First V0 MC Analysis from H.Ricaud
[u/mrichter/AliRoot.git] / TRD / AliTRDv1.cxx
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4c039060 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/* $Id$ */
4c039060 17
030b4415 18////////////////////////////////////////////////////////////////////////////
19// //
20// Transition Radiation Detector version 1 -- slow simulator //
21// //
22////////////////////////////////////////////////////////////////////////////
fe4da5cc 23
769257f4 24#include <stdlib.h>
25
793ff80c 26#include <TF1.h>
1819f4bb 27#include <TLorentzVector.h>
88cb7938 28#include <TMath.h>
29#include <TRandom.h>
30#include <TVector.h>
31#include <TVirtualMC.h>
f57bb418 32#include <TGeoManager.h>
170c35f1 33#include <TGeoPhysicalNode.h>
fe4da5cc 34
d3f347ff 35#include "AliConst.h"
45160b1f 36#include "AliLog.h"
e6add757 37#include "AliTrackReference.h"
45160b1f 38#include "AliMC.h"
88cb7938 39#include "AliRun.h"
030b4415 40
88cb7938 41#include "AliTRDgeometry.h"
793ff80c 42#include "AliTRDhit.h"
cb2f9e9b 43#include "AliTRDsimTR.h"
88cb7938 44#include "AliTRDv1.h"
851d3db9 45
fe4da5cc 46ClassImp(AliTRDv1)
8230f242 47
48//_____________________________________________________________________________
030b4415 49AliTRDv1::AliTRDv1()
50 :AliTRD()
51 ,fTRon(kFALSE)
52 ,fTR(NULL)
53 ,fTypeOfStepManager(0)
54 ,fStepSize(0)
55 ,fDeltaE(NULL)
56 ,fDeltaG(NULL)
57 ,fTrackLength0(0)
58 ,fPrimaryTrackPid(0)
8230f242 59{
60 //
61 // Default constructor
62 //
63
8230f242 64}
65
fe4da5cc 66//_____________________________________________________________________________
67AliTRDv1::AliTRDv1(const char *name, const char *title)
030b4415 68 :AliTRD(name,title)
69 ,fTRon(kTRUE)
70 ,fTR(NULL)
67c47633 71 ,fTypeOfStepManager(2)
030b4415 72 ,fStepSize(0.1)
73 ,fDeltaE(NULL)
74 ,fDeltaG(NULL)
75 ,fTrackLength0(0)
76 ,fPrimaryTrackPid(0)
fe4da5cc 77{
78 //
851d3db9 79 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 80 //
82bbf98a 81
5c7f4665 82 SetBufferSize(128000);
83
84}
85
86//_____________________________________________________________________________
87AliTRDv1::~AliTRDv1()
88{
dd9a6ee3 89 //
90 // AliTRDv1 destructor
91 //
82bbf98a 92
030b4415 93 if (fDeltaE) {
94 delete fDeltaE;
95 fDeltaE = 0;
96 }
97
98 if (fDeltaG) {
99 delete fDeltaG;
100 fDeltaG = 0;
101 }
102
103 if (fTR) {
104 delete fTR;
105 fTR = 0;
106 }
82bbf98a 107
fe4da5cc 108}
109
dd9a6ee3 110//_____________________________________________________________________________
f57bb418 111void AliTRDv1::AddAlignableVolumes() const
112{
113 //
114 // Create entries for alignable volumes associating the symbolic volume
115 // name with the corresponding volume path. Needs to be syncronized with
116 // eventual changes in the geometry.
117 //
118
119 TString volPath;
120 TString symName;
121
92cd97ad 122 TString vpStr = "ALIC_1/B077_1/BSEGMO";
123 TString vpApp1 = "_1/BTRD";
124 TString vpApp2 = "_1";
125 TString vpApp3a = "/UTR1_1/UTS1_1/UTI1_1/UT";
126 TString vpApp3b = "/UTR2_1/UTS2_1/UTI2_1/UT";
127 TString vpApp3c = "/UTR3_1/UTS3_1/UTI3_1/UT";
f57bb418 128
92cd97ad 129 TString snStr = "TRD/sm";
130 TString snApp1 = "/st";
131 TString snApp2 = "/pl";
f57bb418 132
133 //
134 // The super modules
135 // The symbolic names are: TRD/sm00
136 // ...
137 // TRD/sm17
138 //
139 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
140
141 volPath = vpStr;
142 volPath += isect;
143 volPath += vpApp1;
144 volPath += isect;
145 volPath += vpApp2;
146
147 symName = snStr;
148 symName += Form("%02d",isect);
149
150 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
151
152 }
153
154 //
155 // The readout chambers
156 // The symbolic names are: TRD/sm00/st0/pl0
157 // ...
