Missing protection in case no interactions are generated within the orbit. Thanks...
[u/mrichter/AliRoot.git] / EVGEN / AliGenPileup.cxx
CommitLineData
56f3f4a4 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// Class AliGenPileup
18// This is a generator of beam-beam pileup.
19// It generates interactions within 3 orbits (+-1) around
20// the trigger event. The trigger event itself is chosen
21// randomly among the bunch crossings within the central orbit.
22// The user can decide whenever to include in the simulation the
23// "trigger" interaction or not. This is handled by the
24// GenerateTrigInteraction(Bool_t flag) method.
25// In the case the trigger interaction is included, it is
26// generated using the same settings (vertex smear for example) as
27// the pileup events.
28// In case the trigger simulation is not included, the user can make
29// a cocktail of generator used to produce the trigger interaction and
30// AliGenPileup. In this case in order to avoid a fake increase of the rate around the
31// trigger, the number of background events within the bunch
32// crossing of the trigger is readuced by one.
33// The beam profile (the list of the active bunch crossings) can be
34// controlled via the SetBCMask(const char *mask) method. The syntax
35// follows the one in AliTriggerBCMask class. For example:
36// "3564H" would mean that all the bunch corssings within the orbit
37// are aloowed (which is of course unphysical). In case one wants to simulate
38// one-bunch-crossing-per-orbit scenario, the way to do it is to put something like:
39// "1H3563L" or similar.
40// The SetGenerator(AliGenerator *generator, Float_t rate) method is
41// used in order to define the generator to be used. The second argument is the pileup
42// rate in terms of #_of_interactions/bunch-crossing = sigma_tot * luminosity.
43// The pileup generation time window can be set via
44// AliGenerator::SetPileUpTimeWindow(Float_t pileUpTimeW) method. By the default the
45// window is set to 88micros (= TPC readout window).
46//
47// cvetan.cheshkov@cern.ch 9/12/2008
48//-------------------------------------------------------------------------
49
50#include <TParticle.h>
51
52#include "AliGenPileup.h"
53#include "AliLog.h"
54#include "AliGenCocktailEventHeader.h"
55#include "AliGenCocktailEntry.h"
56#include "AliRun.h"
57#include "AliStack.h"
58
59ClassImp(AliGenPileup)
60
61AliGenPileup::AliGenPileup():
62 AliGenCocktail(),
63 fBCMask("bcm","3564H"),
64 fGenTrig(kFALSE)
65{
66// Constructor
67// The pileup time window is by default
68// set to the TPC readout one
69 fName = "Pileup";
70 fTitle= "Beam-beam pileup";
71
72 fPileUpTimeWindow = 88e-6;
73}
74
75AliGenPileup::~AliGenPileup()
76{
77// Destructor
78}
79
80void AliGenPileup::SetGenerator(AliGenerator *generator, Float_t rate)
81{
82 // The method sets the geenrator to be used
83 // for pileup simulation.
84 // The second argument is the pileup rate in terms of
85 // #_of_interactions/bunch-crossing = sigma_tot * luminosity.
86 // There is a protection in case the generator was already set.
87 if (fEntries) {
88 if (FirstGenerator()) {
89 AliError("Pileup generator has been already set! Nothing done");
90 return;
91 }
92 }
93 AddGenerator(generator,"pileup generator",rate);
94}
95
96void AliGenPileup::AddGenerator(AliGenerator *Generator,
97 const char* Name,
98 Float_t RateExp )
99{
100 // The method used to add the pileup generator
101 // in the cocktail list.
102 // The method is protected in order to avoid
103 // its misusage
104 AliGenCocktail::AddGenerator(Generator,Name,RateExp);
105}
106
107Bool_t AliGenPileup::SetBCMask(const char *mask)
108{
109 // Set the active bunch-crossings that
110 // will be included in the pileup
111 // simulation. For more details on the
112 // syntax of the mask - see
113 // STEER/AliTriggerBCMask.* and the comments
114 // in the header of this file
115 return fBCMask.SetMask(mask);
116}
117
118void AliGenPileup::Generate()
119{
120 //
121 // Generate pileup event
122 // For details see the coments inline
123
124 // Check that the pileup generator is correctly set
125 AliGenCocktailEntry *entry = FirstGenerator();
126 if (!entry) {
127 AliFatal("No pileup generator entry is found!");
128 }
129
130 AliGenerator *gen = entry->Generator();
131 if (!gen) {
132 AliFatal("No pileup generator specified!");
133 }
