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[u/mrichter/AliRoot.git] / TPC / AliTPCv3.cxx
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4b0fdcad 1///////////////////////////////////////////////////////////////////////////////
2// //
3// Time Projection Chamber version 3 -- detailed TPC and slow simulation //
4// //
5//Begin_Html
6/*
7<img src="picts/AliTPCv3Class.gif">
8*/
9//End_Html
10// //
11// //
12///////////////////////////////////////////////////////////////////////////////
13
14#include <stdlib.h>
15#include <TMath.h>
16
17#include "AliTPCv3.h"
18#include "AliRun.h"
19#include "AliConst.h"
1283eee5 20#include "AliTPCD.h"
21#include"AliTPCParam.h"
4b0fdcad 22
23ClassImp(AliTPCv3)
24
25//_____________________________________________________________________________
26AliTPCv3::AliTPCv3(const char *name, const char *title) :
27 AliTPC(name, title)
28{
29 //
30 // Standard constructor for Time Projection Chamber version 2
31 //
32
33 SetBufferSize(128000);
34}
35
36//_____________________________________________________________________________
37void AliTPCv3::CreateGeometry()
38{
39 //
1283eee5 40 // Creation of the TPC coarse geometry (version 0)
41 // Origin Marek Kowalski Crakow
4b0fdcad 42 //
43 //Begin_Html
44 /*
1283eee5 45 <img src="picts/AliTPCv0.gif">
4b0fdcad 46 */
47 //End_Html
48 //Begin_Html
49 /*
1283eee5 50 <img src="picts/AliTPCv0Tree.gif">
4b0fdcad 51 */
52 //End_Html
53
1283eee5 54 AliTPCParam * fTPCParam = &(fDigParam->GetParam());
4b0fdcad 55
1283eee5 56 Int_t *idtmed = fIdtmed->GetArray();
57
58 Float_t dm[21];
62a73ee5 59 Int_t idrotm[120];
1283eee5 60
61 Int_t nRotMat = 0;
62
63
4b0fdcad 64 // ----------------------------------------------------
1283eee5 65 // FIELD CAGE WITH ENDCAPS - G10
4b0fdcad 66 // THIS IS ALSO A TPC MOTHER VOLUME
67 // ----------------------------------------------------
1283eee5 68
4b0fdcad 69 dm[0] = 76.;
70 dm[1] = 278.;
71 dm[2] = 275.;
1283eee5 72
73 gMC->Gsvolu("TPC ", "TUBE", idtmed[8], dm, 3);
74
75 //-----------------------------------------------------
76 // Endcap cover c-fibre 0.86% X0
77 //-----------------------------------------------------
78
79 dm[0] = 78.;
80 dm[1] = 258.;
81 dm[2] = 0.95;
82
83 gMC->Gsvolu("TPEC","TUBE",idtmed[10],dm,3);
84
85 //-----------------------------------------------------
86 // Drift gas , leave 2 cm at the outer radius
87 // and inner raddius
88 //-----------------------------------------------------
89
90 dm[0] = 78.;
91 dm[1] = 258.;
4b0fdcad 92 dm[2] = 250.;
93
1283eee5 94 gMC->Gsvolu("TGAS", "TUBE", idtmed[4], dm, 3);
95
4b0fdcad 96
1283eee5 97 //------------------------------------------------------
98 // membrane holder - carbon fiber
99 //------------------------------------------------------
100
101
102 gMC->Gsvolu("TPMH","TUBE",idtmed[6],dm,0);
103
104 dm[0] = 252.;
105 dm[1] = 258.;
106 dm[2] = 0.2;
107
108 gMC->Gsposp("TPMH",1,"TGAS",0.,0.,0.,0,"ONLY",dm,3);
109
110 dm[0] = 78.;
111 dm[2] = 82.;
112 dm[2] = 0.1;
113
114 gMC->Gsposp("TPMH",2,"TGAS",0.,0.,0.,0,"ONLY",dm,3);
115
116 //----------------------------------------------------------
117 // HV membrane - 25 microns of mylar
118 //----------------------------------------------------------
119
120 dm[0] = 82.;
121 dm[1] = 252.;
122 dm[2] = 0.00125;
123
124 gMC->Gsvolu("TPHV","TUBE",idtmed[5],dm,3);
125
126 gMC->Gspos("TPHV",1,"TGAS",0.,0.,0.,0,"ONLY");
127
128 gMC->Gspos("TGAS",1,"TPC ",0.,0.,0.,0,"ONLY");
129
130 //----------------------------------------------------------
131 // "side" gas volume, the same as the drift gas
132 // the readout chambers are placed there.
