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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 | // // | |
49d13e89 | 20 | // Implementation of the external track parameterisation class. // |
51ad6848 | 21 | // // |
49d13e89 | 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 // | |
51ad6848 | 27 | /////////////////////////////////////////////////////////////////////////////// |
51ad6848 | 28 | #include "AliExternalTrackParam.h" |
f76701bf | 29 | #include "AliESDVertex.h" |
6c94f330 | 30 | #include "AliLog.h" |
51ad6848 | 31 | |
32 | ClassImp(AliExternalTrackParam) | |
33 | ||
51ad6848 | 34 | //_____________________________________________________________________________ |
90e48c0c | 35 | AliExternalTrackParam::AliExternalTrackParam() : |
6c94f330 | 36 | TObject(), |
90e48c0c | 37 | fX(0), |
c9ec41e8 | 38 | fAlpha(0) |
51ad6848 | 39 | { |
90e48c0c | 40 | // |
41 | // default constructor | |
42 | // | |
c9ec41e8 | 43 | for (Int_t i = 0; i < 5; i++) fP[i] = 0; |
44 | for (Int_t i = 0; i < 15; i++) fC[i] = 0; | |
51ad6848 | 45 | } |
46 | ||
6c94f330 | 47 | //_____________________________________________________________________________ |
48 | AliExternalTrackParam::AliExternalTrackParam(const AliExternalTrackParam &track): | |
49 | TObject(track), | |
50 | fX(track.fX), | |
51 | fAlpha(track.fAlpha) | |
52 | { | |
53 | // | |
54 | // copy constructor | |
55 | // | |
56 | for (Int_t i = 0; i < 5; i++) fP[i] = track.fP[i]; | |
57 | for (Int_t i = 0; i < 15; i++) fC[i] = track.fC[i]; | |
58 | } | |
59 | ||
51ad6848 | 60 | //_____________________________________________________________________________ |
61 | AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha, | |
62 | const Double_t param[5], | |
90e48c0c | 63 | const Double_t covar[15]) : |
6c94f330 | 64 | TObject(), |
90e48c0c | 65 | fX(x), |
c9ec41e8 | 66 | fAlpha(alpha) |
51ad6848 | 67 | { |
90e48c0c | 68 | // |
69 | // create external track parameters from given arguments | |
70 | // | |
c9ec41e8 | 71 | for (Int_t i = 0; i < 5; i++) fP[i] = param[i]; |
72 | for (Int_t i = 0; i < 15; i++) fC[i] = covar[i]; | |
51ad6848 | 73 | } |
74 | ||
90e48c0c | 75 | //_____________________________________________________________________________ |
6c94f330 | 76 | void AliExternalTrackParam::Set(Double_t x, Double_t alpha, |
77 | const Double_t p[5], const Double_t cov[15]) { | |
c9ec41e8 | 78 | // |
6c94f330 | 79 | // Sets the parameters |
c9ec41e8 | 80 | // |
6c94f330 | 81 | fX=x; |
82 | fAlpha=alpha; | |
83 | for (Int_t i = 0; i < 5; i++) fP[i] = p[i]; | |
84 | for (Int_t i = 0; i < 15; i++) fC[i] = cov[i]; | |
51ad6848 | 85 | } |
86 | ||
87 | //_____________________________________________________________________________ | |
c9ec41e8 | 88 | void AliExternalTrackParam::Reset() { |
1530f89c | 89 | // |
90 | // Resets all the parameters to 0 | |
91 | // | |
c9ec41e8 | 92 | fX=fAlpha=0.; |
93 | for (Int_t i = 0; i < 5; i++) fP[i] = 0; | |
94 | for (Int_t i = 0; i < 15; i++) fC[i] = 0; | |
51ad6848 | 95 | } |
96 | ||
c9ec41e8 | 97 | Double_t AliExternalTrackParam::GetP() const { |
98 | //--------------------------------------------------------------------- | |
99 | // This function returns the track momentum | |
100 | // Results for (nearly) straight tracks are meaningless ! | |
101 | //--------------------------------------------------------------------- | |
06fb4a2f | 102 | if (TMath::Abs(fP[4])<=kAlmost0) return kVeryBig; |
c9ec41e8 | 103 | return TMath::Sqrt(1.+ fP[3]*fP[3])/TMath::Abs(fP[4]); |
51ad6848 | 104 | } |
105 | ||
1d99986f | 106 | Double_t AliExternalTrackParam::Get1P() const { |
107 | //--------------------------------------------------------------------- | |
108 | // This function returns the 1/(track momentum) | |
109 | //--------------------------------------------------------------------- | |
110 | return TMath::Abs(fP[4])/TMath::Sqrt(1.+ fP[3]*fP[3]); | |
111 | } | |
112 | ||
c9ec41e8 | 113 | //_______________________________________________________________________ |
c7bafca9 | 114 | Double_t AliExternalTrackParam::GetD(Double_t x,Double_t y,Double_t b) const { |
c9ec41e8 | 115 | //------------------------------------------------------------------ |
116 | // This function calculates the transverse impact parameter | |
117 | // with respect to a point with global coordinates (x,y) | |
118 | // in the magnetic field "b" (kG) | |
119 | //------------------------------------------------------------------ | |
5773defd | 120 | if (TMath::Abs(b) < kAlmost0Field) return GetLinearD(x,y); |
1530f89c | 121 | Double_t rp4=GetC(b); |
c9ec41e8 | 122 | |
123 | Double_t xt=fX, yt=fP[0]; | |
124 | ||
125 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
126 | Double_t a = x*cs + y*sn; | |
127 | y = -x*sn + y*cs; x=a; | |
128 | xt-=x; yt-=y; | |
129 | ||
130 | sn=rp4*xt - fP[2]; cs=rp4*yt + TMath::Sqrt(1.- fP[2]*fP[2]); | |
131 | a=2*(xt*fP[2] - yt*TMath::Sqrt(1.- fP[2]*fP[2]))-rp4*(xt*xt + yt*yt); | |
1530f89c | 132 | return -a/(1 + TMath::Sqrt(sn*sn + cs*cs)); |
