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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 | // Implementation of the external track parameterisation class. // | |
21 | // // | |
22 | // This parameterisation is used to exchange tracks between the detectors. // | |
23 | // A set of functions returning the position and the momentum of tracks // | |
24 | // in the global coordinate system as well as the track impact parameters // | |
25 | // are implemented. | |
26 | // Origin: I.Belikov, CERN, Jouri.Belikov@cern.ch // | |
27 | /////////////////////////////////////////////////////////////////////////////// | |
28 | #include <cassert> | |
29 | ||
30 | #include <TVectorD.h> | |
31 | #include <TMatrixDSym.h> | |
32 | #include <TPolyMarker3D.h> | |
33 | #include <TVector3.h> | |
34 | #include <TMatrixD.h> | |
35 | ||
36 | #include "AliExternalTrackParam.h" | |
37 | #include "AliVVertex.h" | |
38 | #include "AliLog.h" | |
39 | ||
40 | ClassImp(AliExternalTrackParam) | |
41 | ||
42 | Double32_t AliExternalTrackParam::fgMostProbablePt=kMostProbablePt; | |
43 | Bool_t AliExternalTrackParam::fgUseLogTermMS = kFALSE;; | |
44 | //_____________________________________________________________________________ | |
45 | AliExternalTrackParam::AliExternalTrackParam() : | |
46 | AliVTrack(), | |
47 | fX(0), | |
48 | fAlpha(0) | |
49 | { | |
50 | // | |
51 | // default constructor | |
52 | // | |
53 | for (Int_t i = 0; i < 5; i++) fP[i] = 0; | |
54 | for (Int_t i = 0; i < 15; i++) fC[i] = 0; | |
55 | } | |
56 | ||
57 | //_____________________________________________________________________________ | |
58 | AliExternalTrackParam::AliExternalTrackParam(const AliExternalTrackParam &track): | |
59 | AliVTrack(track), | |
60 | fX(track.fX), | |
61 | fAlpha(track.fAlpha) | |
62 | { | |
63 | // | |
64 | // copy constructor | |
65 | // | |
66 | for (Int_t i = 0; i < 5; i++) fP[i] = track.fP[i]; | |
67 | for (Int_t i = 0; i < 15; i++) fC[i] = track.fC[i]; | |
68 | CheckCovariance(); | |
69 | } | |
70 | ||
71 | //_____________________________________________________________________________ | |
72 | AliExternalTrackParam& AliExternalTrackParam::operator=(const AliExternalTrackParam &trkPar) | |
73 | { | |
74 | // | |
75 | // assignment operator | |
76 | // | |
77 | ||
78 | if (this!=&trkPar) { | |
79 | AliVTrack::operator=(trkPar); | |
80 | fX = trkPar.fX; | |
81 | fAlpha = trkPar.fAlpha; | |
82 | ||
83 | for (Int_t i = 0; i < 5; i++) fP[i] = trkPar.fP[i]; | |
84 | for (Int_t i = 0; i < 15; i++) fC[i] = trkPar.fC[i]; | |
85 | CheckCovariance(); | |
86 | } | |
87 | ||
88 | return *this; | |
89 | } | |
90 | ||
91 | //_____________________________________________________________________________ | |
92 | AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha, | |
93 | const Double_t param[5], | |
94 | const Double_t covar[15]) : | |
95 | AliVTrack(), | |
96 | fX(x), | |
97 | fAlpha(alpha) | |
98 | { | |
99 | // | |
100 | // create external track parameters from given arguments | |
101 | // | |
102 | for (Int_t i = 0; i < 5; i++) fP[i] = param[i]; | |
103 | for (Int_t i = 0; i < 15; i++) fC[i] = covar[i]; | |
104 | CheckCovariance(); | |
105 | } | |
106 | ||
107 | //_____________________________________________________________________________ | |
108 | AliExternalTrackParam::AliExternalTrackParam(const AliVTrack *vTrack) : | |
109 | AliVTrack(), | |
110 | fX(0.), | |
111 | fAlpha(0.) | |
112 | { | |
113 | // | |
114 | // Constructor from virtual track, | |
115 | // This is not a copy contructor ! | |
116 | // | |
117 | ||
118 | if (vTrack->InheritsFrom("AliExternalTrackParam")) { | |
119 | AliError("This is not a copy constructor. Use AliExternalTrackParam(const AliExternalTrackParam &) !"); | |
120 | AliWarning("Calling the default constructor..."); | |
121 | AliExternalTrackParam(); | |
122 | return; | |
123 | } | |
124 | ||
125 | Double_t xyz[3],pxpypz[3],cv[21]; | |
126 | vTrack->GetXYZ(xyz); | |
127 | pxpypz[0]=vTrack->Px(); | |
128 | pxpypz[1]=vTrack->Py(); | |
129 | pxpypz[2]=vTrack->Pz(); | |
130 | vTrack->GetCovarianceXYZPxPyPz(cv); | |
131 | Short_t sign = (Short_t)vTrack->Charge(); | |
132 | ||
133 | Set(xyz,pxpypz,cv,sign); | |
134 | } | |
135 | ||
136 | //_____________________________________________________________________________ | |
137 | AliExternalTrackParam::AliExternalTrackParam(Double_t xyz[3],Double_t pxpypz[3], | |
138 | Double_t cv[21],Short_t sign) : | |
139 | AliVTrack(), | |
140 | fX(0.), | |
141 | fAlpha(0.) | |
142 | { | |
143 | // | |
144 | // constructor from the global parameters | |
145 | // | |
146 | ||
147 | Set(xyz,pxpypz,cv,sign); | |
148 | } | |
149 | ||
150 | //_____________________________________________________________________________ | |
151 | void AliExternalTrackParam::Set(Double_t xyz[3],Double_t pxpypz[3], | |
152 | Double_t cv[21],Short_t sign) | |
153 | { | |
154 | // | |
155 | // create external track parameters from the global parameters | |
156 | // x,y,z,px,py,pz and their 6x6 covariance matrix | |
157 | // A.Dainese 10.10.08 | |
158 | ||
159 | // Calculate alpha: the rotation angle of the corresponding local system. | |
160 | // | |
161 | // For global radial position inside the beam pipe, alpha is the | |
162 | // azimuthal angle of the momentum projected on (x,y). | |
163 | // | |
164 | // For global radial position outside the ITS, alpha is the | |
165 | // azimuthal angle of the centre of the TPC sector in which the point | |
166 | // xyz lies | |
167 | // | |
168 | const double kSafe = 1e-5; | |
169 | Double_t radPos2 = xyz[0]*xyz[0]+xyz[1]*xyz[1]; | |
170 | Double_t radMax = 45.; // approximately ITS outer radius | |
171 | if (radPos2 < radMax*radMax) { // inside the ITS | |
172 | fAlpha = TMath::ATan2(pxpypz[1],pxpypz[0]); | |
173 | } else { // outside the ITS | |
174 | Float_t phiPos = TMath::Pi()+TMath::ATan2(-xyz[1], -xyz[0]); | |
175 | fAlpha = | |
176 | TMath::DegToRad()*(20*((((Int_t)(phiPos*TMath::RadToDeg()))/20))+10); | |
177 | } | |
178 | // | |
179 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
180 | // protection: avoid alpha being too close to 0 or +-pi/2 | |
181 | if (TMath::Abs(sn)<kSafe) { | |
182 | fAlpha = kSafe; | |
183 | cs=TMath::Cos(fAlpha); | |
184 | sn=TMath::Sin(fAlpha); | |
185 | } | |
186 | else if (cs<kSafe) { | |
187 | fAlpha -= TMath::Sign(kSafe, fAlpha); | |
188 | cs=TMath::Cos(fAlpha); | |
189 | sn=TMath::Sin(fAlpha); | |
190 | } | |
191 | // Get the vertex of origin and the momentum | |
192 | TVector3 ver(xyz[0],xyz[1],xyz[2]); | |
193 | TVector3 mom(pxpypz[0],pxpypz[1],pxpypz[2]); | |
194 | // | |
195 | // avoid momenta along axis | |
196 | if (TMath::Abs(mom[0])<kSafe) mom[0] = TMath::Sign(kSafe*TMath::Abs(mom[1]), mom[0]); | |
197 | if (TMath::Abs(mom[1])<kSafe) mom[1] = TMath::Sign(kSafe*TMath::Abs(mom[0]), mom[1]); | |
198 | ||
199 | // Rotate to the local coordinate system | |
200 | ver.RotateZ(-fAlpha); | |
201 | mom.RotateZ(-fAlpha); | |
202 | ||
203 | // x of the reference plane | |
204 | fX = ver.X(); | |
205 | ||
206 | Double_t charge = (Double_t)sign; | |
207 | ||
208 | fP[0] = ver.Y(); | |
209 | fP[1] = ver.Z(); | |
210 | fP[2] = TMath::Sin(mom.Phi()); | |
211 | fP[3] = mom.Pz()/mom.Pt(); | |
212 | fP[4] = TMath::Sign(1/mom.Pt(),charge); | |
213 | ||
214 | // Covariance matrix (formulas to be simplified) | |
215 | ||
216 | if (TMath::Abs( 1-fP[2]) < kSafe) fP[2] = 1.- kSafe; //Protection | |
217 | else if (TMath::Abs(-1-fP[2]) < kSafe) fP[2] =-1.+ kSafe; //Protection | |
218 | ||
219 | Double_t pt=1./TMath::Abs(fP[4]); | |
220 | Double_t r=TMath::Sqrt((1.-fP[2])*(1.+fP[2])); | |
221 | ||
222 | Double_t m00=-sn;// m10=cs; | |
223 | Double_t m23=-pt*(sn + fP[2]*cs/r), m43=-pt*pt*(r*cs - fP[2]*sn); | |
224 | Double_t m24= pt*(cs - fP[2]*sn/r), m44=-pt*pt*(r*sn + fP[2]*cs); | |
225 | Double_t m35=pt, m45=-pt*pt*fP[3]; | |
226 | ||
227 | m43*=GetSign(); | |
228 | m44*=GetSign(); | |
229 | m45*=GetSign(); | |
230 | ||
231 | Double_t cv34 = TMath::Sqrt(cv[3 ]*cv[3 ]+cv[4 ]*cv[4 ]); | |
232 | Double_t a1=cv[13]-cv[9]*(m23*m44+m43*m24)/m23/m43; | |
233 | Double_t a2=m23*m24-m23*(m23*m44+m43*m24)/m43; | |
234 | Double_t a3=m43*m44-m43*(m23*m44+m43*m24)/m23; | |
235 | Double_t a4=cv[14]-2.*cv[9]*m24*m44/m23/m43; | |
236 | Double_t a5=m24*m24-2.*m24*m44*m23/m43; | |
237 | Double_t a6=m44*m44-2.*m24*m44*m43/m23; | |
238 | ||
239 | fC[0 ] = cv[0 ]+cv[2 ]; | |
240 | fC[1 ] = TMath::Sign(cv34,cv[3 ]/m00); | |
241 | fC[2 ] = cv[5 ]; | |
242 | fC[3 ] = (cv[10]/m44-cv[6]/m43)/(m24/m44-m23/m43)/m00; | |
243 | fC[10] = (cv[6]/m00-fC[3 ]*m23)/m43; | |
244 | fC[6 ] = (cv[15]/m00-fC[10]*m45)/m35; | |
245 | fC[4 ] = (cv[12]-cv[8]*m44/m43)/(m24-m23*m44/m43); | |
246 | fC[11] = (cv[8]-fC[4]*m23)/m43; | |
247 | fC[7 ] = cv[17]/m35-fC[11]*m45/m35; | |
248 | fC[5 ] = TMath::Abs((a4-a6*a1/a3)/(a5-a6*a2/a3)); | |
249 | fC[14] = TMath::Abs(a1/a3-a2*fC[5]/a3); | |
250 | fC[12] = (cv[9]-fC[5]*m23*m23-fC[14]*m43*m43)/m23/m43; | |
251 | Double_t b1=cv[18]-fC[12]*m23*m45-fC[14]*m43*m45; | |
252 | Double_t b2=m23*m35; | |
253 | Double_t b3=m43*m35; | |
254 | Double_t b4=cv[19]-fC[12]*m24*m45-fC[14]*m44*m45; | |
255 | Double_t b5=m24*m35; | |
256 | Double_t b6=m44*m35; | |
257 | fC[8 ] = (b4-b6*b1/b3)/(b5-b6*b2/b3); | |
258 | fC[13] = b1/b3-b2*fC[8]/b3; | |
259 | fC[9 ] = TMath::Abs((cv[20]-fC[14]*(m45*m45)-fC[13]*2.*m35*m45)/(m35*m35)); | |
260 | ||
261 | CheckCovariance(); | |
262 | ||
263 | return; | |
264 | } | |
265 | ||
266 | //_____________________________________________________________________________ | |
267 | void AliExternalTrackParam::Reset() { | |
268 | // | |
269 | // Resets all the parameters to 0 | |
270 | // | |
271 | fX=fAlpha=0.; | |
272 | for (Int_t i = 0; i < 5; i++) fP[i] = 0; | |
273 | for (Int_t i = 0; i < 15; i++) fC[i] = 0; | |
274 | } | |
275 | ||
276 | //_____________________________________________________________________________ | |
277 | void AliExternalTrackParam::AddCovariance(const Double_t c[15]) { | |
278 | // | |
279 | // Add "something" to the track covarince matrix. | |
280 | // May be needed to account for unknown mis-calibration/mis-alignment | |
281 | // | |
282 | fC[0] +=c[0]; | |
283 | fC[1] +=c[1]; fC[2] +=c[2]; | |
284 | fC[3] +=c[3]; fC[4] +=c[4]; fC[5] +=c[5]; | |
285 | fC[6] +=c[6]; fC[7] +=c[7]; fC[8] +=c[8]; fC[9] +=c[9]; | |
286 | fC[10]+=c[10]; fC[11]+=c[11]; fC[12]+=c[12]; fC[13]+=c[13]; fC[14]+=c[14]; | |
287 | CheckCovariance(); | |
288 | } | |
289 | ||
290 | ||
291 | Double_t AliExternalTrackParam::GetP() const { | |
292 | //--------------------------------------------------------------------- | |
293 | // This function returns the track momentum | |
294 | // Results for (nearly) straight tracks are meaningless ! | |
295 | //--------------------------------------------------------------------- | |
296 | if (TMath::Abs(fP[4])<=kAlmost0) return kVeryBig; | |
297 | return TMath::Sqrt(1.+ fP[3]*fP[3])/TMath::Abs(fP[4]); | |
298 | } | |
299 | ||
300 | Double_t AliExternalTrackParam::Get1P() const { | |
301 | //--------------------------------------------------------------------- | |
