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Numbers of slow nucleons either from model or user set.
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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$Log$
2904363f 18Revision 1.20 2003/01/28 15:29:07 morsch
19Spelling in name corrected.
20
edbba5db 21Revision 1.19 2003/01/14 10:50:18 alibrary
22Cleanup of STEER coding conventions
23
116cbefd 24Revision 1.18 2002/12/11 11:58:11 morsch
25Bug in formula for pi0 energy for decay corrected.
26
56fcdfe6 27Revision 1.17 2002/12/10 17:44:57 morsch
28Correct mother child relation for pi0.
29
1e66857c 30Revision 1.16 2002/11/28 11:46:15 morsch
31Don't track pi0 if already decayed.
32
1ef5f15d 33Revision 1.15 2002/11/28 11:38:53 morsch
34Typo corrected.
35
7b33c00a 36Revision 1.14 2002/11/26 17:12:36 morsch
37Decay pi0 if requested.
38
2067f62c 39Revision 1.13 2002/10/14 14:55:35 hristov
40Merging the VirtualMC branch to the main development branch (HEAD)
41
b9d0a01d 42Revision 1.11.4.1 2002/07/24 08:56:28 alibrary
43Updating EVGEN on TVirtulaMC
44
45Revision 1.12 2002/06/19 06:56:34 hristov
46Memory leak corrected
47
aecf26a3 48Revision 1.11 2002/03/20 10:21:13 hristov
49Set fPtMax to 15 GeV in order to avoid some numerical problems
50
6b236b6f 51Revision 1.10 2001/10/15 16:44:46 morsch
52- Possibility for vertex distribution truncation.
53- Write mc header with vertex position.
54
971816d4 55Revision 1.9 2001/07/27 17:09:36 morsch
56Use local SetTrack, KeepTrack and SetHighWaterMark methods
57to delegate either to local stack or to stack owned by AliRun.
58(Piotr Skowronski, A.M.)
59
a99cf51f 60Revision 1.8 2001/07/20 11:03:58 morsch
61Issue warning message if used outside allowed eta range (-8 to 8).
62
5b0e4c0f 63Revision 1.7 2001/07/17 12:41:01 morsch
64- Calculation of fraction of event corresponding to selected pt-range corrected
65(R. Turrisi)
66- Parent weight corrected.
67
f25521b2 68Revision 1.6 2001/05/16 14:57:10 alibrary
69New files for folders and Stack
70
9e1a0ddb 71Revision 1.5 2000/12/21 16:24:06 morsch
72Coding convention clean-up
73
675e9664 74Revision 1.4 2000/11/30 07:12:50 alibrary
75Introducing new Rndm and QA classes
76
65fb704d 77Revision 1.3 2000/10/02 21:28:06 fca
78Removal of useless dependecies via forward declarations
79
94de3818 80Revision 1.2 2000/07/11 18:24:55 fca
81Coding convention corrections + few minor bug fixes
82
aee8290b 83Revision 1.1 2000/06/09 20:20:30 morsch
84Same class as previously in AliSimpleGen.cxx
85All coding rule violations except RS3 corrected (AM)
86
790bbabf 87*/
675e9664 88
89// Parameterisation of pi and K, eta and pt distributions
90// used for the ALICE TDRs.
91// eta: according to HIJING (shadowing + quenching)
92// pT : according to CDF measurement at 1.8 TeV
93// Author: andreas.morsch@cern.ch
94
95
790bbabf 96//Begin_Html
97/*
98<img src="picts/AliGeneratorClass.gif">
99</pre>
100<br clear=left>
101<font size=+2 color=red>
102<p>The responsible person for this module is
103<a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
104</font>
105<pre>
106*/
107//End_Html
108// //
109///////////////////////////////////////////////////////////////////
110
971816d4 111#include <TArrayF.h>
2067f62c 112#include <TClonesArray.h>
116cbefd 113#include <TDatabasePDG.h>
114#include <TF1.h>
2067f62c 115#include <TParticle.h>
116cbefd 116#include <TPDGCode.h>
117
118#include "AliConst.h"
119#include "AliDecayer.h"
116cbefd 120#include "AliGenEventHeader.h"
121#include "AliGenHIJINGpara.h"
122#include "AliRun.h"
971816d4 123
790bbabf 124ClassImp(AliGenHIJINGpara)
125
126AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
127{
128// copy constructor
129}
130
131//_____________________________________________________________________________
132static Double_t ptpi(Double_t *px, Double_t *)
133{
134 //
135 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
136 // POWER LAW FOR PT > 500 MEV
137 // MT SCALING BELOW (T=160 MEV)
138 //
139 const Double_t kp0 = 1.3;
140 const Double_t kxn = 8.28;
141 const Double_t kxlim=0.5;
142 const Double_t kt=0.160;
143 const Double_t kxmpi=0.139;
144 const Double_t kb=1.;
145 Double_t y, y1, xmpi2, ynorm, a;
146 Double_t x=*px;
147 //
148 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
149 xmpi2=kxmpi*kxmpi;
150 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
151 a=ynorm/y1;
152 if (x > kxlim)
153 y=a*TMath::Power(kp0/(kp0+x),kxn);
154 else
155 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
156 return y*x;
157}
158
159//_____________________________________________________________________________
160static Double_t ptscal(Double_t pt, Int_t np)
161{
162 // SCALING EN MASSE PAR RAPPORT A PTPI
163 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
164 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
