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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 | ||
88cb7938 | 16 | /* $Id$ */ |
675e9664 | 17 | |
18 | // Parameterisation of pi and K, eta and pt distributions | |
19 | // used for the ALICE TDRs. | |
20 | // eta: according to HIJING (shadowing + quenching) | |
21 | // pT : according to CDF measurement at 1.8 TeV | |
22 | // Author: andreas.morsch@cern.ch | |
23 | ||
24 | ||
790bbabf | 25 | //Begin_Html |
26 | /* | |
27 | <img src="picts/AliGeneratorClass.gif"> | |
28 | </pre> | |
29 | <br clear=left> | |
30 | <font size=+2 color=red> | |
31 | <p>The responsible person for this module is | |
32 | <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>. | |
33 | </font> | |
34 | <pre> | |
35 | */ | |
36 | //End_Html | |
37 | // // | |
38 | /////////////////////////////////////////////////////////////////// | |
39 | ||
971816d4 | 40 | #include <TArrayF.h> |
2067f62c | 41 | #include <TClonesArray.h> |
116cbefd | 42 | #include <TDatabasePDG.h> |
43 | #include <TF1.h> | |
2067f62c | 44 | #include <TParticle.h> |
116cbefd | 45 | #include <TPDGCode.h> |
46 | ||
47 | #include "AliConst.h" | |
48 | #include "AliDecayer.h" | |
116cbefd | 49 | #include "AliGenEventHeader.h" |
50 | #include "AliGenHIJINGpara.h" | |
51 | #include "AliRun.h" | |
971816d4 | 52 | |
790bbabf | 53 | ClassImp(AliGenHIJINGpara) |
54 | ||
55 | AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para) | |
56 | { | |
57 | // copy constructor | |
58 | } | |
59 | ||
60 | //_____________________________________________________________________________ | |
61 | static Double_t ptpi(Double_t *px, Double_t *) | |
62 | { | |
63 | // | |
64 | // PT-PARAMETERIZATION CDF, PRL 61(88) 1819 | |
65 | // POWER LAW FOR PT > 500 MEV | |
66 | // MT SCALING BELOW (T=160 MEV) | |
67 | // | |
68 | const Double_t kp0 = 1.3; | |
69 | const Double_t kxn = 8.28; | |
70 | const Double_t kxlim=0.5; | |
71 | const Double_t kt=0.160; | |
72 | const Double_t kxmpi=0.139; | |
73 | const Double_t kb=1.; | |
74 | Double_t y, y1, xmpi2, ynorm, a; | |
75 | Double_t x=*px; | |
76 | // | |
77 | y1=TMath::Power(kp0/(kp0+kxlim),kxn); | |
78 | xmpi2=kxmpi*kxmpi; | |
79 | ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt)); | |
80 | a=ynorm/y1; | |
81 | if (x > kxlim) | |
82 | y=a*TMath::Power(kp0/(kp0+x),kxn); | |
83 | else | |
84 | y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt); | |
85 | return y*x; | |
86 | } | |
87 | ||
88 | //_____________________________________________________________________________ | |
89 | static Double_t ptscal(Double_t pt, Int_t np) | |
90 | { | |
91 | // SCALING EN MASSE PAR RAPPORT A PTPI | |
92 | // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI | |
93 | const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0}; | |
94 | // VALUE MESON/PI AT 5 GEV | |
95 | const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0}; | |
96 | np--; | |
97 | Double_t f5=TMath::Power((( | |
98 | sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3); | |
99 | Double_t fmax2=f5/kfmax[np]; | |
100 | // PIONS | |
101 | Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0); | |
102 | Double_t fmtscal=TMath::Power((( | |
103 | sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ | |
104 | fmax2; | |
105 | return fmtscal*ptpion; | |
106 | } | |
107 | ||
108 | //_____________________________________________________________________________ | |
109 | static Double_t ptka( Double_t *px, Double_t *) | |
110 | { | |
111 | // | |
112 | // pt parametrisation for k | |