302 | // This function returns the 1/(track momentum) | |
303 | //--------------------------------------------------------------------- | |
304 | return TMath::Abs(fP[4])/TMath::Sqrt(1.+ fP[3]*fP[3]); | |
305 | } | |
306 | ||
307 | //_______________________________________________________________________ | |
308 | Double_t AliExternalTrackParam::GetD(Double_t x,Double_t y,Double_t b) const { | |
309 | //------------------------------------------------------------------ | |
310 | // This function calculates the transverse impact parameter | |
311 | // with respect to a point with global coordinates (x,y) | |
312 | // in the magnetic field "b" (kG) | |
313 | //------------------------------------------------------------------ | |
314 | if (TMath::Abs(b) < kAlmost0Field) return GetLinearD(x,y); | |
315 | Double_t rp4=GetC(b); | |
316 | ||
317 | Double_t xt=fX, yt=fP[0]; | |
318 | ||
319 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
320 | Double_t a = x*cs + y*sn; | |
321 | y = -x*sn + y*cs; x=a; | |
322 | xt-=x; yt-=y; | |
323 | ||
324 | sn=rp4*xt - fP[2]; cs=rp4*yt + TMath::Sqrt((1.- fP[2])*(1.+fP[2])); | |
325 | a=2*(xt*fP[2] - yt*TMath::Sqrt((1.-fP[2])*(1.+fP[2])))-rp4*(xt*xt + yt*yt); | |
326 | return -a/(1 + TMath::Sqrt(sn*sn + cs*cs)); | |
327 | } | |
328 | ||
329 | //_______________________________________________________________________ | |
330 | void AliExternalTrackParam:: | |
331 | GetDZ(Double_t x, Double_t y, Double_t z, Double_t b, Float_t dz[2]) const { | |
332 | //------------------------------------------------------------------ | |
333 | // This function calculates the transverse and longitudinal impact parameters | |
334 | // with respect to a point with global coordinates (x,y) | |
335 | // in the magnetic field "b" (kG) | |
336 | //------------------------------------------------------------------ | |
337 | Double_t f1 = fP[2], r1 = TMath::Sqrt((1.-f1)*(1.+f1)); | |
338 | Double_t xt=fX, yt=fP[0]; | |
339 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
340 | Double_t a = x*cs + y*sn; | |
341 | y = -x*sn + y*cs; x=a; | |
342 | xt-=x; yt-=y; | |
343 | ||
344 | Double_t rp4=GetC(b); | |
345 | if ((TMath::Abs(b) < kAlmost0Field) || (TMath::Abs(rp4) < kAlmost0)) { | |
346 | dz[0] = -(xt*f1 - yt*r1); | |
347 | dz[1] = fP[1] + (dz[0]*f1 - xt)/r1*fP[3] - z; | |
348 | return; | |
349 | } | |
350 | ||
351 | sn=rp4*xt - f1; cs=rp4*yt + r1; | |
352 | a=2*(xt*f1 - yt*r1)-rp4*(xt*xt + yt*yt); | |
353 | Double_t rr=TMath::Sqrt(sn*sn + cs*cs); | |
354 | dz[0] = -a/(1 + rr); | |
355 | Double_t f2 = -sn/rr, r2 = TMath::Sqrt((1.-f2)*(1.+f2)); | |
356 | dz[1] = fP[1] + fP[3]/rp4*TMath::ASin(f2*r1 - f1*r2) - z; | |
357 | } | |
358 | ||
359 | //_______________________________________________________________________ | |
360 | Double_t AliExternalTrackParam::GetLinearD(Double_t xv,Double_t yv) const { | |
361 | //------------------------------------------------------------------ | |
362 | // This function calculates the transverse impact parameter | |
363 | // with respect to a point with global coordinates (xv,yv) | |
364 | // neglecting the track curvature. | |
365 | //------------------------------------------------------------------ | |
366 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
367 | Double_t x= xv*cs + yv*sn; | |
368 | Double_t y=-xv*sn + yv*cs; | |
369 | ||
370 | Double_t d = (fX-x)*fP[2] - (fP[0]-y)*TMath::Sqrt((1.-fP[2])*(1.+fP[2])); | |
371 | ||
372 | return -d; | |
373 | } | |
374 | ||
375 | Bool_t AliExternalTrackParam::CorrectForMeanMaterialdEdx | |
376 | (Double_t xOverX0, Double_t xTimesRho, Double_t mass, | |
377 | Double_t dEdx, | |
378 | Bool_t anglecorr) { | |
379 | //------------------------------------------------------------------ | |
380 | // This function corrects the track parameters for the crossed material. | |
381 | // "xOverX0" - X/X0, the thickness in units of the radiation length. | |
382 | // "xTimesRho" - is the product length*density (g/cm^2). | |
383 | // It should be passed as negative when propagating tracks | |
384 | // from the intreaction point to the outside of the central barrel. | |
385 | // "mass" - the mass of this particle (GeV/c^2). | |
386 | // "dEdx" - mean enery loss (GeV/(g/cm^2) | |
387 | // "anglecorr" - switch for the angular correction | |
388 | //------------------------------------------------------------------ | |
389 | Double_t &fP2=fP[2]; | |
390 | Double_t &fP3=fP[3]; | |
391 | Double_t &fP4=fP[4]; | |
392 | ||
393 | Double_t &fC22=fC[5]; | |
394 | Double_t &fC33=fC[9]; | |
395 | Double_t &fC43=fC[13]; | |
396 | Double_t &fC44=fC[14]; | |
397 | ||
398 | //Apply angle correction, if requested | |
399 | if(anglecorr) { | |
400 | Double_t angle=TMath::Sqrt((1.+ fP3*fP3)/((1-fP2)*(1.+fP2))); | |
401 | xOverX0 *=angle; | |
402 | xTimesRho *=angle; | |
403 | } | |
404 | ||
405 | Double_t p=GetP(); | |
406 | Double_t p2=p*p; | |
407 | Double_t beta2=p2/(p2 + mass*mass); | |
408 | ||
409 | //Calculating the multiple scattering corrections****************** | |
410 | Double_t cC22 = 0.; | |
411 | Double_t cC33 = 0.; | |
412 | Double_t cC43 = 0.; | |
413 | Double_t cC44 = 0.; | |
414 | if (xOverX0 != 0) { | |
415 | //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33; | |
416 | Double_t theta2=0.0136*0.0136/(beta2*p2)*TMath::Abs(xOverX0); | |
417 | if (GetUseLogTermMS()) { | |
418 | double lt = 1+0.038*TMath::Log(TMath::Abs(xOverX0)); | |
419 | if (lt>0) theta2 *= lt*lt; | |
420 | } | |
421 | if(theta2>TMath::Pi()*TMath::Pi()) return kFALSE; | |
422 | cC22 = theta2*((1.-fP2)*(1.+fP2))*(1. + fP3*fP3); | |
423 | cC33 = theta2*(1. + fP3*fP3)*(1. + fP3*fP3); | |
424 | cC43 = theta2*fP3*fP4*(1. + fP3*fP3); | |
425 | cC44 = theta2*fP3*fP4*fP3*fP4; | |
426 | } | |
427 | ||
428 | //Calculating the energy loss corrections************************ | |
429 | Double_t cP4=1.; | |
430 | if ((xTimesRho != 0.) && (beta2 < 1.)) { | |
431 | Double_t dE=dEdx*xTimesRho; | |
432 | Double_t e=TMath::Sqrt(p2 + mass*mass); | |
433 | if ( TMath::Abs(dE) > 0.3*e ) return kFALSE; //30% energy loss is too much! | |
434 | //cP4 = (1.- e/p2*dE); | |
435 | if ( (1.+ dE/p2*(dE + 2*e)) < 0. ) return kFALSE; | |
436 | cP4 = 1./TMath::Sqrt(1.+ dE/p2*(dE + 2*e)); //A precise formula by Ruben ! | |
437 | if (TMath::Abs(fP4*cP4)>100.) return kFALSE; //Do not track below 10 MeV/c | |
438 | ||
439 | ||
440 | // Approximate energy loss fluctuation (M.Ivanov) | |
441 | const Double_t knst=0.07; // To be tuned. | |
442 | Double_t sigmadE=knst*TMath::Sqrt(TMath::Abs(dE)); | |
443 | cC44 += ((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4)); | |
444 | ||
445 | } | |
446 | ||
447 | //Applying the corrections***************************** | |
448 | fC22 += cC22; | |
449 | fC33 += cC33; | |
450 | fC43 += cC43; | |
451 | fC44 += cC44; | |
452 | fP4 *= cP4; | |
453 | ||
454 | CheckCovariance(); | |
455 | ||
456 | return kTRUE; | |
457 | } | |
458 | ||
459 | Bool_t AliExternalTrackParam::CorrectForMeanMaterial | |
460 | (Double_t xOverX0, Double_t xTimesRho, Double_t mass, | |
461 | Bool_t anglecorr, | |
462 | Double_t (*Bethe)(Double_t)) { | |
463 | //------------------------------------------------------------------ | |
464 | // This function corrects the track parameters for the crossed material. | |
465 | // "xOverX0" - X/X0, the thickness in units of the radiation length. | |
466 | // "xTimesRho" - is the product length*density (g/cm^2). | |
467 | // It should be passed as negative when propagating tracks | |
468 | // from the intreaction point to the outside of the central barrel. | |
469 | // "mass" - the mass of this particle (GeV/c^2). | |
470 | // "anglecorr" - switch for the angular correction | |
471 | // "Bethe" - function calculating the energy loss (GeV/(g/cm^2)) | |
472 | //------------------------------------------------------------------ | |
473 | ||
474 | Double_t bg=GetP()/mass; | |
475 | Double_t dEdx=Bethe(bg); | |
476 | ||
477 | return CorrectForMeanMaterialdEdx(xOverX0,xTimesRho,mass,dEdx,anglecorr); | |
478 | } | |
479 | ||
480 | Bool_t AliExternalTrackParam::CorrectForMeanMaterialZA | |
481 | (Double_t xOverX0, Double_t xTimesRho, Double_t mass, | |
482 | Double_t zOverA, | |
483 | Double_t density, | |
484 | Double_t exEnergy, | |
485 | Double_t jp1, | |
486 | Double_t jp2, | |
487 | Bool_t anglecorr) { | |
488 | //------------------------------------------------------------------ | |
489 | // This function corrects the track parameters for the crossed material | |
490 | // using the full Geant-like Bethe-Bloch formula parameterization | |
491 | // "xOverX0" - X/X0, the thickness in units of the radiation length. | |
492 | // "xTimesRho" - is the product length*density (g/cm^2). | |
493 | // It should be passed as negative when propagating tracks | |
494 | // from the intreaction point to the outside of the central barrel. | |
495 | // "mass" - the mass of this particle (GeV/c^2). | |
496 | // "density" - mean density (g/cm^3) | |
497 | // "zOverA" - mean Z/A | |
498 | // "exEnergy" - mean exitation energy (GeV) | |
499 | // "jp1" - density effect first junction point | |
500 | // "jp2" - density effect second junction point | |
501 | // "anglecorr" - switch for the angular correction | |
502 | // | |
503 | // The default values of the parameters are for silicon | |
504 | // | |
505 | //------------------------------------------------------------------ | |
506 | ||
507 | Double_t bg=GetP()/mass; | |
508 | Double_t dEdx=BetheBlochGeant(bg,density,jp1,jp2,exEnergy,zOverA); | |
509 | ||
510 | return CorrectForMeanMaterialdEdx(xOverX0,xTimesRho,mass,dEdx,anglecorr); | |
511 | } | |
512 | ||
513 | ||
514 | ||
515 | Bool_t AliExternalTrackParam::CorrectForMaterial | |
516 | (Double_t d, Double_t x0, Double_t mass, Double_t (*Bethe)(Double_t)) { | |
517 | //------------------------------------------------------------------ | |
518 | // Deprecated function ! | |
519 | // Better use CorrectForMeanMaterial instead of it. | |
520 | // | |
521 | // This function corrects the track parameters for the crossed material | |
522 | // "d" - the thickness (fraction of the radiation length) | |
523 | // It should be passed as negative when propagating tracks | |
524 | // from the intreaction point to the outside of the central barrel. | |
525 | // "x0" - the radiation length (g/cm^2) | |
526 | // "mass" - the mass of this particle (GeV/c^2) | |
527 | //------------------------------------------------------------------ | |
528 | ||
529 | return CorrectForMeanMaterial(d,x0*d,mass,kTRUE,Bethe); | |
530 | ||
531 | } | |
532 | ||
533 | Double_t AliExternalTrackParam::BetheBlochAleph(Double_t bg, | |
534 | Double_t kp1, | |
535 | Double_t kp2, | |
536 | Double_t kp3, | |
537 | Double_t kp4, | |
538 | Double_t kp5) { | |
539 | // | |
540 | // This is the empirical ALEPH parameterization of the Bethe-Bloch formula. | |
541 | // It is normalized to 1 at the minimum. | |
542 | // | |
543 | // bg - beta*gamma | |
544 | // | |
545 | // The default values for the kp* parameters are for ALICE TPC. | |
