1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
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12 * about the suitability of this software for any purpose. It is *
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14 **************************************************************************/
16 // $Id: AliCollider.cxx,v 1.12 2004/05/04 15:33:04 nick Exp $
18 ///////////////////////////////////////////////////////////////////////////
20 // Pythia based universal physics event generator.
21 // This class is derived from TPythia6 and has some extensions to
22 // support also generation of nucleus-nucleus interactions and to allow
23 // investigation of the effect of detector resolving power.
24 // Furthermore, the produced event information is provided in a format
25 // using the AliEvent structure.
26 // For the produced AliTrack objects, the particle ID code is set to the
27 // Pythia KF value, which is compatible with the PDG identifier.
28 // This will allow a direct analysis of the produced data using the
29 // Ralice physics analysis tools.
31 // For further details concerning the produced output structure,
32 // see the docs of the memberfunctions SetVertexMode and SetResolution.
34 // Example job of minimum biased Pb+Pb interactions :
35 // --------------------------------------------------
37 // gSystem->Load("libEG");
38 // gSystem->Load("libEGPythia6");
39 // gSystem->Load("ralice");
41 // AliCollider* gen=new AliCollider();
43 // gen->SetOutputFile("test.root");
44 // gen->SetVertexMode(3);
45 // gen->SetResolution(1e-4); // 1 micron vertex resolution
47 // gen->SetRunNumber(1);
54 // gen->Init("fixt",zp,ap,zt,at,158);
56 // gen->SetTitle("SPS Pb-Pb collision at 158A GeV/c beam energy");
61 // Float_t* rans=new Float_t[nevents];
62 // rndm.Uniform(rans,nevents,2,ap+at);
64 // for (Int_t i=0; i<nevents; i++)
67 // gen->MakeEvent(npart);
69 // AliEvent* evt=gen->GetEvent();
78 // Example job of a cosmic nu+p atmospheric interaction.
79 // -----------------------------------------------------
81 // gSystem->Load("libEG");
82 // gSystem->Load("libEGPythia6");
83 // gSystem->Load("ralice");
85 // AliCollider* gen=new AliCollider();
87 // gen->SetOutputFile("test.root");
89 // gen->SetRunNumber(1);
91 // gen->Init("fixt","nu_mu","p",1e11);
93 // gen->SetTitle("Atmospheric nu_mu-p interaction at 1e20 eV");
97 // for (Int_t i=0; i<nevents; i++)
99 // gen->MakeEvent(0,1);
101 // AliEvent* evt=gen->GetEvent();
110 //--- Author: Nick van Eijndhoven 22-nov-2002 Utrecht University
111 //- Modified: NvE $Date: 2004/05/04 15:33:04 $ Utrecht University
112 ///////////////////////////////////////////////////////////////////////////
114 #include "AliCollider.h"
115 #include "Riostream.h"
117 ClassImp(AliCollider) // Class implementation to enable ROOT I/O
119 AliCollider::AliCollider() : TPythia6()
121 // Default constructor.
122 // All variables initialised to default values.
124 // Some Pythia default MC parameters are automatically modified to provide
125 // more suitable running conditions for soft processes in view of
126 // nucleus-nucleus interactions and astrophysical processes.
127 // The user may initialise the generator with all the default Pythia
128 // parameters and obtain full user control to modify the settings by means
129 // of the SetUserControl memberfunction.
131 // Refer to the SetElastic memberfunction for the inclusion of elastic
132 // and diffractive processes.
133 // By default these processes are not included.
135 fVertexmode=0; // No vertex structure creation
136 fResolution=1e-5; // Standard resolution is 0.1 micron
140 fUserctrl=0; // Automatic optimisation of some MC parameters
141 fElastic=0; // No elastic and diffractive processes
170 ///////////////////////////////////////////////////////////////////////////
171 AliCollider::~AliCollider()
173 // Default destructor
195 ///////////////////////////////////////////////////////////////////////////
196 void AliCollider::SetOutputFile(TString s)
198 // Create the output file containing all the data in ROOT output format.
204 fOutFile=new TFile(s.Data(),"RECREATE","AliCollider data");
211 fOutTree=new TTree("T","AliCollider event data");
215 fOutTree->Branch("Events","AliEvent",&fEvent,bsize,split);
217 ///////////////////////////////////////////////////////////////////////////
218 void AliCollider::SetVertexMode(Int_t mode)
220 // Set the mode of the vertex structure creation.