133 //----------------------------------------------------------
134
135 dm[0] = 78.;
136 dm[1] = 258.;
137 dm[2] = 0.5*(275. - 250.);
138
139 gMC->Gsvolu("TPSG", "TUBE", idtmed[2], dm, 3);
140
141 Float_t z_side = dm[2]; // 1/2 of the side gas thickness
142
143 //-----------------------------------------------------------
144 // Readout chambers , 25% of X0, I use Al as the material
145 //-----------------------------------------------------------
146
147 Float_t InnerOpenAngle = fTPCParam->GetInnerAngle();
148 Float_t OuterOpenAngle = fTPCParam->GetOuterAngle();
149
150 Float_t InnerAngleShift = fTPCParam->GetInnerAngleShift();
151 Float_t OuterAngleShift = fTPCParam->GetOuterAngleShift();
152
153
154 Int_t nInnerSector = fTPCParam->GetNInnerSector()/2;
155 Int_t nOuterSector = fTPCParam->GetNOuterSector()/2;
156
157
158 Float_t InSecLowEdge = fTPCParam->GetInSecLowEdge();
159 Float_t InSecUpEdge = fTPCParam->GetInSecUpEdge();
160
161 Float_t OuSecLowEdge = fTPCParam->GetOuSecLowEdge();
162 Float_t OuSecUpEdge = fTPCParam->GetOuSecUpEdge();
163
164 Float_t SecThick = 2.225; // Al
165
166 Float_t edge = fTPCParam->GetEdge();
167
168 // S (Inner) sectors
169
170 dm[0] = InSecLowEdge*TMath::Tan(0.5*InnerOpenAngle)-edge;
171 dm[1] = InSecUpEdge*TMath::Tan(0.5*InnerOpenAngle)-edge;
172 dm[2] = SecThick;
173 dm[3] = 0.5*(InSecUpEdge-InSecLowEdge);
174
175 Float_t xCenterS = InSecLowEdge+dm[3];
176
177 gMC->Gsvolu("TRCS", "TRD1", idtmed[0], dm, 4);
178
179 // L (Outer) sectors
180
181 dm[0] = OuSecLowEdge*TMath::Tan(0.5*OuterOpenAngle)-edge;
182 dm[1] = OuSecUpEdge*TMath::Tan(0.5*OuterOpenAngle)-edge;
183 dm[2] = SecThick;
184 dm[3] = 0.5*(OuSecUpEdge-OuSecLowEdge);
185
186 Float_t xCenterL = OuSecLowEdge+dm[3];
187
188 gMC->Gsvolu("TRCL", "TRD1", idtmed[0], dm, 4);
189
190 Float_t z1 = -z_side + SecThick*0.5;
191
192 //------------------------------------------------------------------
193 // Positioning of the S-sector readout chambers
194 //------------------------------------------------------------------
195
196 Int_t ns;
197 Float_t theta1,theta2,theta3;
198 Float_t phi1,phi2,phi3;
199 Float_t alpha;
200 Float_t x,y;
201
202 for(ns=0;ns<nInnerSector;ns++){
203
204 phi1 = ns * InnerOpenAngle + 270.*kDegrad + InnerAngleShift;
205 phi1 *= kRaddeg; // in degrees
206
207 phi1 = (Float_t)TMath::Nint(phi1);
208
209 if (phi1 > 360.) phi1 -= 360.;
210
4b0fdcad 211 theta1 = 90.;
212 phi2 = 90.;
213 theta2 = 180.;
1283eee5 214 phi3 = ns * InnerOpenAngle + InnerAngleShift;
215 phi3 *= kRaddeg; // in degrees
216
217 phi3 = (Float_t)TMath::Nint(phi3);
218
219 if(phi3 > 360.) phi3 -= 360.;
220
4b0fdcad 221 theta3 = 90.;
1283eee5 222
223 alpha = phi3*kDegrad;
224
225 x = xCenterS * TMath::Cos(alpha);
226 y = xCenterS * TMath::Sin(alpha);
227
228 AliMatrix(idrotm[nRotMat], theta1, phi1, theta2, phi2, theta3, phi3);
229