546 | // The returned value is in MIP units | |
547 | // | |
548 | ||
549 | Double_t beta = bg/TMath::Sqrt(1.+ bg*bg); | |
550 | ||
551 | Double_t aa = TMath::Power(beta,kp4); | |
552 | Double_t bb = TMath::Power(1./bg,kp5); | |
553 | ||
554 | bb=TMath::Log(kp3+bb); | |
555 | ||
556 | return (kp2-aa-bb)*kp1/aa; | |
557 | } | |
558 | ||
559 | Double_t AliExternalTrackParam::BetheBlochGeant(Double_t bg, | |
560 | Double_t kp0, | |
561 | Double_t kp1, | |
562 | Double_t kp2, | |
563 | Double_t kp3, | |
564 | Double_t kp4) { | |
565 | // | |
566 | // This is the parameterization of the Bethe-Bloch formula inspired by Geant. | |
567 | // | |
568 | // bg - beta*gamma | |
569 | // kp0 - density [g/cm^3] | |
570 | // kp1 - density effect first junction point | |
571 | // kp2 - density effect second junction point | |
572 | // kp3 - mean excitation energy [GeV] | |
573 | // kp4 - mean Z/A | |
574 | // | |
575 | // The default values for the kp* parameters are for silicon. | |
576 | // The returned value is in [GeV/(g/cm^2)]. | |
577 | // | |
578 | ||
579 | const Double_t mK = 0.307075e-3; // [GeV*cm^2/g] | |
580 | const Double_t me = 0.511e-3; // [GeV/c^2] | |
581 | const Double_t rho = kp0; | |
582 | const Double_t x0 = kp1*2.303; | |
583 | const Double_t x1 = kp2*2.303; | |
584 | const Double_t mI = kp3; | |
585 | const Double_t mZA = kp4; | |
586 | const Double_t bg2 = bg*bg; | |
587 | const Double_t maxT= 2*me*bg2; // neglecting the electron mass | |
588 | ||
589 | //*** Density effect | |
590 | Double_t d2=0.; | |
591 | const Double_t x=TMath::Log(bg); | |
592 | const Double_t lhwI=TMath::Log(28.816*1e-9*TMath::Sqrt(rho*mZA)/mI); | |
593 | if (x > x1) { | |
594 | d2 = lhwI + x - 0.5; | |
595 | } else if (x > x0) { | |
596 | const Double_t r=(x1-x)/(x1-x0); | |
597 | d2 = lhwI + x - 0.5 + (0.5 - lhwI - x0)*r*r*r; | |
598 | } | |
599 | ||
600 | return mK*mZA*(1+bg2)/bg2* | |
601 | (0.5*TMath::Log(2*me*bg2*maxT/(mI*mI)) - bg2/(1+bg2) - d2); | |
602 | } | |
603 | ||
604 | Double_t AliExternalTrackParam::BetheBlochSolid(Double_t bg) { | |
605 | //------------------------------------------------------------------ | |
606 | // This is an approximation of the Bethe-Bloch formula, | |
607 | // reasonable for solid materials. | |
608 | // All the parameters are, in fact, for Si. | |
609 | // The returned value is in [GeV/(g/cm^2)] | |
610 | //------------------------------------------------------------------ | |
611 | ||
612 | return BetheBlochGeant(bg); | |
613 | } | |
614 | ||
615 | Double_t AliExternalTrackParam::BetheBlochGas(Double_t bg) { | |
616 | //------------------------------------------------------------------ | |
617 | // This is an approximation of the Bethe-Bloch formula, | |
618 | // reasonable for gas materials. | |
619 | // All the parameters are, in fact, for Ne. | |
620 | // The returned value is in [GeV/(g/cm^2)] | |
621 | //------------------------------------------------------------------ | |
622 | ||
623 | const Double_t rho = 0.9e-3; | |
624 | const Double_t x0 = 2.; | |
625 | const Double_t x1 = 4.; | |
626 | const Double_t mI = 140.e-9; | |
627 | const Double_t mZA = 0.49555; | |
628 | ||
629 | return BetheBlochGeant(bg,rho,x0,x1,mI,mZA); | |
630 | } | |
631 | ||
632 | Bool_t AliExternalTrackParam::Rotate(Double_t alpha) { | |
633 | //------------------------------------------------------------------ | |
634 | // Transform this track to the local coord. system rotated | |
635 | // by angle "alpha" (rad) with respect to the global coord. system. | |
636 | //------------------------------------------------------------------ | |
637 | if (TMath::Abs(fP[2]) >= kAlmost1) { | |
638 | AliError(Form("Precondition is not satisfied: |sin(phi)|>1 ! %f",fP[2])); | |
639 | return kFALSE; | |
640 | } | |
641 | ||
642 | if (alpha < -TMath::Pi()) alpha += 2*TMath::Pi(); | |
643 | else if (alpha >= TMath::Pi()) alpha -= 2*TMath::Pi(); | |
644 | ||
645 | Double_t &fP0=fP[0]; | |
646 | Double_t &fP2=fP[2]; | |
647 | Double_t &fC00=fC[0]; | |
648 | Double_t &fC10=fC[1]; | |
649 | Double_t &fC20=fC[3]; | |
650 | Double_t &fC21=fC[4]; | |
651 | Double_t &fC22=fC[5]; | |
652 | Double_t &fC30=fC[6]; | |
653 | Double_t &fC32=fC[8]; | |
654 | Double_t &fC40=fC[10]; | |
655 | Double_t &fC42=fC[12]; | |
656 | ||
657 | Double_t x=fX; | |
658 | Double_t ca=TMath::Cos(alpha-fAlpha), sa=TMath::Sin(alpha-fAlpha); | |
659 | Double_t sf=fP2, cf=TMath::Sqrt((1.- fP2)*(1.+fP2)); // Improve precision | |
660 | ||
661 | Double_t tmp=sf*ca - cf*sa; | |
662 | if (TMath::Abs(tmp) >= kAlmost1) { | |
663 | if (TMath::Abs(tmp) > 1.+ Double_t(FLT_EPSILON)) | |
664 | AliWarning(Form("Rotation failed ! %.10e",tmp)); | |
665 | return kFALSE; | |
666 | } | |
667 | ||
668 | fAlpha = alpha; | |
669 | fX = x*ca + fP0*sa; | |
670 | fP0= -x*sa + fP0*ca; | |
671 | fP2= tmp; | |
672 | ||
673 | if (TMath::Abs(cf)<kAlmost0) { | |
674 | AliError(Form("Too small cosine value %f",cf)); | |
675 | cf = kAlmost0; | |
676 | } | |
677 | ||
678 | Double_t rr=(ca+sf/cf*sa); | |
679 | ||
680 | fC00 *= (ca*ca); | |
681 | fC10 *= ca; | |
682 | fC20 *= ca*rr; | |
683 | fC21 *= rr; | |
684 | fC22 *= rr*rr; | |
685 | fC30 *= ca; | |
686 | fC32 *= rr; | |
687 | fC40 *= ca; | |
688 | fC42 *= rr; | |
689 | ||
690 | CheckCovariance(); | |
691 | ||
692 | return kTRUE; | |
693 | } | |
694 | ||
695 | Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t b) { | |
696 | //---------------------------------------------------------------- | |
697 | // Propagate this track to the plane X=xk (cm) in the field "b" (kG) | |
698 | //---------------------------------------------------------------- | |
699 | Double_t dx=xk-fX; | |
700 | if (TMath::Abs(dx)<=kAlmost0) return kTRUE; | |
701 | ||
702 | Double_t crv=GetC(b); | |
703 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; | |
704 | ||
705 | Double_t x2r = crv*dx; | |
706 | Double_t f1=fP[2], f2=f1 + x2r; | |
707 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
708 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
709 | if (TMath::Abs(fP[4])< kAlmost0) return kFALSE; | |
710 | ||
711 | Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4]; | |
712 | Double_t | |
713 | &fC00=fC[0], | |
714 | &fC10=fC[1], &fC11=fC[2], | |
715 | &fC20=fC[3], &fC21=fC[4], &fC22=fC[5], | |
716 | &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9], | |
717 | &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14]; | |
718 | ||
719 | Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2)); | |
720 | if (TMath::Abs(r1)<kAlmost0) return kFALSE; | |
721 | if (TMath::Abs(r2)<kAlmost0) return kFALSE; | |
722 | ||
723 | fX=xk; | |
724 | double dy2dx = (f1+f2)/(r1+r2); | |
725 | fP0 += dx*dy2dx; | |
726 | if (TMath::Abs(x2r)<0.05) { | |
727 | fP1 += dx*(r2 + f2*dy2dx)*fP3; // Many thanks to P.Hristov ! | |
728 | fP2 += x2r; | |
729 | } | |
730 | else { | |
731 | // for small dx/R the linear apporximation of the arc by the segment is OK, | |
732 | // but at large dx/R the error is very large and leads to incorrect Z propagation | |
733 | // angle traversed delta = 2*asin(dist_start_end / R / 2), hence the arc is: R*deltaPhi | |
734 | // The dist_start_end is obtained from sqrt(dx^2+dy^2) = x/(r1+r2)*sqrt(2+f1*f2+r1*r2) | |
735 | // Similarly, the rotation angle in linear in dx only for dx<<R | |
736 | double chord = dx*TMath::Sqrt(1+dy2dx*dy2dx); // distance from old position to new one | |
737 | double rot = 2*TMath::ASin(0.5*chord*crv); // angular difference seen from the circle center | |
738 | fP1 += rot/crv*fP3; | |
739 | fP2 = TMath::Sin(rot + TMath::ASin(fP2)); | |
740 | } | |
741 | ||
742 | //f = F - 1 | |
743 | ||
744 | Double_t f02= dx/(r1*r1*r1); Double_t cc=crv/fP4; | |
745 | Double_t f04=0.5*dx*dx/(r1*r1*r1); f04*=cc; | |
746 | Double_t f12= dx*fP3*f1/(r1*r1*r1); | |
747 | Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1); f14*=cc; | |
748 | Double_t f13= dx/r1; | |
749 | Double_t f24= dx; f24*=cc; | |
750 | ||
751 | //b = C*ft | |
752 | Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30; | |
753 | Double_t b02=f24*fC40; | |
754 | Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31; | |
755 | Double_t b12=f24*fC41; | |
756 | Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32; | |
757 | Double_t b22=f24*fC42; | |
758 | Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43; | |
759 | Double_t b42=f24*fC44; | |
760 | Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33; | |
761 | Double_t b32=f24*fC43; | |
762 | ||
763 | //a = f*b = f*C*ft | |
764 | Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42; | |
765 | Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32; | |
766 | Double_t a22=f24*b42; | |
767 | ||
768 | //F*C*Ft = C + (b + bt + a) | |
769 | fC00 += b00 + b00 + a00; | |
770 | fC10 += b10 + b01 + a01; | |
771 | fC20 += b20 + b02 + a02; | |
772 | fC30 += b30; | |
773 | fC40 += b40; | |
774 | fC11 += b11 + b11 + a11; | |
775 | fC21 += b21 + b12 + a12; | |
776 | fC31 += b31; | |
777 | fC41 += b41; | |
778 | fC22 += b22 + b22 + a22; | |
779 | fC32 += b32; | |
780 | fC42 += b42; | |
781 | ||
782 | CheckCovariance(); | |
783 | ||
784 | return kTRUE; | |
785 | } | |
786 | ||
787 | Bool_t | |
788 | AliExternalTrackParam::Propagate(Double_t alpha, Double_t x, Double_t b) { | |
789 | //------------------------------------------------------------------ | |
790 | // Transform this track to the local coord. system rotated | |
791 | // by angle "alpha" (rad) with respect to the global coord. system, | |
792 | // and propagate this track to the plane X=xk (cm) in the field "b" (kG) | |
793 | //------------------------------------------------------------------ | |
794 | ||
795 | //Save the parameters | |
796 | Double_t as=fAlpha; | |
797 | Double_t xs=fX; | |
798 | Double_t ps[5], cs[15]; | |
799 | for (Int_t i=0; i<5; i++) ps[i]=fP[i]; | |
800 | for (Int_t i=0; i<15; i++) cs[i]=fC[i]; | |
801 | ||
802 | if (Rotate(alpha)) | |
803 | if (PropagateTo(x,b)) return kTRUE; | |
804 | ||
805 | //Restore the parameters, if the operation failed | |
806 | fAlpha=as; | |
807 | fX=xs; | |
808 | for (Int_t i=0; i<5; i++) fP[i]=ps[i]; | |
809 | for (Int_t i=0; i<15; i++) fC[i]=cs[i]; | |
810 | return kFALSE; | |
811 | } | |
812 | ||
813 | Bool_t AliExternalTrackParam::PropagateBxByBz | |
814 | (Double_t alpha, Double_t x, Double_t b[3]) { | |
815 | //------------------------------------------------------------------ | |
816 | // Transform this track to the local coord. system rotated | |
817 | // by angle "alpha" (rad) with respect to the global coord. system, | |
818 | // and propagate this track to the plane X=xk (cm), | |
819 | // taking into account all three components of the B field, "b[3]" (kG) | |
820 | //------------------------------------------------------------------ | |
821 | ||
822 | //Save the parameters | |
823 | Double_t as=fAlpha; | |
824 | Double_t xs=fX; | |
825 | Double_t ps[5], cs[15]; | |
826 | for (Int_t i=0; i<5; i++) ps[i]=fP[i]; | |
827 | for (Int_t i=0; i<15; i++) cs[i]=fC[i]; | |
828 | ||
829 | if (Rotate(alpha)) | |
