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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 1.10 2001/10/15 16:44:46 morsch
19 - Possibility for vertex distribution truncation.
20 - Write mc header with vertex position.
22 Revision 1.9 2001/07/27 17:09:36 morsch
23 Use local SetTrack, KeepTrack and SetHighWaterMark methods
24 to delegate either to local stack or to stack owned by AliRun.
25 (Piotr Skowronski, A.M.)
27 Revision 1.8 2001/07/20 11:03:58 morsch
28 Issue warning message if used outside allowed eta range (-8 to 8).
30 Revision 1.7 2001/07/17 12:41:01 morsch
31 - Calculation of fraction of event corresponding to selected pt-range corrected
33 - Parent weight corrected.
35 Revision 1.6 2001/05/16 14:57:10 alibrary
36 New files for folders and Stack
38 Revision 1.5 2000/12/21 16:24:06 morsch
39 Coding convention clean-up
41 Revision 1.4 2000/11/30 07:12:50 alibrary
42 Introducing new Rndm and QA classes
44 Revision 1.3 2000/10/02 21:28:06 fca
45 Removal of useless dependecies via forward declarations
47 Revision 1.2 2000/07/11 18:24:55 fca
48 Coding convention corrections + few minor bug fixes
50 Revision 1.1 2000/06/09 20:20:30 morsch
51 Same class as previously in AliSimpleGen.cxx
52 All coding rule violations except RS3 corrected (AM)
56 // Parameterisation of pi and K, eta and pt distributions
57 // used for the ALICE TDRs.
58 // eta: according to HIJING (shadowing + quenching)
59 // pT : according to CDF measurement at 1.8 TeV
60 // Author: andreas.morsch@cern.ch
65 <img src="picts/AliGeneratorClass.gif">
68 <font size=+2 color=red>
69 <p>The responsible person for this module is
70 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
76 ///////////////////////////////////////////////////////////////////
78 #include "AliGenHIJINGpara.h"
79 #include "AliGenEventHeader.h"
87 ClassImp(AliGenHIJINGpara)
89 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
94 //_____________________________________________________________________________
95 static Double_t ptpi(Double_t *px, Double_t *)
98 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
99 // POWER LAW FOR PT > 500 MEV
100 // MT SCALING BELOW (T=160 MEV)
102 const Double_t kp0 = 1.3;
103 const Double_t kxn = 8.28;
104 const Double_t kxlim=0.5;
105 const Double_t kt=0.160;
106 const Double_t kxmpi=0.139;
107 const Double_t kb=1.;
108 Double_t y, y1, xmpi2, ynorm, a;
111 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
113 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
116 y=a*TMath::Power(kp0/(kp0+x),kxn);
118 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
122 //_____________________________________________________________________________
123 static Double_t ptscal(Double_t pt, Int_t np)
125 // SCALING EN MASSE PAR RAPPORT A PTPI
126 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
127 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
128 // VALUE MESON/PI AT 5 GEV
129 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
131 Double_t f5=TMath::Power(((
132 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
133 Double_t fmax2=f5/kfmax[np];
135 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
136 Double_t fmtscal=TMath::Power(((
137 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
139 return fmtscal*ptpion;
142 //_____________________________________________________________________________
143 static Double_t ptka( Double_t *px, Double_t *)
146 // pt parametrisation for k
148 return ptscal(*px,2);
152 //_____________________________________________________________________________
153 static Double_t etapic( Double_t *py, Double_t *)
156 // eta parametrisation for pi
158 const Double_t ka1 = 4913.;
159 const Double_t ka2 = 1819.;
160 const Double_t keta1 = 0.22;
161 const Double_t keta2 = 3.66;
162 const Double_t kdeta1 = 1.47;
163 const Double_t kdeta2 = 1.51;
164 Double_t y=TMath::Abs(*py);
166 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
167 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
168 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
171 //_____________________________________________________________________________
172 static Double_t etakac( Double_t *py, Double_t *)
175 // eta parametrisation for ka
177 const Double_t ka1 = 497.6;
178 const Double_t ka2 = 215.6;
179 const Double_t keta1 = 0.79;
180 const Double_t keta2 = 4.09;
181 const Double_t kdeta1 = 1.54;
182 const Double_t kdeta2 = 1.40;
183 Double_t y=TMath::Abs(*py);
185 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
186 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
