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1
2/**************************************************************************
3 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * *
5 * Author: The ALICE Off-line Project. *
6 * Contributors are mentioned in the code where appropriate. *
7 * *
8 * Permission to use, copy, modify and distribute this software and its *
9 * documentation strictly for non-commercial purposes is hereby granted *
10 * without fee, provided that the above copyright notice appears in all *
11 * copies and that both the copyright notice and this permission notice *
12 * appear in the supporting documentation. The authors make no claims *
13 * about the suitability of this software for any purpose. It is *
14 * provided "as is" without express or implied warranty. *
15 **************************************************************************/
16
17/*
18$Log$
19Revision 1.9 2002/04/23 12:54:29 morsch
20New options kPi0Flat y kEtaFlat (Gustavo Conesa)
21
22Revision 1.7 2001/03/09 13:01:41 morsch
23- enum constants for paramterisation type (particle family) moved to AliGen*lib.h
24- use AliGenGSIlib::kUpsilon, AliGenPHOSlib::kEtaPrime to access the constants
25
26Revision 1.6 2000/11/30 07:12:50 alibrary
27Introducing new Rndm and QA classes
28
29Revision 1.5 2000/06/29 21:08:27 morsch
30All paramatrisation libraries derive from the pure virtual base class AliGenLib.
31This allows to pass a pointer to a library directly to AliGenParam and avoids the
32use of function pointers in Config.C.
33
34Revision 1.4 2000/06/14 15:21:05 morsch
35Include clean-up (IH)
36
37Revision 1.3 2000/06/09 20:32:54 morsch
38All coding rule violations except RS3 corrected
39
40Revision 1.2 1999/11/04 11:30:48 fca
41Improve comments
42
43Revision 1.1 1999/11/03 17:43:20 fca
44New version from G.Martinez & A.Morsch
45
46*/
47
48//======================================================================
49// AliGenPHOSlib class contains parameterizations of the
50// pion, kaon, eta, omega, etaprime, phi and baryon (proton,
51// antiproton, neutron and anti-neutron) particles for the
52// study of the neutral background in PHOS detector.
53// These parameterizations are used by the
54// AliGenParam class:
55// AliGenParam(npar, param, AliGenPHOSlib::GetPt(param),
56// AliGenPHOSlib::GetY(param),
57// AliGenPHOSlib::GetIp(param) )
58// param represents the particle to be simulated :
59// Pion, Kaon, Eta, Omega, Etaprime, Phi or Baryon
60// Pt distributions are calculated from the transverse mass scaling
61// with Pions, using the PtScal function taken from AliGenMUONlib
62// version aliroot 3.01
63//
64// Gines MARTINEZ. Laurent APHECETCHE and Yves SCHUTZ
65// GPS @ SUBATECH, Nantes , France (October 1999)
66// http://www-subatech.in2p3.fr/~photons/subatech
67// martinez@subatech.in2p3.fr
68//======================================================================
69
70#include "TMath.h"
71#include "TRandom.h"
72
73#include "AliGenPHOSlib.h"
74
75ClassImp(AliGenPHOSlib)
76
77//======================================================================
78// P I O N S
79// (From GetPt, GetY and GetIp as param = Pion)
80// Transverse momentum distribution" PtPion
81// Rapidity distribution YPion
82// Particle distribution IdPion 111, 211 and -211 (pi0, pi+ and pi-)
83//
84 Double_t AliGenPHOSlib::PtPion(Double_t *px, Double_t *)
85{
86// Pion transverse momentum distribtuion taken
87// from AliGenMUONlib class, version 3.01 of aliroot
88// PT-PARAMETERIZATION CDF, PRL 61(88) 1819
89// POWER LAW FOR PT > 500 MEV
90// MT SCALING BELOW (T=160 MEV)
91//
92 const Double_t kp0 = 1.3;
93 const Double_t kxn = 8.28;
94 const Double_t kxlim=0.5;
95 const Double_t kt=0.160;
96 const Double_t kxmpi=0.139;
97 const Double_t kb=1.;
98 Double_t y, y1, kxmpi2, ynorm, a;
99 Double_t x=*px;
100 //
101 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
102 kxmpi2=kxmpi*kxmpi;
103 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+kxmpi2)/kt));
104 a=ynorm/y1;
105 if (x > kxlim)
106 y=a*TMath::Power(kp0/(kp0+x),kxn);
107 else
108 y=kb*TMath::Exp(-sqrt(x*x+kxmpi2)/kt);
109 return y*x;
110}
111 Double_t AliGenPHOSlib::YPion( Double_t *py, Double_t *)
112{
113//
114// pion y-distribution
115//
116
117 const Double_t ka = 7000.;
118 const Double_t kdy = 4.;
119
120 Double_t y=TMath::Abs(*py);
121 //
122 Double_t ex = y*y/(2*kdy*kdy);
123 return ka*TMath::Exp(-ex);
124}
125
126 Int_t AliGenPHOSlib::IpPion(TRandom *ran)
127{
128// particle composition pi+, pi0, pi-
129//
130
131 Float_t random = ran->Rndm();
132
133 if ( (3.*random) < 1. )
134 {
135 return 211 ;
136 }
137 else
138 {
139 if ( (3.*random) >= 2.)