158 // TRD/sm17/st4/pl5
159 //
160 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
8bf0cd64 161
162 if (fGeometry->GetSMstatus(isect) == 0) continue;
163
f57bb418 164 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
165 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
166
167 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
168
169 volPath = vpStr;
170 volPath += isect;
171 volPath += vpApp1;
172 volPath += isect;
173 volPath += vpApp2;
92cd97ad 174 switch (isect) {
175 case 13:
176 case 14:
177 case 15:
178 if (icham == 2) {
179 continue;
180 }
181 volPath += vpApp3c;
182 break;
183 case 11:
184 case 12:
185 volPath += vpApp3b;
186 break;
187 default:
188 volPath += vpApp3a;
189 };
f57bb418 190 volPath += Form("%02d",idet);
191 volPath += vpApp2;
192
193 symName = snStr;
194 symName += Form("%02d",isect);
195 symName += snApp1;
196 symName += icham;
197 symName += snApp2;
198 symName += iplan;
199
51a5f1d0 200 TGeoPNEntry *alignableEntry =
201 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
f57bb418 202
170c35f1 203 // Add the tracking to local matrix following the TPC example
51a5f1d0 204 if (alignableEntry) {
205 const char *path = alignableEntry->GetTitle();
206 if (!gGeoManager->cd(path)) {
207 AliFatal(Form("Volume path %s not valid!",path));
208 }
92cd97ad 209 // Is this correct still????
51a5f1d0 210 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
211 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
212 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
213 t2lMatrix->RotateZ(sectorAngle);
214 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
215 alignableEntry->SetMatrix(t2lMatrix);
216 }
217 else {
218 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
219 }
8bf0cd64 220
f57bb418 221 }
222 }
223 }
224
225}
226
227//_____________________________________________________________________________
fe4da5cc 228void AliTRDv1::CreateGeometry()
229{
230 //
851d3db9 231 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 232 // This version covers the full azimuth.
d3f347ff 233 //
234
82bbf98a 235 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 236 AliModule* frame = gAlice->GetModule("FRAME");
030b4415 237 if (!frame) {
238 AliError("TRD needs FRAME to be present\n");
239 return;
240 }
d3f347ff 241
82bbf98a 242 // Define the chambers
243 AliTRD::CreateGeometry();
d3f347ff 244
fe4da5cc 245}
246
247//_____________________________________________________________________________
248void AliTRDv1::CreateMaterials()
249{
250 //
851d3db9 251 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 252 //
82bbf98a 253
d3f347ff 254 AliTRD::CreateMaterials();
82bbf98a 255
fe4da5cc 256}
257
258//_____________________________________________________________________________
793ff80c 259void AliTRDv1::CreateTRhit(Int_t det)
260{
261 //
262 // Creates an electron cluster from a TR photon.
263 // The photon is assumed to be created a the end of the radiator. The
264 // distance after which it deposits its energy takes into account the
265 // absorbtion of the entrance window and of the gas mixture in drift
266 // volume.
267 //
268
793ff80c 269 // Ionization energy
bc327ce2 270 const Float_t kWion = 23.53;
793ff80c 271
272 // Maximum number of TR photons per track
273 const Int_t kNTR = 50;
274
030b4415 275 TLorentzVector mom;
276 TLorentzVector pos;
793ff80c 277
ce0d6231 278 Float_t eTR[kNTR];
279 Int_t nTR;
793ff80c 280
ce0d6231 281 // Create TR photons
282 gMC->TrackMomentum(mom);
283 Float_t pTot = mom.Rho();
284 fTR->CreatePhotons(11,pTot,nTR,eTR);
285 if (nTR > kNTR) {
286 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
287 }
f73816f5 288
ce0d6231 289 // Loop through the TR photons
290 for (Int_t iTR = 0; iTR < nTR; iTR++) {
793ff80c 291
ce0d6231 292 Float_t energyMeV = eTR[iTR] * 0.001;
293 Float_t energyeV = eTR[iTR] * 1000.0;
294 Float_t absLength = 0.0;
295 Float_t sigma = 0.0;
793ff80c 296
ce0d6231 297 // Take the absorbtion in the entrance window into account
298 Double_t muMy = fTR->GetMuMy(energyMeV);
299 sigma = muMy * fFoilDensity;
300 if (sigma > 0.0) {
301 absLength = gRandom->Exp(1.0/sigma);
302 if (absLength < AliTRDgeometry::MyThick()) {
842287f2 303 continue;
304 }
ce0d6231 305 }
306 else {
307 continue;
308 }
793ff80c 309
ce0d6231 310 // The absorbtion cross sections in the drift gas
311 // Gas-mixture (Xe/CO2)
312 Double_t muXe = fTR->GetMuXe(energyMeV);
313 Double_t muCO = fTR->GetMuCO(energyMeV);
314 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
315
316 // The distance after which the energy of the TR photon
317 // is deposited.
