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Bug fix (I.Hrivnacova)
[u/mrichter/AliRoot.git] / EVGEN / AliGenHIJINGpara.cxx
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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
16/* $Id$ */
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
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
40#include <TArrayF.h>
41#include <TClonesArray.h>
42#include <TDatabasePDG.h>
43#include <TF1.h>
44#include <TParticle.h>
45#include <TPDGCode.h>
46
47#include "AliConst.h"
48#include "AliDecayer.h"
49#include "AliGenEventHeader.h"
50#include "AliGenHIJINGpara.h"
51#include "AliRun.h"
52
53ClassImp(AliGenHIJINGpara)
54
55AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
56{
57// copy constructor
58}
59
60//_____________________________________________________________________________
61static Double_t ptpi(Double_t *px, Double_t *)
62{
63 //
64 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
65 // POWER LAW FOR PT > 500 MEV
66 // MT SCALING BELOW (T=160 MEV)
67 //
68 const Double_t kp0 = 1.3;
69 const Double_t kxn = 8.28;
70 const Double_t kxlim=0.5;
71 const Double_t kt=0.160;
72 const Double_t kxmpi=0.139;
73 const Double_t kb=1.;
74 Double_t y, y1, xmpi2, ynorm, a;
75 Double_t x=*px;
76 //
77 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
78 xmpi2=kxmpi*kxmpi;
79 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
80 a=ynorm/y1;
81 if (x > kxlim)
82 y=a*TMath::Power(kp0/(kp0+x),kxn);
83 else
84 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
85 return y*x;
86}
87
88//_____________________________________________________________________________
89static Double_t ptscal(Double_t pt, Int_t np)
90{
91 // SCALING EN MASSE PAR RAPPORT A PTPI
92 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
93 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
94 // VALUE MESON/PI AT 5 GEV
95 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
96 np--;
97 Double_t f5=TMath::Power(((
98 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
99 Double_t fmax2=f5/kfmax[np];
100 // PIONS
101 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
102 Double_t fmtscal=TMath::Power(((
103 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
104 fmax2;
105 return fmtscal*ptpion;
106}
107
108//_____________________________________________________________________________
109static Double_t ptka( Double_t *px, Double_t *)
110{
111 //
112 // pt parametrisation for k
113 //
114 return ptscal(*px,2);
115}
116
117
118//_____________________________________________________________________________
119static Double_t etapic( Double_t *py, Double_t *)
120{
121 //
122 // eta parametrisation for pi
123 //
124 const Double_t ka1 = 4913.;
125 const Double_t ka2 = 1819.;
126 const Double_t keta1 = 0.22;
127 const Double_t keta2 = 3.66;
128 const Double_t kdeta1 = 1.47;
129 const Double_t kdeta2 = 1.51;
130 Double_t y=TMath::Abs(*py);
131 //
132 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
133 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
134 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
135}
136
137//_____________________________________________________________________________
138static Double_t etakac( Double_t *py, Double_t *)
139{
140 //
141 // eta parametrisation for ka
142 //
143 const Double_t ka1 = 497.6;
144 const Double_t ka2 = 215.6;
145 const Double_t keta1 = 0.79;
146 const Double_t keta2 = 4.09;
147 const Double_t kdeta1 = 1.54;
148 const Double_t kdeta2 = 1.40;
149 Double_t y=TMath::Abs(*py);
150 //
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);
154}
155
156//_____________________________________________________________________________
157AliGenHIJINGpara::AliGenHIJINGpara()
158 :AliGenerator()
159{
160 //
161 // Default constructor
162 //
163 fPtpi = 0;
164 fPtka = 0;
165 fETApic = 0;
166 fETAkac = 0;
167 fDecayer = 0;
168 fNt = -1;
169 SetCutVertexZ();
170 SetPtRange();
171 SetPi0Decays();
172}
173
174//_____________________________________________________________________________
175AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
176 :AliGenerator(npart)
177{
178 //
179 // Standard constructor
180 //
181 fName="HIJINGpara";
182 fTitle="HIJING Parametrisation Particle Generator";
183 fPtpi = 0;
184 fPtka = 0;
185 fETApic = 0;
186 fETAkac = 0;
187 fDecayer = 0;
188 fNt = -1;
189 SetCutVertexZ();
190 SetPtRange();
191 SetPi0Decays();
192}
193
194//_____________________________________________________________________________
195AliGenHIJINGpara::~AliGenHIJINGpara()
196{
197 //
198 // Standard destructor
199 //
200 delete fPtpi;
201 delete fPtka;
202 delete fETApic;
203 delete fETAkac;
204}
205
206//_____________________________________________________________________________
207void AliGenHIJINGpara::Init()
208{
209 //
210 // Initialise the HIJING parametrisation
211 //
212 Float_t etaMin =-TMath::Log(TMath::Tan(
213 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
214 Float_t etaMax = -TMath::Log(TMath::Tan(
215 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
216 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