230 gMC->Gspos("TRCS", ns+1, "TPSG", x, y, z1, idrotm[nRotMat], "ONLY");
231
232 nRotMat++;
233
234 }
4b0fdcad 235
1283eee5 236 //-------------------------------------------------------------------
237 // Positioning of the L-sectors readout chambers
238 //-------------------------------------------------------------------
4b0fdcad 239
1283eee5 240 for(ns=0;ns<nOuterSector;ns++){
241 phi1 = ns * OuterOpenAngle + 270.*kDegrad + OuterAngleShift;
242 phi1 *= kRaddeg; // in degrees
243
244 phi1 = (Float_t)TMath::Nint(phi1);
4b0fdcad 245
1283eee5 246
247 if (phi1 > 360.) phi1 -= 360.;
248
4b0fdcad 249 theta1 = 90.;
250 phi2 = 90.;
251 theta2 = 180.;
1283eee5 252 phi3 = ns * OuterOpenAngle+OuterAngleShift;
253 phi3 *= kRaddeg; // in degrees
254
255 phi3 = (Float_t)TMath::Nint(phi3);
256
257
258 if(phi3 > 360.) phi3 -= 360.;
259
4b0fdcad 260 theta3 = 90.;
1283eee5 261
262 alpha = phi3*kDegrad;
263
264 x = xCenterL * TMath::Cos(alpha);
265 y = xCenterL * TMath::Sin(alpha);
266
267 AliMatrix(idrotm[nRotMat], theta1, phi1, theta2, phi2, theta3, phi3);
268
269
270 gMC->Gspos("TRCL", ns+1, "TPSG", x, y, z1, idrotm[nRotMat], "ONLY");
271
272 nRotMat++;
273
4b0fdcad 274 }
1283eee5 275
276 Float_t z0 = z_side - 0.95;
277
278 gMC->Gspos("TPEC",1,"TPSG",0.,0.,z0,0,"ONLY");
279
4b0fdcad 280 // ==========================================================
281 // wheels
282 // ==========================================================
1283eee5 283
284 //
285 // auxilary structures
286 //
287
288
289 gMC->Gsvolu("TPWI","TUBE",idtmed[24],dm,0); // "air"
290
4b0fdcad 291 // ----------------------------------------------------------
292 // Large wheel -> positioned in the TPC
293 // ----------------------------------------------------------
1283eee5 294
295
296 z0 = 263.5; // TPC length - 1/2 spoke wheel width
297
298 dm[0] = 258.;
4b0fdcad 299 dm[1] = 278.;
300 dm[2] = 11.5;
4b0fdcad 301
1283eee5 302 gMC->Gsvolu("TPWL", "TUBE", idtmed[0], dm, 3);
303
304 dm[0] = dm[0]+2.;
305 dm[1] = 278.;
306 dm[2] = dm[2]-2.;
307
308 gMC->Gsposp("TPWI",1,"TPWL",0.,0.,0.,0,"ONLY",dm,3);
309
310 gMC->Gspos("TPWL", 1, "TPC ", 0, 0, z0, 0, "ONLY");
311 gMC->Gspos("TPWL", 2, "TPC ", 0, 0, -z0, 0, "ONLY");
312
313 //
314 // Outer vessel + CO2 HV degrader
315 //
316
317 dm[0] = 260.;
318 dm[1] = 278.;
319 dm[2] = 252.;
320
321 gMC->Gsvolu("TPCO","TUBE",idtmed[12],dm,3);
322
323 dm[0] = 275.;
4b0fdcad 324 dm[1] = 278.;
4b0fdcad 325
1283eee5 326 gMC->Gsvolu("TPOV","TUBE",idtmed[10],dm,3);
327
328 gMC->Gspos("TPOV",1,"TPCO",0.,0.,0.,0,"ONLY");
329
330
331 // G10 plugs
332
333 dm[0] = 258.;
334 dm[1] = 260.;
335 dm[2] = 1.;
336
337 gMC->Gsvolu("TPG1","TUBE",idtmed[8],dm,3);
338 gMC->Gspos("TPG1",1,"TPCO",0.,0.,251.,0,"ONLY");
339 gMC->Gspos("TPG1",2,"TPCO",0.,0.,-251.,0,"ONLY");
340
341 gMC->Gspos("TPCO",1,"TPC ",0.,0.,0.,0,"ONLY");
342
343
344 //----------------------------------------------------------
