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51ad6848 | 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 | /* $Id$ */ | |
17 | ||
18 | /////////////////////////////////////////////////////////////////////////////// | |
19 | // // | |
20 | // track parameters in "external" format // | |
21 | // // | |
22 | // The track parameters are: // | |
23 | // - local y coordinate // | |
24 | // - local z coordinate // | |
25 | // - sin of azimutal angle // | |
26 | // - tan of dip angle // | |
27 | // - charge/pt // | |
28 | // The parametrisation is given at the local x coordinate fX and the // | |
29 | // azimuthal angle fAlpha. // | |
30 | // // | |
31 | // The external parametrisation can be used to exchange track parameters // | |
32 | // between different detectors. // | |
33 | // // | |
34 | /////////////////////////////////////////////////////////////////////////////// | |
35 | ||
a0209ae4 | 36 | #include <TMath.h> |
37 | #include <TVector3.h> | |
51ad6848 | 38 | |
39 | #include "AliExternalTrackParam.h" | |
40 | #include "AliKalmanTrack.h" | |
a5e407e9 | 41 | #include "AliTrackReference.h" |
0243e825 | 42 | #include "AliLog.h" |
51ad6848 | 43 | |
44 | ClassImp(AliExternalTrackParam) | |
45 | ||
a5e407e9 | 46 | const AliMagF *AliExternalTrackParam::fgkFieldMap=0; |
47 | Double_t AliExternalTrackParam::fgConvConst=0.; | |
48 | ||
51ad6848 | 49 | |
50 | //_____________________________________________________________________________ | |
90e48c0c | 51 | AliExternalTrackParam::AliExternalTrackParam() : |
0243e825 | 52 | fMass(-1), |
90e48c0c | 53 | fX(0), |
a5e407e9 | 54 | fAlpha(0), |
55 | fLocalConvConst(0) | |
51ad6848 | 56 | { |
90e48c0c | 57 | // |
58 | // default constructor | |
59 | // | |
51ad6848 | 60 | for (Int_t i = 0; i < 5; i++) fParam[i] = 0; |
61 | for (Int_t i = 0; i < 15; i++) fCovar[i] = 0; | |
62 | } | |
63 | ||
64 | //_____________________________________________________________________________ | |
65 | AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha, | |
66 | const Double_t param[5], | |
90e48c0c | 67 | const Double_t covar[15]) : |
0243e825 | 68 | fMass(-1), |
90e48c0c | 69 | fX(x), |
a5e407e9 | 70 | fAlpha(alpha), |
71 | fLocalConvConst(0) | |
51ad6848 | 72 | { |
90e48c0c | 73 | // |
74 | // create external track parameters from given arguments | |
75 | // | |
51ad6848 | 76 | for (Int_t i = 0; i < 5; i++) fParam[i] = param[i]; |
77 | for (Int_t i = 0; i < 15; i++) fCovar[i] = covar[i]; | |
78 | } | |
79 | ||
90e48c0c | 80 | //_____________________________________________________________________________ |
81 | AliExternalTrackParam::AliExternalTrackParam(const AliKalmanTrack& track) : | |
0243e825 | 82 | fMass(track.GetMass()), |
90e48c0c | 83 | fX(0), |
0243e825 | 84 | fAlpha(track.GetAlpha()), |
85 | fLocalConvConst(0) | |
51ad6848 | 86 | { |
87 | // | |
88 | // | |
89 | track.GetExternalParameters(fX,fParam); | |
90 | track.GetExternalCovariance(fCovar); | |
80030ed0 | 91 | SaveLocalConvConst(); |
51ad6848 | 92 | } |
93 | ||
a5e407e9 | 94 | |
a5e407e9 | 95 | |
51ad6848 | 96 | //_____________________________________________________________________________ |
97 | const Double_t* AliExternalTrackParam::GetParameter() const | |
98 | { | |
99 | // get a pointer to the array of track parameters | |
100 | ||
101 | return fParam; | |
102 | } | |
103 | ||
104 | //_____________________________________________________________________________ | |