165 // VALUE MESON/PI AT 5 GEV
166 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
167 np--;
168 Double_t f5=TMath::Power(((
169 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
170 Double_t fmax2=f5/kfmax[np];
171 // PIONS
172 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
173 Double_t fmtscal=TMath::Power(((
174 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
175 fmax2;
176 return fmtscal*ptpion;
177}
178
179//_____________________________________________________________________________
180static Double_t ptka( Double_t *px, Double_t *)
181{
182 //
183 // pt parametrisation for k
184 //
185 return ptscal(*px,2);
186}
187
188
189//_____________________________________________________________________________
190static Double_t etapic( Double_t *py, Double_t *)
191{
192 //
193 // eta parametrisation for pi
194 //
195 const Double_t ka1 = 4913.;
196 const Double_t ka2 = 1819.;
197 const Double_t keta1 = 0.22;
198 const Double_t keta2 = 3.66;
199 const Double_t kdeta1 = 1.47;
200 const Double_t kdeta2 = 1.51;
201 Double_t y=TMath::Abs(*py);
202 //
203 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
204 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
205 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
206}
207
208//_____________________________________________________________________________
209static Double_t etakac( Double_t *py, Double_t *)
210{
211 //
212 // eta parametrisation for ka
213 //
214 const Double_t ka1 = 497.6;
215 const Double_t ka2 = 215.6;
216 const Double_t keta1 = 0.79;
217 const Double_t keta2 = 4.09;
218 const Double_t kdeta1 = 1.54;
219 const Double_t kdeta2 = 1.40;
220 Double_t y=TMath::Abs(*py);
221 //
222 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
223 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
224 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
225}
226
227//_____________________________________________________________________________
228AliGenHIJINGpara::AliGenHIJINGpara()
229 :AliGenerator()
230{
231 //
232 // Default constructor
233 //
1e66857c 234 fPtpi = 0;
235 fPtka = 0;
236 fETApic = 0;
237 fETAkac = 0;
238 fDecayer = 0;
239 fNt = -1;
971816d4 240 SetCutVertexZ();
6b236b6f 241 SetPtRange();
2067f62c 242 SetPi0Decays();
790bbabf 243}
244
245//_____________________________________________________________________________
246AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
247 :AliGenerator(npart)
248{
249 //
250 // Standard constructor
251 //
edbba5db 252 fName="HIJINGpara";
790bbabf 253 fTitle="HIJING Parametrisation Particle Generator";
1e66857c 254 fPtpi = 0;
255 fPtka = 0;
256 fETApic = 0;
257 fETAkac = 0;
258 fDecayer = 0;
259 fNt = -1;
971816d4 260 SetCutVertexZ();
6b236b6f 261 SetPtRange();
2067f62c 262 SetPi0Decays();
790bbabf 263}
264
265//_____________________________________________________________________________
266AliGenHIJINGpara::~AliGenHIJINGpara()
267{
268 //
269 // Standard destructor
270 //
271 delete fPtpi;
272 delete fPtka;
273 delete fETApic;
274 delete fETAkac;
275}
276
277//_____________________________________________________________________________
278void AliGenHIJINGpara::Init()
279{
280 //
281 // Initialise the HIJING parametrisation
282 //
283 Float_t etaMin =-TMath::Log(TMath::Tan(
284 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
285 Float_t etaMax = -TMath::Log(TMath::Tan(
286 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
f25521b2 287 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
288 fPtka = new TF1("ptka",&ptka,0,20,0);
790bbabf 289 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
290 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
f25521b2 291
aecf26a3 292 TF1 etaPic0("etapic",&etapic,-7,7,0);
293 TF1 etaKac0("etakac",&etakac,-7,7,0);
f25521b2 294
aecf26a3 295 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
296 TF1 ptKac0("ptka",&ptka,0.,15.,0);
f25521b2 297
aecf26a3 298 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
299 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
f25521b2 300 Float_t scalePi = 7316/(intETApi/1.5);
301 Float_t scaleKa = 684/(intETAka/2.0);
302
303// Fraction of events corresponding to the selected pt-range
aecf26a3 304 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
305 0.123*ptKac0.Integral(0, 15));
306 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
307 0.123*ptKac0.Integral(fPtMin, fPtMax));
f25521b2 308 Float_t ptFrac = intPtSel/intPt;
309
310// Fraction of events corresponding to the selected eta-range
aecf26a3 311 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
312 scaleKa*etaKac0.Integral(etaMin, etaMax));
f25521b2 313// Fraction of events corresponding to the selected phi-range
314 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
315