318 if (sigma > 0.0) {
319 absLength = gRandom->Exp(1.0/sigma);
320 if (absLength > (AliTRDgeometry::DrThick()
321 + AliTRDgeometry::AmThick())) {
842287f2 322 continue;
323 }
ce0d6231 324 }
325 else {
326 continue;
327 }
793ff80c 328
ce0d6231 329 // The position of the absorbtion
330 Float_t posHit[3];
331 gMC->TrackPosition(pos);
332 posHit[0] = pos[0] + mom[0] / pTot * absLength;
333 posHit[1] = pos[1] + mom[1] / pTot * absLength;
334 posHit[2] = pos[2] + mom[2] / pTot * absLength;
793ff80c 335
ce0d6231 336 // Create the charge
337 Int_t q = ((Int_t) (energyeV / kWion));
793ff80c 338
ce0d6231 339 // Add the hit to the array. TR photon hits are marked
340 // by negative charge
341 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
342 ,det
343 ,posHit
344 ,-q
25ca55ce 345 ,gMC->TrackTime()*1.0e06
d4c6453d 346 ,kTRUE);
793ff80c 347
348 }
349
350}
351
352//_____________________________________________________________________________
5c7f4665 353void AliTRDv1::Init()
354{
355 //
356 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 357 //
358
359 AliTRD::Init();
360
45160b1f 361 AliDebug(1,"Slow simulator\n");
bd0f8685 362
363 // Switch on TR simulation as default
364 if (!fTRon) {
45160b1f 365 AliInfo("TR simulation off");
bd0f8685 366 }
367 else {
cb2f9e9b 368 fTR = new AliTRDsimTR();
bd0f8685 369 }
5c7f4665 370
371 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
372 const Float_t kPoti = 12.1;
373 // Maximum energy (50 keV);
374 const Float_t kEend = 50000.0;
375 // Ermilova distribution for the delta-ray spectrum
030b4415 376 Float_t poti = TMath::Log(kPoti);
377 Float_t eEnd = TMath::Log(kEend);
a328fff9 378
379 // Ermilova distribution for the delta-ray spectrum
c4214bc0 380 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
a328fff9 381
382 // Geant3 distribution for the delta-ray spectrum
c4214bc0 383 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
5c7f4665 384
45160b1f 385 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
5c7f4665 386
fe4da5cc 387}
388
389//_____________________________________________________________________________
5c7f4665 390void AliTRDv1::StepManager()
391{
392 //
c4214bc0 393 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 394 // along its path across the drift volume.
395 //
396
397 switch (fTypeOfStepManager) {
a6dd11e9 398 case 0:
399 StepManagerErmilova();
400 break;
401 case 1:
402 StepManagerGeant();
403 break;
404 case 2:
405 StepManagerFixedStep();
406 break;
407 default:
408 AliWarning("Not a valid Step Manager.");
a328fff9 409 }
410
411}
412
413//_____________________________________________________________________________
414void AliTRDv1::SelectStepManager(Int_t t)
415{
416 //
417 // Selects a step manager type:
418 // 0 - Ermilova
419 // 1 - Geant3
420 // 2 - Fixed step size
421 //
422
a328fff9 423 fTypeOfStepManager = t;
45160b1f 424 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
a328fff9 425
426}
427
428//_____________________________________________________________________________
429void AliTRDv1::StepManagerGeant()
430{
431 //
c4214bc0 432 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 433 // along its path across the drift volume. The step size is set acording
434 // to Bethe-Bloch. The energy distribution of the delta electrons follows
435 // a spectrum taken from Geant3.
436 //
f2e3a0b5 437 // Version by A. Bercuci
438 //
439
c4214bc0 440 Int_t pla = 0;
441 Int_t cha = 0;
442 Int_t sec = 0;
443 Int_t det = 0;
444 Int_t iPdg;
445 Int_t qTot;
446
447 Float_t hits[3];
448 Float_t charge;
449 Float_t aMass;
450
030b4415 451 Double_t pTot = 0;
c4214bc0 452 Double_t eDelta;
030b4415 453 Double_t betaGamma;
454 Double_t pp;
f2e3a0b5 455 Double_t stepSize = 0;
c4214bc0 456
457 Bool_t drRegion = kFALSE;
458 Bool_t amRegion = kFALSE;
459
2c8bf4aa 460 TString cIdPath;
461 Char_t cIdSector[3];
462 cIdSector[2] = 0;
463
c4214bc0 464 TString cIdCurrent;
465 TString cIdSensDr = "J";
466 TString cIdSensAm = "K";
467 Char_t cIdChamber[3];
468 cIdChamber[2] = 0;
469
030b4415 470 TLorentzVector pos;
471 TLorentzVector mom;
c4214bc0 472
030b4415 473 TArrayI processes;
f2e3a0b5 474
c4214bc0 475 const Int_t kNplan = AliTRDgeometry::Nplan();
476 const Int_t kNcham = AliTRDgeometry::Ncham();
477 const Int_t kNdetsec = kNplan * kNcham;
478
030b4415 479 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 480 const Float_t kWion = 23.53; // Ionization energy
c4214bc0 481 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
482
483 // Minimum energy for the step size adjustment
484 const Float_t kEkinMinStep = 1.0e-5;
485 // energy threshold for production of delta electrons
f2e3a0b5 486 const Float_t kECut = 1.0e4;
487 // Parameters entering the parametrized range for delta electrons
030b4415 488 const Float_t kRa = 5.37e-4;
f2e3a0b5 489 const Float_t kRb = 0.9815;
030b4415 490 const Float_t kRc = 3.123e-3;
f2e3a0b5 491 // Gas density -> To be made user adjustable !
030b4415 492 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
493 const Float_t kRho = 0.004945 ;
a328fff9 494
c4214bc0 495 // Plateau value of the energy-loss for electron in xenon
030b4415 496 // The averaged value (26/3/99)
c4214bc0 497 const Float_t kPlateau = 1.55;
030b4415 498 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
499 const Float_t kPrim = 19.34;
c4214bc0 500 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
501 const Float_t kPoti = 12.1;
030b4415 502 // PDG code electron
503 const Int_t kPdgElectron = 11;
c4214bc0 504
505 // Set the maximum step size to a very large number for all
506 // neutral particles and those outside the driftvolume
507 gMC->SetMaxStep(kBig);
508
509 // Use only charged tracks
510 if (( gMC->TrackCharge() ) &&
c4214bc0 511 (!gMC->IsTrackDisappeared())) {
512
513 // Inside a sensitive volume?