217 fPtka = new TF1("ptka",&ptka,0,20,0);
218 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
219 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
220
221 TF1 etaPic0("etapic",&etapic,-7,7,0);
222 TF1 etaKac0("etakac",&etakac,-7,7,0);
223
224 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
225 TF1 ptKac0("ptka",&ptka,0.,15.,0);
226
227 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
228 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
229 Float_t scalePi = 7316/(intETApi/1.5);
230 Float_t scaleKa = 684/(intETAka/2.0);
231
232// Fraction of events corresponding to the selected pt-range
233 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
234 0.123*ptKac0.Integral(0, 15));
235 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
236 0.123*ptKac0.Integral(fPtMin, fPtMax));
237 Float_t ptFrac = intPtSel/intPt;
238
239// Fraction of events corresponding to the selected eta-range
240 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
241 scaleKa*etaKac0.Integral(etaMin, etaMax));
242// Fraction of events corresponding to the selected phi-range
243 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
244
245 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
246
247 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
248 ClassName(),100.*fParentWeight);
249
250// Issue warning message if etaMin or etaMax are outside the alowed range
251// of the parametrization
252 if (etaMin < -8.001 || etaMax > 8.001) {
253 printf("\n \n WARNING FROM AliGenHIJINGPara !");
254 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
255 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
256 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
257 }
258//
259//
260 if (fPi0Decays && gMC)
261 fDecayer = gMC->GetDecayer();
262}
263
264
265//_____________________________________________________________________________
266void AliGenHIJINGpara::Generate()
267{
268 //
269 // Generate one trigger
270 //
271
272
273 const Float_t kRaKpic=0.14;
274 const Float_t kBorne=1/(1+kRaKpic);
275 Float_t polar[3]= {0,0,0};
276 //
277 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
278 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
279 //
280 Float_t origin[3];
281 Float_t pt, pl, ptot;
282 Float_t phi, theta;
283 Float_t p[3];
284 Int_t i, part, j;
285 //
286 TF1 *ptf;
287 TF1 *etaf;
288 //
289 Float_t random[6];
290 //
291 for (j=0;j<3;j++) origin[j]=fOrigin[j];
292
293 if(fVertexSmear == kPerEvent) {
294 Vertex();
295 for (j=0; j < 3; j++) origin[j] = fVertex[j];
296 } // if kPerEvent
297 TArrayF eventVertex;
298 eventVertex.Set(3);
299 eventVertex[0] = origin[0];
300 eventVertex[1] = origin[1];
301 eventVertex[2] = origin[2];
302
303 for(i=0;i<fNpart;i++) {
304 while(1) {
305 Rndm(random,3);
306 if(random[0]<kBorne) {
307 part=kPions[Int_t (random[1]*3)];
308 ptf=fPtpi;
309 etaf=fETApic;
310 } else {
311 part=kKaons[Int_t (random[1]*4)];
312 ptf=fPtka;
313 etaf=fETAkac;
314 }
315 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
316 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
317 if(theta<fThetaMin || theta>fThetaMax) continue;
318 pt=ptf->GetRandom();
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);
324 p[2]=pl;
325 if(fVertexSmear==kPerTrack) {
326 Rndm(random,6);
327 for (j=0;j<3;j++) {
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]));
330 }
331 }
332 if (part == kPi0 && fPi0Decays){
333//
334// Decay pi0 if requested
335 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
336 KeepTrack(fNt);
337 DecayPi0(origin, p);
338 } else {
339 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
340 KeepTrack(fNt);
341 }
342
343 break;
344 }
345 SetHighWaterMark(fNt);
346 }
347//
348
349// Header
350 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
351// Event Vertex
352 header->SetPrimaryVertex(eventVertex);
353 gAlice->SetGenEventHeader(header);
354}
355
356AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
357{
358// Assignment operator
359 return *this;
360}
361
362void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
363 AliGenerator::SetPtRange(ptmin, ptmax);
364}
365
366void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
367{
368//
369// Decay the pi0
370// and put decay products on the stack
371//
372 static TClonesArray *particles;
373 if(!particles) particles = new TClonesArray("TParticle",1000);
374//
375 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
376 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
377//
378// Decay the pi0
379 TLorentzVector pmom(p[0], p[1], p[2], e);
380 fDecayer->Decay(kPi0, &pmom);
381
382//
383// Put decay particles on the stack
384//
385 Float_t polar[3] = {0., 0., 0.};
386 Int_t np = fDecayer->ImportParticles(particles);
387 Int_t nt;
388 for (Int_t i = 1; i < np; i++)
389 {
390 TParticle* iParticle = (TParticle *) particles->At(i);
391 p[0] = iParticle->Px();
392 p[1] = iParticle->Py();
393 p[2] = iParticle->Pz();
394 Int_t part = iParticle->GetPdgCode();
395
396 SetTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);
397 KeepTrack(nt);
398 }
399 fNt = nt;
400}