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Major upgrades to the strip structure
[u/mrichter/AliRoot.git] / TRD / AliTRDtrack.cxx
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46d29e70 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$Log$
2a941f4e 18Revision 1.4 2000/12/08 16:07:02 cblume
19Update of the tracking by Sergei
20
bbf92647 21Revision 1.3 2000/10/15 23:40:01 cblume
22Remove AliTRDconst
23
0e9c2ad5 24Revision 1.2 2000/10/06 16:49:46 cblume
25Made Getters const
26
46d29e70 27Revision 1.1.2.1 2000/09/22 14:47:52 cblume
28Add the tracking code
29
30*/
31
32#include <iostream.h>
33
34#include <TObject.h>
35
36#include "AliTRD.h"
46d29e70 37#include "AliTRDgeometry.h"
38#include "AliTRDcluster.h"
39#include "AliTRDtrack.h"
40
41ClassImp(AliTRDtrack)
42
43
44//_____________________________________________________________________________
45
46AliTRDtrack::AliTRDtrack(UInt_t index, const Double_t xx[5],
47const Double_t cc[15], Double_t xref, Double_t alpha) {
48 //-----------------------------------------------------------------
49 // This is the main track constructor.
50 //-----------------------------------------------------------------
51 fLab=-1;
52 fChi2=0.;
53 fdEdx=0.;
54
55 fAlpha=alpha;
56 fX=xref;
57
58 fY=xx[0]; fZ=xx[1]; fC=xx[2]; fE=xx[3]; fT=xx[4];
59
60 fCyy=cc[0];
61 fCzy=cc[1]; fCzz=cc[2];
62 fCcy=cc[3]; fCcz=cc[4]; fCcc=cc[5];
63 fCey=cc[6]; fCez=cc[7]; fCec=cc[8]; fCee=cc[9];
64 fCty=cc[10]; fCtz=cc[11]; fCtc=cc[12]; fCte=cc[13]; fCtt=cc[14];
65
66 fN=0;
67 fIndex[fN++]=index;
68}
69
70//_____________________________________________________________________________
71AliTRDtrack::AliTRDtrack(const AliTRDtrack& t) {
72 //
73 // Copy constructor.
74 //
75
76 fLab=t.fLab;
77
78 fChi2=t.fChi2;
79 fdEdx=t.fdEdx;
80
81 fAlpha=t.fAlpha;
82 fX=t.fX;
83
84 fY=t.fY; fZ=t.fZ; fC=t.fC; fE=t.fE; fT=t.fT;
85
86 fCyy=t.fCyy;
87 fCzy=t.fCzy; fCzz=t.fCzz;
88 fCcy=t.fCcy; fCcz=t.fCcz; fCcc=t.fCcc;
89 fCey=t.fCey; fCez=t.fCez; fCec=t.fCec; fCee=t.fCee;
90 fCty=t.fCty; fCtz=t.fCtz; fCtc=t.fCtc; fCte=t.fCte; fCtt=t.fCtt;
91
92 fN=t.fN;
93 for (Int_t i=0; i<fN; i++) fIndex[i]=t.fIndex[i];
94}
95
96//_____________________________________________________________________________
97void AliTRDtrack::GetCovariance(Double_t cc[15]) const {
98 cc[0]=fCyy;
99 cc[1]=fCzy; cc[2]=fCzz;
100 cc[3]=fCcy; cc[4]=fCcz; cc[5]=fCcc;
101 cc[6]=fCey; cc[7]=fCez; cc[8]=fCec; cc[9]=fCee;
102 cc[10]=fCty; cc[11]=fCtz; cc[12]=fCtc; cc[13]=fCte; cc[14]=fCtt;
103}
104
105//_____________________________________________________________________________
2a941f4e 106Int_t AliTRDtrack::Compare(const TObject *o) const {
46d29e70 107
108// Compares tracks according to their Y2
109
110 AliTRDtrack *t=(AliTRDtrack*)o;
111 // Double_t co=t->GetSigmaY2();
112 // Double_t c =GetSigmaY2();
113
114 Double_t co=TMath::Abs(t->GetC());
115 Double_t c =TMath::Abs(GetC());
116
117 if (c>co) return 1;