105 | const Double_t* AliExternalTrackParam::GetCovariance() const | |
106 | { | |
107 | // get a pointer to the array of the track parameter covariance matrix | |
108 | ||
109 | return fCovar; | |
110 | } | |
111 | ||
112 | //_____________________________________________________________________________ | |
113 | AliExternalTrackParam* AliExternalTrackParam::CreateExternalParam() const | |
114 | { | |
115 | // copy this instance | |
116 | ||
117 | return new AliExternalTrackParam(fX, fAlpha, fParam, fCovar); | |
118 | } | |
119 | ||
120 | //_____________________________________________________________________________ | |
121 | void AliExternalTrackParam::ResetCovariance(Double_t factor, | |
122 | Bool_t clearOffDiagonal) | |
123 | { | |
124 | // reset the covariance matrix ("forget" track history) | |
125 | ||
126 | Int_t k = 0; | |
127 | for (Int_t i = 0; i < 5; i++) { | |
128 | for (Int_t j = 0; j < i; j++) { // off diagonal elements | |
129 | if (clearOffDiagonal) { | |
130 | fCovar[k++] = 0; | |
131 | } else { | |
132 | fCovar[k++] *= factor; | |
133 | } | |
134 | } | |
135 | fCovar[k++] *= factor; // diagonal elements | |
136 | } | |
137 | } | |
138 | ||
139 | ||
140 | //_____________________________________________________________________________ | |
a5e407e9 | 141 | Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t x0, Double_t rho) |
51ad6848 | 142 | { |
a5e407e9 | 143 | // |
144 | // Propagate the track parameters to the given x coordinate assuming vacuum. | |
145 | // If length is not NULL, the change of track length is added to it. | |
146 | // | |
147 | ||
148 | Double_t lcc=GetLocalConvConst(); | |
149 | Double_t cur = fParam[4]/lcc; | |
150 | Double_t x1=fX, x2=xk, dx=x2-x1; | |
151 | Double_t f1=fParam[2], f2=f1 + cur*dx; | |
152 | if (TMath::Abs(f2) >= 0.98) { | |
153 | // MI change - don't propagate highly inclined tracks | |
154 | // covariance matrix distorted | |
155 | return kFALSE; | |
156 | } | |
51ad6848 | 157 | |
a5e407e9 | 158 | // old position [SR, GSI, 17.02.2003] |
159 | Double_t oldX = fX, oldY = fParam[0], oldZ = fParam[1]; | |
160 | Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2); | |
161 | fParam[0] += dx*(f1+f2)/(r1+r2); | |
162 | fParam[1] += dx*(f1+f2)/(f1*r2 + f2*r1)*fParam[3]; | |
163 | fParam[2] += dx*cur; | |
164 | // transform error matrix to the curvature | |
165 | fCovar[10]/=lcc; | |
166 | fCovar[11]/=lcc; | |
167 | fCovar[12]/=lcc; | |
168 | fCovar[13]/=lcc; | |
169 | fCovar[14]/=lcc*lcc; | |
170 | ||
171 | //f = F - 1 | |
172 | ||
173 | Double_t f02= dx/(r1*r1*r1); | |
174 | Double_t f04=0.5*dx*dx/(r1*r1*r1); | |
175 | Double_t f12= dx*fParam[3]*f1/(r1*r1*r1); | |
176 | Double_t f14=0.5*dx*dx*fParam[3]*f1/(r1*r1*r1); | |
177 | Double_t f13= dx/r1; | |
178 | Double_t f24= dx; | |
179 | ||
180 | //b = C*ft | |
181 | Double_t b00=f02*fCovar[3] + f04*fCovar[10], b01=f12*fCovar[3] + f14*fCovar[10] + f13*fCovar[6]; | |
182 | Double_t b02=f24*fCovar[10]; | |
183 | Double_t b10=f02*fCovar[4] + f04*fCovar[11], b11=f12*fCovar[4] + f14*fCovar[11] + f13*fCovar[7]; | |
184 | Double_t b12=f24*fCovar[11]; | |
185 | Double_t b20=f02*fCovar[5] + f04*fCovar[12], b21=f12*fCovar[5] + f14*fCovar[12] + f13*fCovar[8]; | |
186 | Double_t b22=f24*fCovar[12]; | |
187 | Double_t b40=f02*fCovar[12] + f04*fCovar[14], b41=f12*fCovar[12] + f14*fCovar[14] + f13*fCovar[13]; | |
188 | Double_t b42=f24*fCovar[14]; | |