133 | } | |
134 | ||
135 | //_______________________________________________________________________ | |
136 | void AliExternalTrackParam:: | |
137 | GetDZ(Double_t x, Double_t y, Double_t z, Double_t b, Float_t dz[2]) const { | |
138 | //------------------------------------------------------------------ | |
139 | // This function calculates the transverse and longitudinal impact parameters | |
140 | // with respect to a point with global coordinates (x,y) | |
141 | // in the magnetic field "b" (kG) | |
142 | //------------------------------------------------------------------ | |
143 | Double_t f1 = fP[2], r1 = TMath::Sqrt(1. - f1*f1); | |
144 | Double_t xt=fX, yt=fP[0]; | |
145 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
146 | Double_t a = x*cs + y*sn; | |
147 | y = -x*sn + y*cs; x=a; | |
148 | xt-=x; yt-=y; | |
149 | ||
150 | Double_t rp4=GetC(b); | |
151 | if ((TMath::Abs(b) < kAlmost0Field) || (TMath::Abs(rp4) < kAlmost0)) { | |
152 | dz[0] = -(xt*f1 - yt*r1); | |
153 | dz[1] = fP[1] + (dz[0]*f1 - xt)/r1*fP[3] - z; | |
154 | return; | |
155 | } | |
156 | ||
157 | sn=rp4*xt - f1; cs=rp4*yt + r1; | |
158 | a=2*(xt*f1 - yt*r1)-rp4*(xt*xt + yt*yt); | |
159 | Double_t rr=TMath::Sqrt(sn*sn + cs*cs); | |
160 | dz[0] = -a/(1 + rr); | |
161 | Double_t f2 = -sn/rr, r2 = TMath::Sqrt(1. - f2*f2); | |
162 | dz[1] = fP[1] + fP[3]/rp4*TMath::ASin(f2*r1 - f1*r2) - z; | |
51ad6848 | 163 | } |
164 | ||
49d13e89 | 165 | //_______________________________________________________________________ |
166 | Double_t AliExternalTrackParam::GetLinearD(Double_t xv,Double_t yv) const { | |
167 | //------------------------------------------------------------------ | |
168 | // This function calculates the transverse impact parameter | |
169 | // with respect to a point with global coordinates (xv,yv) | |
170 | // neglecting the track curvature. | |
171 | //------------------------------------------------------------------ | |
172 | Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha); | |
173 | Double_t x= xv*cs + yv*sn; | |
174 | Double_t y=-xv*sn + yv*cs; | |
175 | ||
176 | Double_t d = (fX-x)*fP[2] - (fP[0]-y)*TMath::Sqrt(1.- fP[2]*fP[2]); | |
177 | ||
1530f89c | 178 | return -d; |
49d13e89 | 179 | } |
180 | ||
ee5dba5e | 181 | Bool_t AliExternalTrackParam::CorrectForMaterial |
182 | (Double_t d, Double_t x0, Double_t mass, Double_t (*Bethe)(Double_t)) { | |
c7bafca9 | 183 | //------------------------------------------------------------------ |
184 | // This function corrects the track parameters for the crossed material | |
185 | // "d" - the thickness (fraction of the radiation length) | |
186 | // "x0" - the radiation length (g/cm^2) | |
187 | // "mass" - the mass of this particle (GeV/c^2) | |
188 | //------------------------------------------------------------------ | |
189 | Double_t &fP2=fP[2]; | |
190 | Double_t &fP3=fP[3]; | |
191 | Double_t &fP4=fP[4]; | |
192 | ||
193 | Double_t &fC22=fC[5]; | |
194 | Double_t &fC33=fC[9]; | |
195 | Double_t &fC43=fC[13]; | |
196 | Double_t &fC44=fC[14]; | |
197 | ||
7b5ef2e6 | 198 | Double_t p=GetP(); |
199 | Double_t p2=p*p; | |
c7bafca9 | 200 | Double_t beta2=p2/(p2 + mass*mass); |
201 | d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2)); | |
202 | ||
203 | //Multiple scattering****************** | |
204 | if (d!=0) { | |
205 | Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d); | |
206 | //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33; | |
207 | fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3); | |
208 | fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3); | |
209 | fC43 += theta2*fP3*fP4*(1. + fP3*fP3); | |
210 | fC44 += theta2*fP3*fP4*fP3*fP4; | |
211 | } | |
212 | ||
213 | //Energy losses************************ | |
8fc1985d | 214 | if (x0!=0. && beta2<1) { |
c7bafca9 | 215 | d*=x0; |
ee5dba5e | 216 | Double_t dE=Bethe(beta2)*d; |
217 | Double_t e=TMath::Sqrt(p2 + mass*mass); | |
218 | fP4*=(1.- e/p2*dE); | |
219 | ||
220 | // Approximate energy loss fluctuation (M.Ivanov) | |
221 | const Double_t cnst=0.07; // To be tuned. | |
222 | Double_t sigmadE=cnst*TMath::Sqrt(TMath::Abs(dE)); | |
223 | fC44+=((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4)); | |
224 | ||
c7bafca9 | 225 | } |
226 | ||
227 | return kTRUE; | |
228 | } | |
229 | ||
ee5dba5e | 230 | Double_t ApproximateBetheBloch(Double_t beta2) { |
231 | //------------------------------------------------------------------ | |
232 | // This is an approximation of the Bethe-Bloch formula with | |
233 | // the density effect taken into account at beta*gamma > 3.5 | |
234 | // (the approximation is reasonable only for solid materials) | |
235 | //------------------------------------------------------------------ | |
236 | if (beta2/(1-beta2)>3.5*3.5) | |
237 | return 0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2); | |
238 | ||
239 | return 0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2); | |
240 | } | |
241 | ||
