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 1.1.4.1 2003/04/14 17:33:50 hristov
19 Merging with v3-09-08 (part1)
21 Revision 1.2 2003/01/14 10:50:18 alibrary
22 Cleanup of STEER coding conventions
24 Revision 1.1 2002/01/08 09:47:28 morsch
25 HIJING parameterisation including baryons, first commit.
28 ///////////////////////////////////////////////////////////////////
29 // Parameterisation of pi, K, n and p eta and pt distributions //
30 // eta: according to HIJING (shadowing + quenching) //
31 // pT : according to CDF measurement at 1.8 TeV //
32 // Author: andreas.morsch@cern.ch //
34 ///////////////////////////////////////////////////////////////////
41 #include "AliGenEventHeader.h"
42 #include "AliGenHIJINGparaBa.h"
45 ClassImp(AliGenHIJINGparaBa)
48 static Double_t ptpi(Double_t *px, Double_t *)
51 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
52 // POWER LAW FOR PT > 500 MEV
53 // MT SCALING BELOW (T=160 MEV)
55 const Double_t kp0 = 1.3;
56 const Double_t kxn = 8.28;
57 const Double_t kxlim=0.5;
58 const Double_t kt=0.160;
59 const Double_t kxmpi=0.139;
61 Double_t y, y1, xmpi2, ynorm, a;
64 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
66 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
69 y=a*TMath::Power(kp0/(kp0+x),kxn);
71 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
75 //_____________________________________________________________________________
76 static Double_t ptscal(Double_t pt, Int_t np)
78 // SCALING EN MASSE PAR RAPPORT A PTPI
79 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
80 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
81 // VALUE MESON/PI AT 5 GEV
82 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
84 Double_t f5=TMath::Power(((
85 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
86 Double_t fmax2=f5/kfmax[np];
88 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
89 Double_t fmtscal=TMath::Power(((
90 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
92 return fmtscal*ptpion;
95 //_____________________________________________________________________________
96 static Double_t ptka( Double_t *px, Double_t *)
99 // pt parametrisation for k
101 return ptscal(*px,2);
105 //_____________________________________________________________________________
106 static Double_t etapic( Double_t *py, Double_t *)
109 // eta parametrisation for pi
111 const Double_t ka1 = 4913.;
112 const Double_t ka2 = 1819.;
113 const Double_t keta1 = 0.22;
114 const Double_t keta2 = 3.66;
115 const Double_t kdeta1 = 1.47;
116 const Double_t kdeta2 = 1.51;
117 Double_t y=TMath::Abs(*py);
119 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
120 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
121 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
124 //_____________________________________________________________________________
125 static Double_t etakac( Double_t *py, Double_t *)
128 // eta parametrisation for ka
130 const Double_t ka1 = 497.6;
131 const Double_t ka2 = 215.6;
132 const Double_t keta1 = 0.79;
133 const Double_t keta2 = 4.09;
134 const Double_t kdeta1 = 1.54;
135 const Double_t kdeta2 = 1.40;
136 Double_t y=TMath::Abs(*py);
138 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
139 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
140 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
143 static Double_t ptbaryon( Double_t *px, Double_t *)
147 //____________________________________________________________
149 return ptscal(*px,7); // 7==> Baryon in the PtScal function
152 static Double_t etabaryon( Double_t *py, Double_t *)
155 //____________________________________________________________
156 const Float_t p0 = 1.10343e+02;
157 const Float_t p1 = 1.73247e+01;
158 const Float_t p2 = -7.23808e+00;
159 const Float_t p3 = 4.48334e-01;
160 const Double_t y = TMath::Abs(*py);
162 return (p0+p1*y+p2*y*y+p3*y*y*y)/20.;
165 AliGenHIJINGparaBa::AliGenHIJINGparaBa()
169 // Default constructor
171 fName="HIGINGparaBa";
172 fTitle="HIJING Parametrisation Particle Generator with Baryons";
177 //_____________________________________________________________________________
178 AliGenHIJINGparaBa::AliGenHIJINGparaBa(Int_t npart)
179 :AliGenHIJINGpara(npart)
182 // Standard constructor
184 fName="HIGINGparaBa";
185 fTitle="HIJING Parametrisation Particle Generator with Baryons";
190 //_____________________________________________________________________________
191 AliGenHIJINGparaBa::~AliGenHIJINGparaBa()
