1 /**************************************************************************
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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 1.7 2001/07/17 12:41:01 morsch
19 - Calculation of fraction of event corresponding to selected pt-range corrected
21 - Parent weight corrected.
23 Revision 1.6 2001/05/16 14:57:10 alibrary
24 New files for folders and Stack
26 Revision 1.5 2000/12/21 16:24:06 morsch
27 Coding convention clean-up
29 Revision 1.4 2000/11/30 07:12:50 alibrary
30 Introducing new Rndm and QA classes
32 Revision 1.3 2000/10/02 21:28:06 fca
33 Removal of useless dependecies via forward declarations
35 Revision 1.2 2000/07/11 18:24:55 fca
36 Coding convention corrections + few minor bug fixes
38 Revision 1.1 2000/06/09 20:20:30 morsch
39 Same class as previously in AliSimpleGen.cxx
40 All coding rule violations except RS3 corrected (AM)
44 // Parameterisation of pi and K, eta and pt distributions
45 // used for the ALICE TDRs.
46 // eta: according to HIJING (shadowing + quenching)
47 // pT : according to CDF measurement at 1.8 TeV
48 // Author: andreas.morsch@cern.ch
53 <img src="picts/AliGeneratorClass.gif">
56 <font size=+2 color=red>
57 <p>The responsible person for this module is
58 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
64 ///////////////////////////////////////////////////////////////////
66 #include "AliGenHIJINGpara.h"
72 ClassImp(AliGenHIJINGpara)
74 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
79 //_____________________________________________________________________________
80 static Double_t ptpi(Double_t *px, Double_t *)
83 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
84 // POWER LAW FOR PT > 500 MEV
85 // MT SCALING BELOW (T=160 MEV)
87 const Double_t kp0 = 1.3;
88 const Double_t kxn = 8.28;
89 const Double_t kxlim=0.5;
90 const Double_t kt=0.160;
91 const Double_t kxmpi=0.139;
93 Double_t y, y1, xmpi2, ynorm, a;
96 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
98 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
101 y=a*TMath::Power(kp0/(kp0+x),kxn);
103 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
107 //_____________________________________________________________________________
108 static Double_t ptscal(Double_t pt, Int_t np)
110 // SCALING EN MASSE PAR RAPPORT A PTPI
111 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
112 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
113 // VALUE MESON/PI AT 5 GEV
114 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
116 Double_t f5=TMath::Power(((
117 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
118 Double_t fmax2=f5/kfmax[np];
120 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
121 Double_t fmtscal=TMath::Power(((
122 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
124 return fmtscal*ptpion;
127 //_____________________________________________________________________________
128 static Double_t ptka( Double_t *px, Double_t *)
131 // pt parametrisation for k
133 return ptscal(*px,2);
137 //_____________________________________________________________________________
138 static Double_t etapic( Double_t *py, Double_t *)
141 // eta parametrisation for pi
143 const Double_t ka1 = 4913.;
144 const Double_t ka2 = 1819.;
145 const Double_t keta1 = 0.22;
146 const Double_t keta2 = 3.66;
147 const Double_t kdeta1 = 1.47;
148 const Double_t kdeta2 = 1.51;
149 Double_t y=TMath::Abs(*py);
151 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
152 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
153 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
156 //_____________________________________________________________________________
157 static Double_t etakac( Double_t *py, Double_t *)
160 // eta parametrisation for ka
162 const Double_t ka1 = 497.6;
163 const Double_t ka2 = 215.6;
164 const Double_t keta1 = 0.79;
165 const Double_t keta2 = 4.09;
166 const Double_t kdeta1 = 1.54;
167 const Double_t kdeta2 = 1.40;
168 Double_t y=TMath::Abs(*py);
170 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
171 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
172 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
175 //_____________________________________________________________________________
176 AliGenHIJINGpara::AliGenHIJINGpara()
180 // Default constructor
188 //_____________________________________________________________________________
189 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
193 // Standard constructor
196 fTitle="HIJING Parametrisation Particle Generator";
203 //_____________________________________________________________________________
204 AliGenHIJINGpara::~AliGenHIJINGpara()
207 // Standard destructor
215 //_____________________________________________________________________________
216 void AliGenHIJINGpara::Init()
219 // Initialise the HIJING parametrisation
221 Float_t etaMin =-TMath::Log(TMath::Tan(
222 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
223 Float_t etaMax = -TMath::Log(TMath::Tan(
224 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
225 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
226 fPtka = new TF1("ptka",&ptka,0,20,0);
227 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
228 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
230 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
231 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
233 TF1 *ptPic0 = new TF1("ptpi",&ptpi,0.,15.,0);
234 TF1 *ptKac0 = new TF1("ptka",&ptka,0.,15.,0);
236 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
237 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
238 Float_t scalePi = 7316/(intETApi/1.5);
239 Float_t scaleKa = 684/(intETAka/2.0);
241 // Fraction of events corresponding to the selected pt-range
242 Float_t intPt = (0.877*ptPic0->Integral(0, 15)+
243 0.123*ptKac0->Integral(0, 15));
244 Float_t intPtSel = (0.877*ptPic0->Integral(fPtMin, fPtMax)+
245 0.123*ptKac0->Integral(fPtMin, fPtMax));
246 Float_t ptFrac = intPtSel/intPt;
248 // Fraction of events corresponding to the selected eta-range
249 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
250 scaleKa*etaKac0->Integral(etaMin, etaMax));
251 // Fraction of events corresponding to the selected phi-range
252 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
254 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
256 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
257 ClassName(),100.*fParentWeight);
259 // Issue warning message if etaMin or etaMax are outside the alowed range
260 // of the parametrization
261 if (etaMin < -8.001 || etaMax > 8.001) {
262 printf("\n \n WARNING FROM AliGenHIJINGPara !");
263 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
264 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
265 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
269 //_____________________________________________________________________________
270 void AliGenHIJINGpara::Generate()
273 // Generate one trigger
277 const Float_t kRaKpic=0.14;
278 const Float_t kBorne=1/(1+kRaKpic);
279 Float_t polar[3]= {0,0,0};
281 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
282 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
285 Float_t pt, pl, ptot;
288 Int_t i, part, nt, j;
295 for (j=0;j<3;j++) origin[j]=fOrigin[j];
296 if(fVertexSmear==kPerEvent) {
299 origin[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
300 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
303 for(i=0;i<fNpart;i++) {
306 if(random[0]<kBorne) {
307 part=kPions[Int_t (random[1]*3)];
311 part=kKaons[Int_t (random[1]*4)];
315 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
316 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
317 if(theta<fThetaMin || theta>fThetaMax) continue;
319 pl=pt/TMath::Tan(theta);
320 ptot=TMath::Sqrt(pt*pt+pl*pl);
321 if(ptot<fPMin || ptot>fPMax) continue;
322 p[0]=pt*TMath::Cos(phi);
323 p[1]=pt*TMath::Sin(phi);
325 if(fVertexSmear==kPerTrack) {
328 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
329 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
332 gAlice->SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
338 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
340 // Assignment operator