49d13e89 | 242 | Bool_t AliExternalTrackParam::Rotate(Double_t alpha) { |
243 | //------------------------------------------------------------------ | |
244 | // Transform this track to the local coord. system rotated | |
245 | // by angle "alpha" (rad) with respect to the global coord. system. | |
246 | //------------------------------------------------------------------ | |
dfcef74c | 247 | if (TMath::Abs(fP[2]) >= kAlmost1) { |
248 | AliError(Form("Precondition is not satisfied: |sin(phi)|>1 ! %f",fP[2])); | |
249 | return kFALSE; | |
250 | } | |
251 | ||
49d13e89 | 252 | if (alpha < -TMath::Pi()) alpha += 2*TMath::Pi(); |
253 | else if (alpha >= TMath::Pi()) alpha -= 2*TMath::Pi(); | |
254 | ||
255 | Double_t &fP0=fP[0]; | |
256 | Double_t &fP2=fP[2]; | |
257 | Double_t &fC00=fC[0]; | |
258 | Double_t &fC10=fC[1]; | |
259 | Double_t &fC20=fC[3]; | |
260 | Double_t &fC21=fC[4]; | |
261 | Double_t &fC22=fC[5]; | |
262 | Double_t &fC30=fC[6]; | |
263 | Double_t &fC32=fC[8]; | |
264 | Double_t &fC40=fC[10]; | |
265 | Double_t &fC42=fC[12]; | |
266 | ||
267 | Double_t x=fX; | |
268 | Double_t ca=TMath::Cos(alpha-fAlpha), sa=TMath::Sin(alpha-fAlpha); | |
269 | Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2); | |
270 | ||
dfcef74c | 271 | Double_t tmp=sf*ca - cf*sa; |
272 | if (TMath::Abs(tmp) >= kAlmost1) return kFALSE; | |
273 | ||
49d13e89 | 274 | fAlpha = alpha; |
275 | fX = x*ca + fP0*sa; | |
276 | fP0= -x*sa + fP0*ca; | |
dfcef74c | 277 | fP2= tmp; |
49d13e89 | 278 | |
06fb4a2f | 279 | if (TMath::Abs(cf)<kAlmost0) { |
280 | AliError(Form("Too small cosine value %f",cf)); | |
281 | cf = kAlmost0; | |
282 | } | |
283 | ||
49d13e89 | 284 | Double_t rr=(ca+sf/cf*sa); |
285 | ||
286 | fC00 *= (ca*ca); | |
287 | fC10 *= ca; | |
288 | fC20 *= ca*rr; | |
289 | fC21 *= rr; | |
290 | fC22 *= rr*rr; | |
291 | fC30 *= ca; | |
292 | fC32 *= rr; | |
293 | fC40 *= ca; | |
294 | fC42 *= rr; | |
295 | ||
296 | return kTRUE; | |
297 | } | |
298 | ||
299 | Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t b) { | |
300 | //---------------------------------------------------------------- | |
301 | // Propagate this track to the plane X=xk (cm) in the field "b" (kG) | |
302 | //---------------------------------------------------------------- | |
49d13e89 | 303 | Double_t dx=xk-fX; |
e421f556 | 304 | if (TMath::Abs(dx)<=kAlmost0) return kTRUE; |
18ebc5ef | 305 | |
1530f89c | 306 | Double_t crv=GetC(b); |
5773defd | 307 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; |
308 | ||
49d13e89 | 309 | Double_t f1=fP[2], f2=f1 + crv*dx; |
bbefa4c4 | 310 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; |
49d13e89 | 311 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; |
312 | ||
313 | Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4]; | |
314 | Double_t | |
315 | &fC00=fC[0], | |
316 | &fC10=fC[1], &fC11=fC[2], | |
317 | &fC20=fC[3], &fC21=fC[4], &fC22=fC[5], | |
318 | &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9], | |
319 | &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14]; | |
320 | ||
321 | Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2); | |
322 | ||
323 | fX=xk; | |
324 | fP0 += dx*(f1+f2)/(r1+r2); | |
18ebc5ef | 325 | fP1 += dx*(r2 + f2*(f1+f2)/(r1+r2))*fP3; // Many thanks to P.Hristov ! |
49d13e89 | 326 | fP2 += dx*crv; |
327 | ||
328 | //f = F - 1 | |
329 | ||
330 | Double_t f02= dx/(r1*r1*r1); Double_t cc=crv/fP4; | |
331 | Double_t f04=0.5*dx*dx/(r1*r1*r1); f04*=cc; | |
332 | Double_t f12= dx*fP3*f1/(r1*r1*r1); | |
333 | Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1); f14*=cc; | |
334 | Double_t f13= dx/r1; | |
335 | Double_t f24= dx; f24*=cc; | |
336 | ||
337 | //b = C*ft | |
338 | Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30; | |
339 | Double_t b02=f24*fC40; | |
340 | Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31; | |
341 | Double_t b12=f24*fC41; | |
342 | Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32; | |
343 | Double_t b22=f24*fC42; | |
344 | Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43; | |
345 | Double_t b42=f24*fC44; | |
346 | Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33; | |
347 | Double_t b32=f24*fC43; | |
348 | ||
349 | //a = f*b = f*C*ft | |
350 | Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42; | |
351 | Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32; | |
352 | Double_t a22=f24*b42; | |
353 | ||
354 | //F*C*Ft = C + (b + bt + a) | |
355 | fC00 += b00 + b00 + a00; | |
356 | fC10 += b10 + b01 + a01; | |
357 | fC20 += b20 + b02 + a02; | |
358 | fC30 += b30; | |
359 | fC40 += b40; | |
360 | fC11 += b11 + b11 + a11; | |
361 | fC21 += b21 + b12 + a12; | |
362 | fC31 += b31; | |
363 | fC41 += b41; | |
364 | fC22 += b22 + b22 + a22; | |
365 | fC32 += b32; | |
366 | fC42 += b42; | |
367 | ||
368 | return kTRUE; | |
369 | } | |
370 | ||
052daaff | 371 | void AliExternalTrackParam::Propagate(Double_t len, Double_t x[3], |
372 | Double_t p[3], Double_t bz) const { | |
373 | //+++++++++++++++++++++++++++++++++++++++++ | |