222 // By default all generated tracks will only appear in the AliEvent
223 // structure without any primary (and secondary) vertex structure.
224 // The user can build the vertex structure if he/she wants by means
225 // of the beginpoint location of each AliTrack.
227 // However, one can also let AliCollider automatically create
228 // the primary (and secondary) vertex structure(s).
229 // In this case the primary vertex is given Id=1 and all sec. vertices
230 // are given Id's 2,3,4,....
231 // All vertices are created as standalone entities in the AliEvent structure
232 // without any linking between the various vertices.
233 // For this automated process, the user-selected resolution
234 // (see SetResolution) is used to decide whether or not certain vertex
235 // locations can be resolved.
236 // In case no vertex creation is selected (i.e. the default mode=0),
237 // the value of the resolution is totally irrelevant.
239 // The user can also let AliCollider automatically connect the sec. vertices
240 // to the primary vertex (i.e. mode=3). This process will also automatically
241 // generate the tracks connecting the vertices.
242 // Note that the result of the mode=3 operation may be very sensitive to
243 // the resolution parameter. Therefore, no attempt is made to distinguish
244 // between secondary, tertiary etc... vertices. All sec. vertices are
245 // linked to the primary one.
247 // Irrespective of the selected mode, all generated tracks can be obtained
248 // directly from the AliEvent structure.
249 // In case (sec.) vertex creation is selected, all generated vertices can
250 // also be obtained directly from the AliEvent structure.
251 // These (sec.) vertices contain only the corresponding pointers to the various
252 // tracks which are stored in the AliEvent structure.
254 // Overview of vertex creation modes :
255 // -----------------------------------
256 // mode = 0 ==> No vertex structure will be created
257 // 1 ==> Only primary vertex structure will be created
258 // 2 ==> Unconnected primary and secondary vertices will be created
259 // 3 ==> Primary and secondary vertices will be created where all the
260 // sec. vertices will be connected to the primary vertex.
261 // Also the vertex connecting tracks will be automatically
264 if (mode<0 || mode >3)
266 cout << " *AliCollider::SetVertexMode* Invalid argument mode : " << mode << endl;
274 ///////////////////////////////////////////////////////////////////////////
275 Int_t AliCollider::GetVertexMode() const
277 // Provide the current mode for vertex structure creation.
280 ///////////////////////////////////////////////////////////////////////////
281 void AliCollider::SetResolution(Double_t res)
283 // Set the resolution (in cm) for resolving (sec.) vertices.
284 // By default this resolution is set to 0.1 micron.
285 // Note : In case no vertex creation has been selected, the value of
286 // the resolution is totally irrelevant.
287 fResolution=fabs(res);
289 ///////////////////////////////////////////////////////////////////////////
290 Double_t AliCollider::GetResolution() const
292 // Provide the current resolution (in cm) for resolving (sec.) vertices.
295 ///////////////////////////////////////////////////////////////////////////
296 void AliCollider::SetRunNumber(Int_t run)
298 // Set the user defined run number.
299 // By default the run number is set to 0.
302 ///////////////////////////////////////////////////////////////////////////
303 Int_t AliCollider::GetRunNumber() const
305 // Provide the user defined run number.
308 ///////////////////////////////////////////////////////////////////////////
309 void AliCollider::SetPrintFreq(Int_t n)
311 // Set the print frequency for every 'n' events.
312 // By default the printfrequency is set to 1 (i.e. every event).
315 ///////////////////////////////////////////////////////////////////////////
316 Int_t AliCollider::GetPrintFreq() const
318 // Provide the user selected print frequency.
321 ///////////////////////////////////////////////////////////////////////////
322 void AliCollider::SetUserControl(Int_t flag)
324 // Set the user control flag w.r.t. disabling automatic optimisation
325 // of some Pythia default MC parameters for soft interactions in view of
326 // nucleus-nucleus collisions and astrophysical processes.
327 // Flag = 0 : Limited user control (automatic optimisation enabled)
328 // 1 : Full user control (automatic optimisation disabled)
329 // By default the user control is set to 0 (i.e. automatic optimisation).
