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886b6f73 | 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 | $Log$ | |
18 | */ | |
19 | ||
20 | //====================================================================== | |
21 | // AliGenPHOSlib class contains parameterizations of the | |
22 | // pion, kaon, eta, omega, etaprime, phi and baryon (proton, | |
23 | // antiproton, neutron and anti-neutron) particles for the | |
24 | // study of the neutral background in PHOS detector. | |
25 | // These parameterizations are used by the | |
26 | // AliGenParam class: | |
27 | // AliGenParam(npar, param, AliGenPHOSlib::GetPt(param), | |
28 | // AliGenPHOSlib::GetY(param), | |
29 | // AliGenPHOSlib::GetIp(param) ) | |
30 | // param represents the particle to be simulated : | |
31 | // Pion, Kaon, Eta, Omega, Etaprime, Phi or Baryon | |
32 | // Pt distributions are calculated from the transverse mass scaling | |
33 | // with Pions, using the PtScal fonction taken from AliGenMUONlib | |
34 | // version aliroot 3.01 | |
35 | // | |
36 | // Gines MARTINEZ GPS @ SUBATECH, Nantes , France | |
37 | // http://www-subatech.in2p3.fr/~photons/subatech | |
38 | // martinez@subatech.in2p3.fr | |
39 | //====================================================================== | |
40 | ||
41 | #include "AliGenPHOSlib.h" | |
42 | #include "AliRun.h" | |
43 | ||
44 | ClassImp(AliGenPHOSlib) | |
45 | ||
46 | //====================================================================== | |
47 | // P I O N S | |
48 | // (From GetPt, GetY and GetIp as param = Pion) | |
49 | // Transverse momentum distribution" PtPion | |
50 | // Rapidity distribution YPion | |
51 | // Particle distribution IdPion 111, 211 and -211 (pi0, pi+ and pi-) | |
52 | // | |
53 | Double_t AliGenPHOSlib::PtPion(Double_t *px, Double_t *) | |
54 | { | |
55 | // Pion transverse momentum distribtuion taken | |
56 | // from AliGenMUONlib class, version 3.01 of alirrot | |
57 | // PT-PARAMETERIZATION CDF, PRL 61(88) 1819 | |
58 | // POWER LAW FOR PT > 500 MEV | |
59 | // MT SCALING BELOW (T=160 MEV) | |
60 | // | |
61 | const Double_t p0 = 1.3; | |
62 | const Double_t xn = 8.28; | |
63 | const Double_t xlim=0.5; | |
64 | const Double_t t=0.160; | |
65 | const Double_t xmpi=0.139; | |
66 | const Double_t b=1.; | |
67 | Double_t y, y1, xmpi2, ynorm, a; | |
68 | Double_t x=*px; | |
69 | // | |
70 | y1=TMath::Power(p0/(p0+xlim),xn); | |
71 | xmpi2=xmpi*xmpi; | |
72 | ynorm=b*(TMath::Exp(-sqrt(xlim*xlim+xmpi2)/t)); | |
73 | a=ynorm/y1; | |
74 | if (x > xlim) | |
75 | y=a*TMath::Power(p0/(p0+x),xn); | |
76 | else | |
77 | y=b*TMath::Exp(-sqrt(x*x+xmpi2)/t); | |
78 | return y*x; | |
79 | } | |
80 | // | |
81 | // y-distribution | |
82 | // | |
83 | Double_t AliGenPHOSlib::YPion( Double_t *py, Double_t *) | |
84 | { | |
85 | const Double_t a = 7000.; | |
86 | const Double_t dy = 4.; | |
87 | ||
88 | Double_t y=TMath::Abs(*py); | |
89 | // | |
90 | Double_t ex = y*y/(2*dy*dy); | |
91 | return a*TMath::Exp(-ex); | |
92 | } | |
93 | // particle composition pi+, pi0, pi- | |
94 | // | |
95 | Int_t AliGenPHOSlib::IpPion() | |
96 | { | |
97 | Float_t random[1]; | |
98 | gMC->Rndm(random,1); | |
99 | ||
100 | if ( (3.*random[0]) < 1. ) | |
101 | { | |
102 | return 211 ; | |
103 | } | |
104 | else | |
105 | { | |
106 | if ( (3.*random[0]) >= 2.) | |
107 | { | |
108 | return -211 ; | |
109 | } | |
110 | else | |
111 | { | |
112 | return 111 ; | |
113 | } | |
114 | } | |
115 | } | |
116 | // End Pions | |
117 | //============================================================= | |
118 | // | |
119 | // Mt-scaling | |