514 drRegion = kFALSE;
515 amRegion = kFALSE;
516 cIdCurrent = gMC->CurrentVolName();
517 if (cIdSensDr == cIdCurrent[1]) {
518 drRegion = kTRUE;
519 }
520 if (cIdSensAm == cIdCurrent[1]) {
521 amRegion = kTRUE;
522 }
523 if (drRegion || amRegion) {
a328fff9 524
c4214bc0 525 // The hit coordinates and charge
526 gMC->TrackPosition(pos);
527 hits[0] = pos[0];
528 hits[1] = pos[1];
529 hits[2] = pos[2];
530
2c8bf4aa 531 // The sector number (0 - 17), according to standard coordinate system
532 cIdPath = gGeoManager->GetPath();
533 cIdSector[0] = cIdPath[21];
534 cIdSector[1] = cIdPath[22];
535 sec = atoi(cIdSector);
c4214bc0 536
537 // The plane and chamber number
030b4415 538 cIdChamber[0] = cIdCurrent[2];
539 cIdChamber[1] = cIdCurrent[3];
c4214bc0 540 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 541 cha = ((Int_t) idChamber / kNplan);
c4214bc0 542 pla = ((Int_t) idChamber % kNplan);
543
ce0d6231 544 // The detector number
545 det = fGeometry->GetDetector(pla,cha,sec);
c4214bc0 546
ce0d6231 547 // Special hits only in the drift region
548 if ((drRegion) &&
549 (gMC->IsTrackEntering())) {
c4214bc0 550
ce0d6231 551 // Create a track reference at the entrance of each
552 // chamber that contains the momentum components of the particle
553 gMC->TrackMomentum(mom);
e6add757 554 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
c4214bc0 555
ce0d6231 556 // Create the hits from TR photons if electron/positron is
557 // entering the drift volume
558 if ((fTR) &&
559 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
560 CreateTRhit(det);
561 }
f2e3a0b5 562
ce0d6231 563 }
564 else if ((amRegion) &&
565 (gMC->IsTrackExiting())) {
f2e3a0b5 566
ce0d6231 567 // Create a track reference at the exit of each
568 // chamber that contains the momentum components of the particle
569 gMC->TrackMomentum(mom);
e6add757 570 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
c4214bc0 571
ce0d6231 572 }
c4214bc0 573
ce0d6231 574 // Calculate the energy of the delta-electrons
575 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
576 // take into account correlation with the underlying GEANT tracking
577 // mechanism. see
578 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
579 //
580 // determine the most significant process (last on the processes list)
581 // which caused this hit
582 gMC->StepProcesses(processes);
583 Int_t nofprocesses = processes.GetSize();
584 Int_t pid;
585 if (!nofprocesses) {
586 pid = 0;
587 }
588 else {
589 pid = processes[nofprocesses-1];
590 }
f2e3a0b5 591
ce0d6231 592 // Generate Edep according to GEANT parametrisation
593 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
594 eDelta = TMath::Max(eDelta,0.0);
595 Float_t prRange = 0.0;
596 Float_t range = gMC->TrackLength() - fTrackLength0;
597 // merge GEANT tracker information with locally cooked one
598 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
599 if (pid == 27) {
600 if (eDelta >= kECut) {
601 prRange = kRa * eDelta * 0.001
602 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
603 if (prRange >= (3.7 - range)) {
604 eDelta *= 0.1;
605 }
606 }
607 }
608 else if (pid == 1) {
609 if (eDelta < kECut) {
610 eDelta *= 0.5;
611 }
612 else {
613 prRange = kRa * eDelta * 0.001
614 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
615 if (prRange >= ((AliTRDgeometry::DrThick()
616 + AliTRDgeometry::AmThick()) - range)) {
617 eDelta *= 0.05;
618 }
619 else {
f2e3a0b5 620 eDelta *= 0.5;
ce0d6231 621 }
622 }
623 }
f2e3a0b5 624 else {
625 eDelta = 0.0;
ce0d6231 626 }
627 }
628 else {
629 eDelta = 0.0;
630 }
c4214bc0 631
ce0d6231 632 // Generate the electron cluster size
633 if (eDelta > 0.0) {
f2e3a0b5 634
ce0d6231 635 qTot = ((Int_t) (eDelta / kWion) + 1);
636
637 // Create a new dEdx hit
030b4415 638 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
639 ,det
640 ,hits
641 ,qTot
25ca55ce 642 ,gMC->TrackTime()*1.0e06
030b4415 643 ,drRegion);
c4214bc0 644
ce0d6231 645 }
646
647 // Calculate the maximum step size for the next tracking step
648 // Produce only one hit if Ekin is below cutoff
649 aMass = gMC->TrackMass();
650 if ((gMC->Etot() - aMass) > kEkinMinStep) {
651
652 // The energy loss according to Bethe Bloch
653 iPdg = TMath::Abs(gMC->TrackPid());
654 if ((iPdg != kPdgElectron) ||
655 ((iPdg == kPdgElectron) &&
656 (pTot < kPTotMaxEl))) {
657 gMC->TrackMomentum(mom);
658 pTot = mom.Rho();
659 betaGamma = pTot / aMass;
660 pp = BetheBlochGeant(betaGamma);
661 // Take charge > 1 into account
662 charge = gMC->TrackCharge();
663 if (TMath::Abs(charge) > 1) {
664 pp = pp * charge*charge;
665 }
666 }
667 else {
668 // Electrons above 20 Mev/c are at the plateau
669 pp = kPrim * kPlateau;
670 }
f2e3a0b5 671
ce0d6231 672 Int_t nsteps = 0;
673 do {
674 nsteps = gRandom->Poisson(pp);
675 } while(!nsteps);
676 stepSize = 1.0 / nsteps;
677 gMC->SetMaxStep(stepSize);
f2e3a0b5 678
c4214bc0 679 }
f2e3a0b5 680
c4214bc0 681 }
f2e3a0b5 682
c4214bc0 683 }
f2e3a0b5 684
a328fff9 685}
686
687//_____________________________________________________________________________
688void AliTRDv1::StepManagerErmilova()
689{
690 //
691 // Slow simulator. Every charged track produces electron cluster as hits
5c7f4665 692 // along its path across the drift volume. The step size is set acording
693 // to Bethe-Bloch. The energy distribution of the delta electrons follows
694 // a spectrum taken from Ermilova et al.