194 // Standard destructor
200 //_____________________________________________________________________________
201 void AliGenHIJINGparaBa::Init()
204 // Initialise the HIJING parametrisation
206 Float_t etaMin =-TMath::Log(TMath::Tan(
207 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
208 Float_t etaMax = -TMath::Log(TMath::Tan(
209 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
210 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
211 fPtka = new TF1("ptka",&ptka,0,20,0);
212 fPtba = new TF1("ptbaryon",&ptbaryon,0,20,0);
213 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
214 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
215 fETAba = new TF1("etabaryon",&etabaryon,etaMin,etaMax,0);
217 TF1 *etaPic0 = new TF1("etapic",&etapic, -7, 7, 0);
218 TF1 *etaKac0 = new TF1("etakac",&etakac, -7, 7, 0);
219 TF1 *etaBar0 = new TF1("etabar",&etabaryon, -7, 7, 0);
221 TF1 *ptPic0 = new TF1("ptpi", &ptpi, 0., 15., 0);
222 TF1 *ptKac0 = new TF1("ptka", &ptka, 0., 15., 0);
223 TF1 *ptBar0 = new TF1("ptbar", &ptbaryon, 0., 15., 0);
225 Float_t intETApi = etaPic0->Integral(-0.5, 0.5);
226 Float_t intETAka = etaKac0->Integral(-0.5, 0.5);
227 Float_t intETAba = etaBar0->Integral(-0.5, 0.5);
229 Float_t scalePi = 6979./(intETApi/1.5);
230 Float_t scaleKa = 657./(intETAka/2.0);
231 Float_t scaleBa = 364./(intETAba/2.0);
233 // Fraction of events corresponding to the selected pt-range
234 Float_t intPt = (0.837*ptPic0->Integral(0, 15)+
235 0.105*ptKac0->Integral(0, 15)+
236 0.058*ptBar0->Integral(0, 15));
237 Float_t intPtSel = (0.837*ptPic0->Integral(fPtMin, fPtMax)+
238 0.105*ptKac0->Integral(fPtMin, fPtMax)+
239 0.058*ptBar0->Integral(fPtMin, fPtMax));
240 Float_t ptFrac = intPtSel/intPt;
242 // Fraction of events corresponding to the selected eta-range
243 Float_t intETASel = (scalePi*etaPic0->Integral(etaMin, etaMax)+
244 scaleKa*etaKac0->Integral(etaMin, etaMax)+
245 scaleBa*etaBar0->Integral(etaMin, etaMax));
246 // Fraction of events corresponding to the selected phi-range
247 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
249 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
251 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event \n",
252 ClassName(),100.*fParentWeight);
254 // Issue warning message if etaMin or etaMax are outside the alowed range
255 // of the parametrization
256 if (etaMin < -8.001 || etaMax > 8.001) {
257 printf("\n \n WARNING FROM AliGenHIJINGParaBa !");
258 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
259 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
260 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
264 //_____________________________________________________________________________
265 void AliGenHIJINGparaBa::Generate()
268 // Generate one trigger
272 const Float_t kBorne1 = 0.837;
273 const Float_t kBorne2 = kBorne1+0.105;
275 Float_t polar[3]= {0,0,0};
277 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
278 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
279 const Int_t kBaryons[4] = {kProton, kProtonBar, kNeutron, kNeutronBar};
282 Float_t pt, pl, ptot;
285 Int_t i, part, nt, j;
292 for (j=0;j<3;j++) origin[j]=fOrigin[j];
294 if(fVertexSmear == kPerEvent) {
297 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
299 for (j=0; j < 3; j++) {
300 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
301 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
304 for (j=0; j < 3; j++) origin[j] += dv[j];
308 eventVertex[0] = origin[0];
309 eventVertex[1] = origin[1];
310 eventVertex[2] = origin[2];
312 for(i=0;i<fNpart;i++) {
315 if(random[0] < kBorne1) {
316 part = kPions[Int_t (random[1]*3)];
319 } else if (random[0] < kBorne2) {
320 part = kKaons[Int_t (random[1]*4)];
324 part = kBaryons[Int_t (random[1]*4)];
329 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
330 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
331 if(theta<fThetaMin || theta>fThetaMax) continue;
333 pl=pt/TMath::Tan(theta);
334 ptot=TMath::Sqrt(pt*pt+pl*pl);
335 if(ptot<fPMin || ptot>fPMax) continue;
336 p[0]=pt*TMath::Cos(phi);
337 p[1]=pt*TMath::Sin(phi);
339 if(fVertexSmear==kPerTrack) {
342 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
343 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
346 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,nt,fParentWeight);
351 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
353 header->SetPrimaryVertex(eventVertex);
354 gAlice->SetGenEventHeader(header);