140 {
141 return -211 ;
142 }
143 else
144 {
145 return 111 ;
146 }
147 }
148}
149
150//End Pions
151//======================================================================
152// Pi 0 Flat Distribution
153// Transverse momentum distribution PtPi0Flat
154// Rapidity distribution YPi0Flat
155// Particle distribution IdPi0Flat 111 (pi0)
156//
157
158Double_t AliGenPHOSlib::PtPi0Flat(Double_t *px, Double_t *)
159{
160// Pion transverse momentum flat distribution
161
162return 1;
163
164}
165
166Double_t AliGenPHOSlib::YPi0Flat( Double_t *py, Double_t *)
167{
168
169// pion y-distribution
170//
171 return 1.;
172}
173
174 Int_t AliGenPHOSlib::IpPi0Flat(TRandom *)
175{
176
177// particle composition pi0
178//
179 return 111 ;
180}
181// End Pi0Flat
182//=============================================================
183//
184 Double_t AliGenPHOSlib::PtScal(Double_t pt, Int_t np)
185{
186// Mt-scaling
187// Fonction for the calculation of the Pt distribution for a
188// given particle np, from the pion Pt distribution using the
189// mt scaling. This function was taken from AliGenMUONlib
190// aliroot version 3.01, and was extended for baryons
191// np = 1=>Pions 2=>Kaons 3=>Etas 4=>Omegas 5=>ETA' 6=>PHI
192// 7=>BARYONS-BARYONBARS
193
194 // SCALING EN MASSE PAR RAPPORT A PTPI
195 // MASS 1=>PI, 2=>K, 3=>ETA, 4=>OMEGA, 5=>ETA',6=>PHI
196 const Double_t khm[10] = {0.1396, 0.494, 0.547, 0.782, 0.957, 1.02,
197 // MASS 7=>BARYON-BARYONBAR
198 0.938, 0. , 0., 0.};
199 // VALUE MESON/PI AT 5 GEV
200 const Double_t kfmax[10]={1., 1., 1., 1., 1., 1., 1., 1., 1., 1.};
201 np--;
202 Double_t f5=TMath::Power(((sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
203 Double_t kfmax2=f5/kfmax[np];
204 // PIONS
205 Double_t ptpion=100.*PtPion(&pt, (Double_t*) 0);
206 Double_t fmtscal=TMath::Power(((sqrt(pt*pt+0.018215)+2.)/
207 (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/ kfmax2;
208 return fmtscal*ptpion;
209
210}
211// End Scaling
212//============================================================================
213// K A O N S
214 Double_t AliGenPHOSlib::PtKaon( Double_t *px, Double_t *)
215{
216// kaon
217// pt-distribution
218//____________________________________________________________
219
220 return PtScal(*px,2); // 2==> Kaon in the PtScal function
221}
222
223 Double_t AliGenPHOSlib::YKaon( Double_t *py, Double_t *)
224{
225// y-distribution
226//____________________________________________________________
227
228 const Double_t ka = 1000.;
229 const Double_t kdy = 4.;
230
231
232 Double_t y=TMath::Abs(*py);
233 //
234 Double_t ex = y*y/(2*kdy*kdy);
235 return ka*TMath::Exp(-ex);
236}
237
238 Int_t AliGenPHOSlib::IpKaon(TRandom *ran)
239{
240// particle composition
241//
242
243 Float_t random = ran->Rndm();
244 Float_t random2 = ran->Rndm();
245 if (random2 < 0.5)
246 {
247 if (random < 0.5) {
248 return 321; // K+
249 } else {
250 return -321; // K-
251 }
252 }
253 else
254 {
255 if (random < 0.5) {
256 return 130; // K^0 short
257 } else {
258 return 310; // K^0 long
259 }
260 }
261}
262// End Kaons
263//============================================================================
264//============================================================================
265// E T A S
266 Double_t AliGenPHOSlib::PtEta( Double_t *px, Double_t *)
267{
268// etas
269// pt-distribution
270//____________________________________________________________
271
272 return PtScal(*px,3); // 3==> Eta in the PtScal function
273}
274
275 Double_t AliGenPHOSlib::YEta( Double_t *py, Double_t *)
276{
277// y-distribution