695 //
696
851d3db9 697 Int_t pla = 0;
698 Int_t cha = 0;
699 Int_t sec = 0;
793ff80c 700 Int_t det = 0;
851d3db9 701 Int_t iPdg;
793ff80c 702 Int_t qTot;
5c7f4665 703
793ff80c 704 Float_t hits[3];
a5cadd36 705 Double_t random[1];
5c7f4665 706 Float_t charge;
707 Float_t aMass;
708
030b4415 709 Double_t pTot = 0.0;
5c7f4665 710 Double_t eDelta;
030b4415 711 Double_t betaGamma;
712 Double_t pp;
f73816f5 713 Double_t stepSize;
5c7f4665 714
332e9569 715 Bool_t drRegion = kFALSE;
716 Bool_t amRegion = kFALSE;
717
2c8bf4aa 718 TString cIdPath;
719 Char_t cIdSector[3];
720 cIdSector[2] = 0;
721
332e9569 722 TString cIdCurrent;
723 TString cIdSensDr = "J";
724 TString cIdSensAm = "K";
593a9fc3 725 Char_t cIdChamber[3];
726 cIdChamber[2] = 0;
332e9569 727
030b4415 728 TLorentzVector pos;
729 TLorentzVector mom;
82bbf98a 730
332e9569 731 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 732 const Int_t kNcham = AliTRDgeometry::Ncham();
733 const Int_t kNdetsec = kNplan * kNcham;
734
030b4415 735 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 736 const Float_t kWion = 23.53; // Ionization energy
a328fff9 737 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
5c7f4665 738
f73816f5 739 // Minimum energy for the step size adjustment
740 const Float_t kEkinMinStep = 1.0e-5;
a328fff9 741
5c7f4665 742 // Plateau value of the energy-loss for electron in xenon
030b4415 743 // The averaged value (26/3/99)
a3c76cdc 744 const Float_t kPlateau = 1.55;
030b4415 745 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
746 const Float_t kPrim = 48.0;
5c7f4665 747 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 748 const Float_t kPoti = 12.1;
030b4415 749 // PDG code electron
750 const Int_t kPdgElectron = 11;
5c7f4665 751
752 // Set the maximum step size to a very large number for all
753 // neutral particles and those outside the driftvolume
754 gMC->SetMaxStep(kBig);
755
756 // Use only charged tracks
757 if (( gMC->TrackCharge() ) &&
5c7f4665 758 (!gMC->IsTrackDisappeared())) {
fe4da5cc 759
5c7f4665 760 // Inside a sensitive volume?
332e9569 761 drRegion = kFALSE;
762 amRegion = kFALSE;
763 cIdCurrent = gMC->CurrentVolName();
e6674585 764 if (cIdSensDr == cIdCurrent[1]) {
332e9569 765 drRegion = kTRUE;
766 }
e6674585 767 if (cIdSensAm == cIdCurrent[1]) {
332e9569 768 amRegion = kTRUE;
769 }
770 if (drRegion || amRegion) {
fe4da5cc 771
5c7f4665 772 // The hit coordinates and charge
773 gMC->TrackPosition(pos);
774 hits[0] = pos[0];
775 hits[1] = pos[1];
776 hits[2] = pos[2];
5c7f4665 777
2c8bf4aa 778 // The sector number (0 - 17), according to standard coordinate system
779 cIdPath = gGeoManager->GetPath();
780 cIdSector[0] = cIdPath[21];
781 cIdSector[1] = cIdPath[22];
782 sec = atoi(cIdSector);
82bbf98a 783
332e9569 784 // The plane and chamber number
785 cIdChamber[0] = cIdCurrent[2];
786 cIdChamber[1] = cIdCurrent[3];
e644678a 787 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 788 cha = ((Int_t) idChamber / kNplan);
332e9569 789 pla = ((Int_t) idChamber % kNplan);
82bbf98a 790
ce0d6231 791 // The detector number
792 det = fGeometry->GetDetector(pla,cha,sec);
5c7f4665 793
ce0d6231 794 // Special hits only in the drift region
795 if ((drRegion) &&
796 (gMC->IsTrackEntering())) {
5c7f4665 797
ce0d6231 798 // Create a track reference at the entrance of each
799 // chamber that contains the momentum components of the particle
800 gMC->TrackMomentum(mom);
e6add757 801 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
793ff80c 802
ce0d6231 803 // Create the hits from TR photons if electron/positron is
804 // entering the drift volume
805 if ((fTR) &&
806 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
807 CreateTRhit(det);
808 }
f73816f5 809
ce0d6231 810 }
811 else if ((amRegion) &&
812 (gMC->IsTrackExiting())) {