330 // See the Init() memberfunctions for further details w.r.t. the optimisations.
333 ///////////////////////////////////////////////////////////////////////////
334 Int_t AliCollider::GetUserControl() const
336 // Provide the value of the user control flag.
339 ///////////////////////////////////////////////////////////////////////////
340 void AliCollider::SetElastic(Int_t flag)
342 // Set the flag w.r.t. inclusion of elastic and diffractive processes.
343 // By default these processes are not included.
344 // Flag = 0 : Do not include elastic and diffractive processes
345 // 1 : Elastic and diffractive processes will be included
348 ///////////////////////////////////////////////////////////////////////////
349 Int_t AliCollider::GetElastic() const
351 // Provide the value of the control flag for elastic and diffractive processes.
354 ///////////////////////////////////////////////////////////////////////////
355 void AliCollider::Init(char* frame,char* beam,char* target,Float_t win)
357 // Initialisation of the underlying Pythia generator package.
358 // The event number is reset to 0.
359 // This routine just invokes TPythia6::Initialize(...) and the arguments
360 // have the corresponding meaning.
361 // Some Pythia default MC parameters are automatically modified to provide
362 // more suitable running conditions for soft processes in view of
363 // astrophysical processes.
364 // The optimisations consist of :
365 // * Usage of real photons for photon beams of targets
366 // * Minimum CMS energy of 3 GeV for the event
367 // * Activation of the default K factor values
368 // with separate settings for ordinary and color annihilation graphs.
369 // The user may initialise the generator with all the default Pythia
370 // parameters and obtain full user control to modify the settings by means
371 // of invoking the SetUserControl memberfunction before this initialisation.
372 // Note that the inclusion of elastic and diffractive processes is controlled
373 // by invokation of the SetElastic memberfunction before this initialisation,
374 // irrespective of the UserControl selection.
376 if (!fUserctrl) // Optimisation of some MC parameters
378 SetMSTP(14,10); // Real photons for photon beams or targets
379 SetPARP(2,3.); // Minimum CMS energy for the event
380 SetMSTP(33,2); // Activate K factor. Separate for ordinary and color annih. graphs
383 if (fElastic) SetMSEL(2); // Include low-Pt, elastic and diffractive events
389 Initialize(frame,beam,target,win);
392 cout << " *AliCollider::Init* Standard Pythia initialisation." << endl;
393 cout << " Beam particle : " << beam << " Target particle : " << target
394 << " Frame = " << frame << " Energy = " << win
397 ///////////////////////////////////////////////////////////////////////////
398 void AliCollider::Init(char* frame,Int_t zp,Int_t ap,Int_t zt,Int_t at,Float_t win)
400 // Initialisation of the underlying Pythia generator package for the generation
401 // of nucleus-nucleus interactions.
402 // The event number is reset to 0.
403 // In addition to the Pythia standard arguments 'frame' and 'win', the user
404 // can specify here (Z,A) values of the projectile and target nuclei.
406 // Note : The 'win' value denotes either the cms energy per nucleon-nucleon collision
407 // (i.e. frame="cms") or the momentum per nucleon in all other cases.
409 // Some Pythia default MC parameters are automatically modified to provide
410 // more suitable running conditions for soft processes in view of
411 // nucleus-nucleus interactions and astrophysical processes.
412 // The optimisations consist of :
413 // * Minimum CMS energy of 3 GeV for the event
414 // * Activation of the default K factor values
415 // with separate settings for ordinary and color annihilation graphs.
416 // The user may initialise the generator with all the default Pythia
417 // parameters and obtain full user control to modify the settings by means
418 // of invoking the SetUserControl memberfunction before this initialisation.
419 // Note that the inclusion of elastic and diffractive processes is controlled
420 // by invokation of the SetElastic memberfunction before this initialisation,
421 // irrespective of the UserControl selection.