374 | // Origin: K. Shileev (Kirill.Shileev@cern.ch) | |
375 | // Extrapolate track along simple helix in magnetic field | |
376 | // Arguments: len -distance alogn helix, [cm] | |
377 | // bz - mag field, [kGaus] | |
378 | // Returns: x and p contain extrapolated positon and momentum | |
379 | // The momentum returned for straight-line tracks is meaningless ! | |
380 | //+++++++++++++++++++++++++++++++++++++++++ | |
381 | GetXYZ(x); | |
382 | ||
383 | if (TMath::Abs(Get1Pt()) < kAlmost0){ //straight-line tracks | |
384 | Double_t unit[3]; GetDirection(unit); | |
385 | x[0]+=unit[0]*len; | |
386 | x[1]+=unit[1]*len; | |
387 | x[2]+=unit[2]*len; | |
388 | ||
389 | p[0]=unit[0]/kAlmost0; | |
390 | p[1]=unit[1]/kAlmost0; | |
391 | p[2]=unit[2]/kAlmost0; | |
392 | } else { | |
393 | GetPxPyPz(p); | |
394 | Double_t pp=GetP(); | |
395 | Double_t a = -kB2C*bz*GetSign(); | |
396 | Double_t rho = a/pp; | |
397 | x[0] += p[0]*TMath::Sin(rho*len)/a - p[1]*(1-TMath::Cos(rho*len))/a; | |
398 | x[1] += p[1]*TMath::Sin(rho*len)/a + p[0]*(1-TMath::Cos(rho*len))/a; | |
399 | x[2] += p[2]*len/pp; | |
400 | ||
401 | Double_t p0=p[0]; | |
402 | p[0] = p0 *TMath::Cos(rho*len) - p[1]*TMath::Sin(rho*len); | |
403 | p[1] = p[1]*TMath::Cos(rho*len) + p0 *TMath::Sin(rho*len); | |
404 | } | |
405 | } | |
406 | ||
407 | Bool_t AliExternalTrackParam::Intersect(Double_t pnt[3], Double_t norm[3], | |
408 | Double_t bz) const { | |
409 | //+++++++++++++++++++++++++++++++++++++++++ | |
410 | // Origin: K. Shileev (Kirill.Shileev@cern.ch) | |
411 | // Finds point of intersection (if exists) of the helix with the plane. | |
412 | // Stores result in fX and fP. | |
413 | // Arguments: planePoint,planeNorm - the plane defined by any plane's point | |
414 | // and vector, normal to the plane | |
415 | // Returns: kTrue if helix intersects the plane, kFALSE otherwise. | |
416 | //+++++++++++++++++++++++++++++++++++++++++ | |
417 | Double_t x0[3]; GetXYZ(x0); //get track position in MARS | |
418 | ||
419 | //estimates initial helix length up to plane | |
420 | Double_t s= | |
421 | (pnt[0]-x0[0])*norm[0] + (pnt[1]-x0[1])*norm[1] + (pnt[2]-x0[2])*norm[2]; | |
422 | Double_t dist=99999,distPrev=dist; | |
423 | Double_t x[3],p[3]; | |
424 | while(TMath::Abs(dist)>0.00001){ | |
425 | //calculates helix at the distance s from x0 ALONG the helix | |
426 | Propagate(s,x,p,bz); | |
427 | ||
428 | //distance between current helix position and plane | |
429 | dist=(x[0]-pnt[0])*norm[0]+(x[1]-pnt[1])*norm[1]+(x[2]-pnt[2])*norm[2]; | |
430 | ||
431 | if(TMath::Abs(dist) >= TMath::Abs(distPrev)) {return kFALSE;} | |
432 | distPrev=dist; | |
433 | s-=dist; | |
434 | } | |
435 | //on exit pnt is intersection point,norm is track vector at that point, | |
436 | //all in MARS | |
437 | for (Int_t i=0; i<3; i++) {pnt[i]=x[i]; norm[i]=p[i];} | |
438 | return kTRUE; | |
439 | } | |
440 | ||
49d13e89 | 441 | Double_t |
442 | AliExternalTrackParam::GetPredictedChi2(Double_t p[2],Double_t cov[3]) const { | |
443 | //---------------------------------------------------------------- | |
444 | // Estimate the chi2 of the space point "p" with the cov. matrix "cov" | |
445 | //---------------------------------------------------------------- | |
446 | Double_t sdd = fC[0] + cov[0]; | |
447 | Double_t sdz = fC[1] + cov[1]; | |
448 | Double_t szz = fC[2] + cov[2]; | |
449 | Double_t det = sdd*szz - sdz*sdz; | |
450 | ||
451 | if (TMath::Abs(det) < kAlmost0) return kVeryBig; | |
452 | ||
453 | Double_t d = fP[0] - p[0]; | |
454 | Double_t z = fP[1] - p[1]; | |
455 | ||
456 | return (d*szz*d - 2*d*sdz*z + z*sdd*z)/det; | |
457 | } | |
458 | ||
459 | Bool_t AliExternalTrackParam::Update(Double_t p[2], Double_t cov[3]) { | |
460 | //------------------------------------------------------------------ | |
461 | // Update the track parameters with the space point "p" having | |
462 | // the covariance matrix "cov" | |
463 | //------------------------------------------------------------------ | |
464 | Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4]; | |
465 | Double_t | |
466 | &fC00=fC[0], | |
467 | &fC10=fC[1], &fC11=fC[2], | |
468 | &fC20=fC[3], &fC21=fC[4], &fC22=fC[5], | |
469 | &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9], | |
470 | &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14]; | |
471 | ||
472 | Double_t r00=cov[0], r01=cov[1], r11=cov[2]; | |
473 | r00+=fC00; r01+=fC10; r11+=fC11; | |
474 | Double_t det=r00*r11 - r01*r01; | |
475 | ||
476 | if (TMath::Abs(det) < kAlmost0) return kFALSE; | |
477 | ||
478 | ||
479 | Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det; | |
480 | ||
481 | Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11; | |
482 | Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11; | |
483 | Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11; | |
484 | Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11; | |
485 | Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11; | |
486 | ||
487 | Double_t dy=p[0] - fP0, dz=p[1] - fP1; | |
