEV
132 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
134 Double_t f5=TMath::Power(((
135 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
136 Double_t fmax2=f5/kfmax[np];
138 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
139 Double_t fmtscal=TMath::Power(((
140 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
142 return fmtscal*ptpion;
145 //_____________________________________________________________________________
146 static Double_t ptka( Double_t *px, Double_t *)
149 // pt parametrisation for k
151 return ptscal(*px,2);
155 //_____________________________________________________________________________
156 static Double_t etapic( Double_t *py, Double_t *)
159 // eta parametrisation for pi
161 const Double_t ka1 = 4913.;
162 const Double_t ka2 = 1819.;
163 const Double_t keta1 = 0.22;
164 const Double_t keta2 = 3.66;
165 const Double_t kdeta1 = 1.47;
166 const Double_t kdeta2 = 1.51;
167 Double_t y=TMath::Abs(*py);
169 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
170 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
171 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
174 //_____________________________________________________________________________
175 static Double_t etakac( Double_t *py, Double_t *)
178 // eta parametrisation for ka
180 const Double_t ka1 = 497.6;
181 const Double_t ka2 = 215.6;
182 const Double_t keta1 = 0.79;
183 const Double_t keta2 = 4.09;
184 const Double_t kdeta1 = 1.54;
185 const Double_t kdeta2 = 1.40;
186 Double_t y=TMath::Abs(*py);
188 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
189 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
190 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
193 //_____________________________________________________________________________
194 AliGenHIJINGpara::AliGenHIJINGpara()
198 // Default constructor
208 //_____________________________________________________________________________
209 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
213 // Standard constructor
216 fTitle="HIJING Parametrisation Particle Generator";
225 //_____________________________________________________________________________
226 AliGenHIJINGpara::~AliGenHIJINGpara()
229 // Standard destructor
237 //_____________________________________________________________________________
238 void AliGenHIJINGpara::Init()
241 // Initialise the HIJING parametrisation
243 Float_t etaMin =-TMath::Log(TMath::Tan(
244 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
245 Float_t etaMax = -TMath::Log(TMath::Tan(
246 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
247 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
248 fPtka = new TF1("ptka",&ptka,0,20,0);
249 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
250 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
252 TF1 etaPic0("etapic",&etapic,-7,7,0);
253 TF1 etaKac0("etakac",&etakac,-7,7,0);
255 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
256 TF1 ptKac0("ptka",&ptka,0.,15.,0);
258 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
259 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
260 Float_t scalePi = 7316/(intETApi/1.5);
261 Float_t scaleKa = 684/(intETAka/2.0);
263 // Fraction of events corresponding to the selected pt-range
264 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
265 0.123*ptKac0.Integral(0, 15));
266 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
267 0.123*ptKac0.Integral(fPtMin, fPtMax));
268 Float_t ptFrac = intPtSel/intPt;
270 // Fraction of events corresponding to the selected eta-range
271 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
272 scaleKa*etaKac0.Integral(etaMin, etaMax));
273 // Fraction of events corresponding to the selected phi-range
274 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
276 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
278 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
279 ClassName(),100.*fParentWeight);
281 // Issue warning message if etaMin or etaMax are outside the alowed range
282 // of the parametrization
283 if (etaMin < -8.001 || etaMax > 8.001) {
284 printf("\n \n WARNING FROM AliGenHIJINGPara !");
285 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
286 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
287 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
291 //_____________________________________________________________________________
292 void AliGenHIJINGpara::Generate()
295 // Generate one trigger
299 const Float_t kRaKpic=0.14;
300 const Float_t kBorne=1/(1+kRaKpic);
301 Float_t polar[3]= {0,0,0};
303 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
304 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
307 Float_t pt, pl, ptot;
310 Int_t i, part, nt, j;
317 for (j=0;j<3;j++) origin[j]=fOrigin[j];
319 if(fVertexSmear == kPerEvent) {
322 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
324 for (j=0; j < 3; j++) {
325 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
326 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
329 for (j=0; j < 3; j++) origin[j] += dv[j];
333 eventVertex[0] = origin[0];
334 eventVertex[1] = origin[1];
335 eventVertex[2] = origin[2];
337 for(i=0;i<fNpart;i++) {
340 if(random[0]<kBorne) {
341 part=kPions[Int_t (random[1]*3)];
345 part=kKaons[Int_t (random[1]*4)];
349 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
350 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
351 if(theta<fThetaMin || theta>fThetaMax) continue;
353 pl=pt/TMath::Tan(theta);
354 ptot=TMath::Sqrt(pt*pt+pl*pl);
355 if(ptot<fPMin || ptot>fPMax) continue;
356 p[0]=pt*TMath::Cos(phi);
357 p[1]=pt*TMath::Sin(phi);
359 if(fVertexSmear==kPerTrack) {
362 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
363 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
366 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
371 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
373 header->SetPrimaryVertex(eventVertex);
374 gAlice->SetGenEventHeader(header);
377 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
379 // Assignment operator
383 void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
384 AliGenerator::SetPtRange(ptmin, ptmax);