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790bbabf 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
88cb7938 16/* $Id$ */
675e9664 17
18// Parameterisation of pi and K, eta and pt distributions
19// used for the ALICE TDRs.
20// eta: according to HIJING (shadowing + quenching)
21// pT : according to CDF measurement at 1.8 TeV
22// Author: andreas.morsch@cern.ch
23
24
790bbabf 25//Begin_Html
26/*
27<img src="picts/AliGeneratorClass.gif">
28</pre>
29<br clear=left>
30<font size=+2 color=red>
31<p>The responsible person for this module is
32<a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
33</font>
34<pre>
35*/
36//End_Html
37// //
38///////////////////////////////////////////////////////////////////
39
971816d4 40#include <TArrayF.h>
2067f62c 41#include <TClonesArray.h>
116cbefd 42#include <TDatabasePDG.h>
43#include <TF1.h>
cc692c80 44#include <TH1.h>
2067f62c 45#include <TParticle.h>
116cbefd 46#include <TPDGCode.h>
cc692c80 47#include <TCanvas.h>
5d12ce38 48#include <TVirtualMC.h>
116cbefd 49
50#include "AliConst.h"
51#include "AliDecayer.h"
116cbefd 52#include "AliGenEventHeader.h"
53#include "AliGenHIJINGpara.h"
54#include "AliRun.h"
971816d4 55
790bbabf 56ClassImp(AliGenHIJINGpara)
57
198bb1c7 58
59AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para):
60 AliGenerator(para)
790bbabf 61{
198bb1c7 62// Copy constructor
63 para.Copy(*this);
790bbabf 64}
65
66//_____________________________________________________________________________
67static Double_t ptpi(Double_t *px, Double_t *)
68{
69 //
70 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
71 // POWER LAW FOR PT > 500 MEV
72 // MT SCALING BELOW (T=160 MEV)
73 //
cc692c80 74 const Double_t kp0 = 1.3;
75 const Double_t kxn = 8.28;
76 const Double_t kxlim = 0.5;
77 const Double_t kt = 0.160;
78 const Double_t kxmpi = 0.139;
79 const Double_t kb = 1.;
790bbabf 80 Double_t y, y1, xmpi2, ynorm, a;
cc692c80 81 Double_t x = *px;
790bbabf 82 //
cc692c80 83 y1 = TMath::Power(kp0 / (kp0 + kxlim), kxn);
84 xmpi2 = kxmpi * kxmpi;
85 ynorm = kb * (TMath::Exp(-sqrt(kxlim * kxlim + xmpi2) / kt ));
86 a = ynorm / y1;
790bbabf 87 if (x > kxlim)
cc692c80 88 y = a * TMath::Power(kp0 / (kp0 + x), kxn);
790bbabf 89 else
cc692c80 90 y = kb* TMath::Exp(-sqrt(x * x + xmpi2) / kt);
91
790bbabf 92 return y*x;
93}
94
95//_____________________________________________________________________________
96static Double_t ptscal(Double_t pt, Int_t np)
97{
98 // SCALING EN MASSE PAR RAPPORT A PTPI
99 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
100 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
101 // VALUE MESON/PI AT 5 GEV
102 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
103 np--;
104 Double_t f5=TMath::Power(((
105 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
106 Double_t fmax2=f5/kfmax[np];
107 // PIONS
108 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
109 Double_t fmtscal=TMath::Power(((
110 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
111 fmax2;
112 return fmtscal*ptpion;
113}
114
115//_____________________________________________________________________________
116static Double_t ptka( Double_t *px, Double_t *)
117{
118 //
119 // pt parametrisation for k
120 //
121 return ptscal(*px,2);
122}
123
124
125//_____________________________________________________________________________
126static Double_t etapic( Double_t *py, Double_t *)
127{
128 //
129 // eta parametrisation for pi
130 //
131 const Double_t ka1 = 4913.;
132 const Double_t ka2 = 1819.;
133 const Double_t keta1 = 0.22;
134 const Double_t keta2 = 3.66;
135 const Double_t kdeta1 = 1.47;
136 const Double_t kdeta2 = 1.51;
137 Double_t y=TMath::Abs(*py);
138 //
139 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
140 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
141 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
142}
143
144//_____________________________________________________________________________
145static Double_t etakac( Double_t *py, Double_t *)
146{
147 //
148 // eta parametrisation for ka
149 //
150 const Double_t ka1 = 497.6;
151 const Double_t ka2 = 215.6;
152 const Double_t keta1 = 0.79;
153 const Double_t keta2 = 4.09;
154 const Double_t kdeta1 = 1.54;
155 const Double_t kdeta2 = 1.40;
156 Double_t y=TMath::Abs(*py);