118 else if (c<co) return -1;
119 return 0;
120}
121
122//_____________________________________________________________________________
123Int_t AliTRDtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm)
124{
125 // Propagates a track of particle with mass=pm to a reference plane
126 // defined by x=xk through media of density=rho and radiationLength=x0
127
128 if (TMath::Abs(fC*xk - fE) >= 0.99999) {
129 if (fN>4) cerr<<fN<<" AliTRDtrack warning: Propagation failed !\n";
130 return 0;
131 }
132
133 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fY, z1=fZ;
134 Double_t c1=fC*x1 - fE, r1=sqrt(1.- c1*c1);
135 Double_t c2=fC*x2 - fE, r2=sqrt(1.- c2*c2);
136
137 fY += dx*(c1+c2)/(r1+r2);
138 fZ += dx*(c1+c2)/(c1*r2 + c2*r1)*fT;
139
140 //f = F - 1
141 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
142 Double_t f02= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
143 Double_t f03=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
144 Double_t cr=c1*r2+c2*r1;
145 Double_t f12= dx*fT*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
146 Double_t f13=-dx*fT*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
147 Double_t f14= dx*cc/cr;
148
149 //b = C*ft
150 Double_t b00=f02*fCcy + f03*fCey, b01=f12*fCcy + f13*fCey + f14*fCty;
151 Double_t b10=f02*fCcz + f03*fCez, b11=f12*fCcz + f13*fCez + f14*fCtz;
152 Double_t b20=f02*fCcc + f03*fCec, b21=f12*fCcc + f13*fCec + f14*fCtc;
153 Double_t b30=f02*fCec + f03*fCee, b31=f12*fCec + f13*fCee + f14*fCte;
154 Double_t b40=f02*fCtc + f03*fCte, b41=f12*fCtc + f13*fCte + f14*fCtt;
155
156 //a = f*b = f*C*ft
157 Double_t a00=f02*b20+f03*b30,a01=f02*b21+f03*b31,a11=f12*b21+f13*b31+f14*b41;
158
159 //F*C*Ft = C + (a + b + bt)
160 fCyy += a00 + 2*b00;
161 fCzy += a01 + b01 + b10;
162 fCcy += b20;
163 fCey += b30;
164 fCty += b40;
165 fCzz += a11 + 2*b11;
166 fCcz += b21;
167 fCez += b31;
168 fCtz += b41;
169
170 fX=x2;
171
172
173 //Multiple scattering ******************
174
175 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fY)*(y1-fY)+(z1-fZ)*(z1-fZ));
176 Double_t p2=GetPt()*GetPt()*(1.+fT*fT);
177 Double_t beta2=p2/(p2 + pm*pm);
178
179 Double_t ey=fC*fX - fE, ez=fT;
180 Double_t xz=fC*ez, zz1=ez*ez+1, xy=fE+ey;
181
182 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
183 fCcc += xz*xz*theta2;
184 fCec += xz*ez*xy*theta2;
185 fCtc += xz*zz1*theta2;
186 fCee += (2*ey*ez*ez*fE+1-ey*ey+ez*ez+fE*fE*ez*ez)*theta2;
187 fCte += ez*zz1*xy*theta2;
188 fCtt += zz1*zz1*theta2;
189
190
191 //Energy losses************************
192
193 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
194 if (x1 < x2) dE=-dE;
195 fC*=(1.- sqrt(p2+pm*pm)/p2*dE);
196 //fE*=(1.- sqrt(p2+pm*pm)/p2*dE);
197
198 return 1;
199
200}
201
202
203//_____________________________________________________________________________
204void AliTRDtrack::PropagateToVertex(Double_t x0,Double_t rho,Double_t pm)
205{
206 // This function propagates tracks to the "vertex".