f73816f5 813
ce0d6231 814 // Create a track reference at the exit of each
815 // chamber that contains the momentum components of the particle
816 gMC->TrackMomentum(mom);
e6add757 817 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
f73816f5 818
ce0d6231 819 }
820
821 // Calculate the energy of the delta-electrons
822 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
823 eDelta = TMath::Max(eDelta,0.0);
824
825 // Generate the electron cluster size
826 if (eDelta > 0.0) {
827
828 qTot = ((Int_t) (eDelta / kWion) + 1);
f73816f5 829
030b4415 830 // Create a new dEdx hit
332e9569 831 if (drRegion) {
a328fff9 832 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 833 ,det
834 ,hits
835 ,qTot
25ca55ce 836 ,gMC->TrackTime()*1.0e06
030b4415 837 ,kTRUE);
838 }
5c7f4665 839 else {
a328fff9 840 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 841 ,det
842 ,hits
843 ,qTot
25ca55ce 844 ,gMC->TrackTime()*1.0e06
030b4415 845 ,kFALSE);
846 }
f73816f5 847
ce0d6231 848 }
849
850 // Calculate the maximum step size for the next tracking step
851 // Produce only one hit if Ekin is below cutoff
852 aMass = gMC->TrackMass();
853 if ((gMC->Etot() - aMass) > kEkinMinStep) {
854
855 // The energy loss according to Bethe Bloch
856 iPdg = TMath::Abs(gMC->TrackPid());
857 if ((iPdg != kPdgElectron) ||
858 ((iPdg == kPdgElectron) &&
859 (pTot < kPTotMaxEl))) {
860 gMC->TrackMomentum(mom);
861 pTot = mom.Rho();
862 betaGamma = pTot / aMass;
863 pp = kPrim * BetheBloch(betaGamma);
864 // Take charge > 1 into account
865 charge = gMC->TrackCharge();
866 if (TMath::Abs(charge) > 1) {
867 pp = pp * charge*charge;
f73816f5 868 }
ce0d6231 869 }
870 else {
871 // Electrons above 20 Mev/c are at the plateau
872 pp = kPrim * kPlateau;
873 }
f73816f5 874
ce0d6231 875 if (pp > 0.0) {
876 do {
877 gMC->GetRandom()->RndmArray(1,random);
030b4415 878 }
ce0d6231 879 while ((random[0] == 1.0) ||
880 (random[0] == 0.0));
881 stepSize = - TMath::Log(random[0]) / pp;
882 gMC->SetMaxStep(stepSize);
883 }
030b4415 884
5c7f4665 885 }
030b4415 886
d3f347ff 887 }
030b4415 888
5c7f4665 889 }
030b4415 890
5c7f4665 891}
892
893//_____________________________________________________________________________
a328fff9 894void AliTRDv1::StepManagerFixedStep()
895{
896 //
897 // Slow simulator. Every charged track produces electron cluster as hits
898 // along its path across the drift volume. The step size is fixed in
899 // this version of the step manager.
900 //
901
ce0d6231 902 // PDG code electron
903 const Int_t kPdgElectron = 11;
904
a328fff9 905 Int_t pla = 0;
906 Int_t cha = 0;
907 Int_t sec = 0;
908 Int_t det = 0;
909 Int_t qTot;
910
911 Float_t hits[3];
912 Double_t eDep;
913
914 Bool_t drRegion = kFALSE;
915 Bool_t amRegion = kFALSE;
916
2c8bf4aa 917 TString cIdPath;
918 Char_t cIdSector[3];
919 cIdSector[2] = 0;
920
a328fff9 921 TString cIdCurrent;
922 TString cIdSensDr = "J";
923 TString cIdSensAm = "K";
924 Char_t cIdChamber[3];
2c8bf4aa 925 cIdChamber[2] = 0;
a328fff9 926
030b4415 927 TLorentzVector pos;
928 TLorentzVector mom;
a328fff9 929
930 const Int_t kNplan = AliTRDgeometry::Nplan();
931 const Int_t kNcham = AliTRDgeometry::Ncham();
932 const Int_t kNdetsec = kNplan * kNcham;
933
030b4415 934 const Double_t kBig = 1.0e+12;
a328fff9 935
bc327ce2 936 const Float_t kWion = 23.53; // Ionization energy
a328fff9 937 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
938
939 // Set the maximum step size to a very large number for all
940 // neutral particles and those outside the driftvolume
941 gMC->SetMaxStep(kBig);
942
943 // If not charged track or already stopped or disappeared, just return.
944 if ((!gMC->TrackCharge()) ||
ce0d6231 945 gMC->IsTrackDisappeared()) {
946 return;
947 }
a328fff9 948
949 // Inside a sensitive volume?