189 | Double_t b30=f02*fCovar[8] + f04*fCovar[13], b31=f12*fCovar[8] + f14*fCovar[13] + f13*fCovar[9]; | |
190 | Double_t b32=f24*fCovar[13]; | |
191 | ||
192 | //a = f*b = f*C*ft | |
193 | Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42; | |
194 | Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32; | |
195 | Double_t a22=f24*b42; | |
196 | ||
197 | //F*C*Ft = C + (b + bt + a) | |
198 | fCovar[0] += b00 + b00 + a00; | |
199 | fCovar[1] += b10 + b01 + a01; | |
200 | fCovar[2] += b11 + b11 + a11; | |
201 | fCovar[3] += b20 + b02 + a02; | |
202 | fCovar[4] += b21 + b12 + a12; | |
203 | fCovar[5] += b22 + b22 + a22; | |
204 | fCovar[6] += b30; | |
205 | fCovar[7] += b31; | |
206 | fCovar[8] += b32; | |
207 | fCovar[10] += b40; | |
208 | fCovar[11] += b41; | |
209 | fCovar[12] += b42; | |
210 | ||
211 | fX=x2; | |
212 | ||
213 | //Change of the magnetic field ************* | |
214 | SaveLocalConvConst(); | |
215 | // transform back error matrix from curvature to the 1/pt | |
216 | fCovar[10]*=lcc; | |
217 | fCovar[11]*=lcc; | |
218 | fCovar[12]*=lcc; | |
219 | fCovar[13]*=lcc; | |
220 | fCovar[14]*=lcc*lcc; | |
221 | ||
222 | Double_t dist = TMath::Sqrt((fX-oldX)*(fX-oldX)+(fParam[0]-oldY)*(fParam[0]-oldY)+ | |
223 | (fParam[1]-oldZ)*(fParam[1]-oldZ)); | |
224 | if (!CorrectForMaterial(dist,x0,rho)) return 0; | |
225 | ||
226 | // Integrated Time [SR, GSI, 17.02.2003] | |
227 | // if (IsStartedTimeIntegral() && fX>oldX) { | |
228 | // Double_t l2 = (fX-oldX)*(fX-oldX)+(fParam[0]-oldY)*(fParam[0]-oldY)+ | |
229 | // (fParam[1]-oldZ)*(fParam[1]-oldZ); | |
230 | // AddTimeStep(TMath::Sqrt(l2)); | |
231 | // } | |
232 | // | |
233 | ||
234 | return kTRUE; | |
235 | } | |
236 | ||
237 | Bool_t AliExternalTrackParam::PropagateToDCA(Double_t xd, Double_t yd, Double_t x0, Double_t rho){ | |
238 | // | |
239 | // Propagate the track parameters to the nearest point of given xv yv coordinate | |
240 | // | |
241 | Double_t a=fAlpha; | |
242 | Double_t cs=TMath::Cos(a),sn=TMath::Sin(a); | |
243 | ||
244 | Double_t xv= xd*cs + yd*sn; | |
245 | Double_t yv=-xd*sn + yd*cs; // vertex position in local frame | |
246 | // | |
247 | Double_t c=fParam[4]/GetLocalConvConst(), snp=fParam[2]; | |
248 | // | |
249 | Double_t x=fX, y=fParam[1]; | |
250 | Double_t tgfv=-(c*(x-xv)-snp)/(c*(y-yv) + TMath::Sqrt(1.-snp*snp)); | |
251 | Double_t fv=TMath::ATan(tgfv); | |
252 | cs=TMath::Cos(fv); sn=TMath::Sin(fv); | |
253 | x = xv*cs + yv*sn; | |
254 | yv=-xv*sn + yv*cs; xv=x; | |
255 | RotateTo(fv+a); | |
256 | return PropagateTo(xv,x0,rho); | |
51ad6848 | 257 | } |
258 | ||
a5e407e9 | 259 | |
51ad6848 | 260 | //_____________________________________________________________________________ |
a5e407e9 | 261 | Bool_t AliExternalTrackParam::RotateTo(Double_t alp) |
51ad6848 | 262 | { |
a5e407e9 | 263 | // Rotate the reference axis for the parametrisation to the given angle. |
264 | // | |
265 | Double_t x=fX; | |
266 | Double_t p0=fParam[0]; | |
267 | // | |
268 | if (alp < -TMath::Pi()) alp += 2*TMath::Pi(); | |
269 | else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi(); | |
270 | Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha); | |
271 | Double_t sf=fParam[2], cf=TMath::Sqrt(1.- fParam[2]*fParam[2]); | |
272 | // **** rotation ********************** | |
273 | ||
274 | fAlpha = alp; | |
275 | fX = x*ca + p0*sa; | |
276 | fParam[0]= -x*sa + p0*ca; | |
277 | fParam[2]= sf*ca - cf*sa; | |
278 | Double_t rr=(ca+sf/cf*sa); | |