830 | if (PropagateToBxByBz(x,b)) return kTRUE; | |
831 | ||
832 | //Restore the parameters, if the operation failed | |
833 | fAlpha=as; | |
834 | fX=xs; | |
835 | for (Int_t i=0; i<5; i++) fP[i]=ps[i]; | |
836 | for (Int_t i=0; i<15; i++) fC[i]=cs[i]; | |
837 | return kFALSE; | |
838 | } | |
839 | ||
840 | ||
841 | void AliExternalTrackParam::Propagate(Double_t len, Double_t x[3], | |
842 | Double_t p[3], Double_t bz) const { | |
843 | //+++++++++++++++++++++++++++++++++++++++++ | |
844 | // Origin: K. Shileev (Kirill.Shileev@cern.ch) | |
845 | // Extrapolate track along simple helix in magnetic field | |
846 | // Arguments: len -distance alogn helix, [cm] | |
847 | // bz - mag field, [kGaus] | |
848 | // Returns: x and p contain extrapolated positon and momentum | |
849 | // The momentum returned for straight-line tracks is meaningless ! | |
850 | //+++++++++++++++++++++++++++++++++++++++++ | |
851 | GetXYZ(x); | |
852 | ||
853 | if (OneOverPt() < kAlmost0 || TMath::Abs(bz) < kAlmost0Field || GetC(bz) < kAlmost0){ //straight-line tracks | |
854 | Double_t unit[3]; GetDirection(unit); | |
855 | x[0]+=unit[0]*len; | |
856 | x[1]+=unit[1]*len; | |
857 | x[2]+=unit[2]*len; | |
858 | ||
859 | p[0]=unit[0]/kAlmost0; | |
860 | p[1]=unit[1]/kAlmost0; | |
861 | p[2]=unit[2]/kAlmost0; | |
862 | } else { | |
863 | GetPxPyPz(p); | |
864 | Double_t pp=GetP(); | |
865 | Double_t a = -kB2C*bz*GetSign(); | |
866 | Double_t rho = a/pp; | |
867 | x[0] += p[0]*TMath::Sin(rho*len)/a - p[1]*(1-TMath::Cos(rho*len))/a; | |
868 | x[1] += p[1]*TMath::Sin(rho*len)/a + p[0]*(1-TMath::Cos(rho*len))/a; | |
869 | x[2] += p[2]*len/pp; | |
870 | ||
871 | Double_t p0=p[0]; | |
872 | p[0] = p0 *TMath::Cos(rho*len) - p[1]*TMath::Sin(rho*len); | |
873 | p[1] = p[1]*TMath::Cos(rho*len) + p0 *TMath::Sin(rho*len); | |
874 | } | |
875 | } | |
876 | ||
877 | Bool_t AliExternalTrackParam::Intersect(Double_t pnt[3], Double_t norm[3], | |
878 | Double_t bz) const { | |
879 | //+++++++++++++++++++++++++++++++++++++++++ | |
880 | // Origin: K. Shileev (Kirill.Shileev@cern.ch) | |
881 | // Finds point of intersection (if exists) of the helix with the plane. | |
882 | // Stores result in fX and fP. | |
883 | // Arguments: planePoint,planeNorm - the plane defined by any plane's point | |
884 | // and vector, normal to the plane | |
885 | // Returns: kTrue if helix intersects the plane, kFALSE otherwise. | |
886 | //+++++++++++++++++++++++++++++++++++++++++ | |
887 | Double_t x0[3]; GetXYZ(x0); //get track position in MARS | |
888 | ||
889 | //estimates initial helix length up to plane | |
890 | Double_t s= | |
891 | (pnt[0]-x0[0])*norm[0] + (pnt[1]-x0[1])*norm[1] + (pnt[2]-x0[2])*norm[2]; | |
892 | Double_t dist=99999,distPrev=dist; | |
893 | Double_t x[3],p[3]; | |
894 | while(TMath::Abs(dist)>0.00001){ | |
895 | //calculates helix at the distance s from x0 ALONG the helix | |
896 | Propagate(s,x,p,bz); | |
897 | ||
898 | //distance between current helix position and plane | |
899 | dist=(x[0]-pnt[0])*norm[0]+(x[1]-pnt[1])*norm[1]+(x[2]-pnt[2])*norm[2]; | |
900 | ||
901 | if(TMath::Abs(dist) >= TMath::Abs(distPrev)) {return kFALSE;} | |
902 | distPrev=dist; | |
903 | s-=dist; | |
904 | } | |
905 | //on exit pnt is intersection point,norm is track vector at that point, | |
906 | //all in MARS | |
907 | for (Int_t i=0; i<3; i++) {pnt[i]=x[i]; norm[i]=p[i];} | |
908 | return kTRUE; | |
909 | } | |
910 | ||
911 | Double_t | |
912 | AliExternalTrackParam::GetPredictedChi2(Double_t p[2],Double_t cov[3]) const { | |
913 | //---------------------------------------------------------------- | |
914 | // Estimate the chi2 of the space point "p" with the cov. matrix "cov" | |
915 | //---------------------------------------------------------------- | |
916 | Double_t sdd = fC[0] + cov[0]; | |
917 | Double_t sdz = fC[1] + cov[1]; | |
918 | Double_t szz = fC[2] + cov[2]; | |
919 | Double_t det = sdd*szz - sdz*sdz; | |
920 | ||
921 | if (TMath::Abs(det) < kAlmost0) return kVeryBig; | |
922 | ||
923 | Double_t d = fP[0] - p[0]; | |
924 | Double_t z = fP[1] - p[1]; | |
925 | ||
926 | return (d*szz*d - 2*d*sdz*z + z*sdd*z)/det; | |
927 | } | |
928 | ||
929 | Double_t AliExternalTrackParam:: | |
930 | GetPredictedChi2(Double_t p[3],Double_t covyz[3],Double_t covxyz[3]) const { | |
931 | //---------------------------------------------------------------- | |
932 | // Estimate the chi2 of the 3D space point "p" and | |
933 | // the full covariance matrix "covyz" and "covxyz" | |
934 | // | |
935 | // Cov(x,x) ... : covxyz[0] | |
936 | // Cov(y,x) ... : covxyz[1] covyz[0] | |
937 | // Cov(z,x) ... : covxyz[2] covyz[1] covyz[2] | |
938 | //---------------------------------------------------------------- | |
939 | ||
940 | Double_t res[3] = { | |
941 | GetX() - p[0], | |
942 | GetY() - p[1], | |
943 | GetZ() - p[2] | |
944 | }; | |
945 | ||
946 | Double_t f=GetSnp(); | |
947 | if (TMath::Abs(f) >= kAlmost1) return kVeryBig; | |
948 | Double_t r=TMath::Sqrt((1.-f)*(1.+f)); | |
949 | Double_t a=f/r, b=GetTgl()/r; | |
950 | ||
951 | Double_t s2=333.*333.; //something reasonably big (cm^2) | |
952 | ||
953 | TMatrixDSym v(3); | |
954 | v(0,0)= s2; v(0,1)= a*s2; v(0,2)= b*s2;; | |
955 | v(1,0)=a*s2; v(1,1)=a*a*s2 + GetSigmaY2(); v(1,2)=a*b*s2 + GetSigmaZY(); | |
956 | v(2,0)=b*s2; v(2,1)=a*b*s2 + GetSigmaZY(); v(2,2)=b*b*s2 + GetSigmaZ2(); | |
957 | ||
958 | v(0,0)+=covxyz[0]; v(0,1)+=covxyz[1]; v(0,2)+=covxyz[2]; | |
959 | v(1,0)+=covxyz[1]; v(1,1)+=covyz[0]; v(1,2)+=covyz[1]; | |
960 | v(2,0)+=covxyz[2]; v(2,1)+=covyz[1]; v(2,2)+=covyz[2]; | |
961 | ||
962 | v.Invert(); | |
963 | if (!v.IsValid()) return kVeryBig; | |
964 | ||
965 | Double_t chi2=0.; | |
966 | for (Int_t i = 0; i < 3; i++) | |
967 | for (Int_t j = 0; j < 3; j++) chi2 += res[i]*res[j]*v(i,j); | |
968 | ||
969 | return chi2; | |
970 | } | |
971 | ||
972 | Double_t AliExternalTrackParam:: | |
973 | GetPredictedChi2(const AliExternalTrackParam *t) const { | |
974 | //---------------------------------------------------------------- | |
975 | // Estimate the chi2 (5 dof) of this track with respect to the track | |
976 | // given by the argument. | |
977 | // The two tracks must be in the same reference system | |
978 | // and estimated at the same reference plane. | |
979 | //---------------------------------------------------------------- | |
980 | ||
981 | if (TMath::Abs(1. - t->GetAlpha()/GetAlpha()) > FLT_EPSILON) { | |
982 | AliError("The reference systems of the tracks differ !"); | |
983 | return kVeryBig; | |
984 | } | |
985 | if (TMath::Abs(1. - t->GetX()/GetX()) > FLT_EPSILON) { | |
986 | AliError("The reference of the tracks planes differ !"); | |
987 | return kVeryBig; | |
988 | } | |
989 | ||
990 | TMatrixDSym c(5); | |
991 | c(0,0)=GetSigmaY2(); | |
992 | c(1,0)=GetSigmaZY(); c(1,1)=GetSigmaZ2(); | |
993 | c(2,0)=GetSigmaSnpY(); c(2,1)=GetSigmaSnpZ(); c(2,2)=GetSigmaSnp2(); | |
994 | c(3,0)=GetSigmaTglY(); c(3,1)=GetSigmaTglZ(); c(3,2)=GetSigmaTglSnp(); c(3,3)=GetSigmaTgl2(); | |
995 | c(4,0)=GetSigma1PtY(); c(4,1)=GetSigma1PtZ(); c(4,2)=GetSigma1PtSnp(); c(4,3)=GetSigma1PtTgl(); c(4,4)=GetSigma1Pt2(); | |
996 | ||
997 | c(0,0)+=t->GetSigmaY2(); | |
998 | c(1,0)+=t->GetSigmaZY(); c(1,1)+=t->GetSigmaZ2(); | |
999 | c(2,0)+=t->GetSigmaSnpY();c(2,1)+=t->GetSigmaSnpZ();c(2,2)+=t->GetSigmaSnp2(); | |
1000 | c(3,0)+=t->GetSigmaTglY();c(3,1)+=t->GetSigmaTglZ();c(3,2)+=t->GetSigmaTglSnp();c(3,3)+=t->GetSigmaTgl2(); | |
1001 | c(4,0)+=t->GetSigma1PtY();c(4,1)+=t->GetSigma1PtZ();c(4,2)+=t->GetSigma1PtSnp();c(4,3)+=t->GetSigma1PtTgl();c(4,4)+=t->GetSigma1Pt2(); | |
1002 | c(0,1)=c(1,0); | |
1003 | c(0,2)=c(2,0); c(1,2)=c(2,1); | |
1004 | c(0,3)=c(3,0); c(1,3)=c(3,1); c(2,3)=c(3,2); | |
1005 | c(0,4)=c(4,0); c(1,4)=c(4,1); c(2,4)=c(4,2); c(3,4)=c(4,3); | |
1006 | ||
1007 | c.Invert(); | |
1008 | if (!c.IsValid()) return kVeryBig; | |
1009 | ||
1010 | ||
1011 | Double_t res[5] = { | |
1012 | GetY() - t->GetY(), | |
1013 | GetZ() - t->GetZ(), | |
1014 | GetSnp() - t->GetSnp(), | |
1015 | GetTgl() - t->GetTgl(), | |
1016 | GetSigned1Pt() - t->GetSigned1Pt() | |
1017 | }; | |
1018 | ||
1019 | Double_t chi2=0.; | |
1020 | for (Int_t i = 0; i < 5; i++) | |
1021 | for (Int_t j = 0; j < 5; j++) chi2 += res[i]*res[j]*c(i,j); | |
1022 | ||
1023 | return chi2; | |
1024 | } | |
1025 | ||
1026 | Bool_t AliExternalTrackParam:: | |
1027 | PropagateTo(Double_t p[3],Double_t covyz[3],Double_t covxyz[3],Double_t bz) { | |
1028 | //---------------------------------------------------------------- | |
1029 | // Propagate this track to the plane | |
1030 | // the 3D space point "p" (with the covariance matrix "covyz" and "covxyz") | |
1031 | // belongs to. | |
1032 | // The magnetic field is "bz" (kG) | |
1033 | // | |
1034 | // The track curvature and the change of the covariance matrix | |
1035 | // of the track parameters are negleted ! | |
1036 | // (So the "step" should be small compared with 1/curvature) | |
1037 | //---------------------------------------------------------------- | |
1038 | ||
1039 | Double_t f=GetSnp(); | |
1040 | if (TMath::Abs(f) >= kAlmost1) return kFALSE; | |
1041 | Double_t r=TMath::Sqrt((1.-f)*(1.+f)); | |
1042 | Double_t a=f/r, b=GetTgl()/r; | |
1043 | ||
1044 | Double_t s2=333.*333.; //something reasonably big (cm^2) | |
1045 | ||
1046 | TMatrixDSym tV(3); | |
1047 | tV(0,0)= s2; tV(0,1)= a*s2; tV(0,2)= b*s2; | |
1048 | tV(1,0)=a*s2; tV(1,1)=a*a*s2; tV(1,2)=a*b*s2; | |
1049 | tV(2,0)=b*s2; tV(2,1)=a*b*s2; tV(2,2)=b*b*s2; | |
1050 | ||
1051 | TMatrixDSym pV(3); | |
1052 | pV(0,0)=covxyz[0]; pV(0,1)=covxyz[1]; pV(0,2)=covxyz[2]; | |
1053 | pV(1,0)=covxyz[1]; pV(1,1)=covyz[0]; pV(1,2)=covyz[1]; | |
1054 | pV(2,0)=covxyz[2]; pV(2,1)=covyz[1]; pV(2,2)=covyz[2]; | |
1055 | ||
1056 | TMatrixDSym tpV(tV); | |
1057 | tpV+=pV; | |
1058 | tpV.Invert(); | |
1059 | if (!tpV.IsValid()) return kFALSE; | |
1060 | ||
1061 | TMatrixDSym pW(3),tW(3); | |
1062 | for (Int_t i=0; i<3; i++) | |
1063 | for (Int_t j=0; j<3; j++) { | |
1064 | pW(i,j)=tW(i,j)=0.; | |
1065 | for (Int_t k=0; k<3; k++) { | |
1066 | pW(i,j) += tV(i,k)*tpV(k,j); | |
1067 | tW(i,j) += pV(i,k)*tpV(k,j); | |
1068 | } | |
1069 | } | |
1070 | ||
1071 | Double_t t[3] = {GetX(), GetY(), GetZ()}; | |
1072 | ||
1073 | Double_t x=0.; | |
1074 | for (Int_t i=0; i<3; i++) x += (tW(0,i)*t[i] + pW(0,i)*p[i]); | |
1075 | Double_t crv=GetC(bz); | |
1076 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; | |
1077 | f += crv*(x-fX); | |
1078 | if (TMath::Abs(f) >= kAlmost1) return kFALSE; | |
1079 | fX=x; | |
1080 | ||
1081 | fP[0]=0.; | |
1082 | for (Int_t i=0; i<3; i++) fP[0] += (tW(1,i)*t[i] + pW(1,i)*p[i]); | |
1083 | fP[1]=0.; | |
1084 | for (Int_t i=0; i<3; i++) fP[1] += (tW(2,i)*t[i] + pW(2,i)*p[i]); | |
1085 | ||
1086 | return kTRUE; | |
1087 | } | |
1088 | ||
1089 | Double_t *AliExternalTrackParam::GetResiduals( | |
1090 | Double_t *p,Double_t *cov,Bool_t updated) const { | |
1091 | //------------------------------------------------------------------ | |
1092 | // Returns the track residuals with the space point "p" having | |
