Moving to the new VMC naming convention
[u/mrichter/AliRoot.git] / TPHIC / AliGenTPHIC.cxx
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0b5dd071 1/**************************************************************************
2 * Copyright(c) 1998-2003, 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/* $Id$ */
18
0b5dd071 19// Event generator of two-photon processes
20// in ultra-peripheral ion collisions.
21// 5 two-photon process are implemented, see comments to SetProcess().
22//%
23// The example of the generator initialization for the process
24// gamma gamma -> X in CaCa collisions at 7000 TeV/nucleon is the following:
25//%
26// AliGenTPHIC *gener = new AliGenTPHIC();
27// gener->SetProcess(1);
28// gener->SetBeamEnergy(3500.);
29// gener->SetBeamZ(20);
30// gener->SetBeamA(40);
31// gener->SetMggRange(70.,200.);
32// gener->SetYggRange(-5.,5.);
33// gener->SetLumFunName("lum_ca_70_200.dat");
34// gener->SetLumFunFlag(-1);
35// gener->Init();
36//%
37// The two-photon luminosity function needed for the process cross section
38// calculation is time-consuming, therefore it can be calculated once for a
39// selected two-photon energy and rapidity range and selected ion species,
40// saved into a file and then can be reused in further calculation.
41//%
42// The integral cross section of the process is calculated in each event
43// by the Monte Carlo integration procedure, the differential cross section
44// of each thrown event is assigned as a weight to each track of the event
45// which can be then used during the event analysis by retreiving this weight
46// from any of the event tracks.
47//
48// The manual of the fortran generator is available in
49// $ALICE_ROOT/TPHIC/TPHIC_doc.ps.gz
50// For the two-photon physics in heavy ion collisions see
51// G.Baur et al, Phys.Rep. 364 (2002), 359.
52//%
53// Author: Yuri.Kharlov@cern.ch
54// 15 April 2003
55
56#include <TParticle.h>
57#include <TParticlePDG.h>
58#include <TDatabasePDG.h>
59#include "AliPythia.h"
60#include "AliRun.h"
61#include <AliGenTPHIC.h>
62#include <TPHICgen.h>
63#include <TPHICcommon.h>
64
65ClassImp(AliGenTPHIC)
66
67//------------------------------------------------------------
68
69AliGenTPHIC::AliGenTPHIC()
70{
71 // Constructor: create generator instance,
72 // create particle array
73 // Set TPHIC parameters to default values:
74 // eta_b production in Ca-Ca collisions at 7 A*TeV
75
76 SetMC(new TPHICgen());
77 fPythia = AliPythia::Instance();
78 fParticles = new TClonesArray("TParticle",100);
79
80 SetProcess ();
81 SetBeamEnergy();
82 SetBeamZ ();
83 SetBeamA ();
84 SetYggRange ();
85 SetMggRange ();
86 SetNgridY ();
87 SetNgridM ();
88 SetLumFunName();
89 SetLumFunFlag();
90 SetKfOnium ();
91}
92
93//____________________________________________________________
94AliGenTPHIC::AliGenTPHIC(const AliGenTPHIC & gen)
95{
96 // copy constructor
97 gen.Copy(*this);
98}
99
100//____________________________________________________________
101AliGenTPHIC::~AliGenTPHIC()
102{
103 // Destroys the object, deletes and disposes all TParticles currently on list.
104 if (fParticles) {
105 fParticles->Delete();
106 delete fParticles;
107 fParticles = 0;
108 }
109}
110
111//____________________________________________________________
112void AliGenTPHIC::Init()
113{
114 // Initialize the generator TPHIC
115
116 fTPHICgen->Initialize();
117 fEvent = 0;
118}
119
120//____________________________________________________________
121void AliGenTPHIC::Generate()
122{
123 // Generate one event of two-photon process.
124 // Gaussian smearing on the vertex is done if selected.
125 // All particles from the TPHIC/PYTHIA event listing
126 // are stored in TreeK, and only final-state particles are tracked.
127 // The event differectial cross section is assigned as a weight
128 // to each track of the event.