157 //
158 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
159 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
160 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
161}
162
163//_____________________________________________________________________________
164AliGenHIJINGpara::AliGenHIJINGpara()
165 :AliGenerator()
166{
167 //
168 // Default constructor
169 //
1e66857c 170 fPtpi = 0;
171 fPtka = 0;
172 fETApic = 0;
173 fETAkac = 0;
174 fDecayer = 0;
175 fNt = -1;
971816d4 176 SetCutVertexZ();
6b236b6f 177 SetPtRange();
2067f62c 178 SetPi0Decays();
790bbabf 179}
180
181//_____________________________________________________________________________
182AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
183 :AliGenerator(npart)
184{
185 //
186 // Standard constructor
187 //
edbba5db 188 fName="HIJINGpara";
790bbabf 189 fTitle="HIJING Parametrisation Particle Generator";
1e66857c 190 fPtpi = 0;
191 fPtka = 0;
192 fETApic = 0;
193 fETAkac = 0;
194 fDecayer = 0;
195 fNt = -1;
971816d4 196 SetCutVertexZ();
6b236b6f 197 SetPtRange();
2067f62c 198 SetPi0Decays();
790bbabf 199}
200
201//_____________________________________________________________________________
202AliGenHIJINGpara::~AliGenHIJINGpara()
203{
204 //
205 // Standard destructor
206 //
207 delete fPtpi;
208 delete fPtka;
209 delete fETApic;
210 delete fETAkac;
211}
212
213//_____________________________________________________________________________
214void AliGenHIJINGpara::Init()
215{
216 //
217 // Initialise the HIJING parametrisation
218 //
219 Float_t etaMin =-TMath::Log(TMath::Tan(
220 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
221 Float_t etaMax = -TMath::Log(TMath::Tan(
222 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
f25521b2 223 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
224 fPtka = new TF1("ptka",&ptka,0,20,0);
cc692c80 225 fPtpi->SetNpx(1000);
226 fPtka->SetNpx(1000);
790bbabf 227 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
228 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
f25521b2 229
bbbc190a 230 TF1 etaPic0("etaPic0",&etapic,-7,7,0);
231 TF1 etaKac0("etaKac0",&etakac,-7,7,0);
f25521b2 232
bbbc190a 233 TF1 ptPic0("ptPic0",&ptpi,0.,15.,0);
234 TF1 ptKac0("ptKac0",&ptka,0.,15.,0);
f25521b2 235
aecf26a3 236 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
237 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
f25521b2 238 Float_t scalePi = 7316/(intETApi/1.5);
239 Float_t scaleKa = 684/(intETAka/2.0);
240
241// Fraction of events corresponding to the selected pt-range
aecf26a3 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));
f25521b2 246 Float_t ptFrac = intPtSel/intPt;
247
248// Fraction of events corresponding to the selected eta-range
aecf26a3 249 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
250 scaleKa*etaKac0.Integral(etaMin, etaMax));
f25521b2 251// Fraction of events corresponding to the selected phi-range
252 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
253
0af12c00 254
f25521b2 255 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
790bbabf 256
0af12c00 257 if (fAnalog != 0) {
258 fPtWgtPi = (fPtMax - fPtMin) / fPtpi->Integral(0., 20.);
259 fPtWgtKa = (fPtMax - fPtMin) / fPtka->Integral(0., 20.);
260 fParentWeight = Float_t(fNpart)/(intETASel*phiFrac);
261 }
262
263
9e1a0ddb 264 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
265 ClassName(),100.*fParentWeight);
5b0e4c0f 266
267// Issue warning message if etaMin or etaMax are outside the alowed range
268// of the parametrization
269 if (etaMin < -8.001 || etaMax > 8.001) {
270 printf("\n \n WARNING FROM AliGenHIJINGPara !");
271 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
272 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
273 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
274 }
2067f62c 275//
276//
2904363f 277 if (fPi0Decays && gMC)
278 fDecayer = gMC->GetDecayer();
790bbabf 279}
280
2067f62c 281
790bbabf 282//_____________________________________________________________________________
283void AliGenHIJINGpara::Generate()
284{
285 //
286 // Generate one trigger
287 //
288
289
290 const Float_t kRaKpic=0.14;
291 const Float_t kBorne=1/(1+kRaKpic);
292 Float_t polar[3]= {0,0,0};
293 //
294 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