278//____________________________________________________________
279
280 const Double_t ka = 1000.;
281 const Double_t kdy = 4.;
282
283
284 Double_t y=TMath::Abs(*py);
285 //
286 Double_t ex = y*y/(2*kdy*kdy);
287 return ka*TMath::Exp(-ex);
288}
289
290 Int_t AliGenPHOSlib::IpEta(TRandom *)
291{
292// particle composition
293//
294
295 return 221; // eta
296}
297// End Etas
298
299//======================================================================
300// Eta Flat Distribution
301// Transverse momentum distribution PtEtaFlat
302// Rapidity distribution YEtaFlat
303// Particle distribution IdEtaFlat 111 (pi0)
304//
305
306Double_t AliGenPHOSlib::PtEtaFlat(Double_t *px, Double_t *)
307{
308// Eta transverse momentum flat distribution
309
310 return 1;
311
312}
313
314Double_t AliGenPHOSlib::YEtaFlat( Double_t *py, Double_t *)
315{
316//
317// pion y-distribution
318//
319 return 1.;
320}
321
322 Int_t AliGenPHOSlib::IpEtaFlat(TRandom *)
323{
324//
325// particle composition eta
326//
327 return 221 ;
328}
329// End Pi0Flat
330//============================================================================
331//============================================================================
332// O M E G A S
333 Double_t AliGenPHOSlib::PtOmega( Double_t *px, Double_t *)
334{
335// omegas
336// pt-distribution
337//____________________________________________________________
338
339 return PtScal(*px,4); // 4==> Omega in the PtScal function
340}
341
342 Double_t AliGenPHOSlib::YOmega( Double_t *py, Double_t *)
343{
344// y-distribution
345//____________________________________________________________
346
347 const Double_t ka = 1000.;
348 const Double_t kdy = 4.;
349
350
351 Double_t y=TMath::Abs(*py);
352 //
353 Double_t ex = y*y/(2*kdy*kdy);
354 return ka*TMath::Exp(-ex);
355}
356
357 Int_t AliGenPHOSlib::IpOmega(TRandom *)
358{
359// particle composition
360//
361
362 return 223; // Omega
363}
364// End Omega
365//============================================================================
366//============================================================================
367// E T A P R I M E
368 Double_t AliGenPHOSlib::PtEtaprime( Double_t *px, Double_t *)
369{
370// etaprime
371// pt-distribution
372//____________________________________________________________
373
374 return PtScal(*px,5); // 5==> Etaprime in the PtScal function
375}
376
377 Double_t AliGenPHOSlib::YEtaprime( Double_t *py, Double_t *)
378{
379// y-distribution
380//____________________________________________________________
381
382 const Double_t ka = 1000.;
383 const Double_t kdy = 4.;
384
385
386 Double_t y=TMath::Abs(*py);
387 //
388 Double_t ex = y*y/(2*kdy*kdy);
389 return ka*TMath::Exp(-ex);
390}
391
392 Int_t AliGenPHOSlib::IpEtaprime(TRandom *)
393{
394// particle composition
395//
396
397 return 331; // Etaprime
398}
399// End EtaPrime
400//===================================================================
401//============================================================================
402// P H I S
403 Double_t AliGenPHOSlib::PtPhi( Double_t *px, Double_t *)
404{
405// phi
406// pt-distribution
407//____________________________________________________________
408
409 return PtScal(*px,6); // 6==> Phi in the PtScal function
410}
411
412 Double_t AliGenPHOSlib::YPhi( Double_t *py, Double_t *)
413{
414// y-distribution
415//____________________________________________________________
416
417 const Double_t ka = 1000.;
418 const Double_t kdy = 4.;
419
420
421 Double_t y=TMath::Abs(*py);
422 //
423 Double_t ex = y*y/(2*kdy*kdy);
424 return ka*TMath::Exp(-ex);
425}
426