279 | // | |
280 | fCovar[0] *= (ca*ca); | |
281 | fCovar[1] *= ca; | |
282 | fCovar[3] *= ca*rr; | |
283 | fCovar[6] *= ca; | |
284 | fCovar[10] *= ca; | |
285 | fCovar[4] *= rr; | |
286 | fCovar[5] *= rr*rr; | |
287 | fCovar[7] *= rr; | |
288 | fCovar[11] *= rr; | |
289 | return kTRUE; | |
51ad6848 | 290 | } |
291 | ||
292 | //_____________________________________________________________________________ | |
a5e407e9 | 293 | Bool_t AliExternalTrackParam::CorrectForMaterial(Double_t d, Double_t x0, Double_t rho) |
51ad6848 | 294 | { |
a5e407e9 | 295 | // |
296 | // Take into account material effects assuming: | |
297 | // x0 - mean rad length | |
298 | // rho - mean density | |
299 | ||
300 | // | |
301 | // multiple scattering | |
302 | // | |
0243e825 | 303 | if (fMass<=0) { |
304 | AliError("Non-positive mass"); | |
305 | return kFALSE; | |
306 | } | |
a5e407e9 | 307 | Double_t p2=(1.+ fParam[3]*fParam[3])/(fParam[4]*fParam[4]); |
308 | Double_t beta2=p2/(p2 + fMass*fMass); | |
309 | Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho; | |
310 | // | |
311 | fCovar[5] += theta2*(1.- fParam[2]*fParam[2])*(1. + fParam[3]*fParam[3]); | |
312 | fCovar[9] += theta2*(1. + fParam[3]*fParam[3])*(1. + fParam[3]*fParam[3]); | |
313 | fCovar[13] += theta2*fParam[3]*fParam[4]*(1. + fParam[3]*fParam[3]); | |
314 | fCovar[14] += theta2*fParam[3]*fParam[4]*fParam[3]*fParam[4]; | |
315 | ||
316 | Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2+1e-10)) - beta2)*d*rho; | |
317 | fParam[4] *=(1.- TMath::Sqrt(p2+fMass*fMass)/p2*dE); | |
318 | // | |
319 | Double_t sigmade = 0.02*TMath::Sqrt(TMath::Abs(dE)); // energy loss fluctuation | |
320 | Double_t sigmac2 = sigmade*sigmade*fParam[4]*fParam[4]*(p2+fMass*fMass)/(p2*p2); | |
321 | fCovar[14] += sigmac2; | |
322 | // | |
323 | // | |
324 | ||
51ad6848 | 325 | |
a5e407e9 | 326 | |
327 | return kTRUE; | |
51ad6848 | 328 | } |
329 | ||
330 | //_____________________________________________________________________________ | |
a5e407e9 | 331 | Bool_t AliExternalTrackParam::GetProlongationAt(Double_t xk, |
332 | Double_t& y, | |
333 | Double_t& z) const | |
51ad6848 | 334 | { |
a5e407e9 | 335 | // |
336 | // Get the local y and z coordinates at the given x value | |
337 | // | |
338 | Double_t lcc=GetLocalConvConst(); | |
339 | Double_t cur = fParam[4]/lcc; | |
340 | Double_t x1=fX, x2=xk, dx=x2-x1; | |
341 | Double_t f1=fParam[2], f2=f1 + cur*dx; | |
342 | // | |
343 | if (TMath::Abs(f2) >= 0.98) { | |
344 | // MI change - don't propagate highly inclined tracks | |
345 | // covariance matrix distorted | |
346 | return kFALSE; | |
347 | } | |
348 | Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2); | |
349 | y = fParam[0] + dx*(f1+f2)/(r1+r2); | |
350 | z = fParam[1] + dx*(f1+f2)/(f1*r2 + f2*r1)*fParam[3]; | |
351 | return kTRUE; | |
51ad6848 | 352 | } |
353 | ||
354 | //_____________________________________________________________________________ | |
355 | Double_t AliExternalTrackParam::GetXAtVertex(Double_t /*x*/, | |
356 | Double_t /*y*/) const | |
357 | { | |
358 | // Get the x coordinate at the given vertex (x,y) | |
359 | // | |
360 | // NOT IMPLEMENTED for this class | |
361 | ||
362 | return 0; | |
363 | } | |
364 | ||
365 | ||
a5e407e9 | 366 | // //_____________________________________________________________________________ |
367 | // Double_t AliExternalTrackParam::GetPredictedChi2(const AliCluster* /*cluster*/) | |
