Correct mother child relation for pi0.
[u/mrichter/AliRoot.git] / EVGEN / AliGenHIJINGpara.cxx
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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
16/*
17$Log$
1e66857c 18Revision 1.16 2002/11/28 11:46:15 morsch
19Don't track pi0 if already decayed.
20
1ef5f15d 21Revision 1.15 2002/11/28 11:38:53 morsch
22Typo corrected.
23
7b33c00a 24Revision 1.14 2002/11/26 17:12:36 morsch
25Decay pi0 if requested.
26
2067f62c 27Revision 1.13 2002/10/14 14:55:35 hristov
28Merging the VirtualMC branch to the main development branch (HEAD)
29
b9d0a01d 30Revision 1.11.4.1 2002/07/24 08:56:28 alibrary
31Updating EVGEN on TVirtulaMC
32
33Revision 1.12 2002/06/19 06:56:34 hristov
34Memory leak corrected
35
aecf26a3 36Revision 1.11 2002/03/20 10:21:13 hristov
37Set fPtMax to 15 GeV in order to avoid some numerical problems
38
6b236b6f 39Revision 1.10 2001/10/15 16:44:46 morsch
40- Possibility for vertex distribution truncation.
41- Write mc header with vertex position.
42
971816d4 43Revision 1.9 2001/07/27 17:09:36 morsch
44Use local SetTrack, KeepTrack and SetHighWaterMark methods
45to delegate either to local stack or to stack owned by AliRun.
46(Piotr Skowronski, A.M.)
47
a99cf51f 48Revision 1.8 2001/07/20 11:03:58 morsch
49Issue warning message if used outside allowed eta range (-8 to 8).
50
5b0e4c0f 51Revision 1.7 2001/07/17 12:41:01 morsch
52- Calculation of fraction of event corresponding to selected pt-range corrected
53(R. Turrisi)
54- Parent weight corrected.
55
f25521b2 56Revision 1.6 2001/05/16 14:57:10 alibrary
57New files for folders and Stack
58
9e1a0ddb 59Revision 1.5 2000/12/21 16:24:06 morsch
60Coding convention clean-up
61
675e9664 62Revision 1.4 2000/11/30 07:12:50 alibrary
63Introducing new Rndm and QA classes
64
65fb704d 65Revision 1.3 2000/10/02 21:28:06 fca
66Removal of useless dependecies via forward declarations
67
94de3818 68Revision 1.2 2000/07/11 18:24:55 fca
69Coding convention corrections + few minor bug fixes
70
aee8290b 71Revision 1.1 2000/06/09 20:20:30 morsch
72Same class as previously in AliSimpleGen.cxx
73All coding rule violations except RS3 corrected (AM)
74
790bbabf 75*/
675e9664 76
77// Parameterisation of pi and K, eta and pt distributions
78// used for the ALICE TDRs.
79// eta: according to HIJING (shadowing + quenching)
80// pT : according to CDF measurement at 1.8 TeV
81// Author: andreas.morsch@cern.ch
82
83
790bbabf 84//Begin_Html
85/*
86<img src="picts/AliGeneratorClass.gif">
87</pre>
88<br clear=left>
89<font size=+2 color=red>
90<p>The responsible person for this module is
91<a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
92</font>
93<pre>
94*/
95//End_Html
96// //
97///////////////////////////////////////////////////////////////////
98
99#include "AliGenHIJINGpara.h"
971816d4 100#include "AliGenEventHeader.h"
790bbabf 101#include "AliRun.h"
102#include "AliConst.h"
2067f62c 103#include "AliDecayer.h"
104#include "AliDecayerPythia.h"
790bbabf 105#include "AliPDG.h"
106
971816d4 107#include <TF1.h>
108#include <TArrayF.h>
2067f62c 109#include <TDatabasePDG.h>
110#include <TClonesArray.h>
111#include <TParticle.h>
971816d4 112
790bbabf 113ClassImp(AliGenHIJINGpara)
114
115AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
116{
117// copy constructor
118}
119
120//_____________________________________________________________________________
121static Double_t ptpi(Double_t *px, Double_t *)
122{
123 //
124 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
125 // POWER LAW FOR PT > 500 MEV
126 // MT SCALING BELOW (T=160 MEV)
127 //
128 const Double_t kp0 = 1.3;
129 const Double_t kxn = 8.28;
130 const Double_t kxlim=0.5;
131 const Double_t kt=0.160;
132 const Double_t kxmpi=0.139;
133 const Double_t kb=1.;
134 Double_t y, y1, xmpi2, ynorm, a;
135 Double_t x=*px;
136 //
137 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
138 xmpi2=kxmpi*kxmpi;
139 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
140 a=ynorm/y1;
141 if (x > kxlim)
142 y=a*TMath::Power(kp0/(kp0+x),kxn);
143 else
144 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
145 return y*x;
146}
147
148//_____________________________________________________________________________
149static Double_t ptscal(Double_t pt, Int_t np)
150{
151 // SCALING EN MASSE PAR RAPPORT A PTPI
152 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
153 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
154 // VALUE MESON/PI AT 5 GEV
155 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
156 np--;
157 Double_t f5=TMath::Power(((
158 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
159 Double_t fmax2=f5/kfmax[np];