345 // Small wheel -> positioned in "side gas
346 //----------------------------------------------------------
347
348 dm[0] = 78.;
4b0fdcad 349 dm[1] = 82.;
350 dm[2] = 11.5;
1283eee5 351
352 gMC->Gsvolu("TPWS", "TUBE", idtmed[0], dm, 3);
353
354 dm[0] = 78.;
355 dm[1] = dm[1]-2;
356 dm[2] = dm[2]-2.;
357
358 gMC->Gsvolu("TPW1", "TUBE", idtmed[2], dm, 3);
4b0fdcad 359
1283eee5 360 gMC->Gspos("TPW1", 1, "TPWS", 0., 0., 0., 0, "ONLY");
361
362 z0 = 1.; // spoke wheel is shifted w.r.t. center of the "side gas"
363
364 gMC->Gspos("TPWS", 1, "TPSG", 0, 0, z0, 0, "ONLY");
365
366
367 // to avoid overlaps
368
369 dm[0] = 76.;
370 dm[1] = 78.;
371 dm[2] = 11.5;
372
373 gMC->Gsvolu("TPS1","TUBE",idtmed[0],dm,3);
374
4b0fdcad 375 dm[2] = 9.5;
1283eee5 376
377 gMC->Gsvolu("TPS2","TUBE",idtmed[24],dm,3);
378
379 gMC->Gspos("TPS2",1,"TPS1",0.,0.,0.,0,"ONLY");
380
381 z0= 263.5;
4b0fdcad 382
1283eee5 383 gMC->Gspos("TPS1",1,"TPC ",0.,0.,z0,0,"ONLY");
384 gMC->Gspos("TPS1",2,"TPC ",0.,0.,-z0,0,"ONLY");
385
386 // G10 plug
387
388 dm[0] = 76.;
389 dm[2] = 78.;
390 dm[3] = 1.;
391
392 gMC->Gsvolu("TPG2","TUBE",idtmed[8],dm,3);
393
394 z0 = 251.;
395
396 gMC->Gspos("TPG2",1,"TPC ",0.,0.,z0,0,"ONLY");
397 gMC->Gspos("TPG2",2,"TPC ",0.,0.,-z0,0,"ONLY");
398
399
400 //---------------------------------------------------------
401 // central wheel 6 (radial direction) x 4 (along z) cm2
402 //---------------------------------------------------------
403
404 dm[0] = 140.;
405 dm[1] = 146.;
4b0fdcad 406 dm[2] = 2.;
4b0fdcad 407
1283eee5 408 gMC->Gsvolu("TPWC","TUBE",idtmed[0],dm,3);
409
410 dm[0] = dm[0] + 2.;
411 dm[1] = dm[1] - 2.;
412 dm[2] = dm[2] - 1.;
413
414 gMC->Gsposp("TPWI",2,"TPWC",0.,0.,0.,0,"ONLY",dm,3);
415
416 z0 = z_side - 1.9 - 2.;
417
418 gMC->Gspos("TPWC",1,"TPSG",0.,0.,z0,0,"ONLY");
419
420 //
421
422 gMC->Gsvolu("TPSE","BOX ",idtmed[24],dm,0); // "empty" part of the spoke
423
424
425 //---------------------------------------------------------
426 // inner spokes (nSectorInner)
427 //---------------------------------------------------------
428
429 dm[0] = 0.5*(139.9-82.1);
4b0fdcad 430 dm[1] = 3.;
431 dm[2] = 2.;
1283eee5 432
433 Float_t x1 = dm[0]+82.;
434
435 gMC->Gsvolu("TPSI","BOX",idtmed[0],dm,3);
436
437 dm[1] = dm[1]-1.;
438 dm[2] = dm[2]-1.;
439
440 gMC->Gsposp("TPSE",1,"TPSI",0.,0.,0.,0,"ONLY",dm,3);
441
442 for(ns=0;ns<nInnerSector;ns++){
443
444 phi1 = 0.5*InnerOpenAngle + ns*InnerOpenAngle + InnerAngleShift;
445 theta1=90.;
446 phi1 *=kRaddeg;
447
448 phi1 = (Float_t)TMath::Nint(phi1);
449
450 phi2 = phi1+90.;
451 if(phi2>360.) phi2 -= 360.;
452 theta2=90.;
453 phi3=0.;
454 theta3=0.;
455
4b0fdcad 456 alpha = phi1 * kDegrad;
457 x = x1 * TMath::Cos(alpha);
1283eee5 458 y = x1 * TMath::Sin(alpha);
459
460 AliMatrix(idrotm[nRotMat],theta1,phi1,theta2,phi2,theta3,phi3);
461
462 gMC->Gspos("TPSI",ns+1,"TPSG",x,y,z0,idrotm[nRotMat],"ONLY");