295 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
296 //
297 Float_t origin[3];
0af12c00 298 Float_t pt, pl, ptot, wgt;
790bbabf 299 Float_t phi, theta;
300 Float_t p[3];
1e66857c 301 Int_t i, part, j;
790bbabf 302 //
303 TF1 *ptf;
304 TF1 *etaf;
305 //
306 Float_t random[6];
307 //
308 for (j=0;j<3;j++) origin[j]=fOrigin[j];
971816d4 309
310 if(fVertexSmear == kPerEvent) {
c8f7f6f9 311 Vertex();
312 for (j=0; j < 3; j++) origin[j] = fVertex[j];
971816d4 313 } // if kPerEvent
314 TArrayF eventVertex;
315 eventVertex.Set(3);
316 eventVertex[0] = origin[0];
317 eventVertex[1] = origin[1];
318 eventVertex[2] = origin[2];
0af12c00 319
790bbabf 320 for(i=0;i<fNpart;i++) {
321 while(1) {
0af12c00 322 Rndm(random,4);
790bbabf 323 if(random[0]<kBorne) {
324 part=kPions[Int_t (random[1]*3)];
325 ptf=fPtpi;
2067f62c 326 etaf=fETApic;
0af12c00 327 wgt = fPtWgtPi;
790bbabf 328 } else {
329 part=kKaons[Int_t (random[1]*4)];
330 ptf=fPtka;
331 etaf=fETAkac;
0af12c00 332 wgt = fPtWgtKa;
790bbabf 333 }
334 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
335 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
336 if(theta<fThetaMin || theta>fThetaMax) continue;
0af12c00 337
338 if (fAnalog == 0) {
339 pt = ptf->GetRandom();
340 } else {
341 pt = fPtMin + random[3] * (fPtMax - fPtMin);
342 }
343
344
790bbabf 345 pl=pt/TMath::Tan(theta);
346 ptot=TMath::Sqrt(pt*pt+pl*pl);
347 if(ptot<fPMin || ptot>fPMax) continue;
348 p[0]=pt*TMath::Cos(phi);
349 p[1]=pt*TMath::Sin(phi);
350 p[2]=pl;
aee8290b 351 if(fVertexSmear==kPerTrack) {
65fb704d 352 Rndm(random,6);
790bbabf 353 for (j=0;j<3;j++) {
354 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
355 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
356 }
357 }
0af12c00 358
359 if (fAnalog == 0) {
360 wgt = fParentWeight;
361 } else {
362 wgt *= (fParentWeight * ptf->Eval(pt));
363 }
364
365
1ef5f15d 366 if (part == kPi0 && fPi0Decays){
2067f62c 367//
368// Decay pi0 if requested
642f15cf 369 PushTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
1e66857c 370 KeepTrack(fNt);
1ef5f15d 371 DecayPi0(origin, p);
372 } else {
642f15cf 373 PushTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
1e66857c 374 KeepTrack(fNt);
1ef5f15d 375 }
376
790bbabf 377 break;
378 }
1e66857c 379 SetHighWaterMark(fNt);
790bbabf 380 }
1e66857c 381//
382
971816d4 383// Header
384 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
385// Event Vertex
386 header->SetPrimaryVertex(eventVertex);
387 gAlice->SetGenEventHeader(header);
790bbabf 388}
389
6b236b6f 390void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
2067f62c 391 AliGenerator::SetPtRange(ptmin, ptmax);
6b236b6f 392}
790bbabf 393
2067f62c 394void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
395{
396//
397// Decay the pi0
398// and put decay products on the stack
399//
400 static TClonesArray *particles;
401 if(!particles) particles = new TClonesArray("TParticle",1000);
402//
403 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
56fcdfe6 404 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
2067f62c 405//
406// Decay the pi0
407 TLorentzVector pmom(p[0], p[1], p[2], e);
408 fDecayer->Decay(kPi0, &pmom);
56fcdfe6 409
2067f62c 410//
411// Put decay particles on the stack
412//
2067f62c 413 Float_t polar[3] = {0., 0., 0.};
414 Int_t np = fDecayer->ImportParticles(particles);
1e66857c 415 Int_t nt;
2067f62c 416 for (Int_t i = 1; i < np; i++)
417 {
7b33c00a 418 TParticle* iParticle = (TParticle *) particles->At(i);
419 p[0] = iParticle->Px();
420 p[1] = iParticle->Py();
421 p[2] = iParticle->Pz();
2067f62c 422 Int_t part = iParticle->GetPdgCode();
1e66857c 423
642f15cf 424 PushTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);
1e66857c 425 KeepTrack(nt);
2067f62c 426 }
1e66857c 427 fNt = nt;
2067f62c 428}
198bb1c7 429
dc1d768c 430void AliGenHIJINGpara::Copy(TObject &) const
198bb1c7 431{
432 Fatal("Copy","Not implemented!\n");
433}
cc692c80 434
435
436void AliGenHIJINGpara::Draw( const char * /*opt*/)
437{
438 //
439 // Draw the pT and y Distributions
440 //
441 TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
442 c0->Divide(2,1);
443 c0->cd(1);
444 fPtpi->Draw();
445 fPtpi->GetHistogram()->SetXTitle("p_{T} (GeV)");
446 c0->cd(2);
447 fPtka->Draw();
448 fPtka->GetHistogram()->SetXTitle("p_{T} (GeV)");
449
450}