423 if (!fUserctrl) // Optimisation of some MC parameters
425 SetPARP(2,3.); // Minimum CMS energy for the event
426 SetMSTP(33,2); // Activate K factor. Separate for ordinary and color annih. graphs
429 if (fElastic) SetMSEL(2); // Include low-Pt, elastic and diffractive events
444 if (ap<1 || at<1 || zp>ap || zt>at)
447 cout << " *AliCollider::Init* Invalid input value(s). Zproj = " << zp
448 << " Aproj = " << ap << " Ztarg = " << zt << " Atarg = " << at << endl;
458 cout << " *AliCollider::Init* Nucleus-Nucleus generator initialisation." << endl;
459 cout << " Zproj = " << zp << " Aproj = " << ap << " Ztarg = " << zt << " Atarg = " << at
460 << " Frame = " << frame << " Energy = " << win
463 ///////////////////////////////////////////////////////////////////////////
464 void AliCollider::GetFractions(Float_t zp,Float_t ap,Float_t zt,Float_t at)
466 // Determine the fractions for the various N-N collision processes.
467 // The various processes are : p+p, n+p, p+n and n+n.
478 fFracpp=(zp/ap)*(zt/at);
479 fFracnp=(1.-zp/ap)*(zt/at);
480 fFracpn=(zp/ap)*(1.-zt/at);
481 fFracnn=(1.-zp/ap)*(1.-zt/at);
484 ///////////////////////////////////////////////////////////////////////////
485 void AliCollider::MakeEvent(Int_t npt,Int_t mlist,Int_t medit)
487 // Generate one event.
488 // In case of a nucleus-nucleus interaction, the argument 'npt' denotes
489 // the number of participant nucleons.
490 // Normally also the spectator tracks will be stored into the event structure.
491 // The spectator tracks have a negative user Id to distinguish them from the
492 // ordinary generated tracks.
493 // In case the user has selected the creation of vertex structures, the spectator
494 // tracks will be linked to the primary vertex.
495 // However, specification of npt<0 will suppress the storage of spectator tracks.
496 // In the latter case abs(npt) will be taken as the number of participants.
497 // In case of a standard Pythia run for 'elementary' particle interactions,
498 // the value of npt is totally irrelevant.
500 // The argument 'mlist' denotes the list mode used for Pylist().
501 // Note : mlist<0 suppresses the invokation of Pylist().
502 // By default, no listing is produced (i.e. mlist=-1).
504 // The argument 'medit' denotes the edit mode used for Pyedit().
505 // Note : medit<0 suppresses the invokation of Pyedit().
506 // By default, only 'stable' final particles are kept (i.e. medit=1).
508 // In the case of a standard Pythia run concerning 'elementary' particle
509 // interactions, the projectile and target particle ID's for the created
510 // event structure are set to the corresponding Pythia KF codes.
511 // All the A and Z values are in that case set to zero.
512 // In case of a nucleus-nucleus interaction, the proper A and Z values for
513 // the projectile and target particles are set in the event structure.
514 // However, in this case both particle ID's are set to zero.
516 // Note : Only in case an event passed the selection criteria as specified
517 // via SelectEvent(), the event will appear on the output file.
528 // Counters for the various (proj,targ) combinations : p+p, n+p, p+n and n+n
529 Int_t ncols[4]={0,0,0,0};
539 if (npt<1 || npt>(fAproj+fAtarg))
541 cout << " *AliCollider::MakeEvent* Invalid input value. npt = " << npt
542 << " Aproj = " << fAproj << " Atarg = " << fAtarg << endl;
546 // Determine the number of nucleon-nucleon collisions
548 if (npt%2 && fRan.Uniform()>0.5) ncol+=1;
550 // Determine the number of the various types of N+N interactions
555 Int_t maxa=2; // Indicator whether proj (1) or target (2) has maximal A left
557 Float_t* rans=new Float_t[ncol];
558 fRan.Uniform(rans,ncol);
560 for (Int_t i=0; i<ncol; i++)
562 GetFractions(zp,ap,zt,at);
564 if (rndm<=fFracpp) // p+p interaction
578 if (rndm>fFracpp && rndm<=(fFracpp+fFracnp)) // n+p interaction