120 | // Fonction for the calculation of the Pt distribution for a | |
121 | // given particle np, from the pion Pt distribution using the | |
122 | // mt scaling. This function was taken from AliGenMUONlib | |
123 | // aliroot version 3.01, and was extended for baryons | |
124 | // np = 1=>Pions 2=>Kaons 3=>Etas 4=>Omegas 5=>ETA' 6=>PHI | |
125 | // 7=>BARYONS-BARYONBARS | |
126 | Double_t AliGenPHOSlib::PtScal(Double_t pt, Int_t np) | |
127 | { | |
128 | // SCALING EN MASSE PAR RAPPORT A PTPI | |
129 | // MASS 1=>PI, 2=>K, 3=>ETA, 4=>OMEGA, 5=>ETA',6=>PHI | |
130 | const Double_t hm[10] = {0.1396, 0.494, 0.547, 0.782, 0.957, 1.02, | |
131 | // MASS 7=>BARYON-BARYONBAR | |
132 | 0.938, 0. , 0., 0.}; | |
133 | // VALUE MESON/PI AT 5 GEV | |
134 | const Double_t fmax[10]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1.}; | |
135 | np--; | |
136 | Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+hm[np]*hm[np])+2.0)),12.3); | |
137 | Double_t fmax2=f5/fmax[np]; | |
138 | // PIONS | |
139 | Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0); | |
140 | Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/ | |
141 | (sqrt(pt*pt+hm[np]*hm[np])+2.0)),12.3)/ fmax2; | |
142 | return fmtscal*ptpion; | |
143 | } | |
144 | // End Scaling | |
145 | //============================================================================ | |
146 | // K A O N S | |
147 | // kaon | |
148 | // pt-distribution | |
149 | //____________________________________________________________ | |
150 | Double_t AliGenPHOSlib::PtKaon( Double_t *px, Double_t *) | |
151 | { | |
152 | return PtScal(*px,2); // 2==> Kaon in the PtScal function | |
153 | } | |
154 | ||
155 | // y-distribution | |
156 | //____________________________________________________________ | |
157 | Double_t AliGenPHOSlib::YKaon( Double_t *py, Double_t *) | |
158 | { | |
159 | const Double_t a = 1000.; | |
160 | const Double_t dy = 4.; | |
161 | ||
162 | ||
163 | Double_t y=TMath::Abs(*py); | |
164 | // | |
165 | Double_t ex = y*y/(2*dy*dy); | |
166 | return a*TMath::Exp(-ex); | |
167 | } | |
168 | ||
169 | // particle composition | |
170 | // | |
171 | Int_t AliGenPHOSlib::IpKaon() | |
172 | { | |
173 | Float_t random[1],random2[1]; | |
174 | gMC->Rndm(random,1); | |
175 | gMC->Rndm(random2,1); | |
176 | if (random2[0] < 0.5) | |
177 | { | |
178 | if (random[0] < 0.5) { | |
179 | return 321; // K+ | |
180 | } else { | |
181 | return -321; // K- | |
182 | } | |
183 | } | |
184 | else | |
185 | { | |
186 | if (random[0] < 0.5) { | |
187 | return 311; // K^0 | |
188 | } else { | |
189 | return -311; // K^0 bar | |
190 | } | |
191 | } | |
192 | } | |
193 | // End Kaons | |
194 | //============================================================================ | |
195 | //============================================================================ | |
196 | // E T A S | |
197 | // etas | |
198 | // pt-distribution | |
199 | //____________________________________________________________ | |
200 | Double_t AliGenPHOSlib::PtEta( Double_t *px, Double_t *) | |
201 | { | |
202 | return PtScal(*px,3); // 3==> Eta in the PtScal function | |
203 | } | |
204 | ||
205 | // y-distribution | |
206 | //____________________________________________________________ | |
207 | Double_t AliGenPHOSlib::YEta( Double_t *py, Double_t *) | |
208 | { | |
209 | const Double_t a = 1000.; | |
210 | const Double_t dy = 4.; | |
211 | ||
212 | ||
213 | Double_t y=TMath::Abs(*py); | |
214 | // | |
215 | Double_t ex = y*y/(2*dy*dy); | |
216 | return a*TMath::Exp(-ex); | |
217 | } | |
218 | ||
219 | // particle composition | |
220 | // | |