207
208 Double_t c=fC*fX - fE;
209 Double_t tgf=-fE/(fC*fY + sqrt(1-c*c));
210 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
211 Double_t xv=(fE+snf)/fC;
212 PropagateTo(xv,x0,rho,pm);
213}
214
215
216//_____________________________________________________________________________
217void AliTRDtrack::Update(const AliTRDcluster *c, Double_t chisq, UInt_t index)
218{
219 // Assignes found cluster to the track and updates track information
220
221 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2()*12;
222 r00+=fCyy; r01+=fCzy; r11+=fCzz;
223 Double_t det=r00*r11 - r01*r01;
224 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
225
226 Double_t k00=fCyy*r00+fCzy*r01, k01=fCyy*r01+fCzy*r11;
227 Double_t k10=fCzy*r00+fCzz*r01, k11=fCzy*r01+fCzz*r11;
228 Double_t k20=fCcy*r00+fCcz*r01, k21=fCcy*r01+fCcz*r11;
229 Double_t k30=fCey*r00+fCez*r01, k31=fCey*r01+fCez*r11;
230 Double_t k40=fCty*r00+fCtz*r01, k41=fCty*r01+fCtz*r11;
231
232 Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;
233 Double_t cur=fC + k20*dy + k21*dz, eta=fE + k30*dy + k31*dz;
234 if (TMath::Abs(cur*fX-eta) >= 0.99999) {
235 if (fN>4) cerr<<fN<<" AliTRDtrack warning: Filtering failed !\n";
236 return;
237 }
238
239 fY += k00*dy + k01*dz;
240 fZ += k10*dy + k11*dz;
241 fC = cur;
242 fE = eta;
243 fT += k40*dy + k41*dz;
244
245 Double_t c01=fCzy, c02=fCcy, c03=fCey, c04=fCty;
246 Double_t c12=fCcz, c13=fCez, c14=fCtz;
247
248 fCyy-=k00*fCyy+k01*fCzy; fCzy-=k00*c01+k01*fCzz;
249 fCcy-=k00*c02+k01*c12; fCey-=k00*c03+k01*c13;
250 fCty-=k00*c04+k01*c14;
251
252 fCzz-=k10*c01+k11*fCzz;
253 fCcz-=k10*c02+k11*c12; fCez-=k10*c03+k11*c13;
254 fCtz-=k10*c04+k11*c14;
255
256 fCcc-=k20*c02+k21*c12; fCec-=k20*c03+k21*c13;
257 fCtc-=k20*c04+k21*c14;
258
259 fCee-=k30*c03+k31*c13;
260 fCte-=k30*c04+k31*c14;
261
262 fCtt-=k40*c04+k41*c14;
263
264 fIndex[fN++]=index;
265 fChi2 += chisq;
266
267 // cerr<<"in update: fIndex["<<fN<<"] = "<<index<<endl;
268}
269
270//_____________________________________________________________________________
271Int_t AliTRDtrack::Rotate(Double_t alpha)
272{
273 // Rotates track parameters in R*phi plane
274
275 fAlpha += alpha;
276
277 Double_t x1=fX, y1=fY;
278 Double_t ca=cos(alpha), sa=sin(alpha);
279 Double_t r1=fC*fX - fE;
280
281 fX = x1*ca + y1*sa;
282 fY=-x1*sa + y1*ca;
283 fE=fE*ca + (fC*y1 + sqrt(1.- r1*r1))*sa;
284
285 Double_t r2=fC*fX - fE;
286 if (TMath::Abs(r2) >= 0.99999) {
287 if (fN>4) cerr<<fN<<" AliTRDtrack warning: Rotation failed !\n";
288 return 0;
289 }
290
291 Double_t y0=fY + sqrt(1.- r2*r2)/fC;
292 if ((fY-y0)*fC >= 0.) {
293 if (fN>4) cerr<<fN<<" AliTRDtrack warning: Rotation failed !!!\n";
294 return 0;
295 }
296
297 //f = F - 1
298 Double_t f00=ca-1, f32=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
299 f30=fC*sa, f33=(ca + sa*r1/sqrt(1.- r1*r1))-1;
300
301 //b = C*ft
302 Double_t b00=fCyy*f00, b03=fCyy*f30+fCcy*f32+fCey*f33;
303 Double_t b10=fCzy*f00, b13=fCzy*f30+fCcz*f32+fCez*f33;
304 Double_t b20=fCcy*f00, b23=fCcy*f30+fCcc*f32+fCec*f33;
305 Double_t b30=fCey*f00, b33=fCey*f30+fCec*f32+fCee*f33;