463
464 nRotMat++;
465
4b0fdcad 466 }
1283eee5 467
468 //-------------------------------------------------------------
469 // outer spokes (nSectorOuter)
470 //-------------------------------------------------------------
471
472 dm[0] = 0.5*(257.9-146.1);
473 dm[1] = 3.;
474 dm[2] = 2.;
475
476 x1 = dm[0] + 146.;
477
478 gMC->Gsvolu("TPSO","BOX ",idtmed[0],dm,3);
479
480 dm[1] = dm[1] - 1.;
481 dm[2] = dm[2] - 1.;
482
483 gMC->Gsposp("TPSE",2,"TPSO",0.,0.,0.,0,"ONLY",dm,3);
484
485 for(ns=0;ns<nOuterSector;ns++){
486
487 phi1 = 0.5*OuterOpenAngle + ns*OuterOpenAngle + OuterAngleShift;
488 theta1=90.;
489 phi1 *=kRaddeg;
490
491 phi1 = (Float_t)TMath::Nint(phi1);
492
493 phi2 = phi1+90.;
494 if(phi2>360.) phi2 -= 360.;
495 theta2=90.;
496 phi3=0.;
497 theta3=0.;
498
4b0fdcad 499 alpha = phi1 * kDegrad;
1283eee5 500 x = x1 * TMath::Cos(alpha);
501 y = x1 * TMath::Sin(alpha);
502
503 AliMatrix(idrotm[nRotMat],theta1,phi1,theta2,phi2,theta3,phi3);
504
505 gMC->Gspos("TPSO",ns+1,"TPSG",x,y,z0,idrotm[nRotMat],"ONLY");
506
507 nRotMat++;
508
509 }
4b0fdcad 510
1283eee5 511
4b0fdcad 512
4b0fdcad 513 // --------------------------------------------------------
514 // put the readout chambers into the TPC
515 // --------------------------------------------------------
1283eee5 516
4b0fdcad 517 theta1 = 90.;
518 phi1 = 0.;
519 theta2 = 90.;
520 phi2 = 270.;
521 theta3 = 180.;
522 phi3 = 0.;
523
1283eee5 524 AliMatrix(idrotm[nRotMat], theta1, phi1, theta2, phi2, theta3, phi3);
4b0fdcad 525
526 z0 = z_side + 250.;
527
528 gMC->Gspos("TPSG", 1, "TPC ", 0, 0, z0, 0, "ONLY");
1283eee5 529 gMC->Gspos("TPSG", 2, "TPC ", 0, 0, -z0, idrotm[nRotMat], "ONLY");
4b0fdcad 530
531 gMC->Gspos("TPC ", 1, "ALIC", 0, 0, 0, 0, "ONLY");
1283eee5 532
533 //----------------------------------------------------
534 // Inner vessel and HV degrader
535 //----------------------------------------------------
536
4b0fdcad 537 dm[0] = 0.;
538 dm[1] = 360.;
539 dm[2] = 4.;
540
541 dm[3] = -250.;
1283eee5 542 dm[4] = 74.4;
4b0fdcad 543 dm[5] = 76.;
1283eee5 544
4b0fdcad 545 dm[6] = -64.5;
546 dm[7] = 50.;
547 dm[8] = 76.;
1283eee5 548
549 dm[9] = -64.5;
4b0fdcad 550 dm[10] = 50.;
551 dm[11] = 76.;
1283eee5 552
4b0fdcad 553 dm[12] = 250.;
1283eee5 554 dm[13] = 74.4;
4b0fdcad 555 dm[14] = 76.;
1283eee5 556
557 gMC->Gsvolu("TPVD", "PCON", idtmed[12], dm, 15); // CO2
558
559 // cone parts
560
4b0fdcad 561 dm[0] = 0.;
562 dm[1] = 360.;
1283eee5 563 dm[2] = 2.;
564
565 dm[3] = 64.5;
566 dm[4] = 50.;
567 dm[5] = 51.6;
568
569 dm[6] = 250.;
570 dm[7] = 74.4;
571 dm[8] = 76.;
572
573
574 gMC->Gsvolu("TIVC","PCON",idtmed[11],dm,9); // C-fibre
575
576 gMC->Gspos("TIVC",1,"TPVD",0.,0.,0.,0,"ONLY");
577 gMC->Gspos("TIVC",2,"TPVD",0.,0.,0.,idrotm[nRotMat],"ONLY");
578
579 // barrel part
580
581 dm[0] = 50.;
582 dm[1] = 50.5;
583 dm[2] = 32.25;
584
585 gMC->Gsvolu("TIVB","TUBE",idtmed[9],dm,3);