591 if (rndm>(fFracpp+fFracnp) && rndm<=(fFracpp+fFracnp+fFracpn)) // p+n interaction
604 if (rndm>(fFracpp+fFracnp+fFracpn)) // n+n interaction
620 if (!(fEventnum%fPrintfreq))
622 cout << " *AliCollider::MakeEvent* Run : " << fRunnum << " Event : " << fEventnum
626 cout << " npart = " << npt << " ncol = " << ncol
627 << " ncolpp = " << ncols[0] << " ncolnp = " << ncols[1]
628 << " ncolpn = " << ncols[2] << " ncolnn = " << ncols[3] << endl;
634 fEvent=new AliEvent();
636 fEvent->SetName(GetName());
637 fEvent->SetTitle(GetTitle());
641 fEvent->SetRunNumber(fRunnum);
642 fEvent->SetEventNumber(fEventnum);
649 Ali3Vector pproj,ptarg;
653 // Make sure the primary vertex gets correct location and Id=1
657 r.SetPosition(v,"car");
661 r.SetPositionErrors(v,"car");
664 vert.SetTrackCopy(0);
665 vert.SetVertexCopy(0);
667 fEvent->AddVertex(vert,0);
671 Float_t charge=0,mass=0;
676 // Singular settings for a normal Pythia elementary particle interation
683 // Generate all the various collisions
684 fSelect=0; // Flag to indicate whether the total event is selected or not
685 Int_t select=0; // Flag to indicate whether the sub-event is selected or not
686 Int_t first=1; // Flag to indicate the first collision process
690 for (Int_t itype=0; itype<ntypes; itype++)
694 if (itype==0 && ncols[itype]) Initialize(fFrame,"p","p",fWin);
695 if (itype==1 && ncols[itype]) Initialize(fFrame,"n","p",fWin);
696 if (itype==2 && ncols[itype]) Initialize(fFrame,"p","n",fWin);
697 if (itype==3 && ncols[itype]) Initialize(fFrame,"n","n",fWin);
699 for (Int_t jcol=0; jcol<ncols[itype]; jcol++)
704 if (select) fSelect=1;
706 if (first) // Store projectile and target information in the event structure
713 pproj.SetVector(v,"car");
714 pnucl=pproj.GetNorm();
715 fEvent->SetProjectile(fAproj,fZproj,pnucl);
719 ptarg.SetVector(v,"car");
720 pnucl=ptarg.GetNorm();
721 fEvent->SetTarget(fAtarg,fZtarg,pnucl);
728 pnucl=sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);
730 fEvent->SetProjectile(0,0,pnucl,kf);
734 pnucl=sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);
736 fEvent->SetTarget(0,0,pnucl,kf);
741 if (medit >= 0) Pyedit(medit); // Define which particles are to be kept
743 if (mlist>=0 && select)
750 for (Int_t jpart=1; jpart<=npart; jpart++)
753 charge=Pychge(kf)/3.;
757 // 3-momentum in GeV/c
761 p.SetVector(v,"car");
763 // Production location in cm.
764 v[0]=GetV(jpart,1)/10;
765 v[1]=GetV(jpart,2)/10;
766 v[2]=GetV(jpart,3)/10;
767 r.SetPosition(v,"car");
773 t.SetParticleCode(kf);
774 t.SetName(name.Data());
782 // Build the vertex structures if requested
785 // Check if track belongs within the resolution to an existing vertex
787 for (Int_t jv=1; jv<=fEvent->GetNvertices(); jv++)
789 AliVertex* vx=fEvent->GetVertex(jv);
792 rx=vx->GetPosition();
793 dist=rx.GetDistance(r);
794 if (dist < fResolution)
796 AliTrack* tx=fEvent->GetIdTrack(ntk);
804 if (add) break; // No need to look further for vertex candidates
807 // If track was not close enough to an existing vertex
808 // a new secondary vertex is created
809 if (!add && fVertexmode>1)
811 AliTrack* tx=fEvent->GetIdTrack(ntk);
817 r.SetPositionErrors(v,"car");
819 vert.SetTrackCopy(0);
820 vert.SetVertexCopy(0);
821 vert.SetId((fEvent->GetNvertices())+1);
824 fEvent->AddVertex(vert,0);
828 } // End of loop over the produced particles for each collision
829 } // End of loop over number of collisions for each type
830 } // End of loop over collision types
832 // Link sec. vertices to primary if requested
833 // Note that also the connecting tracks are automatically created
836 AliVertex* vp=fEvent->GetIdVertex(1); // Primary vertex
839 for (Int_t i=2; i<=fEvent->GetNvertices(); i++)
841 AliVertex* vx=fEvent->GetVertex(i);
844 if (vx->GetId() != 1) vp->AddVertex(vx);
850 // Include the spectator tracks in the event structure.