427 Int_t AliGenPHOSlib::IpPhi(TRandom *)
428{
429// particle composition
430//
431
432 return 333; // Phi
433}
434// End Phis
435//===================================================================
436//============================================================================
437// B A R Y O N S == protons, protonsbar, neutrons, and neutronsbars
438 Double_t AliGenPHOSlib::PtBaryon( Double_t *px, Double_t *)
439{
440// baryons
441// pt-distribution
442//____________________________________________________________
443
444 return PtScal(*px,7); // 7==> Baryon in the PtScal function
445}
446
447 Double_t AliGenPHOSlib::YBaryon( Double_t *py, Double_t *)
448{
449// y-distribution
450//____________________________________________________________
451
452 const Double_t ka = 1000.;
453 const Double_t kdy = 4.;
454
455
456 Double_t y=TMath::Abs(*py);
457 //
458 Double_t ex = y*y/(2*kdy*kdy);
459 return ka*TMath::Exp(-ex);
460}
461
462 Int_t AliGenPHOSlib::IpBaryon(TRandom *ran)
463{
464// particle composition
465//
466
467 Float_t random = ran->Rndm();
468 Float_t random2 = ran->Rndm();
469 if (random2 < 0.5)
470 {
471 if (random < 0.5) {
472 return 2212; // p
473 } else {
474 return -2212; // pbar
475 }
476 }
477 else
478 {
479 if (random < 0.5) {
480 return 2112; // n
481 } else {
482 return -2112; // n bar
483 }
484 }
485}
486// End Baryons
487//===================================================================
488
489
490typedef Double_t (*GenFunc) (Double_t*, Double_t*);
491 GenFunc AliGenPHOSlib::GetPt(Int_t param, const char* tname) const
492{
493// Return pinter to pT parameterisation
494 GenFunc func;
495
496 switch (param)
497 {
498 case kPion:
499 func=PtPion;
500 break;
501 case kPi0Flat:
502 func=PtPi0Flat;
503 break;
504 case kKaon:
505 func=PtKaon;
506 break;
507 case kEta:
508 func=PtEta;
509 break;
510 case kEtaFlat:
511 func=PtEtaFlat;
512 break;
513 case kOmega:
514 func=PtOmega;
515 break;
516 case kEtaPrime:
517 func=PtEtaprime;
518 break;
519 case kBaryon:
520 func=PtBaryon;
521 break;
522 default:
523 func=0;
524 printf("<AliGenPHOSlib::GetPt> unknown parametrisationn");
525 }
526 return func;
527}
528
529 GenFunc AliGenPHOSlib::GetY(Int_t param, const char* tname) const
530{
531// Return pointer to Y parameterisation
532 GenFunc func;
533 switch (param)
534 {
535 case kPion:
536 func=YPion;
537 break;
538 case kPi0Flat:
539 func=YPi0Flat;
540 break;
541 case kKaon:
542 func=YKaon;
543 break;
544 case kEta:
545 func=YEta;
546 break;
547 case kEtaFlat:
548 func=YEtaFlat;
549 break;
550 case kOmega:
551 func=YOmega;
552 break;
553 case kEtaPrime:
554 func=YEtaprime;
555 break;
556 case kPhi:
557 func=YPhi;
558 break;
559 case kBaryon:
560 func=YBaryon;
561 break;
562 default:
563 func=0;
564 printf("<AliGenPHOSlib::GetY> unknown parametrisationn");
565 }
566 return func;
567}
568typedef Int_t (*GenFuncIp) (TRandom *);
569 GenFuncIp AliGenPHOSlib::GetIp(Int_t param, const char* tname) const
570{
571// Return pointer to particle composition
572 GenFuncIp func;
573 switch (param)
574 {
575 case kPion:
576 func=IpPion;
577 break;
578 case kPi0Flat:
579 func=IpPi0Flat;
580 break;
581 case kKaon:
582 func=IpKaon;
583 break;
584 case kEta:
585 func=IpEta;
586 break;
587 case kEtaFlat:
588 func=IpEtaFlat;
589 break;
590
591 case kOmega:
592 func=IpOmega;
593 break;
594 case kEtaPrime:
595 func=IpEtaprime;
596 break;
597 case kPhi:
598 func=IpPhi;
599 break;
600 case kBaryon:
601 func=IpBaryon;
602 break;
603 default:
604 func=0;
605 printf("<AliGenPHOSlib::GetIp> unknown parametrisationn");
606 }
607 return func;
608}
609