134 else if (gen->NeedsCollisionGeometry()) {
135 AliFatal("No Collision Geometry Provided");
136 }
137
138 // Check that the pileup rate is correctly set
139 Float_t rate = entry->Rate();
140 if (rate <= 0) {
141 AliFatal(Form("Invalid rate value: %f",rate));
142 }
143
144 // Create cocktail header
145 if (fHeader) delete fHeader;
146 fHeader = new AliGenCocktailEventHeader("Pileup Cocktail Header");
147
148 // Generate time of all
149 // the collisions within one orbit
150 Int_t *nIntBC = new Int_t[3*AliTriggerBCMask::kNBits];
151 Int_t *indexBC = new Int_t[3*AliTriggerBCMask::kNBits];
152 Int_t nTotBC = 0;
660b9a45 153 while (nTotBC == 0) {
154 for(Int_t iBC = 0; iBC < AliTriggerBCMask::kNBits; iBC++) {
56f3f4a4 155
660b9a45 156 if (!fBCMask.GetMask(iBC)) continue;
56f3f4a4 157
660b9a45 158 Int_t nInteractions = gRandom->Poisson(rate);
159 if (nInteractions == 0) continue;
56f3f4a4 160
660b9a45 161 nIntBC[nTotBC] = nInteractions;
162 indexBC[nTotBC] = iBC;
163 nTotBC++;
164 }
56f3f4a4 165 }
166
167 // Select the bunch crossing for triggered event
168 Int_t iTrgBC = gRandom->Integer(nTotBC);
169 // Subtract one from the number of events
170 // generated within this bc (only in case
171 // the user disabled the generation of the trigger
172 // interaction)
aee85673 173 if (!fGenTrig) nIntBC[iTrgBC]--;
56f3f4a4 174
175 // Remove bunch crossings outside pileup
176 // time window
177 for(Int_t iBC = 0; iBC < nTotBC; iBC++) {
178 if (TMath::Abs(25e-9*(indexBC[iBC]-indexBC[iTrgBC])) > fPileUpTimeWindow)
179 nIntBC[iBC] = 0;
180 }
181
182 // Generate the two orbits around the central one
183 // taking into account the pileup time window
184 for(Int_t iBC = 0; iBC < AliTriggerBCMask::kNBits; iBC++) {
185
186 if (!fBCMask.GetMask(iBC)) continue;
187
188 if (TMath::Abs(25e-9*(iBC-AliTriggerBCMask::kNBits-indexBC[iTrgBC])) > fPileUpTimeWindow) continue;
189
190 Int_t nInteractions = gRandom->Poisson(rate);
191 if (nInteractions == 0) continue;
192
193 nIntBC[nTotBC] = nInteractions;
194 indexBC[nTotBC] = iBC-AliTriggerBCMask::kNBits;
195 nTotBC++;
196 }
197 for(Int_t iBC = 0; iBC < AliTriggerBCMask::kNBits; iBC++) {
198
199 if (!fBCMask.GetMask(iBC)) continue;
200
201 if (TMath::Abs(25e-9*(iBC+AliTriggerBCMask::kNBits-indexBC[iTrgBC])) > fPileUpTimeWindow) continue;
202
203 Int_t nInteractions = gRandom->Poisson(rate);
204 if (nInteractions == 0) continue;
205
206 nIntBC[nTotBC] = nInteractions;
207 indexBC[nTotBC] = iBC+AliTriggerBCMask::kNBits;
208 nTotBC++;
209 }
210
211 // Loop over the generated collision times, call the generator
212 // and correct the partcile times in the stack
33c3c91a 213 AliStack *stack = AliRunLoader::Instance()->Stack();
56f3f4a4 214 Int_t lastpart=0;
215 entry->SetFirst(lastpart);
216
217 for(Int_t iBC = 0; iBC < nTotBC; iBC++) {
218 Float_t deltat = 25e-9*(indexBC[iBC] - indexBC[iTrgBC]);
219 for (Int_t i = 0; i < nIntBC[iBC]; i++) {
220 // Generate the vertex position and time
221 Vertex();
222 TArrayF eventVertex(3);
223 for (Int_t j=0; j < 3; j++) eventVertex[j] = fVertex[j];
224 Double_t vTime = deltat + gRandom->Gaus(0,fOsigma[2]/TMath::Ccgs());
225
226 gen->SetVertex(fVertex.At(0), fVertex.At(1), fVertex.At(2));
227 gen->Generate();
228
229 for (Int_t k = lastpart; k < stack->GetNprimary(); k++) {
230 TLorentzVector v;
231 stack->Particle(k)->ProductionVertex(v);
232 v[3] = vTime;
233 stack->Particle(k)->SetProductionVertex(v);
234 }
235 lastpart = stack->GetNprimary();
236
237 // Store the interaction header in the container of the headers
238 ((AliGenEventHeader*) fHeader->GetHeaders()->Last())->SetPrimaryVertex(eventVertex);
239 }
240 }
241 delete [] nIntBC;
242 delete [] indexBC;
243
244 entry->SetLast(stack->GetNprimary());
245
246 fHeader->CalcNProduced();
247
248 if (fContainer) {
249 fContainer->AddHeader(fHeader);
250 } else {
251 gAlice->SetGenEventHeader(fHeader);
252 }
253
254}
255
256void AliGenPileup::SetRandomise(Bool_t /*flag*/)
257{
258 // This setting is not implemented in
259 // case of pileup generation
260 // So the method gives an warning and exits
261 AliWarning("This setting has no effect on the generator!");
262}
263
264void AliGenPileup::UsePerEventRates()
265{
266 // This setting is not implemented in
267 // case of pileup generation
268 // So the method gives an warning and exits
269 AliWarning("This setting has no effect on the generator!");
270}