851 if (fNucl && specmode)
856 r.SetPosition(v,"car");
858 zp=fZproj-(ncols[0]+ncols[2]);
860 ap=fAproj-(ncols[0]+ncols[1]+ncols[2]+ncols[3]);
862 zt=fZtarg-(ncols[0]+ncols[1]);
864 at=fAtarg-(ncols[0]+ncols[1]+ncols[2]+ncols[3]);
869 if (pproj.GetNorm() > fSpecpmin)
871 kf=2212; // Projectile spectator protons
872 charge=Pychge(kf)/3.;
873 mass=GetPMAS(Pycomp(kf),1);
875 for (Int_t iprojp=1; iprojp<=zp; iprojp++)
880 t.SetParticleCode(kf);
881 t.SetName(name.Data());
882 t.SetTitle("Projectile spectator proton");
885 t.Set3Momentum(pproj);
891 kf=2112; // Projectile spectator neutrons
892 charge=Pychge(kf)/3.;
893 mass=GetPMAS(Pycomp(kf),1);
895 for (Int_t iprojn=1; iprojn<=(ap-zp); iprojn++)
900 t.SetParticleCode(kf);
901 t.SetName(name.Data());
902 t.SetTitle("Projectile spectator neutron");
905 t.Set3Momentum(pproj);
912 if (ptarg.GetNorm() > fSpecpmin)
914 kf=2212; // Target spectator protons
915 charge=Pychge(kf)/3.;
916 mass=GetPMAS(Pycomp(kf),1);
918 for (Int_t itargp=1; itargp<=zt; itargp++)
923 t.SetParticleCode(kf);
924 t.SetName(name.Data());
925 t.SetTitle("Target spectator proton");
928 t.Set3Momentum(ptarg);
934 kf=2112; // Target spectator neutrons
935 charge=Pychge(kf)/3.;
936 mass=GetPMAS(Pycomp(kf),1);
938 for (Int_t itargn=1; itargn<=(at-zt); itargn++)
943 t.SetParticleCode(kf);
944 t.SetName(name.Data());
945 t.SetTitle("Target spectator neutron");
948 t.Set3Momentum(ptarg);
955 // Link the spectator tracks to the primary vertex.
958 AliVertex* vp=fEvent->GetIdVertex(1);
961 for (Int_t ispec=1; ispec<=nspec; ispec++)
963 AliTrack* tx=fEvent->GetIdTrack(-ispec);
964 if (tx) vp->AddTrack(tx);
970 if (!(fEventnum%fPrintfreq) && (mlist || fEvent))
974 cout << " Number of tracks in the event structure : "
975 << fEvent->GetNtracks() << endl;
977 cout << endl; // Create empty output line after the event
980 if (fOutTree && fSelect) fOutTree->Fill();
982 ///////////////////////////////////////////////////////////////////////////
983 AliEvent* AliCollider::GetEvent(Int_t select) const
985 // Provide pointer to the generated event structure.
987 // select = 0 : Always return the pointer to the generated event.
988 // 1 : Only return the pointer to the generated event in case
989 // the event passed the selection criteria as specified via
990 // SelectEvent(). Otherwise the value 0 will be returned.
992 // By invoking GetEvent() the default of select=0 will be used.
994 if (!select || fSelect)
1003 ///////////////////////////////////////////////////////////////////////////
1004 void AliCollider::EndRun()
1006 // Properly close the output file (if needed).
1011 cout << " *AliCollider::EndRun* Output file correctly closed." << endl;
1014 ///////////////////////////////////////////////////////////////////////////
1015 void AliCollider::SetStable(Int_t id,Int_t mode)
1017 // Declare whether a particle must be regarded as stable or not.
1018 // The parameter "id" indicates the Pythia KF particle code, which
1019 // basically is the PDG particle identifier code.
1020 // The parameter "mode" indicates the action to be taken.
1022 // mode = 0 : Particle will be able to decay
1023 // 1 : Particle will be regarded as stable.
1025 // In case the user does NOT explicitly invoke this function, the standard
1026 // Pythia settings for the decay tables are used.
1028 // When this function is invoked without the "mode" argument, then the
1029 // default of mode=1 will be used for the specified particle.
1033 // 1) This function should be invoked after the initialisation call
1034 // to AliCollider::Init.