1093 | // the covariance matrix "cov". | |
1094 | // If "updated" is kTRUE, the track parameters expected to be updated, | |
1095 | // otherwise they must be predicted. | |
1096 | //------------------------------------------------------------------ | |
1097 | static Double_t res[2]; | |
1098 | ||
1099 | Double_t r00=cov[0], r01=cov[1], r11=cov[2]; | |
1100 | if (updated) { | |
1101 | r00-=fC[0]; r01-=fC[1]; r11-=fC[2]; | |
1102 | } else { | |
1103 | r00+=fC[0]; r01+=fC[1]; r11+=fC[2]; | |
1104 | } | |
1105 | Double_t det=r00*r11 - r01*r01; | |
1106 | ||
1107 | if (TMath::Abs(det) < kAlmost0) return 0; | |
1108 | ||
1109 | Double_t tmp=r00; r00=r11/det; r11=tmp/det; | |
1110 | ||
1111 | if (r00 < 0.) return 0; | |
1112 | if (r11 < 0.) return 0; | |
1113 | ||
1114 | Double_t dy = fP[0] - p[0]; | |
1115 | Double_t dz = fP[1] - p[1]; | |
1116 | ||
1117 | res[0]=dy*TMath::Sqrt(r00); | |
1118 | res[1]=dz*TMath::Sqrt(r11); | |
1119 | ||
1120 | return res; | |
1121 | } | |
1122 | ||
1123 | Bool_t AliExternalTrackParam::Update(Double_t p[2], Double_t cov[3]) { | |
1124 | //------------------------------------------------------------------ | |
1125 | // Update the track parameters with the space point "p" having | |
1126 | // the covariance matrix "cov" | |
1127 | //------------------------------------------------------------------ | |
1128 | Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4]; | |
1129 | Double_t | |
1130 | &fC00=fC[0], | |
1131 | &fC10=fC[1], &fC11=fC[2], | |
1132 | &fC20=fC[3], &fC21=fC[4], &fC22=fC[5], | |
1133 | &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9], | |
1134 | &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14]; | |
1135 | ||
1136 | Double_t r00=cov[0], r01=cov[1], r11=cov[2]; | |
1137 | r00+=fC00; r01+=fC10; r11+=fC11; | |
1138 | Double_t det=r00*r11 - r01*r01; | |
1139 | ||
1140 | if (TMath::Abs(det) < kAlmost0) return kFALSE; | |
1141 | ||
1142 | ||
1143 | Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det; | |
1144 | ||
1145 | Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11; | |
1146 | Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11; | |
1147 | Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11; | |
1148 | Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11; | |
1149 | Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11; | |
1150 | ||
1151 | Double_t dy=p[0] - fP0, dz=p[1] - fP1; | |
1152 | Double_t sf=fP2 + k20*dy + k21*dz; | |
1153 | if (TMath::Abs(sf) > kAlmost1) return kFALSE; | |
1154 | ||
1155 | fP0 += k00*dy + k01*dz; | |
1156 | fP1 += k10*dy + k11*dz; | |
1157 | fP2 = sf; | |
1158 | fP3 += k30*dy + k31*dz; | |
1159 | fP4 += k40*dy + k41*dz; | |
1160 | ||
1161 | Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40; | |
1162 | Double_t c12=fC21, c13=fC31, c14=fC41; | |
1163 | ||
1164 | fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11; | |
1165 | fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13; | |
1166 | fC40-=k00*c04+k01*c14; | |
1167 | ||
1168 | fC11-=k10*c01+k11*fC11; | |
1169 | fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13; | |
1170 | fC41-=k10*c04+k11*c14; | |
1171 | ||
1172 | fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13; | |
1173 | fC42-=k20*c04+k21*c14; | |
1174 | ||
1175 | fC33-=k30*c03+k31*c13; | |
1176 | fC43-=k30*c04+k31*c14; | |
1177 | ||
1178 | fC44-=k40*c04+k41*c14; | |
1179 | ||
1180 | CheckCovariance(); | |
1181 | ||
1182 | return kTRUE; | |
1183 | } | |
1184 | ||
1185 | void | |
1186 | AliExternalTrackParam::GetHelixParameters(Double_t hlx[6], Double_t b) const { | |
1187 | //-------------------------------------------------------------------- | |
1188 | // External track parameters -> helix parameters | |
1189 | // "b" - magnetic field (kG) | |
1190 | //-------------------------------------------------------------------- | |
1191 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
1192 | ||
1193 | hlx[0]=fP[0]; hlx[1]=fP[1]; hlx[2]=fP[2]; hlx[3]=fP[3]; | |
1194 | ||
1195 | hlx[5]=fX*cs - hlx[0]*sn; // x0 | |
1196 | hlx[0]=fX*sn + hlx[0]*cs; // y0 | |
1197 | //hlx[1]= // z0 | |
1198 | hlx[2]=TMath::ASin(hlx[2]) + fAlpha; // phi0 | |
1199 | //hlx[3]= // tgl | |
1200 | hlx[4]=GetC(b); // C | |
1201 | } | |
1202 | ||
1203 | ||
1204 | static void Evaluate(const Double_t *h, Double_t t, | |
1205 | Double_t r[3], //radius vector | |
1206 | Double_t g[3], //first defivatives | |
1207 | Double_t gg[3]) //second derivatives | |
1208 | { | |
1209 | //-------------------------------------------------------------------- | |
1210 | // Calculate position of a point on a track and some derivatives | |
1211 | //-------------------------------------------------------------------- | |
1212 | Double_t phase=h[4]*t+h[2]; | |
1213 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
1214 | ||
1215 | r[0] = h[5]; | |
1216 | r[1] = h[0]; | |
1217 | if (TMath::Abs(h[4])>kAlmost0) { | |
1218 | r[0] += (sn - h[6])/h[4]; | |
1219 | r[1] -= (cs - h[7])/h[4]; | |
1220 | } | |
1221 | r[2] = h[1] + h[3]*t; | |
1222 | ||
1223 | g[0] = cs; g[1]=sn; g[2]=h[3]; | |
1224 | ||
1225 | gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.; | |
1226 | } | |
1227 | ||
1228 | Double_t AliExternalTrackParam::GetDCA(const AliExternalTrackParam *p, | |
1229 | Double_t b, Double_t &xthis, Double_t &xp) const { | |
1230 | //------------------------------------------------------------ | |
1231 | // Returns the (weighed !) distance of closest approach between | |
1232 | // this track and the track "p". | |
1233 | // Other returned values: | |
1234 | // xthis, xt - coordinates of tracks' reference planes at the DCA | |
1235 | //----------------------------------------------------------- | |
1236 | Double_t dy2=GetSigmaY2() + p->GetSigmaY2(); | |
1237 | Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2(); | |
1238 | Double_t dx2=dy2; | |
1239 | ||
1240 | Double_t p1[8]; GetHelixParameters(p1,b); | |
1241 | p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]); | |
1242 | Double_t p2[8]; p->GetHelixParameters(p2,b); | |
1243 | p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]); | |
1244 | ||
1245 | ||
1246 | Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.; | |
1247 | Evaluate(p1,t1,r1,g1,gg1); | |
1248 | Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.; | |
1249 | Evaluate(p2,t2,r2,g2,gg2); | |
1250 | ||
1251 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; | |
1252 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
1253 | ||
1254 | Int_t max=27; | |
1255 | while (max--) { | |
1256 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
1257 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
1258 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
1259 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
1260 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
1261 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
1262 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
1263 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
1264 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
1265 | ||
1266 | Double_t det=h11*h22-h12*h12; | |
1267 | ||
1268 | Double_t dt1,dt2; | |
1269 | if (TMath::Abs(det)<1.e-33) { | |
1270 | //(quasi)singular Hessian | |
1271 | dt1=-gt1; dt2=-gt2; | |
1272 | } else { | |
1273 | dt1=-(gt1*h22 - gt2*h12)/det; | |
1274 | dt2=-(h11*gt2 - h12*gt1)/det; | |
1275 | } | |
1276 | ||
1277 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
1278 | ||
1279 | //check delta(phase1) ? | |
1280 | //check delta(phase2) ? | |
1281 | ||
1282 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
1283 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
1284 | if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) | |
1285 | AliDebug(1," stopped at not a stationary point !"); | |
1286 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); | |
1287 | if (lmb < 0.) | |
1288 | AliDebug(1," stopped at not a minimum !"); | |
1289 | break; | |
1290 | } | |
1291 | ||
1292 | Double_t dd=dm; | |
1293 | for (Int_t div=1 ; ; div*=2) { | |
1294 | Evaluate(p1,t1+dt1,r1,g1,gg1); | |
1295 | Evaluate(p2,t2+dt2,r2,g2,gg2); | |
1296 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
1297 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
1298 | if (dd<dm) break; | |
1299 | dt1*=0.5; dt2*=0.5; | |
1300 | if (div>512) { | |
1301 | AliDebug(1," overshoot !"); break; | |
1302 | } | |
1303 | } | |
1304 | dm=dd; | |
1305 | ||
1306 | t1+=dt1; | |
1307 | t2+=dt2; | |
1308 | ||
1309 | } | |
1310 | ||
1311 | if (max<=0) AliDebug(1," too many iterations !"); | |
1312 | ||
1313 | Double_t cs=TMath::Cos(GetAlpha()); | |
1314 | Double_t sn=TMath::Sin(GetAlpha()); | |
1315 | xthis=r1[0]*cs + r1[1]*sn; | |
1316 | ||
1317 | cs=TMath::Cos(p->GetAlpha()); | |
1318 | sn=TMath::Sin(p->GetAlpha()); | |
1319 | xp=r2[0]*cs + r2[1]*sn; | |
1320 | ||
1321 | return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2)); | |
1322 | } | |
1323 | ||
1324 | Double_t AliExternalTrackParam:: | |
1325 | PropagateToDCA(AliExternalTrackParam *p, Double_t b) { | |
1326 | //-------------------------------------------------------------- | |
1327 | // Propagates this track and the argument track to the position of the | |
1328 | // distance of closest approach. | |
1329 | // Returns the (weighed !) distance of closest approach. | |
1330 | //-------------------------------------------------------------- | |
1331 | Double_t xthis,xp; | |
1332 | Double_t dca=GetDCA(p,b,xthis,xp); | |
1333 | ||
1334 | if (!PropagateTo(xthis,b)) { | |
1335 | //AliWarning(" propagation failed !"); | |
1336 | return 1e+33; | |
1337 | } | |
1338 | ||
1339 | if (!p->PropagateTo(xp,b)) { | |
1340 | //AliWarning(" propagation failed !"; | |
1341 | return 1e+33; | |
1342 | } | |
1343 | ||
1344 | return dca; | |
1345 | } | |
1346 | ||
1347 | ||
1348 | Bool_t AliExternalTrackParam::PropagateToDCA(const AliVVertex *vtx, | |
1349 | Double_t b, Double_t maxd, Double_t dz[2], Double_t covar[3]) { | |
1350 | // | |
1351 | // Propagate this track to the DCA to vertex "vtx", | |
1352 | // if the (rough) transverse impact parameter is not bigger then "maxd". | |
1353 | // Magnetic field is "b" (kG). | |
1354 | // | |
1355 | // a) The track gets extapolated to the DCA to the vertex. | |
1356 | // b) The impact parameters and their covariance matrix are calculated. | |
1357 | // | |
1358 | // In the case of success, the returned value is kTRUE | |
1359 | // (otherwise, it's kFALSE) | |
1360 | // | |
1361 | Double_t alpha=GetAlpha(); | |
1362 | Double_t sn=TMath::Sin(alpha), cs=TMath::Cos(alpha); | |
1363 | Double_t x=GetX(), y=GetParameter()[0], snp=GetParameter()[2]; | |
1364 | Double_t xv= vtx->GetX()*cs + vtx->GetY()*sn; | |
1365 | Double_t yv=-vtx->GetX()*sn + vtx->GetY()*cs, zv=vtx->GetZ(); | |
1366 | x-=xv; y-=yv; | |
1367 | ||
1368 | //Estimate the impact parameter neglecting the track curvature | |
1369 | Double_t d=TMath::Abs(x*snp - y*TMath::Sqrt((1.-snp)*(1.+snp))); | |
1370 | if (d > maxd) return kFALSE; | |
1371 | ||
1372 | //Propagate to the DCA | |
1373 | Double_t crv=GetC(b); | |