306 Double_t b40=fCty*f00, b43=fCty*f30+fCtc*f32+fCte*f33;
307
308 //a = f*b = f*C*ft
309 Double_t a00=f00*b00, a03=f00*b03, a33=f30*b03+f32*b23+f33*b33;
310
311 // *** Double_t dy2=fCyy;
312
313 //F*C*Ft = C + (a + b + bt)
314 fCyy += a00 + 2*b00;
315 fCzy += b10;
316 fCcy += b20;
317 fCey += a03+b30+b03;
318 fCty += b40;
319 fCez += b13;
320 fCec += b23;
321 fCee += a33 + 2*b33;
322 fCte += b43;
323
324 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
325 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
326
327 return 1;
328}
329
330
331
332
333//_____________________________________________________________________________
334Double_t AliTRDtrack::GetPredictedChi2(const AliTRDcluster *c) const
335{
336 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2()*12;
337 r00+=fCyy; r01+=fCzy; r11+=fCzz;
338
339 Double_t det=r00*r11 - r01*r01;
340 if (TMath::Abs(det) < 1.e-10) {
341 if (fN>4) cerr<<fN<<" AliTRDtrack warning: Singular matrix !\n";
342 return 1e10;
343 }
344 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
345
346 Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;
347
348 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
349}
350
351
352//_________________________________________________________________________
353void AliTRDtrack::GetPxPyPz(Double_t& px, Double_t& py, Double_t& pz) const
354{
355 // Returns reconstructed track momentum in the global system.
356
357 Double_t pt=TMath::Abs(GetPt()); // GeV/c
358 Double_t r=fC*fX-fE;
359 Double_t y0=fY + sqrt(1.- r*r)/fC;
360 px=-pt*(fY-y0)*fC; //cos(phi);
361 py=-pt*(fE-fX*fC); //sin(phi);
362 pz=pt*fT;
363 Double_t tmp=px*TMath::Cos(fAlpha) - py*TMath::Sin(fAlpha);
364 py=px*TMath::Sin(fAlpha) + py*TMath::Cos(fAlpha);
365 px=tmp;
366
367}
368
369//____________________________________________________________________________
370void AliTRDtrack::Streamer(TBuffer &R__b)
371{
372 if (R__b.IsReading()) {
373 Version_t R__v = R__b.ReadVersion(); if (R__v) { }
374 TObject::Streamer(R__b);
375 R__b >> fLab;
376 R__b >> fChi2;
377 R__b >> fdEdx;
378 R__b >> fAlpha;
379 R__b >> fX;
380 R__b >> fY;
381 R__b >> fZ;
382 R__b >> fC;
383 R__b >> fE;
384 R__b >> fT;
385 R__b >> fCyy;
386 R__b >> fCzy;
387 R__b >> fCzz;
388 R__b >> fCcy;
389 R__b >> fCcz;
390 R__b >> fCcc;
391 R__b >> fCey;
392 R__b >> fCez;
393 R__b >> fCec;
394 R__b >> fCee;
395 R__b >> fCty;
396 R__b >> fCtz;
397 R__b >> fCtc;
398 R__b >> fCte;
399 R__b >> fCtt;
400 R__b >> fN;
401 for (Int_t i=0; i<fN; i++) R__b >> fIndex[i];
402 } else {
403 R__b.WriteVersion(AliTRDtrack::IsA());
404 TObject::Streamer(R__b);
405 R__b << fLab;
406 R__b << fChi2;
407 R__b << fdEdx;
408 R__b << fAlpha;
409 R__b << fX;
410 R__b << fY;
411 R__b << fZ;
412 R__b << fC;
413 R__b << fE;
414 R__b << fT;
415 R__b << fCyy;
416 R__b << fCzy;
417 R__b << fCzz;
418 R__b << fCcy;
419 R__b << fCcz;
420 R__b << fCcc;
421 R__b << fCey;
422 R__b << fCez;
423 R__b << fCec;
424 R__b << fCee;
425 R__b << fCty;
426 R__b << fCtz;
427 R__b << fCtc;
428 R__b << fCte;
429 R__b << fCtt;
430 R__b << fN;
431 for (Int_t i=0; i<fN; i++) R__b << fIndex[i];
432 }
433}
434
46d29e70 435