586
587 gMC->Gspos("TIVB",1,"TPVD",0.,0.,0.,0,"ONLY");
588
589 gMC->Gspos("TPVD",1,"ALIC",0.,0.,0.,0,"ONLY");
590
4b0fdcad 591
1283eee5 592
4b0fdcad 593
1283eee5 594
4b0fdcad 595 // ---------------------------------------------------
596 // volumes ordering
597 // ---------------------------------------------------
598 gMC->Gsord("TPSG", 6);
1283eee5 599
600} // end of function
601
4b0fdcad 602
603
604//_____________________________________________________________________________
605void AliTPCv3::DrawDetector()
606{
607 //
608 // Draw a shaded view of the Time Projection Chamber version 1
609 //
610
611
612 // Set everything unseen
613 gMC->Gsatt("*", "seen", -1);
614 //
615 // Set ALIC mother transparent
616 gMC->Gsatt("ALIC","SEEN",0);
617 //
618 // Set the volumes visible
619 gMC->Gsatt("TPC","SEEN",0);
620 gMC->Gsatt("TGAS","SEEN",0);
621 gMC->Gsatt("TPSG","SEEN",0);
622 gMC->Gsatt("TPHV","SEEN",1);
1283eee5 623 gMC->Gsatt("TPMH","SEEN",1);
624 gMC->Gsatt("TPEC","SEEN",0);
4b0fdcad 625 gMC->Gsatt("TRCS","SEEN",1);
626 gMC->Gsatt("TRCL","SEEN",1);
1283eee5 627 gMC->Gsatt("TPWL","SEEN",1);
628 gMC->Gsatt("TPWI","SEEN",1);
629 gMC->Gsatt("TPWS","SEEN",1);
4b0fdcad 630 gMC->Gsatt("TPW1","SEEN",1);
1283eee5 631 gMC->Gsatt("TPS1","SEEN",1);
632 gMC->Gsatt("TPS2","SEEN",1);
633 gMC->Gsatt("TPG1","SEEN",1);
634 gMC->Gsatt("TPG2","SEEN",1);
635 gMC->Gsatt("TPWC","SEEN",1);
636 gMC->Gsatt("TPSI","SEEN",1);
637 gMC->Gsatt("TPSO","SEEN",1);
638 gMC->Gsatt("TPCO","SEEN",1);
639 gMC->Gsatt("TPOV","SEEN",1);
4b0fdcad 640 gMC->Gsatt("TPVD","SEEN",1);
641 //
642 gMC->Gdopt("hide", "on");
643 gMC->Gdopt("shad", "on");
644 gMC->Gsatt("*", "fill", 7);
645 gMC->SetClipBox(".");
646 gMC->SetClipBox("*", 0, 1000, -1000, 1000, -1000, 1000);
647 gMC->DefaultRange();
648 gMC->Gdraw("alic", 40, 30, 0, 12, 9.5, .025, .025);
649 gMC->Gdhead(1111, "Time Projection Chamber");
650 gMC->Gdman(18, 4, "MAN");
651 gMC->Gdopt("hide","off");
652}
653
654//_____________________________________________________________________________
655void AliTPCv3::CreateMaterials()
656{
657 //
658 // Define materials for version 2 of the Time Projection Chamber
659 //
660
661
662 //
663 // Increase maximum number of steps
664 gMC->SetMaxNStep(30000);
665 //
666 AliTPC::CreateMaterials();
667}
668
669//_____________________________________________________________________________
670void AliTPCv3::Init()
671{
672 //
673 // Initialises version 3 of the TPC after that it has been built
674 //
675 Int_t *idtmed = fIdtmed->GetArray()-399;
676
677 AliTPC::Init();
678
679 fIdSens1=gMC->VolId("TGAS"); // drift gas as a sensitive volume
680
681 gMC->SetMaxNStep(30000); // max. number of steps increased
682
683 gMC->Gstpar(idtmed[403],"LOSS",5);
684
685 printf("*** TPC version 3 initialized ***\n");
686 printf("Maximum number of steps = %d\n",gMC->GetMaxNStep());
687
688 //
689