316 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
790bbabf 317
9e1a0ddb 318 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
319 ClassName(),100.*fParentWeight);
5b0e4c0f 320
321// Issue warning message if etaMin or etaMax are outside the alowed range
322// of the parametrization
323 if (etaMin < -8.001 || etaMax > 8.001) {
324 printf("\n \n WARNING FROM AliGenHIJINGPara !");
325 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
326 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
327 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
328 }
2067f62c 329//
330//
2904363f 331 if (fPi0Decays && gMC)
332 fDecayer = gMC->GetDecayer();
790bbabf 333}
334
2067f62c 335
790bbabf 336//_____________________________________________________________________________
337void AliGenHIJINGpara::Generate()
338{
339 //
340 // Generate one trigger
341 //
342
343
344 const Float_t kRaKpic=0.14;
345 const Float_t kBorne=1/(1+kRaKpic);
346 Float_t polar[3]= {0,0,0};
347 //
348 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
349 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
350 //
351 Float_t origin[3];
352 Float_t pt, pl, ptot;
353 Float_t phi, theta;
354 Float_t p[3];
1e66857c 355 Int_t i, part, j;
790bbabf 356 //
357 TF1 *ptf;
358 TF1 *etaf;
359 //
360 Float_t random[6];
361 //
362 for (j=0;j<3;j++) origin[j]=fOrigin[j];
971816d4 363
364 if(fVertexSmear == kPerEvent) {
365 Float_t dv[3];
366 dv[2] = 1.e10;
367 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
368 Rndm(random,6);
369 for (j=0; j < 3; j++) {
370 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
371 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
372 }
790bbabf 373 }
971816d4 374 for (j=0; j < 3; j++) origin[j] += dv[j];
375 } // if kPerEvent
376 TArrayF eventVertex;
377 eventVertex.Set(3);
378 eventVertex[0] = origin[0];
379 eventVertex[1] = origin[1];
380 eventVertex[2] = origin[2];
381
790bbabf 382 for(i=0;i<fNpart;i++) {
383 while(1) {
65fb704d 384 Rndm(random,3);
790bbabf 385 if(random[0]<kBorne) {
386 part=kPions[Int_t (random[1]*3)];
387 ptf=fPtpi;
2067f62c 388 etaf=fETApic;
790bbabf 389 } else {
390 part=kKaons[Int_t (random[1]*4)];
391 ptf=fPtka;
392 etaf=fETAkac;
393 }
394 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
395 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
396 if(theta<fThetaMin || theta>fThetaMax) continue;
397 pt=ptf->GetRandom();
398 pl=pt/TMath::Tan(theta);
399 ptot=TMath::Sqrt(pt*pt+pl*pl);
400 if(ptot<fPMin || ptot>fPMax) continue;
401 p[0]=pt*TMath::Cos(phi);
402 p[1]=pt*TMath::Sin(phi);
403 p[2]=pl;
aee8290b 404 if(fVertexSmear==kPerTrack) {
65fb704d 405 Rndm(random,6);
790bbabf 406 for (j=0;j<3;j++) {
407 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
408 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
409 }
410 }
1ef5f15d 411 if (part == kPi0 && fPi0Decays){
2067f62c 412//
413// Decay pi0 if requested
1e66857c 414 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
415 KeepTrack(fNt);
1ef5f15d 416 DecayPi0(origin, p);
417 } else {
1e66857c 418 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
419 KeepTrack(fNt);
1ef5f15d 420 }
421
790bbabf 422 break;
423 }
1e66857c 424 SetHighWaterMark(fNt);
790bbabf 425 }
1e66857c 426//
427
971816d4 428// Header
429 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
430// Event Vertex
431 header->SetPrimaryVertex(eventVertex);
432 gAlice->SetGenEventHeader(header);
790bbabf 433}
434
435AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
436{
437// Assignment operator
438 return *this;
439}
440
6b236b6f 441void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
2067f62c 442 AliGenerator::SetPtRange(ptmin, ptmax);
6b236b6f 443}
790bbabf 444
2067f62c 445void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
446{
447//
448// Decay the pi0
449// and put decay products on the stack
450//
451 static TClonesArray *particles;
452 if(!particles) particles = new TClonesArray("TParticle",1000);
453//
454 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
56fcdfe6 455 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
2067f62c 456//
457// Decay the pi0
458 TLorentzVector pmom(p[0], p[1], p[2], e);
459 fDecayer->Decay(kPi0, &pmom);
56fcdfe6 460
2067f62c 461//
462// Put decay particles on the stack
463//
2067f62c 464 Float_t polar[3] = {0., 0., 0.};
465 Int_t np = fDecayer->ImportParticles(particles);
1e66857c 466 Int_t nt;
2067f62c 467 for (Int_t i = 1; i < np; i++)
468 {
7b33c00a 469 TParticle* iParticle = (TParticle *) particles->At(i);
470 p[0] = iParticle->Px();
471 p[1] = iParticle->Py();
472 p[2] = iParticle->Pz();
2067f62c 473 Int_t part = iParticle->GetPdgCode();
1e66857c 474
475 SetTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);
476 KeepTrack(nt);
2067f62c 477 }
1e66857c 478 fNt = nt;
2067f62c 479}