1374 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; | |
1375 | ||
1376 | Double_t tgfv=-(crv*x - snp)/(crv*y + TMath::Sqrt((1.-snp)*(1.+snp))); | |
1377 | sn=tgfv/TMath::Sqrt(1.+ tgfv*tgfv); cs=TMath::Sqrt((1.-sn)*(1.+sn)); | |
1378 | if (TMath::Abs(tgfv)>0.) cs = sn/tgfv; | |
1379 | else cs=1.; | |
1380 | ||
1381 | x = xv*cs + yv*sn; | |
1382 | yv=-xv*sn + yv*cs; xv=x; | |
1383 | ||
1384 | if (!Propagate(alpha+TMath::ASin(sn),xv,b)) return kFALSE; | |
1385 | ||
1386 | if (dz==0) return kTRUE; | |
1387 | dz[0] = GetParameter()[0] - yv; | |
1388 | dz[1] = GetParameter()[1] - zv; | |
1389 | ||
1390 | if (covar==0) return kTRUE; | |
1391 | Double_t cov[6]; vtx->GetCovarianceMatrix(cov); | |
1392 | ||
1393 | //***** Improvements by A.Dainese | |
1394 | alpha=GetAlpha(); sn=TMath::Sin(alpha); cs=TMath::Cos(alpha); | |
1395 | Double_t s2ylocvtx = cov[0]*sn*sn + cov[2]*cs*cs - 2.*cov[1]*cs*sn; | |
1396 | covar[0] = GetCovariance()[0] + s2ylocvtx; // neglecting correlations | |
1397 | covar[1] = GetCovariance()[1]; // between (x,y) and z | |
1398 | covar[2] = GetCovariance()[2] + cov[5]; // in vertex's covariance matrix | |
1399 | //***** | |
1400 | ||
1401 | return kTRUE; | |
1402 | } | |
1403 | ||
1404 | Bool_t AliExternalTrackParam::PropagateToDCABxByBz(const AliVVertex *vtx, | |
1405 | Double_t b[3], Double_t maxd, Double_t dz[2], Double_t covar[3]) { | |
1406 | // | |
1407 | // Propagate this track to the DCA to vertex "vtx", | |
1408 | // if the (rough) transverse impact parameter is not bigger then "maxd". | |
1409 | // | |
1410 | // This function takes into account all three components of the magnetic | |
1411 | // field given by the b[3] arument (kG) | |
1412 | // | |
1413 | // a) The track gets extapolated to the DCA to the vertex. | |
1414 | // b) The impact parameters and their covariance matrix are calculated. | |
1415 | // | |
1416 | // In the case of success, the returned value is kTRUE | |
1417 | // (otherwise, it's kFALSE) | |
1418 | // | |
1419 | Double_t alpha=GetAlpha(); | |
1420 | Double_t sn=TMath::Sin(alpha), cs=TMath::Cos(alpha); | |
1421 | Double_t x=GetX(), y=GetParameter()[0], snp=GetParameter()[2]; | |
1422 | Double_t xv= vtx->GetX()*cs + vtx->GetY()*sn; | |
1423 | Double_t yv=-vtx->GetX()*sn + vtx->GetY()*cs, zv=vtx->GetZ(); | |
1424 | x-=xv; y-=yv; | |
1425 | ||
1426 | //Estimate the impact parameter neglecting the track curvature | |
1427 | Double_t d=TMath::Abs(x*snp - y*TMath::Sqrt((1.-snp)*(1.+snp))); | |
1428 | if (d > maxd) return kFALSE; | |
1429 | ||
1430 | //Propagate to the DCA | |
1431 | Double_t crv=GetC(b[2]); | |
1432 | if (TMath::Abs(b[2]) < kAlmost0Field) crv=0.; | |
1433 | ||
1434 | Double_t tgfv=-(crv*x - snp)/(crv*y + TMath::Sqrt((1.-snp)*(1.+snp))); | |
1435 | sn=tgfv/TMath::Sqrt(1.+ tgfv*tgfv); cs=TMath::Sqrt((1.-sn)*(1.+sn)); | |
1436 | if (TMath::Abs(tgfv)>0.) cs = sn/tgfv; | |
1437 | else cs=1.; | |
1438 | ||
1439 | x = xv*cs + yv*sn; | |
1440 | yv=-xv*sn + yv*cs; xv=x; | |
1441 | ||
1442 | if (!PropagateBxByBz(alpha+TMath::ASin(sn),xv,b)) return kFALSE; | |
1443 | ||
1444 | if (dz==0) return kTRUE; | |
1445 | dz[0] = GetParameter()[0] - yv; | |
1446 | dz[1] = GetParameter()[1] - zv; | |
1447 | ||
1448 | if (covar==0) return kTRUE; | |
1449 | Double_t cov[6]; vtx->GetCovarianceMatrix(cov); | |
1450 | ||
1451 | //***** Improvements by A.Dainese | |
1452 | alpha=GetAlpha(); sn=TMath::Sin(alpha); cs=TMath::Cos(alpha); | |
1453 | Double_t s2ylocvtx = cov[0]*sn*sn + cov[2]*cs*cs - 2.*cov[1]*cs*sn; | |
1454 | covar[0] = GetCovariance()[0] + s2ylocvtx; // neglecting correlations | |
1455 | covar[1] = GetCovariance()[1]; // between (x,y) and z | |
1456 | covar[2] = GetCovariance()[2] + cov[5]; // in vertex's covariance matrix | |
1457 | //***** | |
1458 | ||
1459 | return kTRUE; | |
1460 | } | |
1461 | ||
1462 | void AliExternalTrackParam::GetDirection(Double_t d[3]) const { | |
1463 | //---------------------------------------------------------------- | |
1464 | // This function returns a unit vector along the track direction | |
1465 | // in the global coordinate system. | |
1466 | //---------------------------------------------------------------- | |
1467 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
1468 | Double_t snp=fP[2]; | |
1469 | Double_t csp =TMath::Sqrt((1.-snp)*(1.+snp)); | |
1470 | Double_t norm=TMath::Sqrt(1.+ fP[3]*fP[3]); | |
1471 | d[0]=(csp*cs - snp*sn)/norm; | |
1472 | d[1]=(snp*cs + csp*sn)/norm; | |
1473 | d[2]=fP[3]/norm; | |
1474 | } | |
1475 | ||
1476 | Bool_t AliExternalTrackParam::GetPxPyPz(Double_t p[3]) const { | |
1477 | //--------------------------------------------------------------------- | |
1478 | // This function returns the global track momentum components | |
1479 | // Results for (nearly) straight tracks are meaningless ! | |
1480 | //--------------------------------------------------------------------- | |
1481 | p[0]=fP[4]; p[1]=fP[2]; p[2]=fP[3]; | |
1482 | return Local2GlobalMomentum(p,fAlpha); | |
1483 | } | |
1484 | ||
1485 | Double_t AliExternalTrackParam::Px() const { | |
1486 | //--------------------------------------------------------------------- | |
1487 | // Returns x-component of momentum | |
1488 | // Result for (nearly) straight tracks is meaningless ! | |
1489 | //--------------------------------------------------------------------- | |
1490 | ||
1491 | Double_t p[3]={kVeryBig,kVeryBig,kVeryBig}; | |
1492 | GetPxPyPz(p); | |
1493 | ||
1494 | return p[0]; | |
1495 | } | |
1496 | ||
1497 | Double_t AliExternalTrackParam::Py() const { | |
1498 | //--------------------------------------------------------------------- | |
1499 | // Returns y-component of momentum | |
1500 | // Result for (nearly) straight tracks is meaningless ! | |
1501 | //--------------------------------------------------------------------- | |
1502 | ||
1503 | Double_t p[3]={kVeryBig,kVeryBig,kVeryBig}; | |
1504 | GetPxPyPz(p); | |
1505 | ||
1506 | return p[1]; | |
1507 | } | |
1508 | ||
1509 | Double_t AliExternalTrackParam::Xv() const { | |
1510 | //--------------------------------------------------------------------- | |
1511 | // Returns x-component of first track point | |
1512 | //--------------------------------------------------------------------- | |
1513 | ||
1514 | Double_t r[3]={0.,0.,0.}; | |
1515 | GetXYZ(r); | |
1516 | ||
1517 | return r[0]; | |
1518 | } | |
1519 | ||
1520 | Double_t AliExternalTrackParam::Yv() const { | |
1521 | //--------------------------------------------------------------------- | |
1522 | // Returns y-component of first track point | |
1523 | //--------------------------------------------------------------------- | |
1524 | ||
1525 | Double_t r[3]={0.,0.,0.}; | |
1526 | GetXYZ(r); | |
1527 | ||
1528 | return r[1]; | |
1529 | } | |
1530 | ||
1531 | Double_t AliExternalTrackParam::Theta() const { | |
1532 | // return theta angle of momentum | |
1533 | ||
1534 | return 0.5*TMath::Pi() - TMath::ATan(fP[3]); | |
1535 | } | |
1536 | ||
1537 | Double_t AliExternalTrackParam::Phi() const { | |
1538 | //--------------------------------------------------------------------- | |
1539 | // Returns the azimuthal angle of momentum | |
1540 | // 0 <= phi < 2*pi | |
1541 | //--------------------------------------------------------------------- | |
1542 | ||
1543 | Double_t phi=TMath::ASin(fP[2]) + fAlpha; | |
1544 | if (phi<0.) phi+=2.*TMath::Pi(); | |
1545 | else if (phi>=2.*TMath::Pi()) phi-=2.*TMath::Pi(); | |
1546 | ||
1547 | return phi; | |
1548 | } | |
1549 | ||
1550 | Double_t AliExternalTrackParam::M() const { | |
1551 | // return particle mass | |
1552 | ||
1553 | // No mass information available so far. | |
1554 | // Redifine in derived class! | |
1555 | ||
1556 | return -999.; | |
1557 | } | |
1558 | ||
1559 | Double_t AliExternalTrackParam::E() const { | |
1560 | // return particle energy | |
1561 | ||
1562 | // No PID information available so far. | |
1563 | // Redifine in derived class! | |
1564 | ||
1565 | return -999.; | |
1566 | } | |
1567 | ||
1568 | Double_t AliExternalTrackParam::Eta() const { | |
1569 | // return pseudorapidity | |
1570 | ||
1571 | return -TMath::Log(TMath::Tan(0.5 * Theta())); | |
1572 | } | |
1573 | ||
1574 | Double_t AliExternalTrackParam::Y() const { | |
1575 | // return rapidity | |
1576 | ||
1577 | // No PID information available so far. | |
1578 | // Redifine in derived class! | |
1579 | ||
1580 | return -999.; | |
1581 | } | |
1582 | ||
1583 | Bool_t AliExternalTrackParam::GetXYZ(Double_t *r) const { | |
1584 | //--------------------------------------------------------------------- | |
1585 | // This function returns the global track position | |
1586 | //--------------------------------------------------------------------- | |
1587 | r[0]=fX; r[1]=fP[0]; r[2]=fP[1]; | |
1588 | return Local2GlobalPosition(r,fAlpha); | |
1589 | } | |
1590 | ||
1591 | Bool_t AliExternalTrackParam::GetCovarianceXYZPxPyPz(Double_t cv[21]) const { | |
1592 | //--------------------------------------------------------------------- | |
1593 | // This function returns the global covariance matrix of the track params | |
1594 | // | |
1595 | // Cov(x,x) ... : cv[0] | |
1596 | // Cov(y,x) ... : cv[1] cv[2] | |
1597 | // Cov(z,x) ... : cv[3] cv[4] cv[5] | |
1598 | // Cov(px,x)... : cv[6] cv[7] cv[8] cv[9] | |
1599 | // Cov(py,x)... : cv[10] cv[11] cv[12] cv[13] cv[14] | |
1600 | // Cov(pz,x)... : cv[15] cv[16] cv[17] cv[18] cv[19] cv[20] | |
1601 | // | |
1602 | // Results for (nearly) straight tracks are meaningless ! | |
1603 | //--------------------------------------------------------------------- | |
1604 | if (TMath::Abs(fP[4])<=kAlmost0) { | |
1605 | for (Int_t i=0; i<21; i++) cv[i]=0.; | |
1606 | return kFALSE; | |
1607 | } | |
1608 | if (TMath::Abs(fP[2]) > kAlmost1) { | |
1609 | for (Int_t i=0; i<21; i++) cv[i]=0.; | |
1610 | return kFALSE; | |
1611 | } | |
1612 | Double_t pt=1./TMath::Abs(fP[4]); | |
1613 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
1614 | Double_t r=TMath::Sqrt((1.-fP[2])*(1.+fP[2])); | |
1615 | ||
1616 | Double_t m00=-sn, m10=cs; | |
1617 | Double_t m23=-pt*(sn + fP[2]*cs/r), m43=-pt*pt*(r*cs - fP[2]*sn); | |
1618 | Double_t m24= pt*(cs - fP[2]*sn/r), m44=-pt*pt*(r*sn + fP[2]*cs); | |
1619 | Double_t m35=pt, m45=-pt*pt*fP[3]; | |
1620 | ||
1621 | m43*=GetSign(); | |
1622 | m44*=GetSign(); | |
1623 | m45*=GetSign(); | |
1624 | ||
1625 | cv[0 ] = fC[0]*m00*m00; | |
1626 | cv[1 ] = fC[0]*m00*m10; | |
1627 | cv[2 ] = fC[0]*m10*m10; | |
1628 | cv[3 ] = fC[1]*m00; | |
1629 | cv[4 ] = fC[1]*m10; | |
1630 | cv[5 ] = fC[2]; | |
1631 | cv[6 ] = m00*(fC[3]*m23 + fC[10]*m43); | |
1632 | cv[7 ] = m10*(fC[3]*m23 + fC[10]*m43); | |
1633 | cv[8 ] = fC[4]*m23 + fC[11]*m43; | |
1634 | cv[9 ] = m23*(fC[5]*m23 + fC[12]*m43) + m43*(fC[12]*m23 + fC[14]*m43); | |
1635 | cv[10] = m00*(fC[3]*m24 + fC[10]*m44); | |
1636 | cv[11] = m10*(fC[3]*m24 + fC[10]*m44); | |
1637 | cv[12] = fC[4]*m24 + fC[11]*m44; | |
1638 | cv[13] = m23*(fC[5]*m24 + fC[12]*m44) + m43*(fC[12]*m24 + fC[14]*m44); | |