160 // PIONS
161 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
162 Double_t fmtscal=TMath::Power(((
163 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
164 fmax2;
165 return fmtscal*ptpion;
166}
167
168//_____________________________________________________________________________
169static Double_t ptka( Double_t *px, Double_t *)
170{
171 //
172 // pt parametrisation for k
173 //
174 return ptscal(*px,2);
175}
176
177
178//_____________________________________________________________________________
179static Double_t etapic( Double_t *py, Double_t *)
180{
181 //
182 // eta parametrisation for pi
183 //
184 const Double_t ka1 = 4913.;
185 const Double_t ka2 = 1819.;
186 const Double_t keta1 = 0.22;
187 const Double_t keta2 = 3.66;
188 const Double_t kdeta1 = 1.47;
189 const Double_t kdeta2 = 1.51;
190 Double_t y=TMath::Abs(*py);
191 //
192 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
193 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
194 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
195}
196
197//_____________________________________________________________________________
198static Double_t etakac( Double_t *py, Double_t *)
199{
200 //
201 // eta parametrisation for ka
202 //
203 const Double_t ka1 = 497.6;
204 const Double_t ka2 = 215.6;
205 const Double_t keta1 = 0.79;
206 const Double_t keta2 = 4.09;
207 const Double_t kdeta1 = 1.54;
208 const Double_t kdeta2 = 1.40;
209 Double_t y=TMath::Abs(*py);
210 //
211 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
212 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
213 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
214}
215
216//_____________________________________________________________________________
217AliGenHIJINGpara::AliGenHIJINGpara()
218 :AliGenerator()
219{
220 //
221 // Default constructor
222 //
1e66857c 223 fPtpi = 0;
224 fPtka = 0;
225 fETApic = 0;
226 fETAkac = 0;
227 fDecayer = 0;
228 fNt = -1;
971816d4 229 SetCutVertexZ();
6b236b6f 230 SetPtRange();
2067f62c 231 SetPi0Decays();
790bbabf 232}
233
234//_____________________________________________________________________________
235AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
236 :AliGenerator(npart)
237{
238 //
239 // Standard constructor
240 //
241 fName="HIGINGpara";
242 fTitle="HIJING Parametrisation Particle Generator";
1e66857c 243 fPtpi = 0;
244 fPtka = 0;
245 fETApic = 0;
246 fETAkac = 0;
247 fDecayer = 0;
248 fNt = -1;
971816d4 249 SetCutVertexZ();
6b236b6f 250 SetPtRange();
2067f62c 251 SetPi0Decays();
790bbabf 252}
253
254//_____________________________________________________________________________
255AliGenHIJINGpara::~AliGenHIJINGpara()
256{
257 //
258 // Standard destructor
259 //
260 delete fPtpi;
261 delete fPtka;
262 delete fETApic;
263 delete fETAkac;
264}
265
266//_____________________________________________________________________________
267void AliGenHIJINGpara::Init()
268{
269 //
270 // Initialise the HIJING parametrisation
271 //
272 Float_t etaMin =-TMath::Log(TMath::Tan(
273 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
274 Float_t etaMax = -TMath::Log(TMath::Tan(
275 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
f25521b2 276 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
277 fPtka = new TF1("ptka",&ptka,0,20,0);
790bbabf 278 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
279 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
f25521b2 280
aecf26a3 281 TF1 etaPic0("etapic",&etapic,-7,7,0);
282 TF1 etaKac0("etakac",&etakac,-7,7,0);
f25521b2 283
aecf26a3 284 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
285 TF1 ptKac0("ptka",&ptka,0.,15.,0);
f25521b2 286
aecf26a3 287 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
288 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
f25521b2 289 Float_t scalePi = 7316/(intETApi/1.5);
290 Float_t scaleKa = 684/(intETAka/2.0);
291
292// Fraction of events corresponding to the selected pt-range
aecf26a3 293 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
294 0.123*ptKac0.Integral(0, 15));
295 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
296 0.123*ptKac0.Integral(fPtMin, fPtMax));
f25521b2 297 Float_t ptFrac = intPtSel/intPt;
298
299// Fraction of events corresponding to the selected eta-range
aecf26a3 300 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
301 scaleKa*etaKac0.Integral(etaMin, etaMax));
f25521b2 302// Fraction of events corresponding to the selected phi-range
303 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
304
305 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
790bbabf 306
9e1a0ddb 307 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