690}
691
692//_____________________________________________________________________________
693void AliTPCv3::StepManager()
694{
695 //
696 // Called for every step in the Time Projection Chamber
697 //
698
699 //
700 // parameters used for the energy loss calculations
701 //
702 const Float_t prim = 14.35; // number of primary collisions per 1 cm
703 const Float_t poti = 20.77e-9; // first ionization potential for Ne/CO2
704 const Float_t w_ion = 35.97e-9; // energy for the ion-electron pair creation
705
706
707 const Float_t big = 1.e10;
708
709 Int_t id,copy;
710 TLorentzVector pos;
711 Float_t hits[4];
712 Int_t vol[2];
713 TClonesArray &lhits = *fHits;
714
715 vol[1]=0;
716 vol[0]=0;
717
718 //
719
720 gMC->SetMaxStep(big);
721
722 if(!gMC->IsTrackAlive()) return; // particle has disappeared
723
724 Float_t charge = gMC->TrackCharge();
725
726 if(TMath::Abs(charge)<=0.) return; // take only charged particles
727
728
729 id=gMC->CurrentVolID(copy);
730
731 // Check the sensitive volume
732
733 if (id != fIdSens1) return;
734
735 //
736 // charged particle is in the sensitive volume
737 //
738
739 if(gMC->TrackStep() > 0) {
740
741
742 Int_t nel = (Int_t)(((gMC->Edep())-poti)/w_ion) + 1;
743 nel=TMath::Min(nel,300); // 300 electrons corresponds to 10 keV
744
745 gMC->TrackPosition(pos);
746 hits[0]=pos[0];
747 hits[1]=pos[1];
748 hits[2]=pos[2];
749
750 //
751 // check the selected side of the TPC
752 //
753
754 if(fSide && fSide*hits[2]<=0.) return;
755
756 hits[3]=(Float_t)nel;
757
758 // Add this hit
759
760 new(lhits[fNhits++]) AliTPChit(fIshunt,gAlice->CurrentTrack(),vol,hits);
761
762 }
763
764 // Stemax calculation for the next step
765
766 Float_t pp;
767 TLorentzVector mom;
768 gMC->TrackMomentum(mom);
769 Float_t ptot=mom.Rho();
770 Float_t beta_gamma = ptot/gMC->TrackMass();
771
8022212f 772 if(gMC->IdFromPDG(gMC->TrackPid()) <= 3 && ptot > 0.002)
4b0fdcad 773 {
774 pp = prim*1.58; // electrons above 20 MeV/c are on the plateau!
775 }
776 else
777 {
778 pp=prim*BetheBloch(beta_gamma);
779 if(TMath::Abs(charge) > 1.) pp *= (charge*charge);
780 }
781
782 Float_t random[1];
783 gMC->Rndm(random,1); // good, old GRNDM from Geant3
784
785 Double_t rnd = (Double_t)random[0];
786
787 gMC->SetMaxStep(-TMath::Log(rnd)/pp);
788
789}
790
791//_____________________________________________________________________________
792Float_t AliTPCv3::BetheBloch(Float_t bg)
793{
794 //
795 // Bethe-Bloch energy loss formula
796 //
797 const Double_t p1=0.76176e-1;
798 const Double_t p2=10.632;
799 const Double_t p3=0.13279e-4;
800 const Double_t p4=1.8631;
801 const Double_t p5=1.9479;
802
803 Double_t dbg = (Double_t) bg;
804
805 Double_t beta = dbg/TMath::Sqrt(1.+dbg*dbg);
806
807 Double_t aa = TMath::Power(beta,p4);
808 Double_t bb = TMath::Power(1./dbg,p5);
809
810 bb=TMath::Log(p3+bb);
811
812 return ((Float_t)((p2-aa-bb)*p1/aa));
813}