221 | Int_t AliGenPHOSlib::IpEta() | |
222 | { | |
223 | return 221; // eta | |
224 | } | |
225 | // End Etas | |
226 | //============================================================================ | |
227 | //============================================================================ | |
228 | // O M E G A S | |
229 | // omegas | |
230 | // pt-distribution | |
231 | //____________________________________________________________ | |
232 | Double_t AliGenPHOSlib::PtOmega( Double_t *px, Double_t *) | |
233 | { | |
234 | return PtScal(*px,4); // 4==> Omega in the PtScal function | |
235 | } | |
236 | ||
237 | // y-distribution | |
238 | //____________________________________________________________ | |
239 | Double_t AliGenPHOSlib::YOmega( Double_t *py, Double_t *) | |
240 | { | |
241 | const Double_t a = 1000.; | |
242 | const Double_t dy = 4.; | |
243 | ||
244 | ||
245 | Double_t y=TMath::Abs(*py); | |
246 | // | |
247 | Double_t ex = y*y/(2*dy*dy); | |
248 | return a*TMath::Exp(-ex); | |
249 | } | |
250 | ||
251 | // particle composition | |
252 | // | |
253 | Int_t AliGenPHOSlib::IpOmega() | |
254 | { | |
255 | return 223; // Omega | |
256 | } | |
257 | // End Omega | |
258 | //============================================================================ | |
259 | //============================================================================ | |
260 | // E T A P R I M E | |
261 | // etaprime | |
262 | // pt-distribution | |
263 | //____________________________________________________________ | |
264 | Double_t AliGenPHOSlib::PtEtaprime( Double_t *px, Double_t *) | |
265 | { | |
266 | return PtScal(*px,5); // 5==> Etaprime in the PtScal function | |
267 | } | |
268 | ||
269 | // y-distribution | |
270 | //____________________________________________________________ | |
271 | Double_t AliGenPHOSlib::YEtaprime( Double_t *py, Double_t *) | |
272 | { | |
273 | const Double_t a = 1000.; | |
274 | const Double_t dy = 4.; | |
275 | ||
276 | ||
277 | Double_t y=TMath::Abs(*py); | |
278 | // | |
279 | Double_t ex = y*y/(2*dy*dy); | |
280 | return a*TMath::Exp(-ex); | |
281 | } | |
282 | ||
283 | // particle composition | |
284 | // | |
285 | Int_t AliGenPHOSlib::IpEtaprime() | |
286 | { | |
287 | return 331; // Etaprime | |
288 | } | |
289 | // End EtaPrime | |
290 | //=================================================================== | |
291 | //============================================================================ | |
292 | // P H I S | |
293 | // phi | |
294 | // pt-distribution | |
295 | //____________________________________________________________ | |
296 | Double_t AliGenPHOSlib::PtPhi( Double_t *px, Double_t *) | |
297 | { | |
298 | return PtScal(*px,6); // 6==> Phi in the PtScal function | |
299 | } | |
300 | ||
301 | // y-distribution | |
302 | //____________________________________________________________ | |
303 | Double_t AliGenPHOSlib::YPhi( Double_t *py, Double_t *) | |
304 | { | |
305 | const Double_t a = 1000.; | |
306 | const Double_t dy = 4.; | |
307 | ||
308 | ||
309 | Double_t y=TMath::Abs(*py); | |
310 | // | |
311 | Double_t ex = y*y/(2*dy*dy); | |
312 | return a*TMath::Exp(-ex); | |
313 | } | |
314 | ||
315 | // particle composition | |
316 | // | |
317 | Int_t AliGenPHOSlib::IpPhi() | |
318 | { | |
319 | return 333; // Phi | |
320 | } | |
321 | // End Phis | |
322 | //=================================================================== | |
323 | //============================================================================ | |
324 | // B A R Y O N S == protons, protonsbar, neutrons, and neutronsbars | |
325 | // baryons | |