488 | Double_t sf=fP2 + k20*dy + k21*dz; | |
489 | if (TMath::Abs(sf) > kAlmost1) return kFALSE; | |
490 | ||
491 | fP0 += k00*dy + k01*dz; | |
492 | fP1 += k10*dy + k11*dz; | |
493 | fP2 = sf; | |
494 | fP3 += k30*dy + k31*dz; | |
495 | fP4 += k40*dy + k41*dz; | |
496 | ||
497 | Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40; | |
498 | Double_t c12=fC21, c13=fC31, c14=fC41; | |
499 | ||
500 | fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11; | |
501 | fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13; | |
502 | fC40-=k00*c04+k01*c14; | |
503 | ||
504 | fC11-=k10*c01+k11*fC11; | |
505 | fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13; | |
506 | fC41-=k10*c04+k11*c14; | |
507 | ||
508 | fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13; | |
509 | fC42-=k20*c04+k21*c14; | |
510 | ||
511 | fC33-=k30*c03+k31*c13; | |
512 | fC43-=k30*c04+k31*c14; | |
513 | ||
514 | fC44-=k40*c04+k41*c14; | |
515 | ||
516 | return kTRUE; | |
517 | } | |
518 | ||
c7bafca9 | 519 | void |
520 | AliExternalTrackParam::GetHelixParameters(Double_t hlx[6], Double_t b) const { | |
521 | //-------------------------------------------------------------------- | |
522 | // External track parameters -> helix parameters | |
523 | // "b" - magnetic field (kG) | |
524 | //-------------------------------------------------------------------- | |
525 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
526 | ||
1530f89c | 527 | hlx[0]=fP[0]; hlx[1]=fP[1]; hlx[2]=fP[2]; hlx[3]=fP[3]; |
c7bafca9 | 528 | |
529 | hlx[5]=fX*cs - hlx[0]*sn; // x0 | |
530 | hlx[0]=fX*sn + hlx[0]*cs; // y0 | |
531 | //hlx[1]= // z0 | |
532 | hlx[2]=TMath::ASin(hlx[2]) + fAlpha; // phi0 | |
533 | //hlx[3]= // tgl | |
1530f89c | 534 | hlx[4]=GetC(b); // C |
c7bafca9 | 535 | } |
536 | ||
537 | ||
538 | static void Evaluate(const Double_t *h, Double_t t, | |
539 | Double_t r[3], //radius vector | |
540 | Double_t g[3], //first defivatives | |
541 | Double_t gg[3]) //second derivatives | |
542 | { | |
543 | //-------------------------------------------------------------------- | |
544 | // Calculate position of a point on a track and some derivatives | |
545 | //-------------------------------------------------------------------- | |
546 | Double_t phase=h[4]*t+h[2]; | |
547 | Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase); | |
548 | ||
549 | r[0] = h[5] + (sn - h[6])/h[4]; | |
550 | r[1] = h[0] - (cs - h[7])/h[4]; | |
551 | r[2] = h[1] + h[3]*t; | |
552 | ||
553 | g[0] = cs; g[1]=sn; g[2]=h[3]; | |
554 | ||
555 | gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.; | |
556 | } | |
557 | ||
558 | Double_t AliExternalTrackParam::GetDCA(const AliExternalTrackParam *p, | |
559 | Double_t b, Double_t &xthis, Double_t &xp) const { | |
560 | //------------------------------------------------------------ | |
561 | // Returns the (weighed !) distance of closest approach between | |
562 | // this track and the track "p". | |
563 | // Other returned values: | |
564 | // xthis, xt - coordinates of tracks' reference planes at the DCA | |
565 | //----------------------------------------------------------- | |
566 | Double_t dy2=GetSigmaY2() + p->GetSigmaY2(); | |
567 | Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2(); | |
568 | Double_t dx2=dy2; | |
569 | ||
570 | //dx2=dy2=dz2=1.; | |
571 | ||
572 | Double_t p1[8]; GetHelixParameters(p1,b); | |
573 | p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]); | |
574 | Double_t p2[8]; p->GetHelixParameters(p2,b); | |
575 | p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]); | |
576 | ||
577 | ||
578 | Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.; | |
579 | Evaluate(p1,t1,r1,g1,gg1); | |
580 | Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.; | |
581 | Evaluate(p2,t2,r2,g2,gg2); | |
582 | ||
583 | Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2]; | |
584 | Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
585 | ||
586 | Int_t max=27; | |
587 | while (max--) { | |
588 | Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2); | |
589 | Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2); | |
590 | Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 + | |
591 | (g1[1]*g1[1] - dy*gg1[1])/dy2 + | |
592 | (g1[2]*g1[2] - dz*gg1[2])/dz2; | |
593 | Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 + | |
594 | (g2[1]*g2[1] + dy*gg2[1])/dy2 + | |
595 | (g2[2]*g2[2] + dz*gg2[2])/dz2; | |
596 | Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2); | |
597 | ||
598 | Double_t det=h11*h22-h12*h12; | |
599 | ||
600 | Double_t dt1,dt2; | |
601 | if (TMath::Abs(det)<1.e-33) { | |
602 | //(quasi)singular Hessian | |
603 | dt1=-gt1; dt2=-gt2; | |
604 | } else { | |
605 | dt1=-(gt1*h22 - gt2*h12)/det; | |
606 | dt2=-(h11*gt2 - h12*gt1)/det; | |
607 | } | |
608 | ||
609 | if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;} | |
610 | ||
611 | //check delta(phase1) ? | |
612 | //check delta(phase2) ? | |
613 | ||
614 | if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4) | |