950 cIdCurrent = gMC->CurrentVolName();
951
ce0d6231 952 if (cIdSensDr == cIdCurrent[1]) {
953 drRegion = kTRUE;
954 }
955 if (cIdSensAm == cIdCurrent[1]) {
956 amRegion = kTRUE;
957 }
a328fff9 958
030b4415 959 if ((!drRegion) &&
960 (!amRegion)) {
961 return;
962 }
a328fff9 963
964 // The hit coordinates and charge
965 gMC->TrackPosition(pos);
966 hits[0] = pos[0];
967 hits[1] = pos[1];
968 hits[2] = pos[2];
969
2c8bf4aa 970 // The sector number (0 - 17), according to standard coordinate system
971 cIdPath = gGeoManager->GetPath();
972 cIdSector[0] = cIdPath[21];
973 cIdSector[1] = cIdPath[22];
974 sec = atoi(cIdSector);
a328fff9 975
976 // The plane and chamber number
030b4415 977 cIdChamber[0] = cIdCurrent[2];
978 cIdChamber[1] = cIdCurrent[3];
a328fff9 979 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 980 cha = ((Int_t) idChamber / kNplan);
a328fff9 981 pla = ((Int_t) idChamber % kNplan);
e0d47c25 982
030b4415 983 // The detector number
984 det = fGeometry->GetDetector(pla,cha,sec);
985
25ca55ce 986 // 0: InFlight 1:Entering 2:Exiting
030b4415 987 Int_t trkStat = 0;
a328fff9 988
989 // Special hits only in the drift region
ce0d6231 990 if ((drRegion) &&
991 (gMC->IsTrackEntering())) {
a328fff9 992
ce0d6231 993 // Create a track reference at the entrance of each
994 // chamber that contains the momentum components of the particle
995 gMC->TrackMomentum(mom);
e6add757 996 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
ce0d6231 997 trkStat = 1;
a328fff9 998
ce0d6231 999 // Create the hits from TR photons if electron/positron is
1000 // entering the drift volume
1001 if ((fTR) &&
1002 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
030b4415 1003 CreateTRhit(det);
1004 }
a328fff9 1005
1006 }
ce0d6231 1007 else if ((amRegion) &&
1008 (gMC->IsTrackExiting())) {
1009
1010 // Create a track reference at the exit of each
1011 // chamber that contains the momentum components of the particle
1012 gMC->TrackMomentum(mom);
e6add757 1013 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
ce0d6231 1014 trkStat = 2;
1015
1016 }
a328fff9 1017
1018 // Calculate the charge according to GEANT Edep
1019 // Create a new dEdx hit
1020 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1021 qTot = (Int_t) (eDep / kWion);
ce0d6231 1022 if ((qTot) ||
1023 (trkStat)) {
1024 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1025 ,det
1026 ,hits
1027 ,qTot
25ca55ce 1028 ,gMC->TrackTime()*1.0e06
ce0d6231 1029 ,drRegion);
1030 }
a328fff9 1031
1032 // Set Maximum Step Size
1033 // Produce only one hit if Ekin is below cutoff
030b4415 1034 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1035 return;
1036 }
a328fff9 1037 gMC->SetMaxStep(fStepSize);
1038
1039}
1040
1041//_____________________________________________________________________________
5c7f4665 1042Double_t AliTRDv1::BetheBloch(Double_t bg)
1043{
1044 //
1045 // Parametrization of the Bethe-Bloch-curve
1046 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1047 //
1048
1049 // This parameters have been adjusted to averaged values from GEANT
f57bb418 1050 const Double_t kP1 = 7.17960e-02;
1051 const Double_t kP2 = 8.54196;
1052 const Double_t kP3 = 1.38065e-06;
1053 const Double_t kP4 = 5.30972;
1054 const Double_t kP5 = 2.83798;
5c7f4665 1055
f73816f5 1056 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1057 const Double_t kBgMin = 0.8;
1058 const Double_t kBBMax = 6.83298;
f73816f5 1059
1060 if (bg > kBgMin) {
030b4415 1061 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
5c7f4665 1062 Double_t aa = TMath::Power(yy,kP4);
030b4415 1063 Double_t bb = TMath::Power((1.0/bg),kP5);
5c7f4665 1064 bb = TMath::Log(kP3 + bb);
030b4415 1065 return ((kP2 - aa - bb) * kP1 / aa);
5c7f4665 1066 }
f73816f5 1067 else {
1068 return kBBMax;
1069 }
d3f347ff 1070
fe4da5cc 1071}
5c7f4665 1072
1073//_____________________________________________________________________________
c4214bc0 1074Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
a328fff9 1075{
1076 //
1077 // Return dN/dx (number of primary collisions per centimeter)
1078 // for given beta*gamma factor.
1079 //
1080 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1081 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1082 // This must be used as a set with IntSpecGeant.
1083 //
1084
030b4415 1085 Int_t i = 0;
a328fff9 1086
030b4415 1087 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1088 , 1.800000, 2.000000, 2.500000, 3.000000
1089 , 4.000000, 7.000000, 10.000000, 20.000000
1090 , 40.000000, 70.000000, 100.000000, 300.000000
1091 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
a328fff9 1092
030b4415 1093 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1094 , 22.734999, 21.411915, 19.934095, 19.449375
1095 , 19.344431, 20.185553, 21.027925, 22.912676
1096 , 24.933352, 26.504053, 27.387468, 29.566597
1097 , 30.353779, 30.787134, 31.129285, 31.157350 };
1098
1099 // Betagamma to gamma
1100 Double_t g = TMath::Sqrt(1.0 + bg*bg);
a328fff9 1101
1102 // Find the index just before the point we need.