129
130 Float_t polar[3]= {0,0,0};
131 Float_t origin0[3],origin[3];
132 Float_t p[3], tof;
133 Double_t weight;
134
135 Int_t ks,kf,iparent,nt, trackIt;
136 Float_t random[6];
137 const Float_t kconv=0.001/2.999792458e8;
138
139 fTPHICgen->GenerateEvent();
140 weight = GetXSectionCurrent();
141 if (gAlice->GetEvNumber()>=fDebugEventFirst &&
142 gAlice->GetEvNumber()<=fDebugEventLast) fPythia->Pylist(1);
143 fPythia->ImportParticles(fParticles,"All");
144
145 if (fDebug == 1)
146 Info("Generate()","one event is produced");
147
148 Int_t j;
149 for (j=0;j<3;j++) origin[j]=fOrigin[j];
150 if(fVertexSmear==kPerEvent) {
151 Rndm(random,6);
152 for (j=0;j<3;j++) {
153 origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
154 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
155 }
156 }
157
158 Int_t ip;
159 Int_t np = fParticles->GetEntriesFast();
160 TParticle *iparticle;
161// Int_t* pParent = new Int_t[np];
162 for (ip=0; ip<np; ip++) {
163 iparticle = (TParticle *) fParticles->At(ip);
164 ks = iparticle->GetStatusCode();
165// // No initial state partons
166// if (ks==21) continue;
167 p[0] = iparticle->Px();
168 p[1] = iparticle->Py();
169 p[2] = iparticle->Pz();
170 origin[0] = origin0[0]+iparticle->Vx()/10.;
171 origin[1] = origin0[1]+iparticle->Vy()/10.;
172 origin[2] = origin0[2]+iparticle->Vz()/10.;
173 kf = CheckPDGCode(iparticle->GetPdgCode());
174 iparent = -1;
175 tof = kconv*iparticle->T();
176 if (ks == 1) trackIt = 1;
177 else trackIt = 0;
642f15cf 178 PushTrack(fTrackIt*trackIt,iparent,kf,p,origin,polar,tof,kPPrimary,nt,weight,ks);
0b5dd071 179 KeepTrack(nt);
180
181 if (fDebug == 2)
182 printf("id=%+4d, parent=%3d, ks=%d, p = (%+11.4e,%+11.4e,%+11.4e) GeV\n",
183 kf,iparent,fTrackIt*trackIt,p[0],p[1],p[2]);
184 }
185 fEvent++;
186 fTPHICgen->SetNEVENT(fEvent);
187 if (fDebug == 1 && fEvent%100 == 0) {
188 Info("Generate","Event %d\n",fEvent);
189 fTPHICgen->Finish();
190 }
191}
192
193//____________________________________________________________
194void AliGenTPHIC::SetEventListRange(Int_t eventFirst, Int_t eventLast)
195{
196 // Set a range of event numbers, for which a table
197 // of generated particle will be printed
198 fDebugEventFirst = eventFirst;
199 fDebugEventLast = eventLast;
200 if (fDebugEventLast==-1) fDebugEventLast=fDebugEventFirst;
201}
202
203//____________________________________________________________
204void AliGenTPHIC::SetProcess (Int_t proc )
205{
206 // Set process number:
207 // proc=1 - gamma gamma -> X
208 // proc=2 - gamma gamma -> quarkonium
209 // proc=3 - gamma gamma -> fermion+ fermion-
210 // proc=4 - gamma gamma -> W+ W-
211 // proc=5 - not implemented
212 // proc=6 - gamma gamma -> V1 V2 (vector meson pair)
213
214 fTPHICgen->SetIPROC(proc);
215}
216//____________________________________________________________
217 void AliGenTPHIC::SetBeamEnergy (Float_t energy)
218{
219 // Set energy of the beam ion per nucleon in GeV
220 fTPHICgen->SetEBMN(energy);
221}
222//____________________________________________________________
223 void AliGenTPHIC::SetBeamZ (Int_t z )
224{
225 // Set beam ion charge
226 fTPHICgen->SetIZ(z);
227}
228//____________________________________________________________
229 void AliGenTPHIC::SetBeamA (Int_t a )
230{
231 // Set beam ion atomic number
232 fTPHICgen->SetIA(a);
233}
234//____________________________________________________________
235 void AliGenTPHIC::SetYggRange (Float_t ymin, Float_t ymax)
236{
237 // Set rapidity range of 2-photon system for the
238 // luminosity function calculation
239 fTPHICgen->SetYMIN(ymin);
240 fTPHICgen->SetYMAX(ymax);
241}
242//____________________________________________________________
243 void AliGenTPHIC::SetMggRange (Float_t mmin, Float_t mmax)
244{
245 // Set invariant mass range of 2-photon system for the
246 // luminosity function calculation
247 fTPHICgen->SetAMIN(mmin);
248 fTPHICgen->SetAMAX(mmax);
249}
250//____________________________________________________________
251 void AliGenTPHIC::SetNgridY (Int_t ny )
252{
253 // Set number of nodes on the grid along the rapidity axis
254 // to calculate the 2-photon luminosity function
255 fTPHICgen->SetNY(ny);
256}
257//____________________________________________________________
258 void AliGenTPHIC::SetNgridM (Int_t nm )
259{
260 // Set number of nodes on the grid along the mass axis
261 // to calculate the 2-photon luminosity function
262 fTPHICgen->SetNMAS(nm);
263}
264//____________________________________________________________
265 void AliGenTPHIC::SetLumFunName (TString name )
266{
267 // Set filename to store the 2-photon luminosity
268 // function calculated on the grid
269 fTPHICgen->SetLUMFIL(name);
270}
271//____________________________________________________________
272 void AliGenTPHIC::SetLumFunFlag (Int_t flag )
273{
274 // Set flag to calculate the 2-photon luminosity function:
275 // flag=-1 if a new lumimosity function to be calculated
276 // and stored in a file
277 // flag=+1 if a previously calculated function to be read
278 // from a file
279 fTPHICgen->SetILUMF(flag);
280}
281//____________________________________________________________
282 void AliGenTPHIC::SetKfFermion (Int_t kf )
283{
284 // Set a PDG flavour code of a fermion for the process 3,
285 // gamma gamma -> fermion+ fermion-
286 fTPHICgen->SetKFERM(kf);
287}
288//____________________________________________________________
289 void AliGenTPHIC::SetKfOnium (Int_t kf )
290{
291 // Set a PDG flavour code of a quarkonium for the process 2,
292 // gamma gamma -> quarkonium
293 fTPHICgen->SetKFONIUM(kf);
294}
295//____________________________________________________________
296 void AliGenTPHIC::SetMassOnium (Float_t mass )
297{
298 // Set a quarkonium mass [GeV] for the process 2 if it
299 // differes from the Pythia's particle table.