615 | if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) { | |
616 | if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2) | |
617 | AliWarning(" stopped at not a stationary point !"); | |
618 | Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det); | |
619 | if (lmb < 0.) | |
620 | AliWarning(" stopped at not a minimum !"); | |
621 | break; | |
622 | } | |
623 | ||
624 | Double_t dd=dm; | |
625 | for (Int_t div=1 ; ; div*=2) { | |
626 | Evaluate(p1,t1+dt1,r1,g1,gg1); | |
627 | Evaluate(p2,t2+dt2,r2,g2,gg2); | |
628 | dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2]; | |
629 | dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2; | |
630 | if (dd<dm) break; | |
631 | dt1*=0.5; dt2*=0.5; | |
632 | if (div>512) { | |
633 | AliWarning(" overshoot !"); break; | |
634 | } | |
635 | } | |
636 | dm=dd; | |
637 | ||
638 | t1+=dt1; | |
639 | t2+=dt2; | |
640 | ||
641 | } | |
642 | ||
643 | if (max<=0) AliWarning(" too many iterations !"); | |
644 | ||
645 | Double_t cs=TMath::Cos(GetAlpha()); | |
646 | Double_t sn=TMath::Sin(GetAlpha()); | |
647 | xthis=r1[0]*cs + r1[1]*sn; | |
648 | ||
649 | cs=TMath::Cos(p->GetAlpha()); | |
650 | sn=TMath::Sin(p->GetAlpha()); | |
651 | xp=r2[0]*cs + r2[1]*sn; | |
652 | ||
653 | return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2)); | |
654 | } | |
655 | ||
656 | Double_t AliExternalTrackParam:: | |
657 | PropagateToDCA(AliExternalTrackParam *p, Double_t b) { | |
658 | //-------------------------------------------------------------- | |
659 | // Propagates this track and the argument track to the position of the | |
660 | // distance of closest approach. | |
661 | // Returns the (weighed !) distance of closest approach. | |
662 | //-------------------------------------------------------------- | |
663 | Double_t xthis,xp; | |
664 | Double_t dca=GetDCA(p,b,xthis,xp); | |
665 | ||
666 | if (!PropagateTo(xthis,b)) { | |
667 | //AliWarning(" propagation failed !"); | |
668 | return 1e+33; | |
669 | } | |
670 | ||
671 | if (!p->PropagateTo(xp,b)) { | |
672 | //AliWarning(" propagation failed !"; | |
673 | return 1e+33; | |
674 | } | |
675 | ||
676 | return dca; | |
677 | } | |
678 | ||
679 | ||
680 | ||
f76701bf | 681 | |
682 | Bool_t AliExternalTrackParam::PropagateToDCA(const AliESDVertex *vtx, Double_t b, Double_t maxd){ | |
683 | // | |
684 | // Try to relate this track to the vertex "vtx", | |
685 | // if the (rough) transverse impact parameter is not bigger then "maxd". | |
686 | // Magnetic field is "b" (kG). | |
687 | // | |
688 | // a) The track gets extapolated to the DCA to the vertex. | |
689 | // b) The impact parameters and their covariance matrix are calculated. | |
690 | // | |
691 | // In the case of success, the returned value is kTRUE | |
692 | // (otherwise, it's kFALSE) | |
693 | // | |
694 | Double_t alpha=GetAlpha(); | |
695 | Double_t sn=TMath::Sin(alpha), cs=TMath::Cos(alpha); | |
696 | Double_t x=GetX(), y=GetParameter()[0], snp=GetParameter()[2]; | |
697 | Double_t xv= vtx->GetXv()*cs + vtx->GetYv()*sn; | |
29fbcc93 | 698 | Double_t yv=-vtx->GetXv()*sn + vtx->GetYv()*cs; |
f76701bf | 699 | x-=xv; y-=yv; |
700 | ||
701 | //Estimate the impact parameter neglecting the track curvature | |
702 | Double_t d=TMath::Abs(x*snp - y*TMath::Sqrt(1.- snp*snp)); | |
703 | if (d > maxd) return kFALSE; | |
704 | ||
705 | //Propagate to the DCA | |
706 | Double_t crv=0.299792458e-3*b*GetParameter()[4]; | |
707 | Double_t tgfv=-(crv*x - snp)/(crv*y + TMath::Sqrt(1.-snp*snp)); | |
708 | sn=tgfv/TMath::Sqrt(1.+ tgfv*tgfv); cs=TMath::Sqrt(1.- sn*sn); | |
709 | ||
710 | x = xv*cs + yv*sn; | |
711 | yv=-xv*sn + yv*cs; xv=x; | |
712 | ||
713 | if (!Propagate(alpha+TMath::ASin(sn),xv,b)) return kFALSE; | |
29fbcc93 | 714 | return kTRUE; |
f76701bf | 715 | } |
716 | ||
717 | ||
718 | ||
719 | ||
c9ec41e8 | 720 | Bool_t Local2GlobalMomentum(Double_t p[3],Double_t alpha) { |
721 | //---------------------------------------------------------------- | |
722 | // This function performs local->global transformation of the | |
723 | // track momentum. | |
724 | // When called, the arguments are: | |
725 | // p[0] = 1/pt of the track; | |
726 | // p[1] = sine of local azim. angle of the track momentum; | |
727 | // p[2] = tangent of the track momentum dip angle; | |
728 | // alpha - rotation angle. | |
729 | // The result is returned as: | |
730 | // p[0] = px | |
731 | // p[1] = py | |
732 | // p[2] = pz | |
733 | // Results for (nearly) straight tracks are meaningless ! | |
734 | //---------------------------------------------------------------- | |
e421f556 | 735 | if (TMath::Abs(p[0])<=kAlmost0) return kFALSE; |
49d13e89 | 736 | if (TMath::Abs(p[1])> kAlmost1) return kFALSE; |
c9ec41e8 | 737 | |
738 | Double_t pt=1./TMath::Abs(p[0]); | |
739 | Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha); | |
740 | Double_t r=TMath::Sqrt(1 - p[1]*p[1]); | |
741 | p[0]=pt*(r*cs - p[1]*sn); p[1]=pt*(p[1]*cs + r*sn); p[2]=pt*p[2]; | |
a5e407e9 | 742 | |