113 | // | |
114 | return ptscal(*px,2); | |
115 | } | |
116 | ||
117 | ||
118 | //_____________________________________________________________________________ | |
119 | static Double_t etapic( Double_t *py, Double_t *) | |
120 | { | |
121 | // | |
122 | // eta parametrisation for pi | |
123 | // | |
124 | const Double_t ka1 = 4913.; | |
125 | const Double_t ka2 = 1819.; | |
126 | const Double_t keta1 = 0.22; | |
127 | const Double_t keta2 = 3.66; | |
128 | const Double_t kdeta1 = 1.47; | |
129 | const Double_t kdeta2 = 1.51; | |
130 | Double_t y=TMath::Abs(*py); | |
131 | // | |
132 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
133 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
134 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
135 | } | |
136 | ||
137 | //_____________________________________________________________________________ | |
138 | static Double_t etakac( Double_t *py, Double_t *) | |
139 | { | |
140 | // | |
141 | // eta parametrisation for ka | |
142 | // | |
143 | const Double_t ka1 = 497.6; | |
144 | const Double_t ka2 = 215.6; | |
145 | const Double_t keta1 = 0.79; | |
146 | const Double_t keta2 = 4.09; | |
147 | const Double_t kdeta1 = 1.54; | |
148 | const Double_t kdeta2 = 1.40; | |
149 | Double_t y=TMath::Abs(*py); | |
150 | // | |
151 | Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1); | |
152 | Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2); | |
153 | return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2); | |
154 | } | |
155 | ||
156 | //_____________________________________________________________________________ | |
157 | AliGenHIJINGpara::AliGenHIJINGpara() | |
158 | :AliGenerator() | |
159 | { | |
160 | // | |
161 | // Default constructor | |
162 | // | |
1e66857c | 163 | fPtpi = 0; |
164 | fPtka = 0; | |
165 | fETApic = 0; | |
166 | fETAkac = 0; | |
167 | fDecayer = 0; | |
168 | fNt = -1; | |
971816d4 | 169 | SetCutVertexZ(); |
6b236b6f | 170 | SetPtRange(); |
2067f62c | 171 | SetPi0Decays(); |
790bbabf | 172 | } |
173 | ||
174 | //_____________________________________________________________________________ | |
175 | AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart) | |
176 | :AliGenerator(npart) | |
177 | { | |
178 | // | |
179 | // Standard constructor | |
180 | // | |
edbba5db | 181 | fName="HIJINGpara"; |
790bbabf | 182 | fTitle="HIJING Parametrisation Particle Generator"; |
1e66857c | 183 | fPtpi = 0; |
184 | fPtka = 0; | |
185 | fETApic = 0; | |
186 | fETAkac = 0; | |
187 | fDecayer = 0; | |
188 | fNt = -1; | |
971816d4 | 189 | SetCutVertexZ(); |
6b236b6f | 190 | SetPtRange(); |
2067f62c | 191 | SetPi0Decays(); |
790bbabf | 192 | } |
193 | ||
194 | //_____________________________________________________________________________ | |
195 | AliGenHIJINGpara::~AliGenHIJINGpara() | |
196 | { | |
197 | // | |
198 | // Standard destructor | |
199 | // | |
200 | delete fPtpi; | |
201 | delete fPtka; | |
202 | delete fETApic; | |
203 | delete fETAkac; | |
204 | } | |
205 | ||
206 | //_____________________________________________________________________________ | |
207 | void AliGenHIJINGpara::Init() | |
208 | { | |
209 | // | |
210 | // Initialise the HIJING parametrisation | |
211 | // | |
212 | Float_t etaMin =-TMath::Log(TMath::Tan( | |
213 | TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10))); | |
214 | Float_t etaMax = -TMath::Log(TMath::Tan( | |
215 | TMath::Max((Double_t)fThetaMin/2,1.e-10))); | |
f25521b2 | 216 | fPtpi = new TF1("ptpi",&ptpi,0,20,0); |