368 | // { | |
369 | // // calculate the chi2 contribution of the given cluster | |
370 | // // | |
371 | // // NOT IMPLEMENTED for this class | |
51ad6848 | 372 | |
a5e407e9 | 373 | // return -1; |
374 | // } | |
51ad6848 | 375 | |
a5e407e9 | 376 | // //_____________________________________________________________________________ |
377 | // Bool_t AliExternalTrackParam::Update(const AliCluster* /*cluster*/) | |
378 | // { | |
379 | // // update the track parameters using the position and error | |
380 | // // of the given cluster | |
381 | // // | |
382 | // // NOT IMPLEMENTED for this class | |
51ad6848 | 383 | |
a5e407e9 | 384 | // return kFALSE; |
385 | // } | |
51ad6848 | 386 | |
387 | ||
388 | //_____________________________________________________________________________ | |
389 | Double_t AliExternalTrackParam::SigmaPhi() const | |
390 | { | |
391 | // get the error of the azimuthal angle | |
392 | ||
393 | return TMath::Sqrt(TMath::Abs(fCovar[5] / (1. - fParam[2]*fParam[2]))); | |
394 | } | |
395 | ||
396 | //_____________________________________________________________________________ | |
397 | Double_t AliExternalTrackParam::SigmaTheta() const | |
398 | { | |
399 | // get the error of the polar angle | |
400 | ||
401 | return TMath::Sqrt(TMath::Abs(fCovar[9])) / (1. + fParam[3]*fParam[3]); | |
402 | } | |
403 | ||
404 | //_____________________________________________________________________________ | |
405 | Double_t AliExternalTrackParam::SigmaPt() const | |
406 | { | |
407 | // get the error of the transversal component of the momentum | |
408 | ||
409 | return TMath::Sqrt(fCovar[14]) / TMath::Abs(fParam[4]); | |
410 | } | |
411 | ||
412 | //_____________________________________________________________________________ | |
413 | TVector3 AliExternalTrackParam::Momentum() const | |
414 | { | |
415 | // get the momentum vector | |
416 | ||
417 | Double_t phi = TMath::ASin(fParam[2]) + fAlpha; | |
418 | Double_t pt = 1. / TMath::Abs(fParam[4]); | |
419 | return TVector3(pt * TMath::Cos(phi), | |
420 | pt * TMath::Sin(phi), | |
421 | pt * fParam[3]); | |
422 | } | |
423 | ||
424 | //_____________________________________________________________________________ | |
425 | TVector3 AliExternalTrackParam::Position() const | |
426 | { | |
427 | // get the current spatial position in global coordinates | |
428 | ||
429 | return TVector3(fX * TMath::Cos(fAlpha) - fParam[0] * TMath::Sin(fAlpha), | |
430 | fX * TMath::Sin(fAlpha) + fParam[0] * TMath::Cos(fAlpha), | |
431 | fParam[1]); | |
432 | } | |
433 | ||
434 | ||
435 | //_____________________________________________________________________________ | |
436 | void AliExternalTrackParam::Print(Option_t* /*option*/) const | |
437 | { | |
438 | // print the parameters and the covariance matrix | |
439 | ||
440 | printf("AliExternalTrackParam: x = %-12g alpha = %-12g\n", fX, fAlpha); | |
441 | printf(" parameters: %12g %12g %12g %12g %12g\n", | |
442 | fParam[0], fParam[1], fParam[2], fParam[3], fParam[4]); | |
443 | printf(" covariance: %12g\n", fCovar[0]); | |
444 | printf(" %12g %12g\n", fCovar[1], fCovar[2]); | |
445 | printf(" %12g %12g %12g\n", fCovar[3], fCovar[4], fCovar[5]); | |
446 | printf(" %12g %12g %12g %12g\n", | |
447 | fCovar[6], fCovar[7], fCovar[8], fCovar[9]); | |
448 | printf(" %12g %12g %12g %12g %12g\n", | |
449 | fCovar[10], fCovar[11], fCovar[12], fCovar[13], fCovar[14]); | |
450 | } |