743 | return kTRUE; | |
744 | } | |
745 | ||
c9ec41e8 | 746 | Bool_t Local2GlobalPosition(Double_t r[3],Double_t alpha) { |
747 | //---------------------------------------------------------------- | |
748 | // This function performs local->global transformation of the | |
749 | // track position. | |
750 | // When called, the arguments are: | |
751 | // r[0] = local x | |
752 | // r[1] = local y | |
753 | // r[2] = local z | |
754 | // alpha - rotation angle. | |
755 | // The result is returned as: | |
756 | // r[0] = global x | |
757 | // r[1] = global y | |
758 | // r[2] = global z | |
759 | //---------------------------------------------------------------- | |
760 | Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha), x=r[0]; | |
761 | r[0]=x*cs - r[1]*sn; r[1]=x*sn + r[1]*cs; | |
a5e407e9 | 762 | |
a5e407e9 | 763 | return kTRUE; |
51ad6848 | 764 | } |
765 | ||
b1149664 | 766 | void AliExternalTrackParam::GetDirection(Double_t d[3]) const { |
767 | //---------------------------------------------------------------- | |
768 | // This function returns a unit vector along the track direction | |
769 | // in the global coordinate system. | |
770 | //---------------------------------------------------------------- | |
771 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
772 | Double_t snp=fP[2]; | |
92934324 | 773 | Double_t csp =TMath::Sqrt((1.- snp)*(1.+snp)); |
b1149664 | 774 | Double_t norm=TMath::Sqrt(1.+ fP[3]*fP[3]); |
775 | d[0]=(csp*cs - snp*sn)/norm; | |
776 | d[1]=(snp*cs + csp*sn)/norm; | |
777 | d[2]=fP[3]/norm; | |
778 | } | |
779 | ||
c9ec41e8 | 780 | Bool_t AliExternalTrackParam::GetPxPyPz(Double_t *p) const { |
781 | //--------------------------------------------------------------------- | |
782 | // This function returns the global track momentum components | |
783 | // Results for (nearly) straight tracks are meaningless ! | |
784 | //--------------------------------------------------------------------- | |
785 | p[0]=fP[4]; p[1]=fP[2]; p[2]=fP[3]; | |
786 | return Local2GlobalMomentum(p,fAlpha); | |
787 | } | |
a5e407e9 | 788 | |
c9ec41e8 | 789 | Bool_t AliExternalTrackParam::GetXYZ(Double_t *r) const { |
790 | //--------------------------------------------------------------------- | |
791 | // This function returns the global track position | |
792 | //--------------------------------------------------------------------- | |
793 | r[0]=fX; r[1]=fP[0]; r[2]=fP[1]; | |
794 | return Local2GlobalPosition(r,fAlpha); | |
51ad6848 | 795 | } |
796 | ||
c9ec41e8 | 797 | Bool_t AliExternalTrackParam::GetCovarianceXYZPxPyPz(Double_t cv[21]) const { |
798 | //--------------------------------------------------------------------- | |
799 | // This function returns the global covariance matrix of the track params | |
800 | // | |
801 | // Cov(x,x) ... : cv[0] | |
802 | // Cov(y,x) ... : cv[1] cv[2] | |
803 | // Cov(z,x) ... : cv[3] cv[4] cv[5] | |
804 | // Cov(px,x)... : cv[6] cv[7] cv[8] cv[9] | |
805 | // Cov(py,x)... : cv[10] cv[11] cv[12] cv[13] cv[14] | |
806 | // Cov(pz,x)... : cv[15] cv[16] cv[17] cv[18] cv[19] cv[20] | |
a5e407e9 | 807 | // |
c9ec41e8 | 808 | // Results for (nearly) straight tracks are meaningless ! |
809 | //--------------------------------------------------------------------- | |
e421f556 | 810 | if (TMath::Abs(fP[4])<=kAlmost0) { |
c9ec41e8 | 811 | for (Int_t i=0; i<21; i++) cv[i]=0.; |
812 | return kFALSE; | |
a5e407e9 | 813 | } |
49d13e89 | 814 | if (TMath::Abs(fP[2]) > kAlmost1) { |
c9ec41e8 | 815 | for (Int_t i=0; i<21; i++) cv[i]=0.; |
816 | return kFALSE; | |
817 | } | |
818 | Double_t pt=1./TMath::Abs(fP[4]); | |
819 | Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha); | |
92934324 | 820 | Double_t r=TMath::Sqrt((1.-fP[2])*(1.+fP[2])); |
c9ec41e8 | 821 | |
822 | Double_t m00=-sn, m10=cs; | |
823 | Double_t m23=-pt*(sn + fP[2]*cs/r), m43=-pt*pt*(r*cs - fP[2]*sn); | |
824 | Double_t m24= pt*(cs - fP[2]*sn/r), m44=-pt*pt*(r*sn + fP[2]*cs); | |
825 | Double_t m35=pt, m45=-pt*pt*fP[3]; | |
826 | ||
827 | cv[0 ] = fC[0]*m00*m00; | |
828 | cv[1 ] = fC[0]*m00*m10; | |
829 | cv[2 ] = fC[0]*m10*m10; | |
830 | cv[3 ] = fC[1]*m00; | |
831 | cv[4 ] = fC[1]*m10; | |
832 | cv[5 ] = fC[2]; | |
833 | cv[6 ] = m00*(fC[3]*m23 + fC[10]*m43); | |
834 | cv[7 ] = m10*(fC[3]*m23 + fC[10]*m43); | |
835 | cv[8 ] = fC[4]*m23 + fC[11]*m43; | |
836 | cv[9 ] = m23*(fC[5]*m23 + fC[12]*m43) + m43*(fC[12]*m23 + fC[14]*m43); | |
837 | cv[10] = m00*(fC[3]*m24 + fC[10]*m44); | |
838 | cv[11] = m10*(fC[3]*m24 + fC[10]*m44); | |
839 | cv[12] = fC[4]*m24 + fC[11]*m44; | |
840 | cv[13] = m23*(fC[5]*m24 + fC[12]*m44) + m43*(fC[12]*m24 + fC[14]*m44); | |
841 | cv[14] = m24*(fC[5]*m24 + fC[12]*m44) + m44*(fC[12]*m24 + fC[14]*m44); | |
842 | cv[15] = m00*(fC[6]*m35 + fC[10]*m45); | |
843 | cv[16] = m10*(fC[6]*m35 + fC[10]*m45); | |
844 | cv[17] = fC[7]*m35 + fC[11]*m45; | |
845 | cv[18] = m23*(fC[8]*m35 + fC[12]*m45) + m43*(fC[13]*m35 + fC[14]*m45); | |