187 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
190 //_____________________________________________________________________________
191 AliGenHIJINGpara::AliGenHIJINGpara()
195 // Default constructor
205 //_____________________________________________________________________________
206 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
210 // Standard constructor
213 fTitle="HIJING Parametrisation Particle Generator";
222 //_____________________________________________________________________________
223 AliGenHIJINGpara::~AliGenHIJINGpara()
226 // Standard destructor
234 //_____________________________________________________________________________
235 void AliGenHIJINGpara::Init()
238 // Initialise the HIJING parametrisation
240 Float_t etaMin =-TMath::Log(TMath::Tan(
241 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
242 Float_t etaMax = -TMath::Log(TMath::Tan(
243 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
244 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
245 fPtka = new TF1("ptka",&ptka,0,20,0);
246 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
247 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
249 TF1 *etaPic0 = new TF1("etapic",&etapic,-7,7,0);
250 TF1 *etaKac0 = new TF1("etakac",&etakac,-7,7,0);
252 TF1 *ptPic0 = new TF1("ptpi",&ptpi,0.,15.,0);
253 TF1 *ptKac0 = new TF1("ptka",&ptka,0.,15.,0);
255 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
256 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
257 Float_t scalePi = 7316/(intETApi/1.5);
258 Float_t scaleKa = 684/(intETAka/2.0);
260 // Fraction of events corresponding to the selected pt-range
261 Float_t intPt = (0.877*ptPic0->Integral(0, 15)+
262 0.123*ptKac0->Integral(0, 15));
263 Float_t intPtSel = (0.877*ptPic0->Integral(fPtMin, fPtMax)+
264 0.123*ptKac0->Integral(fPtMin, fPtMax));
265 Float_t ptFrac = intPtSel/intPt;
267 // Fraction of events corresponding to the selected eta-range
268 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
269 scaleKa*etaKac0->Integral(etaMin, etaMax));
270 // Fraction of events corresponding to the selected phi-range
271 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
273 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
275 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
276 ClassName(),100.*fParentWeight);
278 // Issue warning message if etaMin or etaMax are outside the alowed range
279 // of the parametrization
280 if (etaMin < -8.001 || etaMax > 8.001) {
281 printf("\n \n WARNING FROM AliGenHIJINGPara !");
282 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
283 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
284 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
288 //_____________________________________________________________________________
289 void AliGenHIJINGpara::Generate()
292 // Generate one trigger
296 const Float_t kRaKpic=0.14;
297 const Float_t kBorne=1/(1+kRaKpic);
298 Float_t polar[3]= {0,0,0};
300 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
301 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
304 Float_t pt, pl, ptot;
307 Int_t i, part, nt, j;
314 for (j=0;j<3;j++) origin[j]=fOrigin[j];
316 if(fVertexSmear == kPerEvent) {
319 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
321 for (j=0; j < 3; j++) {
322 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
323 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
326 for (j=0; j < 3; j++) origin[j] += dv[j];
330 eventVertex[0] = origin[0];
331 eventVertex[1] = origin[1];
332 eventVertex[2] = origin[2];
334 for(i=0;i<fNpart;i++) {
337 if(random[0]<kBorne) {
338 part=kPions[Int_t (random[1]*3)];
342 part=kKaons[Int_t (random[1]*4)];
346 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
347 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
348 if(theta<fThetaMin || theta>fThetaMax) continue;
350 pl=pt/TMath::Tan(theta);
351 ptot=TMath::Sqrt(pt*pt+pl*pl);
352 if(ptot<fPMin || ptot>fPMax) continue;
353 p[0]=pt*TMath::Cos(phi);
354 p[1]=pt*TMath::Sin(phi);
356 if(fVertexSmear==kPerTrack) {
359 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
360 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
363 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
368 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
370 header->SetPrimaryVertex(eventVertex);
371 gAlice->SetGenEventHeader(header);
374 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
376 // Assignment operator
380 void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
381 AliGenerator::SetPtRange(ptmin, ptmax);