217 | fPtka = new TF1("ptka",&ptka,0,20,0); | |
790bbabf | 218 | fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0); |
219 | fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0); | |
f25521b2 | 220 | |
aecf26a3 | 221 | TF1 etaPic0("etapic",&etapic,-7,7,0); |
222 | TF1 etaKac0("etakac",&etakac,-7,7,0); | |
f25521b2 | 223 | |
aecf26a3 | 224 | TF1 ptPic0("ptpi",&ptpi,0.,15.,0); |
225 | TF1 ptKac0("ptka",&ptka,0.,15.,0); | |
f25521b2 | 226 | |
aecf26a3 | 227 | Float_t intETApi = etaPic0.Integral(-0.5, 0.5); |
228 | Float_t intETAka = etaKac0.Integral(-0.5, 0.5); | |
f25521b2 | 229 | Float_t scalePi = 7316/(intETApi/1.5); |
230 | Float_t scaleKa = 684/(intETAka/2.0); | |
231 | ||
232 | // Fraction of events corresponding to the selected pt-range | |
aecf26a3 | 233 | Float_t intPt = (0.877*ptPic0.Integral(0, 15)+ |
234 | 0.123*ptKac0.Integral(0, 15)); | |
235 | Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+ | |
236 | 0.123*ptKac0.Integral(fPtMin, fPtMax)); | |
f25521b2 | 237 | Float_t ptFrac = intPtSel/intPt; |
238 | ||
239 | // Fraction of events corresponding to the selected eta-range | |
aecf26a3 | 240 | Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+ |
241 | scaleKa*etaKac0.Integral(etaMin, etaMax)); | |
f25521b2 | 242 | // Fraction of events corresponding to the selected phi-range |
243 | Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi(); | |
244 | ||
245 | fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac); | |
790bbabf | 246 | |
9e1a0ddb | 247 | printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ", |
248 | ClassName(),100.*fParentWeight); | |
5b0e4c0f | 249 | |
250 | // Issue warning message if etaMin or etaMax are outside the alowed range | |
251 | // of the parametrization | |
252 | if (etaMin < -8.001 || etaMax > 8.001) { | |
253 | printf("\n \n WARNING FROM AliGenHIJINGPara !"); | |
254 | printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE "); | |
255 | printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)"); | |
256 | printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax); | |
257 | } | |
2067f62c | 258 | // |
259 | // | |
2904363f | 260 | if (fPi0Decays && gMC) |
261 | fDecayer = gMC->GetDecayer(); | |
790bbabf | 262 | } |
263 | ||
2067f62c | 264 | |
790bbabf | 265 | //_____________________________________________________________________________ |
266 | void AliGenHIJINGpara::Generate() | |
267 | { | |
268 | // | |
269 | // Generate one trigger | |
270 | // | |
271 | ||
272 | ||
273 | const Float_t kRaKpic=0.14; | |
274 | const Float_t kBorne=1/(1+kRaKpic); | |
275 | Float_t polar[3]= {0,0,0}; | |
276 | // | |
277 | const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus}; | |
278 | const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus}; | |
279 | // | |
280 | Float_t origin[3]; | |
281 | Float_t pt, pl, ptot; | |
282 | Float_t phi, theta; | |
283 | Float_t p[3]; | |
1e66857c | 284 | Int_t i, part, j; |
790bbabf | 285 | // |
286 | TF1 *ptf; | |
287 | TF1 *etaf; | |
288 | // | |
289 | Float_t random[6]; | |
290 | // | |
291 | for (j=0;j<3;j++) origin[j]=fOrigin[j]; | |
971816d4 | 292 | |
293 | if(fVertexSmear == kPerEvent) { | |
c8f7f6f9 | 294 | Vertex(); |
295 | for (j=0; j < 3; j++) origin[j] = fVertex[j]; | |
971816d4 | 296 | } // if kPerEvent |
297 | TArrayF eventVertex; | |
298 | eventVertex.Set(3); | |
299 | eventVertex[0] = origin[0]; | |
300 | eventVertex[1] = origin[1]; | |
301 | eventVertex[2] = origin[2]; | |
302 | ||
790bbabf | 303 | for(i=0;i<fNpart;i++) { |