1035 // 2) Due to the internals of Pythia, there is no need to specify particles
1036 // and their corresponding anti-particles separately as (un)stable.
1037 // Once a particle has been declared (un)stable, the corresponding
1038 // anti-particle will be treated in the same way.
1040 if (mode==0 || mode==1)
1042 Int_t kc=Pycomp(id);
1046 SetMDCY(kc,1,decay);
1050 cout << " *AliCollider::SetStable* Unknown particle code. id = " << id << endl;
1055 cout << " *AliCollider::SetStable* Invalid parameter. mode = " << mode << endl;
1058 ///////////////////////////////////////////////////////////////////////////
1059 void AliCollider::SelectEvent(Int_t id)
1061 // Add a particle to the event selection list.
1062 // The parameter "id" indicates the Pythia KF particle code, which
1063 // basically is the PDG particle identifier code.
1064 // In case the user has built a selection list via this procedure, only the
1065 // events in which one of the particles specified in the list was generated
1067 // The investigation of the generated particles takes place when the complete
1068 // event is in memory, including all (shortlived) mother particles and resonances.
1069 // So, the settings of the various particle decay modes have no influence on
1070 // the event selection described here.
1072 // If no list has been specified, all events will be accepted.
1074 // Note : id=0 will delete the selection list.
1076 // Be aware of the fact that severe selection criteria (i.e. selecting only
1077 // rare events) may result in long runtimes before an event sample has been
1090 Int_t kc=Pycomp(id);
1093 fSelections=new TArrayI(1);
1094 fSelections->AddAt(kc,0);
1099 Int_t size=fSelections->GetSize();
1100 for (Int_t i=0; i<size; i++)
1102 if (kc==fSelections->At(i))
1111 fSelections->Set(size+1);
1112 fSelections->AddAt(kc,size);
1117 ///////////////////////////////////////////////////////////////////////////
1118 Int_t AliCollider::GetSelectionFlag() const
1120 // Return the value of the selection flag for the total event.
1121 // When the event passed the selection criteria as specified via
1122 // SelectEvent() the value 1 is returned, otherwise the value 0 is returned.
1125 ///////////////////////////////////////////////////////////////////////////
1126 Int_t AliCollider::IsSelected()
1128 // Check whether the generated (sub)event contains one of the particles
1129 // specified in the selection list via SelectEvent().
1130 // If this is the case or when no selection list is present, the value 1
1131 // will be returned, indicating the event is selected to be kept.
1132 // Otherwise the value 0 will be returned.
1134 if (!fSelections) return 1;
1136 Int_t nsel=fSelections->GetSize();
1141 for (Int_t jpart=1; jpart<=npart; jpart++)
1145 for (Int_t i=0; i<nsel; i++)
1147 if (kc==fSelections->At(i))
1157 ///////////////////////////////////////////////////////////////////////////
1158 void AliCollider::SetSpectatorPmin(Float_t pmin)
1160 // Set minimal momentum in GeV/c for spectator tracks to be stored.
1161 // Spectator tracks with a momentum below this threshold will not be stored
1162 // in the (output) event structure.
1163 // This facility allows to minimise the output file size.
1164 // Note that when the user wants to boost the event into another reference
1165 // frame these spectator tracks might have got momenta above the threshold.
1166 // However, when the spectator tracks were not stored in the event structure
1167 // in the original frame, there is no way to retreive them anymore.
1170 ///////////////////////////////////////////////////////////////////////////
1171 Float_t AliCollider::GetSpectatorPmin() const
1173 // Provide the minimal spectator momentum in GeV/c.
1176 ///////////////////////////////////////////////////////////////////////////
1177 TString AliCollider::GetPyname(Int_t kf)
1179 // Provide the correctly truncated Pythia particle name for PGD code kf
1181 // The TPythia6::Pyname returned name is copied into a TString and truncated
1182 // at the first blank to prevent funny trailing characters due to incorrect
1183 // stripping of empty characters in TPythia6::Pyname.
1184 // The truncation at the first blank is allowed due to the Pythia convention
1185 // that particle names never contain blanks.
1190 for (Int_t i=1; i<16; i++)
1192 if (name[i]==' ') break;
1193 sname=sname+name[i];
1197 ///////////////////////////////////////////////////////////////////////////