326 | // pt-distribution | |
327 | //____________________________________________________________ | |
328 | Double_t AliGenPHOSlib::PtBaryon( Double_t *px, Double_t *) | |
329 | { | |
330 | return PtScal(*px,7); // 7==> Baryon in the PtScal function | |
331 | } | |
332 | ||
333 | // y-distribution | |
334 | //____________________________________________________________ | |
335 | Double_t AliGenPHOSlib::YBaryon( Double_t *py, Double_t *) | |
336 | { | |
337 | const Double_t a = 1000.; | |
338 | const Double_t dy = 4.; | |
339 | ||
340 | ||
341 | Double_t y=TMath::Abs(*py); | |
342 | // | |
343 | Double_t ex = y*y/(2*dy*dy); | |
344 | return a*TMath::Exp(-ex); | |
345 | } | |
346 | ||
347 | // particle composition | |
348 | // | |
349 | Int_t AliGenPHOSlib::IpBaryon() | |
350 | { | |
351 | Float_t random[1],random2[1]; | |
352 | gMC->Rndm(random,1); | |
353 | gMC->Rndm(random2,1); | |
354 | if (random2[0] < 0.5) | |
355 | { | |
356 | if (random[0] < 0.5) { | |
357 | return 2212; // p | |
358 | } else { | |
359 | return -2212; // pbar | |
360 | } | |
361 | } | |
362 | else | |
363 | { | |
364 | if (random[0] < 0.5) { | |
365 | return 2112; // n | |
366 | } else { | |
367 | return -2112; // n bar | |
368 | } | |
369 | } | |
370 | } | |
371 | // End Baryons | |
372 | //=================================================================== | |
373 | ||
374 | ||
375 | typedef Double_t (*GenFunc) (Double_t*, Double_t*); | |
376 | GenFunc AliGenPHOSlib::GetPt(Param_t param) | |
377 | { | |
378 | GenFunc func; | |
379 | ||
380 | switch (param) | |
381 | { | |
382 | case Pion: | |
383 | func=PtPion; | |
384 | break; | |
385 | case Kaon: | |
386 | func=PtKaon; | |
387 | break; | |
388 | case Eta: | |
389 | func=PtEta; | |
390 | break; | |
391 | case Omega: | |
392 | func=PtOmega; | |
393 | break; | |
394 | case Etaprime: | |
395 | func=PtEtaprime; | |
396 | break; | |
397 | case Baryon: | |
398 | func=PtBaryon; | |
399 | break; | |
400 | default: | |
401 | func=0; | |
402 | printf("<AliGenPHOSlib::GetPt> unknown parametrisationn"); | |
403 | } | |
404 | return func; | |
405 | } | |
406 | ||
407 | GenFunc AliGenPHOSlib::GetY(Param_t param) | |
408 | { | |
409 | GenFunc func; | |
410 | switch (param) | |
411 | { | |
412 | case Pion: | |
413 | func=YPion; | |
414 | break; | |
415 | case Kaon: | |
416 | func=YKaon; | |
417 | break; | |
418 | case Eta: | |
419 | func=YEta; | |
420 | break; | |
421 | case Omega: | |
422 | func=YOmega; | |
423 | break; | |
424 | case Etaprime: | |
425 | func=YEtaprime; | |
426 | break; | |
427 | case Phi: | |
428 | func=YPhi; | |
429 | break; | |
430 | case Baryon: | |
431 | func=YBaryon; | |
432 | break; | |
433 | default: | |
434 | func=0; | |
435 | printf("<AliGenPHOSlib::GetY> unknown parametrisationn"); | |
436 | } | |
437 | return func; | |
438 | } | |
439 | typedef Int_t (*GenFuncIp) (); | |
440 | GenFuncIp AliGenPHOSlib::GetIp(Param_t param) | |
441 | { | |
442 | GenFuncIp func; | |
443 | switch (param) | |
444 | { | |
445 | case Pion: | |
446 | ||
447 | func=IpPion; | |
448 | break; | |
449 | case Kaon: | |
450 | func=IpKaon; | |
451 | break; | |
452 | case Eta: | |
453 | func=IpEta; | |
454 | break; | |
455 | case Omega: | |
456 | func=IpOmega; | |
457 | break; | |
458 | case Etaprime: | |
459 | func=IpEtaprime; | |
460 | break; | |
461 | case Phi: | |
462 | func=IpPhi; | |
463 | break; | |
464 | case Baryon: | |
465 | func=IpBaryon; | |
466 | break; | |
467 | default: | |
468 | func=0; | |
469 | printf("<AliGenPHOSlib::GetIp> unknown parametrisationn"); | |
470 | } | |
471 | return func; | |
472 | } | |
473 |