030b4415 1103 for (i = 0; i < 18; i++) {
1104 if ((arrG[i] < g) &&
1105 (arrG[i+1] > g)) {
a328fff9 1106 break;
030b4415 1107 }
1108 }
a328fff9 1109
1110 // Simple interpolation.
030b4415 1111 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1112 * (g - arrG[i]) + arrNC[i];
a328fff9 1113
030b4415 1114 return pp;
a328fff9 1115
1116}
1117
1118//_____________________________________________________________________________
5c7f4665 1119Double_t Ermilova(Double_t *x, Double_t *)
1120{
1121 //
1122 // Calculates the delta-ray energy distribution according to Ermilova.
1123 // Logarithmic scale !
1124 //
1125
1126 Double_t energy;
1127 Double_t dpos;
1128 Double_t dnde;
1129
030b4415 1130 Int_t pos1;
1131 Int_t pos2;
5c7f4665 1132
8230f242 1133 const Int_t kNv = 31;
5c7f4665 1134
030b4415 1135 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1136 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1137 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1138 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1139 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1140 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1141 , 11.5129 };
1142
1143 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1144 , 20.9, 20.8, 20.0, 16.0, 11.0
1145 , 8.0, 6.0, 5.2, 4.6, 4.0
1146 , 3.5, 3.0, 1.4, 0.67, 0.44
1147 , 0.3, 0.18, 0.12, 0.08, 0.056
1148 , 0.04, 0.023, 0.015, 0.011, 0.01
1149 , 0.004 };
5c7f4665 1150
1151 energy = x[0];
1152
1153 // Find the position
030b4415 1154 pos1 = 0;
1155 pos2 = 0;
5c7f4665 1156 dpos = 0;
1157 do {
1158 dpos = energy - vxe[pos2++];
1159 }
1160 while (dpos > 0);
1161 pos2--;
030b4415 1162 if (pos2 > kNv) {
1163 pos2 = kNv - 1;
1164 }
5c7f4665 1165 pos1 = pos2 - 1;
1166
1167 // Differentiate between the sampling points
1168 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1169
1170 return dnde;
1171
1172}
a328fff9 1173
1174//_____________________________________________________________________________
1175Double_t IntSpecGeant(Double_t *x, Double_t *)
1176{
1177 //
1178 // Integrated spectrum from Geant3
1179 //
1180
96efaf83 1181 const Int_t npts = 83;
030b4415 1182 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1183 , 2.672067, 2.813299, 3.015059, 3.216819
1184 , 3.418579, 3.620338, 3.868209, 3.920198
1185 , 3.978284, 4.063923, 4.186264, 4.308605
1186 , 4.430946, 4.553288, 4.724261, 4.837736
1187 , 4.999842, 5.161949, 5.324056, 5.486163
1188 , 5.679688, 5.752998, 5.857728, 5.962457
1189 , 6.067185, 6.171914, 6.315653, 6.393674
1190 , 6.471694, 6.539689, 6.597658, 6.655627
1191 , 6.710957, 6.763648, 6.816338, 6.876198
1192 , 6.943227, 7.010257, 7.106285, 7.252151
1193 , 7.460531, 7.668911, 7.877290, 8.085670
1194 , 8.302979, 8.353585, 8.413120, 8.483500
1195 , 8.541030, 8.592857, 8.668865, 8.820485
1196 , 9.037086, 9.253686, 9.470286, 9.686887
1197 , 9.930838, 9.994655, 10.085822, 10.176990
1198 , 10.268158, 10.359325, 10.503614, 10.627565
1199 , 10.804637, 10.981709, 11.158781, 11.335854
1200 , 11.593397, 11.781165, 12.049404, 12.317644
1201 , 12.585884, 12.854123, 14.278421, 16.975889
1202 , 20.829416, 24.682943, 28.536469 };
1203
1204 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1205 , 9.1601500, 8.206670, 6.919630, 5.655430
1206 , 4.6221300, 3.777610, 3.019560, 2.591950
1207 , 2.5414600, 2.712920, 3.327460, 4.928240
1208 , 7.6185300, 10.966700, 12.225800, 8.094750
1209 , 3.3586900, 1.553650, 1.209600, 1.263840
1210 , 1.3241100, 1.312140, 1.255130, 1.165770
1211 , 1.0594500, 0.945450, 0.813231, 0.699837
1212 , 0.6235580, 2.260990, 2.968350, 2.240320
1213 , 1.7988300, 1.553300, 1.432070, 1.535520
1214 , 1.4429900, 1.247990, 1.050750, 0.829549
1215 , 0.5900280, 0.395897, 0.268741, 0.185320
1216 , 0.1292120, 0.103545, 0.0949525, 0.101535
1217 , 0.1276380, 0.134216, 0.123816, 0.104557
1218 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1219 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1220 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1221 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1222 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1223 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1224 , 3.63304e-06, 0.0000000, 0.0000000 };
1225
1226 Int_t i;
a328fff9 1227 Double_t energy = x[0];
a328fff9 1228
225211c8 1229 if (energy >= arre[npts-1]) {
1230 return 0.0;
1231 }
1232
030b4415 1233 for (i = 0; i < npts; i++) {
1234 if (energy < arre[i]) {
1235 break;
1236 }
1237 }
a328fff9 1238
030b4415 1239 if (i == 0) {
1240 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");
1241 }
a328fff9 1242
f57bb418 1243 return arrdnde[i];
a328fff9 1244
1245}