846 | cv[19] = m24*(fC[8]*m35 + fC[12]*m45) + m44*(fC[13]*m35 + fC[14]*m45); | |
847 | cv[20] = m35*(fC[9]*m35 + fC[13]*m45) + m45*(fC[13]*m35 + fC[14]*m45); | |
51ad6848 | 848 | |
c9ec41e8 | 849 | return kTRUE; |
51ad6848 | 850 | } |
851 | ||
51ad6848 | 852 | |
c9ec41e8 | 853 | Bool_t |
854 | AliExternalTrackParam::GetPxPyPzAt(Double_t x, Double_t b, Double_t *p) const { | |
855 | //--------------------------------------------------------------------- | |
856 | // This function returns the global track momentum extrapolated to | |
857 | // the radial position "x" (cm) in the magnetic field "b" (kG) | |
858 | //--------------------------------------------------------------------- | |
c9ec41e8 | 859 | p[0]=fP[4]; |
1530f89c | 860 | p[1]=fP[2]+(x-fX)*GetC(b); |
c9ec41e8 | 861 | p[2]=fP[3]; |
862 | return Local2GlobalMomentum(p,fAlpha); | |
51ad6848 | 863 | } |
864 | ||
7cf7bb6c | 865 | Bool_t |
866 | AliExternalTrackParam::GetYAt(Double_t x, Double_t b, Double_t &y) const { | |
867 | //--------------------------------------------------------------------- | |
868 | // This function returns the local Y-coordinate of the intersection | |
869 | // point between this track and the reference plane "x" (cm). | |
870 | // Magnetic field "b" (kG) | |
871 | //--------------------------------------------------------------------- | |
872 | Double_t dx=x-fX; | |
873 | if(TMath::Abs(dx)<=kAlmost0) {y=fP[0]; return kTRUE;} | |
874 | ||
1530f89c | 875 | Double_t f1=fP[2], f2=f1 + dx*GetC(b); |
7cf7bb6c | 876 | |
877 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
878 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
879 | ||
880 | Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2); | |
881 | y = fP[0] + dx*(f1+f2)/(r1+r2); | |
882 | return kTRUE; | |
883 | } | |
884 | ||
6c94f330 | 885 | Bool_t |
886 | AliExternalTrackParam::GetZAt(Double_t x, Double_t b, Double_t &z) const { | |
887 | //--------------------------------------------------------------------- | |
888 | // This function returns the local Z-coordinate of the intersection | |
889 | // point between this track and the reference plane "x" (cm). | |
890 | // Magnetic field "b" (kG) | |
891 | //--------------------------------------------------------------------- | |
892 | Double_t dx=x-fX; | |
893 | if(TMath::Abs(dx)<=kAlmost0) {z=fP[1]; return kTRUE;} | |
894 | ||
895 | Double_t f1=fP[2], f2=f1 + dx*fP[4]*b*kB2C; | |
896 | ||
897 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; | |
898 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; | |
899 | ||
900 | Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2); | |
901 | z = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3]; // Many thanks to P.Hristov ! | |
902 | return kTRUE; | |
903 | } | |
904 | ||
c9ec41e8 | 905 | Bool_t |
906 | AliExternalTrackParam::GetXYZAt(Double_t x, Double_t b, Double_t *r) const { | |
907 | //--------------------------------------------------------------------- | |
908 | // This function returns the global track position extrapolated to | |
909 | // the radial position "x" (cm) in the magnetic field "b" (kG) | |
910 | //--------------------------------------------------------------------- | |
c9ec41e8 | 911 | Double_t dx=x-fX; |
e421f556 | 912 | if(TMath::Abs(dx)<=kAlmost0) return GetXYZ(r); |
913 | ||
1530f89c | 914 | Double_t f1=fP[2], f2=f1 + dx*GetC(b); |
c9ec41e8 | 915 | |
e421f556 | 916 | if (TMath::Abs(f1) >= kAlmost1) return kFALSE; |
49d13e89 | 917 | if (TMath::Abs(f2) >= kAlmost1) return kFALSE; |
c9ec41e8 | 918 | |
919 | Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2); | |
920 | r[0] = x; | |
921 | r[1] = fP[0] + dx*(f1+f2)/(r1+r2); | |
6c94f330 | 922 | r[2] = fP[1] + dx*(f1+f2)/(f1*r2 + f2*r1)*fP[3]; |
c9ec41e8 | 923 | return Local2GlobalPosition(r,fAlpha); |
51ad6848 | 924 | } |
925 | ||
51ad6848 | 926 | //_____________________________________________________________________________ |
927 | void AliExternalTrackParam::Print(Option_t* /*option*/) const | |
928 | { | |
929 | // print the parameters and the covariance matrix | |
930 | ||
931 | printf("AliExternalTrackParam: x = %-12g alpha = %-12g\n", fX, fAlpha); | |
932 | printf(" parameters: %12g %12g %12g %12g %12g\n", | |
c9ec41e8 | 933 | fP[0], fP[1], fP[2], fP[3], fP[4]); |
934 | printf(" covariance: %12g\n", fC[0]); | |
935 | printf(" %12g %12g\n", fC[1], fC[2]); | |
936 | printf(" %12g %12g %12g\n", fC[3], fC[4], fC[5]); | |
51ad6848 | 937 | printf(" %12g %12g %12g %12g\n", |
c9ec41e8 | 938 | fC[6], fC[7], fC[8], fC[9]); |
51ad6848 | 939 | printf(" %12g %12g %12g %12g %12g\n", |
c9ec41e8 | 940 | fC[10], fC[11], fC[12], fC[13], fC[14]); |
51ad6848 | 941 | } |
5b77d93c | 942 | |
c194ba83 | 943 | Double_t AliExternalTrackParam::GetSnpAt(Double_t x,Double_t b) const { |
944 | // | |
945 | // Get sinus at given x | |
946 | // | |
1530f89c | 947 | Double_t crv=GetC(b); |
c194ba83 | 948 | if (TMath::Abs(b) < kAlmost0Field) crv=0.; |
949 | Double_t dx = x-fX; | |
950 | Double_t res = fP[2]+dx*crv; | |
951 | return res; | |
952 | } |