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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 | /* $Id$ */ | |
17 | ||
18 | ||
19 | ||
20 | //------------------------------------------------------------- | |
21 | // Generate Beam-Gas-Events | |
22 | // Default: underlying event: pO @ 7 TeV (fixed target) | |
23 | // | |
24 | // underlying event can be changed by adding generators | |
25 | // in the same way as to AliGenCocktail before calling | |
26 | // the Init() | |
27 | // Author: Jochen Klein | |
28 | //------------------------------------------------------------- | |
29 | ||
30 | #include <TList.h> | |
31 | #include <TObjArray.h> | |
32 | #include <TParticle.h> | |
33 | ||
34 | #include "AliGenBeamGasNew.h" | |
35 | #include "AliGenCocktail.h" | |
36 | #include "AliGenCocktailEntry.h" | |
37 | #include "AliGenCocktailEventHeader.h" | |
38 | #include "AliGenHijing.h" | |
39 | #include "AliCollisionGeometry.h" | |
40 | #include "AliRun.h" | |
41 | #include "AliMC.h" | |
42 | #include "AliStack.h" | |
43 | #include "AliLog.h" | |
44 | ||
45 | #include "AliHeader.h" | |
46 | #include "AliGenEventHeader.h" | |
47 | ||
48 | ClassImp(AliGenBeamGasNew) | |
49 | ||
50 | Float_t EtaToTheta(Float_t arg) { return (180./TMath::Pi())*2.*atan(exp(-arg)); } | |
51 | ||
52 | AliGenBeamGasNew::AliGenBeamGasNew() : | |
53 | AliGenCocktail(), | |
54 | fItime(0), | |
55 | fTwindow(88e-6), | |
56 | fZwindow(2000), | |
57 | fRate(1e3) | |
58 | { | |
59 | // Default constructor | |
60 | } | |
61 | ||
62 | AliGenBeamGasNew::~AliGenBeamGasNew() | |
63 | { | |
64 | } | |
65 | ||
66 | void AliGenBeamGasNew::SetTimeWindow(Float_t twindow) { fTwindow = twindow; } | |
67 | ||
68 | bool AliGenBeamGasNew::SetRate(Float_t rate) { | |
69 | // Set the Rate | |
70 | if (rate >= 0) { | |
71 | fRate = rate; | |
72 | return true; | |
73 | } else | |
74 | return false; | |
75 | } | |
76 | ||
77 | void AliGenBeamGasNew::SetZWindow(Float_t zwindow) { fZwindow = zwindow; } | |
78 | ||
79 | void AliGenBeamGasNew::Init() | |
80 | { | |
81 | // Initialisation of the class | |
82 | // if no generators were added before calling Init() | |
83 | // AliGenHijing is added configured for pO | |
84 | ||
85 | fVertexSmear = kPerEvent; | |
86 | fVertexSource = kInternal; | |
87 | fSRandom = kTRUE; | |
88 | ||
89 | // Adding default underlying event in case none was specified | |
90 | // p-O-collision at 7 TeV (fixed target) | |
91 | if (!fEntries) { | |
92 | AliGenHijing *gen = new AliGenHijing(-1); | |
93 | gen->SetReferenceFrame("LAB"); | |
94 | gen->SetEnergyCMS(7000); | |
95 | gen->SetProjectile("P",1,1); | |
96 | gen->SetTarget("A",16,8); | |
97 | gen->SetPhiRange(0,360); | |
98 | Float_t thmin = EtaToTheta(8); | |
99 | Float_t thmax = EtaToTheta(-8); | |
100 | gen->SetThetaRange(thmin, thmax); | |
101 | gen->SetOrigin(0,0,0); | |
102 | gen->SetSigma(0,0,0); | |
103 | gen->KeepFullEvent(); | |
104 | gen->SetShadowing(1); | |
105 | gen->SetDecaysOff(1); | |
106 | gen->SetSpectators(1); | |
107 | gen->SetSelectAll(1); | |
108 | gen->SetRandomPz(kFALSE); | |
109 | gen->SetPileUpTimeWindow(0.); | |
110 | AddGenerator(gen,"Hijing pO",1); | |
111 | } | |
112 | ||
113 | TIter next(fEntries); | |
114 | AliGenCocktailEntry *entry; | |
115 | ||
116 | // Loop over generators and initialize | |
117 | while((entry = (AliGenCocktailEntry*)next())) { | |
118 | if (fStack) entry->Generator()->SetStack(fStack); | |
119 | entry->Generator()->Init(); | |
120 | } | |
121 | ||
122 | next.Reset(); | |
123 | ||
124 | if (fSRandom) { | |
125 | fProb.Set(fNGenerators); | |
126 | next.Reset(); | |
127 | Float_t sum = 0.; | |
128 | while((entry = (AliGenCocktailEntry*)next())) { | |
129 | sum += entry->Rate(); | |
130 | } | |
131 | ||
132 | next.Reset(); | |
133 | Int_t i = 0; | |
134 | Float_t psum = 0.; | |
135 | while((entry = (AliGenCocktailEntry*)next())) { | |
136 | psum += entry->Rate() / sum; | |
137 | fProb[i++] = psum; | |
138 | } | |
139 | } | |
140 | next.Reset(); | |
141 | } | |
142 | ||
143 | void AliGenBeamGasNew::VertexInternal() | |