1639 | cv[14] = m24*(fC[5]*m24 + fC[12]*m44) + m44*(fC[12]*m24 + fC[14]*m44); | |
1640 | cv[15] = m00*(fC[6]*m35 + fC[10]*m45); | |
1641 | cv[16] = m10*(fC[6]*m35 + fC[10]*m45); | |
1642 | cv[17] = fC[7]*m35 + fC[11]*m45; | |
1643 | cv[18] = m23*(fC[8]*m35 + fC[12]*m45) + m43*(fC[13]*m35 + fC[14]*m45); | |
1644 | cv[19] = m24*(fC[8]*m35 + fC[12]*m45) + m44*(fC[13]*m35 + fC[14]*m45); | |
1645 | cv[20] = m35*(fC[9]*m35 + fC[13]*m45) + m45*(fC[13]*m35 + fC[14]*m45); | |
1646 | ||
1647 | return kTRUE; | |
1648 | } | |
1649 | ||
1650 | ||
1651 | Bool_t | |
1652 | AliExternalTrackParam::GetPxPyPzAt(Double_t x, Double_t b, Double_t *p) const { | |
1653 | //--------------------------------------------------------------------- | |
1654 | // This function returns the global track momentum extrapolated to | |
1655 | // the radial position "x" (cm) in the magnetic field "b" (kG) | |
1656 | //--------------------------------------------------------------------- | |
1657 | p[0]=fP[4]; | |
1658 | p[1]=fP[2]+(x-fX)*GetC(b); | |
1659 | p[2]=fP[3]; | |
1660 | return Local2GlobalMomentum(p,fAlpha); | |
1661 | } | |
1662 | ||
1663 | Bool_t | |
1664 | AliExternalTrackParam::GetYAt(Double_t x, Double_t b, Double_t &y) const { | |
1665 | //--------------------------------------------------------------------- | |
1666 | // This function returns the local Y-coordinate of the intersection | |
1667 | // point between this track and the reference plane "x" (cm). | |
1668 | // Magnetic field "b" (kG) | |
1669 | //--------------------------------------------------------------------- | |
1670 | Double_t dx=x-fX; | |
1671 | if(TMath::Abs(dx)<=kAlmost0) {y=fP[0]; return kTRUE;} | |
1672 | ||
1673 | Double_t f1=fP[2], f2=f1 + dx*GetC(b); | |
1674 | ||
1675 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
1676 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
1677 | ||
1678 | Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2)); | |
1679 | y = fP[0] + dx*(f1+f2)/(r1+r2); | |
1680 | return kTRUE; | |
1681 | } | |
1682 | ||
1683 | Bool_t | |
1684 | AliExternalTrackParam::GetZAt(Double_t x, Double_t b, Double_t &z) const { | |
1685 | //--------------------------------------------------------------------- | |
1686 | // This function returns the local Z-coordinate of the intersection | |
1687 | // point between this track and the reference plane "x" (cm). | |
1688 | // Magnetic field "b" (kG) | |
1689 | //--------------------------------------------------------------------- | |
1690 | Double_t dx=x-fX; | |
1691 | if(TMath::Abs(dx)<=kAlmost0) {z=fP[1]; return kTRUE;} | |
1692 | ||
1693 | Double_t f1=fP[2], f2=f1 + dx*GetC(b); | |
1694 | ||
1695 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
1696 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
1697 | ||
1698 | Double_t r1=sqrt((1.-f1)*(1.+f1)), r2=sqrt((1.-f2)*(1.+f2)); | |
1699 | z = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3]; // Many thanks to P.Hristov ! | |
1700 | return kTRUE; | |
1701 | } | |
1702 | ||
1703 | Bool_t | |
1704 | AliExternalTrackParam::GetXYZAt(Double_t x, Double_t b, Double_t *r) const { | |
1705 | //--------------------------------------------------------------------- | |
1706 | // This function returns the global track position extrapolated to | |
1707 | // the radial position "x" (cm) in the magnetic field "b" (kG) | |
1708 | //--------------------------------------------------------------------- | |
1709 | Double_t dx=x-fX; | |
1710 | if(TMath::Abs(dx)<=kAlmost0) return GetXYZ(r); | |
1711 | ||
1712 | Double_t f1=fP[2], f2=f1 + dx*GetC(b); | |
1713 | ||
1714 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
1715 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
1716 | ||
1717 | Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2)); | |
1718 | r[0] = x; | |
1719 | r[1] = fP[0] + dx*(f1+f2)/(r1+r2); | |
1720 | r[2] = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3];//Thanks to Andrea & Peter | |
1721 | ||
1722 | return Local2GlobalPosition(r,fAlpha); | |
1723 | } | |
1724 | ||
1725 | //_____________________________________________________________________________ | |
1726 | void AliExternalTrackParam::Print(Option_t* /*option*/) const | |
1727 | { | |
1728 | // print the parameters and the covariance matrix | |
1729 | ||
1730 | printf("AliExternalTrackParam: x = %-12g alpha = %-12g\n", fX, fAlpha); | |
1731 | printf(" parameters: %12g %12g %12g %12g %12g\n", | |
1732 | fP[0], fP[1], fP[2], fP[3], fP[4]); | |
1733 | printf(" covariance: %12g\n", fC[0]); | |
1734 | printf(" %12g %12g\n", fC[1], fC[2]); | |
1735 | printf(" %12g %12g %12g\n", fC[3], fC[4], fC[5]); | |
1736 | printf(" %12g %12g %12g %12g\n", | |
1737 | fC[6], fC[7], fC[8], fC[9]); | |
1738 | printf(" %12g %12g %12g %12g %12g\n", | |
1739 | fC[10], fC[11], fC[12], fC[13], fC[14]); | |
1740 | } | |
1741 | ||
1742 | Double_t AliExternalTrackParam::GetSnpAt(Double_t x,Double_t b) const { | |
1743 | // | |
1744 | // Get sinus at given x | |
1745 | // | |
1746 | Double_t crv=GetC(b); | |
1747 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; | |
1748 | Double_t dx = x-fX; | |
1749 | Double_t res = fP[2]+dx*crv; | |
1750 | return res; | |
1751 | } | |
1752 | ||
1753 | Bool_t AliExternalTrackParam::GetDistance(AliExternalTrackParam *param2, Double_t x, Double_t dist[3], Double_t bz){ | |
1754 | //------------------------------------------------------------------------ | |
1755 | // Get the distance between two tracks at the local position x | |
1756 | // working in the local frame of this track. | |
1757 | // Origin : Marian.Ivanov@cern.ch | |
1758 | //----------------------------------------------------------------------- | |
1759 | Double_t xyz[3]; | |
1760 | Double_t xyz2[3]; | |
1761 | xyz[0]=x; | |
1762 | if (!GetYAt(x,bz,xyz[1])) return kFALSE; | |
1763 | if (!GetZAt(x,bz,xyz[2])) return kFALSE; | |
1764 | // | |
1765 | // | |
1766 | if (TMath::Abs(GetAlpha()-param2->GetAlpha())<kAlmost0){ | |
1767 | xyz2[0]=x; | |
1768 | if (!param2->GetYAt(x,bz,xyz2[1])) return kFALSE; | |
1769 | if (!param2->GetZAt(x,bz,xyz2[2])) return kFALSE; | |
1770 | }else{ | |
1771 | // | |
1772 | Double_t xyz1[3]; | |
1773 | Double_t dfi = param2->GetAlpha()-GetAlpha(); | |
1774 | Double_t ca = TMath::Cos(dfi), sa = TMath::Sin(dfi); | |
1775 | xyz2[0] = xyz[0]*ca+xyz[1]*sa; | |
1776 | xyz2[1] = -xyz[0]*sa+xyz[1]*ca; | |
1777 | // | |
1778 | xyz1[0]=xyz2[0]; | |
1779 | if (!param2->GetYAt(xyz2[0],bz,xyz1[1])) return kFALSE; | |
1780 | if (!param2->GetZAt(xyz2[0],bz,xyz1[2])) return kFALSE; | |
1781 | // | |
1782 | xyz2[0] = xyz1[0]*ca-xyz1[1]*sa; | |
1783 | xyz2[1] = +xyz1[0]*sa+xyz1[1]*ca; | |
1784 | xyz2[2] = xyz1[2]; | |
1785 | } | |
1786 | dist[0] = xyz[0]-xyz2[0]; | |
1787 | dist[1] = xyz[1]-xyz2[1]; | |
1788 | dist[2] = xyz[2]-xyz2[2]; | |
1789 | ||
1790 | return kTRUE; | |
1791 | } | |
1792 | ||
1793 | ||
1794 | // | |
1795 | // Draw functionality. | |
1796 | // Origin: Marian Ivanov, Marian.Ivanov@cern.ch | |
1797 | // | |
1798 | ||
1799 | void AliExternalTrackParam::DrawTrack(Float_t magf, Float_t minR, Float_t maxR, Float_t stepR){ | |
1800 | // | |
1801 | // Draw track line | |
1802 | // | |
1803 | if (minR>maxR) return ; | |
1804 | if (stepR<=0) return ; | |
1805 | Int_t npoints = TMath::Nint((maxR-minR)/stepR)+1; | |
1806 | if (npoints<1) return; | |
1807 | TPolyMarker3D *polymarker = new TPolyMarker3D(npoints); | |
1808 | FillPolymarker(polymarker, magf,minR,maxR,stepR); | |
1809 | polymarker->Draw(); | |
1810 | } | |
1811 | ||
1812 | // | |
1813 | void AliExternalTrackParam::FillPolymarker(TPolyMarker3D *pol, Float_t magF, Float_t minR, Float_t maxR, Float_t stepR){ | |
1814 | // | |
1815 | // Fill points in the polymarker | |
1816 | // | |
1817 | Int_t counter=0; | |
1818 | for (Double_t r=minR; r<maxR; r+=stepR){ | |
1819 | Double_t point[3]; | |
1820 | GetXYZAt(r,magF,point); | |
1821 | pol->SetPoint(counter,point[0],point[1], point[2]); | |
1822 | printf("xyz\t%f\t%f\t%f\n",point[0], point[1],point[2]); | |
1823 | counter++; | |
1824 | } | |
1825 | } | |
1826 | ||
1827 | Int_t AliExternalTrackParam::GetIndex(Int_t i, Int_t j) const { | |
1828 | // | |
1829 | Int_t min = TMath::Min(i,j); | |
1830 | Int_t max = TMath::Max(i,j); | |
1831 | ||
1832 | return min+(max+1)*max/2; | |
1833 | } | |
1834 | ||
1835 | ||
1836 | void AliExternalTrackParam::g3helx3(Double_t qfield, | |
1837 | Double_t step, | |
1838 | Double_t vect[7]) { | |
1839 | /****************************************************************** | |
1840 | * * | |
1841 | * GEANT3 tracking routine in a constant field oriented * | |
1842 | * along axis 3 * | |
1843 | * Tracking is performed with a conventional * | |
1844 | * helix step method * | |
1845 | * * | |
1846 | * Authors R.Brun, M.Hansroul ********* * | |
1847 | * Rewritten V.Perevoztchikov * | |
1848 | * * | |
1849 | * Rewritten in C++ by I.Belikov * | |
1850 | * * | |
1851 | * qfield (kG) - particle charge times magnetic field * | |
1852 | * step (cm) - step length along the helix * | |
1853 | * vect[7](cm,GeV/c) - input/output x, y, z, px/p, py/p ,pz/p, p * | |
1854 | * * | |
1855 | ******************************************************************/ | |
1856 | const Int_t ix=0, iy=1, iz=2, ipx=3, ipy=4, ipz=5, ipp=6; | |
1857 | const Double_t kOvSqSix=TMath::Sqrt(1./6.); | |
1858 | ||
1859 | Double_t cosx=vect[ipx], cosy=vect[ipy], cosz=vect[ipz]; | |
1860 | ||
1861 | Double_t rho = qfield*kB2C/vect[ipp]; | |
1862 | Double_t tet = rho*step; | |
1863 | ||
1864 | Double_t tsint, sintt, sint, cos1t; | |
1865 | if (TMath::Abs(tet) > 0.03) { | |
1866 | sint = TMath::Sin(tet); | |
1867 | sintt = sint/tet; | |
1868 | tsint = (tet - sint)/tet; | |
1869 | Double_t t=TMath::Sin(0.5*tet); | |
1870 | cos1t = 2*t*t/tet; | |
1871 | } else { | |
1872 | tsint = tet*tet/6.; | |
1873 | sintt = (1.-tet*kOvSqSix)*(1.+tet*kOvSqSix); // 1.- tsint; | |
1874 | sint = tet*sintt; | |
1875 | cos1t = 0.5*tet; | |
1876 | } | |
1877 | ||
1878 | Double_t f1 = step*sintt; | |
1879 | Double_t f2 = step*cos1t; | |
1880 | Double_t f3 = step*tsint*cosz; | |
1881 | Double_t f4 = -tet*cos1t; | |
1882 | Double_t f5 = sint; | |
1883 | ||
1884 | vect[ix] += f1*cosx - f2*cosy; | |
1885 | vect[iy] += f1*cosy + f2*cosx; | |
1886 | vect[iz] += f1*cosz + f3; | |
1887 | ||
1888 | vect[ipx] += f4*cosx - f5*cosy; | |
1889 | vect[ipy] += f4*cosy + f5*cosx; | |
1890 | ||
1891 | } | |
1892 | ||
1893 | Bool_t AliExternalTrackParam::PropagateToBxByBz(Double_t xk, const Double_t b[3]) { | |
1894 | //---------------------------------------------------------------- | |
1895 | // Extrapolate this track to the plane X=xk in the field b[]. | |
1896 | // | |
1897 | // X [cm] is in the "tracking coordinate system" of this track. | |
1898 | // b[]={Bx,By,Bz} [kG] is in the Global coordidate system. | |
1899 | //---------------------------------------------------------------- | |
1900 | ||
1901 | Double_t dx=xk-fX; | |
1902 | if (TMath::Abs(dx)<=kAlmost0) return kTRUE; | |
1903 | if (TMath::Abs(fP[4])<=kAlmost0) return kFALSE; | |
1904 | // Do not propagate tracks outside the ALICE detector | |