304 | while(1) { | |
65fb704d | 305 | Rndm(random,3); |
790bbabf | 306 | if(random[0]<kBorne) { |
307 | part=kPions[Int_t (random[1]*3)]; | |
308 | ptf=fPtpi; | |
2067f62c | 309 | etaf=fETApic; |
790bbabf | 310 | } else { |
311 | part=kKaons[Int_t (random[1]*4)]; | |
312 | ptf=fPtka; | |
313 | etaf=fETAkac; | |
314 | } | |
315 | phi=fPhiMin+random[2]*(fPhiMax-fPhiMin); | |
316 | theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom())); | |
317 | if(theta<fThetaMin || theta>fThetaMax) continue; | |
318 | pt=ptf->GetRandom(); | |
319 | pl=pt/TMath::Tan(theta); | |
320 | ptot=TMath::Sqrt(pt*pt+pl*pl); | |
321 | if(ptot<fPMin || ptot>fPMax) continue; | |
322 | p[0]=pt*TMath::Cos(phi); | |
323 | p[1]=pt*TMath::Sin(phi); | |
324 | p[2]=pl; | |
aee8290b | 325 | if(fVertexSmear==kPerTrack) { |
65fb704d | 326 | Rndm(random,6); |
790bbabf | 327 | for (j=0;j<3;j++) { |
328 | origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())* | |
329 | TMath::Sqrt(-2*TMath::Log(random[2*j+1])); | |
330 | } | |
331 | } | |
1ef5f15d | 332 | if (part == kPi0 && fPi0Decays){ |
2067f62c | 333 | // |
334 | // Decay pi0 if requested | |
642f15cf | 335 | PushTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight); |
1e66857c | 336 | KeepTrack(fNt); |
1ef5f15d | 337 | DecayPi0(origin, p); |
338 | } else { | |
642f15cf | 339 | PushTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight); |
1e66857c | 340 | KeepTrack(fNt); |
1ef5f15d | 341 | } |
342 | ||
790bbabf | 343 | break; |
344 | } | |
1e66857c | 345 | SetHighWaterMark(fNt); |
790bbabf | 346 | } |
1e66857c | 347 | // |
348 | ||
971816d4 | 349 | // Header |
350 | AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam"); | |
351 | // Event Vertex | |
352 | header->SetPrimaryVertex(eventVertex); | |
353 | gAlice->SetGenEventHeader(header); | |
790bbabf | 354 | } |
355 | ||
356 | AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs) | |
357 | { | |
358 | // Assignment operator | |
359 | return *this; | |
360 | } | |
361 | ||
6b236b6f | 362 | void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) { |
2067f62c | 363 | AliGenerator::SetPtRange(ptmin, ptmax); |
6b236b6f | 364 | } |
790bbabf | 365 | |
2067f62c | 366 | void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p) |
367 | { | |
368 | // | |
369 | // Decay the pi0 | |
370 | // and put decay products on the stack | |
371 | // | |
372 | static TClonesArray *particles; | |
373 | if(!particles) particles = new TClonesArray("TParticle",1000); | |
374 | // | |
375 | const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass(); | |
56fcdfe6 | 376 | Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass); |
2067f62c | 377 | // |
378 | // Decay the pi0 | |
379 | TLorentzVector pmom(p[0], p[1], p[2], e); | |
380 | fDecayer->Decay(kPi0, &pmom); | |
56fcdfe6 | 381 | |
2067f62c | 382 | // |
383 | // Put decay particles on the stack | |
384 | // | |
2067f62c | 385 | Float_t polar[3] = {0., 0., 0.}; |
386 | Int_t np = fDecayer->ImportParticles(particles); | |
1e66857c | 387 | Int_t nt; |
2067f62c | 388 | for (Int_t i = 1; i < np; i++) |
389 | { | |
7b33c00a | 390 | TParticle* iParticle = (TParticle *) particles->At(i); |
391 | p[0] = iParticle->Px(); | |
392 | p[1] = iParticle->Py(); | |
393 | p[2] = iParticle->Pz(); | |
2067f62c | 394 | Int_t part = iParticle->GetPdgCode(); |
1e66857c | 395 | |
642f15cf | 396 | PushTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight); |
1e66857c | 397 | KeepTrack(nt); |
2067f62c | 398 | } |
1e66857c | 399 | fNt = nt; |
2067f62c | 400 | } |