144 | { | |
145 | // calculation of the interaction vertex for the beam gas event | |
146 | // both spatial and time coordinate are adjusted. | |
147 | ||
148 | Float_t random[2]; | |
149 | Float_t nbunch; | |
150 | Float_t bunch; | |
151 | ||
152 | gRandom->RndmArray(2,random); | |
153 | fVertex[0] = fVertex[1] = 0; | |
154 | fVertex[2] = random[0] * 2 * fZwindow - fZwindow; | |
155 | nbunch = fTwindow/25e-9; | |
156 | bunch = floor(2*nbunch * random[1] - nbunch); | |
157 | fItime = fVertex[2] / 100 / 3e8 + bunch * 25e-9; | |
158 | AliInfo(Form("fItime: %13.3e \n", fItime)); | |
159 | } | |
160 | ||
161 | void AliGenBeamGasNew::Generate() | |
162 | { | |
163 | // | |
164 | // Generate the collisions for one event | |
165 | // | |
166 | Int_t numbg = gRandom->Poisson(fRate*fZwindow/100*2*fTwindow); | |
167 | if (numbg == 0) return; | |
168 | ||
169 | TIter next(fEntries); | |
170 | AliGenCocktailEntry *entry = 0; | |
171 | AliGenCocktailEntry *preventry = 0; | |
172 | AliGenerator* gen = 0; | |
173 | TLorentzVector v; | |
174 | TArrayF eventVertex; | |
175 | Int_t lastpart=0; | |
176 | Float_t sign; | |
177 | ||
178 | if (fHeader) delete fHeader; | |
179 | fHeader = new AliGenCocktailEventHeader("Beamgas Header"); | |
180 | ||
181 | const TObjArray *partArray = gAlice->GetMCApp()->Particles(); | |
182 | AliStack *stack = AliRunLoader::Instance()->Stack(); | |
183 | ||
184 | for (Int_t l = 0; l < numbg; l++) { | |
185 | Vertex(); | |
186 | sign = (gRandom->Rndm() < 0.5)? -1. : 1.; | |
187 | eventVertex.Set(3); | |
188 | for (Int_t j=0; j < 3; j++) eventVertex[j] = fVertex[j]; | |
189 | ||
190 | if (!fRandom) { | |
191 | Int_t igen=0; | |
192 | while((entry = (AliGenCocktailEntry*)next())) { | |
193 | if (fUsePerEventRate && (gRandom->Rndm() > entry->Rate())) continue; | |
194 | ||
195 | igen++; | |
196 | if (igen ==1) { | |
197 | entry->SetFirst(lastpart); | |
198 | } else { | |
199 | entry->SetFirst((partArray->GetEntriesFast())+1); | |
200 | } | |
201 | // | |
202 | // Handle case in which current generator needs collision geometry from previous generator | |
203 | // | |
204 | gen = entry->Generator(); | |
205 | if (gen->NeedsCollisionGeometry()) | |
206 | { | |
207 | if (preventry && preventry->Generator()->ProvidesCollisionGeometry()) | |
208 | { | |
209 | gen->SetCollisionGeometry(preventry->Generator()->CollisionGeometry()); | |
210 | } else { | |
211 | Fatal("Generate()", "No Collision Geometry Provided"); | |
212 | } | |
213 | } | |
214 | entry->Generator()->SetVertex(fVertex.At(0), fVertex.At(1), fVertex.At(2)); | |
215 | entry->Generator()->Generate(); | |
216 | entry->SetLast(partArray->GetEntriesFast()); | |
217 | preventry = entry; | |
218 | } | |
219 | } else { | |
220 | // | |
221 | // Select a generator randomly | |
222 | // | |
223 | Int_t i = 0; | |
224 | Float_t p0 = gRandom->Rndm(); | |
225 | ||
226 | for (i = 0; i < fNGenerators; i++) { | |
227 | if (p0 < fProb[i]) break; | |
228 | } | |
229 | ||
230 | entry = (AliGenCocktailEntry*) fEntries->At(i); | |
231 | entry->SetFirst(lastpart); | |
232 | gen = entry->Generator(); | |
233 | gen->SetVertex(fVertex.At(0), fVertex.At(1), fVertex.At(2)); | |
234 | gen->Generate(); | |
235 | entry->SetLast(partArray->GetEntriesFast()); | |
236 | } | |
237 | ||
238 | for (Int_t k = lastpart; k < stack->GetNprimary(); k++) { | |
239 | stack->Particle(k)->ProductionVertex(v); | |
240 | v[2] *= sign; | |
241 | eventVertex[2] *= sign; | |
242 | v[3] = fItime; // ??? += | |
243 | stack->Particle(k)->SetProductionVertex(v); | |
244 | stack->Particle(k)->Momentum(v); | |
245 | v[2] *= sign; | |
246 | stack->Particle(k)->SetMomentum(v); | |
247 | } | |
248 | ||
249 | ((AliGenEventHeader*) fHeader->GetHeaders()->Last())->SetPrimaryVertex(eventVertex); | |
250 | ||
251 | lastpart = stack->GetNprimary(); | |
252 | next.Reset(); | |
253 | } | |
254 | ||
255 | fHeader->CalcNProduced(); | |
256 | ||
257 | if (fContainer) { | |
258 | fContainer->AddHeader(fHeader); | |
259 | } else { | |
260 | gAlice->SetGenEventHeader(fHeader); | |
261 | } | |
262 | } |