1905 | if (TMath::Abs(dx)>1e5 || | |
1906 | TMath::Abs(GetY())>1e5 || | |
1907 | TMath::Abs(GetZ())>1e5) { | |
1908 | AliWarning(Form("Anomalous track, target X:%f",xk)); | |
1909 | Print(); | |
1910 | return kFALSE; | |
1911 | } | |
1912 | ||
1913 | Double_t crv=GetC(b[2]); | |
1914 | if (TMath::Abs(b[2]) < kAlmost0Field) crv=0.; | |
1915 | ||
1916 | Double_t x2r = crv*dx; | |
1917 | Double_t f1=fP[2], f2=f1 + x2r; | |
1918 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
1919 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
1920 | ||
1921 | ||
1922 | // Estimate the covariance matrix | |
1923 | Double_t &fP3=fP[3], &fP4=fP[4]; | |
1924 | Double_t | |
1925 | &fC00=fC[0], | |
1926 | &fC10=fC[1], &fC11=fC[2], | |
1927 | &fC20=fC[3], &fC21=fC[4], &fC22=fC[5], | |
1928 | &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9], | |
1929 | &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14]; | |
1930 | ||
1931 | Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2)); | |
1932 | ||
1933 | //f = F - 1 | |
1934 | Double_t f02= dx/(r1*r1*r1); Double_t cc=crv/fP4; | |
1935 | Double_t f04=0.5*dx*dx/(r1*r1*r1); f04*=cc; | |
1936 | Double_t f12= dx*fP3*f1/(r1*r1*r1); | |
1937 | Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1); f14*=cc; | |
1938 | Double_t f13= dx/r1; | |
1939 | Double_t f24= dx; f24*=cc; | |
1940 | ||
1941 | //b = C*ft | |
1942 | Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30; | |
1943 | Double_t b02=f24*fC40; | |
1944 | Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31; | |
1945 | Double_t b12=f24*fC41; | |
1946 | Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32; | |
1947 | Double_t b22=f24*fC42; | |
1948 | Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43; | |
1949 | Double_t b42=f24*fC44; | |
1950 | Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33; | |
1951 | Double_t b32=f24*fC43; | |
1952 | ||
1953 | //a = f*b = f*C*ft | |
1954 | Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42; | |
1955 | Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32; | |
1956 | Double_t a22=f24*b42; | |
1957 | ||
1958 | //F*C*Ft = C + (b + bt + a) | |
1959 | fC00 += b00 + b00 + a00; | |
1960 | fC10 += b10 + b01 + a01; | |
1961 | fC20 += b20 + b02 + a02; | |
1962 | fC30 += b30; | |
1963 | fC40 += b40; | |
1964 | fC11 += b11 + b11 + a11; | |
1965 | fC21 += b21 + b12 + a12; | |
1966 | fC31 += b31; | |
1967 | fC41 += b41; | |
1968 | fC22 += b22 + b22 + a22; | |
1969 | fC32 += b32; | |
1970 | fC42 += b42; | |
1971 | ||
1972 | CheckCovariance(); | |
1973 | ||
1974 | // Appoximate step length | |
1975 | double dy2dx = (f1+f2)/(r1+r2); | |
1976 | Double_t step = (TMath::Abs(x2r)<0.05) ? dx*TMath::Abs(r2 + f2*dy2dx) // chord | |
1977 | : 2.*TMath::ASin(0.5*dx*TMath::Sqrt(1.+dy2dx*dy2dx)*crv)/crv; // arc | |
1978 | step *= TMath::Sqrt(1.+ GetTgl()*GetTgl()); | |
1979 | ||
1980 | // Get the track's (x,y,z) and (px,py,pz) in the Global System | |
1981 | Double_t r[3]; GetXYZ(r); | |
1982 | Double_t p[3]; GetPxPyPz(p); | |
1983 | Double_t pp=GetP(); | |
1984 | p[0] /= pp; | |
1985 | p[1] /= pp; | |
1986 | p[2] /= pp; | |
1987 | ||
1988 | ||
1989 | // Rotate to the system where Bx=By=0. | |
1990 | Double_t bt=TMath::Sqrt(b[0]*b[0] + b[1]*b[1]); | |
1991 | Double_t cosphi=1., sinphi=0.; | |
1992 | if (bt > kAlmost0) {cosphi=b[0]/bt; sinphi=b[1]/bt;} | |
1993 | Double_t bb=TMath::Sqrt(b[0]*b[0] + b[1]*b[1] + b[2]*b[2]); | |
1994 | Double_t costet=1., sintet=0.; | |
1995 | if (bb > kAlmost0) {costet=b[2]/bb; sintet=bt/bb;} | |
1996 | Double_t vect[7]; | |
1997 | ||
1998 | vect[0] = costet*cosphi*r[0] + costet*sinphi*r[1] - sintet*r[2]; | |
1999 | vect[1] = -sinphi*r[0] + cosphi*r[1]; | |
2000 | vect[2] = sintet*cosphi*r[0] + sintet*sinphi*r[1] + costet*r[2]; | |
2001 | ||
2002 | vect[3] = costet*cosphi*p[0] + costet*sinphi*p[1] - sintet*p[2]; | |
2003 | vect[4] = -sinphi*p[0] + cosphi*p[1]; | |
2004 | vect[5] = sintet*cosphi*p[0] + sintet*sinphi*p[1] + costet*p[2]; | |
2005 | ||
2006 | vect[6] = pp; | |
2007 | ||
2008 | ||
2009 | // Do the helix step | |
2010 | g3helx3(GetSign()*bb,step,vect); | |
2011 | ||
2012 | ||
2013 | // Rotate back to the Global System | |
2014 | r[0] = cosphi*costet*vect[0] - sinphi*vect[1] + cosphi*sintet*vect[2]; | |
2015 | r[1] = sinphi*costet*vect[0] + cosphi*vect[1] + sinphi*sintet*vect[2]; | |
2016 | r[2] = -sintet*vect[0] + costet*vect[2]; | |
2017 | ||
2018 | p[0] = cosphi*costet*vect[3] - sinphi*vect[4] + cosphi*sintet*vect[5]; | |
2019 | p[1] = sinphi*costet*vect[3] + cosphi*vect[4] + sinphi*sintet*vect[5]; | |
2020 | p[2] = -sintet*vect[3] + costet*vect[5]; | |
2021 | ||
2022 | ||
2023 | // Rotate back to the Tracking System | |
2024 | Double_t cosalp = TMath::Cos(fAlpha); | |
2025 | Double_t sinalp =-TMath::Sin(fAlpha); | |
2026 | ||
2027 | Double_t | |
2028 | t = cosalp*r[0] - sinalp*r[1]; | |
2029 | r[1] = sinalp*r[0] + cosalp*r[1]; | |
2030 | r[0] = t; | |
2031 | ||
2032 | t = cosalp*p[0] - sinalp*p[1]; | |
2033 | p[1] = sinalp*p[0] + cosalp*p[1]; | |
2034 | p[0] = t; | |
2035 | ||
2036 | ||
2037 | // Do the final correcting step to the target plane (linear approximation) | |
2038 | Double_t x=r[0], y=r[1], z=r[2]; | |
2039 | if (TMath::Abs(dx) > kAlmost0) { | |
2040 | if (TMath::Abs(p[0]) < kAlmost0) return kFALSE; | |
2041 | dx = xk - r[0]; | |
2042 | x += dx; | |
2043 | y += p[1]/p[0]*dx; | |
2044 | z += p[2]/p[0]*dx; | |
2045 | } | |
2046 | ||
2047 | ||
2048 | // Calculate the track parameters | |
2049 | t=TMath::Sqrt(p[0]*p[0] + p[1]*p[1]); | |
2050 | fX = x; | |
2051 | fP[0] = y; | |
2052 | fP[1] = z; | |
2053 | fP[2] = p[1]/t; | |
2054 | fP[3] = p[2]/t; | |
2055 | fP[4] = GetSign()/(t*pp); | |
2056 | ||
2057 | return kTRUE; | |
2058 | } | |
2059 | ||
2060 | Bool_t AliExternalTrackParam::Translate(Double_t *vTrasl,Double_t *covV){ | |
2061 | // | |
2062 | //Translation: in the event mixing, the tracks can be shifted | |
2063 | //of the difference among primary vertices (vTrasl) and | |
2064 | //the covariance matrix is changed accordingly | |
2065 | //(covV = covariance of the primary vertex). | |
2066 | //Origin: "Romita, Rossella" <R.Romita@gsi.de> | |
2067 | // | |
2068 | TVector3 translation; | |
2069 | // vTrasl coordinates in the local system | |
2070 | translation.SetXYZ(vTrasl[0],vTrasl[1],vTrasl[2]); | |
2071 | translation.RotateZ(-fAlpha); | |
2072 | translation.GetXYZ(vTrasl); | |
2073 | ||
2074 | //compute the new x,y,z of the track | |
2075 | Double_t newX=fX-vTrasl[0]; | |
2076 | Double_t newY=fP[0]-vTrasl[1]; | |
2077 | Double_t newZ=fP[1]-vTrasl[2]; | |
2078 | ||
2079 | //define the new parameters | |
2080 | Double_t newParam[5]; | |
2081 | newParam[0]=newY; | |
2082 | newParam[1]=newZ; | |
2083 | newParam[2]=fP[2]; | |
2084 | newParam[3]=fP[3]; | |
2085 | newParam[4]=fP[4]; | |
2086 | ||
2087 | // recompute the covariance matrix: | |
2088 | // 1. covV in the local system | |
2089 | Double_t cosRot=TMath::Cos(fAlpha), sinRot=TMath::Sin(fAlpha); | |
2090 | TMatrixD qQi(3,3); | |
2091 | qQi(0,0) = cosRot; | |
2092 | qQi(0,1) = sinRot; | |
2093 | qQi(0,2) = 0.; | |
2094 | qQi(1,0) = -sinRot; | |
2095 | qQi(1,1) = cosRot; | |
2096 | qQi(1,2) = 0.; | |
2097 | qQi(2,0) = 0.; | |
2098 | qQi(2,1) = 0.; | |
2099 | qQi(2,2) = 1.; | |
2100 | TMatrixD uUi(3,3); | |
2101 | uUi(0,0) = covV[0]; | |
2102 | uUi(0,0) = covV[0]; | |
2103 | uUi(1,0) = covV[1]; | |
2104 | uUi(0,1) = covV[1]; | |
2105 | uUi(2,0) = covV[3]; | |
2106 | uUi(0,2) = covV[3]; | |
2107 | uUi(1,1) = covV[2]; | |
2108 | uUi(2,2) = covV[5]; | |
2109 | uUi(1,2) = covV[4]; | |
2110 | if(uUi.Determinant() <= 0.) {return kFALSE;} | |
2111 | TMatrixD uUiQi(uUi,TMatrixD::kMult,qQi); | |
2112 | TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiQi); | |
2113 | ||
2114 | //2. compute the new covariance matrix of the track | |
2115 | Double_t sigmaXX=m(0,0); | |
2116 | Double_t sigmaXZ=m(2,0); | |
2117 | Double_t sigmaXY=m(1,0); | |
2118 | Double_t sigmaYY=GetSigmaY2()+m(1,1); | |
2119 | Double_t sigmaYZ=fC[1]+m(1,2); | |
2120 | Double_t sigmaZZ=fC[2]+m(2,2); | |
2121 | Double_t covarianceYY=sigmaYY + (-1.)*((sigmaXY*sigmaXY)/sigmaXX); | |
2122 | Double_t covarianceYZ=sigmaYZ-(sigmaXZ*sigmaXY/sigmaXX); | |
2123 | Double_t covarianceZZ=sigmaZZ-((sigmaXZ*sigmaXZ)/sigmaXX); | |
2124 | ||
2125 | Double_t newCov[15]; | |
2126 | newCov[0]=covarianceYY; | |
2127 | newCov[1]=covarianceYZ; | |
2128 | newCov[2]=covarianceZZ; | |
2129 | for(Int_t i=3;i<15;i++){ | |
2130 | newCov[i]=fC[i]; | |
2131 | } | |
2132 | ||
2133 | // set the new parameters | |
2134 | ||
2135 | Set(newX,fAlpha,newParam,newCov); | |
2136 | ||
2137 | return kTRUE; | |
2138 | } | |
2139 | ||
2140 | void AliExternalTrackParam::CheckCovariance() { | |
2141 | ||
2142 | // This function forces the diagonal elements of the covariance matrix to be positive. | |
2143 | // In case the diagonal element is bigger than the maximal allowed value, it is set to | |
2144 | // the limit and the off-diagonal elements that correspond to it are set to zero. | |
2145 | ||
2146 | fC[0] = TMath::Abs(fC[0]); | |
2147 | if (fC[0]>kC0max) { | |
2148 | fC[0] = kC0max; | |
2149 | fC[1] = 0; | |
2150 | fC[3] = 0; | |
2151 | fC[6] = 0; | |
2152 | fC[10] = 0; | |
2153 | } | |
2154 | fC[2] = TMath::Abs(fC[2]); | |
2155 | if (fC[2]>kC2max) { | |
2156 | fC[2] = kC2max; | |
2157 | fC[1] = 0; | |
2158 | fC[4] = 0; | |
2159 | fC[7] = 0; | |
2160 | fC[11] = 0; | |
2161 | } | |
2162 | fC[5] = TMath::Abs(fC[5]); | |
2163 | if (fC[5]>kC5max) { | |
2164 | fC[5] = kC5max; | |
2165 | fC[3] = 0; | |
2166 | fC[4] = 0; | |
2167 | fC[8] = 0; | |
2168 | fC[12] = 0; | |
2169 | } | |
2170 | fC[9] = TMath::Abs(fC[9]); | |
2171 | if (fC[9]>kC9max) { | |
2172 | fC[9] = kC9max; | |
2173 | fC[6] = 0; | |
2174 | fC[7] = 0; | |
2175 | fC[8] = 0; | |
2176 | fC[13] = 0; | |
2177 | } | |
2178 | fC[14] = TMath::Abs(fC[14]); | |
2179 | if (fC[14]>kC14max) { | |
2180 | fC[14] = kC14max; | |
2181 | fC[10] = 0; | |
2182 | fC[11] = 0; | |
2183 | fC[12] = 0; | |
2184 | fC[13] = 0; | |
2185 | } | |
2186 | ||
2187 | // The part below is used for tests and normally is commented out | |
2188 | // TMatrixDSym m(5); | |
2189 | // TVectorD eig(5); | |
2190 | ||
2191 | // m(0,0)=fC[0]; | |
2192 | // m(1,0)=fC[1]; m(1,1)=fC[2]; | |
2193 | // m(2,0)=fC[3]; m(2,1)=fC[4]; m(2,2)=fC[5]; | |
2194 | // m(3,0)=fC[6]; m(3,1)=fC[7]; m(3,2)=fC[8]; m(3,3)=fC[9]; | |
2195 | // m(4,0)=fC[10]; m(4,1)=fC[11]; m(4,2)=fC[12]; m(4,3)=fC[13]; m(4,4)=fC[14]; | |
2196 | ||
2197 | // m(0,1)=m(1,0); | |
2198 | // m(0,2)=m(2,0); m(1,2)=m(2,1); | |
2199 | // m(0,3)=m(3,0); m(1,3)=m(3,1); m(2,3)=m(3,2); | |
2200 | // m(0,4)=m(4,0); m(1,4)=m(4,1); m(2,4)=m(4,2); m(3,4)=m(4,3); | |
2201 | // m.EigenVectors(eig); | |
2202 | ||
2203 | // // assert(eig(0)>=0 && eig(1)>=0 && eig(2)>=0 && eig(3)>=0 && eig(4)>=0); | |
2204 | // if (!(eig(0)>=0 && eig(1)>=0 && eig(2)>=0 && eig(3)>=0 && eig(4)>=0)) { | |
2205 | // AliWarning("Negative eigenvalues of the covariance matrix!"); | |
2206 | // this->Print(); | |
2207 | // eig.Print(); | |
2208 | // } | |
2209 | } |