300 // For the well-known quarkonia no need to set this mass
301 // because it will be taken from the Pythia table
302 fTPHICgen->SetXMRES(mass);
303}
304//____________________________________________________________
305 void AliGenTPHIC::SetGGwidthOnium(Float_t width )
306{
307 // Set 2-photon partial width [GeV] of the quarkonium for
308 // the process 2 if it differes fromthe Pythia's particle table.
309 // For the well-known quarkonia no need to set this width
310 // because it will be taken from the Pythia table
311 fTPHICgen->SetXGGRES(width);
312}
313//____________________________________________________________
314 void AliGenTPHIC::SetKfVmesons (Int_t kf1, Int_t kf2)
315{
316 // Set PDG flavour codes of the two vector vesons
317 // for the process 2: gamma gamma -> V1 V2
318 // So far this processes is implemented for the following
319 // mesons and their combinations only:
320 // pho0 (113), omega (223), phi (333), J/psi (443)
321 fTPHICgen->SetKV1(kf1);
322 fTPHICgen->SetKV2(kf2);
323}
324//____________________________________________________________
325 Float_t AliGenTPHIC::GetGGmass ()
326{
327 // Get invariant mass of generated 2-photon system
328 return fTPHICgen->GetWSQ();
329}
330//____________________________________________________________
331 Float_t AliGenTPHIC::GetGGrapidity()
332{
333 // Get rapidity of generated 2-photon system
334 return fTPHICgen->GetYGG();
335}
336//____________________________________________________________
337 Float_t AliGenTPHIC::GetG1mass ()
338{
339 // Get a mass of the first virtual photon of
340 // the 2-photon process (-sqrt(q1^2)).
341 return fTPHICgen->GetXMG1();
342}
343//____________________________________________________________
344 Float_t AliGenTPHIC::GetG2mass ()
345{
346 // Get a mass of the second virtual photon of
347 // the 2-photon process (-sqrt(q2^2)).
348 return fTPHICgen->GetXMG2();
349}
350//____________________________________________________________
351 TClonesArray* AliGenTPHIC::GetParticleList ()
352{
353 // Get array of particles of the event listing
354 return fParticles;
355}
356//____________________________________________________________
357 TLorentzVector AliGenTPHIC::MomentumRecNucl1()
358{
359 // Get 4-momentum of the first recoil nucleus after
360 // the 2-photon process.
361 return TLorentzVector(fTPHICgen->GetPTAG1(1),
362 fTPHICgen->GetPTAG1(2),
363 fTPHICgen->GetPTAG1(3),
364 fTPHICgen->GetPTAG1(4));
365}
366//____________________________________________________________
367 TLorentzVector AliGenTPHIC::MomentumRecNucl2()
368{
369 // Get 4-momentum of the first recoil nucleus after
370 // the 2-photon process.
371 return TLorentzVector(fTPHICgen->GetPTAG2(1),
372 fTPHICgen->GetPTAG2(2),
373 fTPHICgen->GetPTAG2(3),
374 fTPHICgen->GetPTAG2(4));
375}
376//____________________________________________________________
377 Float_t AliGenTPHIC::GetXSectionCurrent()
378{
379 // Get the cross section of the produced event for the
380 // Monte Carlo integral cross section calculation
381 return fTPHICgen->GetXSCUR();
382}
383//____________________________________________________________
384 Float_t AliGenTPHIC::GetXSection ()
385{
386 // Get the integral cross section of the process
387 // calculated so far
388 return fTPHICgen->GetXSTOT();
389}
390//____________________________________________________________
391 Float_t AliGenTPHIC::GetXSectionError ()
392{
393 // Get the error of the integral cross section of the process
394 // calculated so far
395 return fTPHICgen->GetXSTOTE();
396}