308 ClassName(),100.*fParentWeight);
5b0e4c0f 309
310// Issue warning message if etaMin or etaMax are outside the alowed range
311// of the parametrization
312 if (etaMin < -8.001 || etaMax > 8.001) {
313 printf("\n \n WARNING FROM AliGenHIJINGPara !");
314 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
315 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
316 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
317 }
2067f62c 318//
319//
320 if (fPi0Decays) fDecayer = new AliDecayerPythia();
790bbabf 321}
322
2067f62c 323
790bbabf 324//_____________________________________________________________________________
325void AliGenHIJINGpara::Generate()
326{
327 //
328 // Generate one trigger
329 //
330
331
332 const Float_t kRaKpic=0.14;
333 const Float_t kBorne=1/(1+kRaKpic);
334 Float_t polar[3]= {0,0,0};
335 //
336 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
337 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
338 //
339 Float_t origin[3];
340 Float_t pt, pl, ptot;
341 Float_t phi, theta;
342 Float_t p[3];
1e66857c 343 Int_t i, part, j;
790bbabf 344 //
345 TF1 *ptf;
346 TF1 *etaf;
347 //
348 Float_t random[6];
349 //
350 for (j=0;j<3;j++) origin[j]=fOrigin[j];
971816d4 351
352 if(fVertexSmear == kPerEvent) {
353 Float_t dv[3];
354 dv[2] = 1.e10;
355 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
356 Rndm(random,6);
357 for (j=0; j < 3; j++) {
358 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
359 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
360 }
790bbabf 361 }
971816d4 362 for (j=0; j < 3; j++) origin[j] += dv[j];
363 } // if kPerEvent
364 TArrayF eventVertex;
365 eventVertex.Set(3);
366 eventVertex[0] = origin[0];
367 eventVertex[1] = origin[1];
368 eventVertex[2] = origin[2];
369
790bbabf 370 for(i=0;i<fNpart;i++) {
371 while(1) {
65fb704d 372 Rndm(random,3);
790bbabf 373 if(random[0]<kBorne) {
374 part=kPions[Int_t (random[1]*3)];
375 ptf=fPtpi;
2067f62c 376 etaf=fETApic;
790bbabf 377 } else {
378 part=kKaons[Int_t (random[1]*4)];
379 ptf=fPtka;
380 etaf=fETAkac;
381 }
382 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
383 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
384 if(theta<fThetaMin || theta>fThetaMax) continue;
385 pt=ptf->GetRandom();
386 pl=pt/TMath::Tan(theta);
387 ptot=TMath::Sqrt(pt*pt+pl*pl);
388 if(ptot<fPMin || ptot>fPMax) continue;
389 p[0]=pt*TMath::Cos(phi);
390 p[1]=pt*TMath::Sin(phi);
391 p[2]=pl;
aee8290b 392 if(fVertexSmear==kPerTrack) {
65fb704d 393 Rndm(random,6);
790bbabf 394 for (j=0;j<3;j++) {
395 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
396 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
397 }
398 }
1ef5f15d 399 if (part == kPi0 && fPi0Decays){
2067f62c 400//
401// Decay pi0 if requested
1e66857c 402 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
403 KeepTrack(fNt);
1ef5f15d 404 DecayPi0(origin, p);
405 } else {
1e66857c 406 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
407 KeepTrack(fNt);
1ef5f15d 408 }
409
790bbabf 410 break;
411 }
1e66857c 412 SetHighWaterMark(fNt);
790bbabf 413 }
1e66857c 414//
415
971816d4 416// Header
417 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
418// Event Vertex
419 header->SetPrimaryVertex(eventVertex);
420 gAlice->SetGenEventHeader(header);
790bbabf 421}
422
423AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
424{
425// Assignment operator
426 return *this;
427}
428
6b236b6f 429void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
2067f62c 430 AliGenerator::SetPtRange(ptmin, ptmax);
6b236b6f 431}
790bbabf 432
2067f62c 433void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
434{
435//
436// Decay the pi0
437// and put decay products on the stack
438//
439 static TClonesArray *particles;
440 if(!particles) particles = new TClonesArray("TParticle",1000);
441//
442 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
443 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] +p[2] * p[2] * kMass * kMass);
444//
445// Decay the pi0
446 TLorentzVector pmom(p[0], p[1], p[2], e);
447 fDecayer->Decay(kPi0, &pmom);
448//
449// Put decay particles on the stack
450//
2067f62c 451 Float_t polar[3] = {0., 0., 0.};
452 Int_t np = fDecayer->ImportParticles(particles);
1e66857c 453 Int_t nt;
2067f62c 454 for (Int_t i = 1; i < np; i++)
455 {
7b33c00a 456 TParticle* iParticle = (TParticle *) particles->At(i);
457 p[0] = iParticle->Px();
458 p[1] = iParticle->Py();
459 p[2] = iParticle->Pz();
2067f62c 460 Int_t part = iParticle->GetPdgCode();
1e66857c 461
462 SetTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);
463 KeepTrack(nt);
2067f62c 464 }
1e66857c 465 fNt = nt;
2067f62c 466}