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Commit | Line | Data |
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3e87ef69 | 1 | // @(#) $Id$ |
6d4f1901 | 2 | |
2d04dcbf | 3 | // Author: Anders Vestbo <mailto:vestbo$fi.uib.no>, Uli Frankenfeld <mailto:franken@fi.uib.no> |
3e87ef69 | 4 | //*-- Copyright © ALICE HLT Group |
108615fc | 5 | |
118c26c3 | 6 | #include "AliL3StandardIncludes.h" |
108615fc | 7 | |
8 | #include "AliL3RootTypes.h" | |
108615fc | 9 | #include "AliL3Logging.h" |
10 | #include "AliL3Track.h" | |
0391971c | 11 | #include "AliL3Transform.h" |
6d4f1901 | 12 | #include "AliL3Vertex.h" |
de3c3890 | 13 | #include "AliL3SpacePointData.h" |
118c26c3 | 14 | |
0bd0c1ef | 15 | #if __GNUC__ == 3 |
3e87ef69 | 16 | using namespace std; |
17 | #endif | |
108615fc | 18 | |
3e87ef69 | 19 | /** \class AliL3Track |
20 | //<pre> | |
2d04dcbf | 21 | //_____________________________________________________________ |
22 | // AliL3Track | |
23 | // | |
24 | // Track base class | |
02cb36b2 | 25 | //Begin_Html |
3e87ef69 | 26 | //<img src="track_coordinates.gif"> |
02cb36b2 | 27 | //End_Html |
3e87ef69 | 28 | </pre> |
29 | */ | |
0391971c | 30 | |
108615fc | 31 | ClassImp(AliL3Track) |
32 | ||
108615fc | 33 | |
34 | AliL3Track::AliL3Track() | |
35 | { | |
36 | //Constructor | |
37 | ||
38 | fNHits = 0; | |
39 | fMCid = -1; | |
40 | fKappa=0; | |
41 | fRadius=0; | |
42 | fCenterX=0; | |
43 | fCenterY=0; | |
44 | ComesFromMainVertex(false); | |
45 | fQ = 0; | |
46 | fPhi0=0; | |
47 | fPsi=0; | |
48 | fR0=0; | |
49 | fTanl=0; | |
50 | fZ0=0; | |
51 | fPt=0; | |
52 | fLength=0; | |
53 | fIsLocal=true; | |
54 | fRowRange[0]=0; | |
55 | fRowRange[1]=0; | |
3e87ef69 | 56 | SetFirstPoint(0,0,0); |
57 | SetLastPoint(0,0,0); | |
68a27388 | 58 | memset(fHitNumbers,0,159*sizeof(UInt_t)); |
de3c3890 | 59 | fPID = 0; |
108615fc | 60 | } |
61 | ||
62 | void AliL3Track::Set(AliL3Track *tpt){ | |
63 | ||
3a735e00 | 64 | SetRowRange(tpt->GetFirstRow(),tpt->GetLastRow()); |
65 | SetPhi0(tpt->GetPhi0()); | |
66 | SetKappa(tpt->GetKappa()); | |
67 | SetNHits(tpt->GetNHits()); | |
68 | SetFirstPoint(tpt->GetFirstPointX(),tpt->GetFirstPointY(),tpt->GetFirstPointZ()); | |
69 | SetLastPoint(tpt->GetLastPointX(),tpt->GetLastPointY(),tpt->GetLastPointZ()); | |
70 | SetPt(tpt->GetPt()); | |
71 | SetPsi(tpt->GetPsi()); | |
72 | SetTgl(tpt->GetTgl()); | |
73 | SetCharge(tpt->GetCharge()); | |
74 | SetHits(tpt->GetNHits(),(UInt_t *)tpt->GetHitNumbers()); | |
4a0bee4e | 75 | #ifdef do_mc |
76 | SetMCid(tpt->GetMCid()); | |
77 | #endif | |
de3c3890 | 78 | SetPID(tpt->GetPID()); |
79 | SetSector(tpt->GetSector()); | |
108615fc | 80 | } |
81 | ||
203925a9 | 82 | Int_t AliL3Track::Compare(const AliL3Track *track) const |
83 | { | |
84 | if(track->GetNHits() < GetNHits()) return 1; | |
85 | if(track->GetNHits() > GetNHits()) return -1; | |
86 | return 0; | |
87 | } | |
108615fc | 88 | |
89 | AliL3Track::~AliL3Track() | |
90 | { | |
203925a9 | 91 | //Nothing to do |
108615fc | 92 | } |
93 | ||
94 | Double_t AliL3Track::GetP() const | |
95 | { | |
203925a9 | 96 | // Returns total momentum. |
108615fc | 97 | return fabs(GetPt())*sqrt(1. + GetTgl()*GetTgl()); |
108615fc | 98 | } |
99 | ||
100 | Double_t AliL3Track::GetPseudoRapidity() const | |
101 | { | |
102 | return 0.5 * log((GetP() + GetPz()) / (GetP() - GetPz())); | |
103 | } | |
eeddc64d | 104 | |
203925a9 | 105 | /* |
108615fc | 106 | Double_t AliL3Track::GetEta() const |
107 | { | |
108 | return GetPseudoRapidity(); | |
109 | } | |
203925a9 | 110 | */ |
eeddc64d | 111 | |
108615fc | 112 | Double_t AliL3Track::GetRapidity() const |
113 | { | |
5a31e9df | 114 | const Double_t m_pi = 0.13957; |
108615fc | 115 | return 0.5 * log((m_pi + GetPz()) / (m_pi - GetPz())); |
116 | } | |
117 | ||
203925a9 | 118 | void AliL3Track::Rotate(Int_t slice,Bool_t tolocal) |
0391971c | 119 | { |
0391971c | 120 | //Rotate track to global parameters |
203925a9 | 121 | //If flag tolocal is set, the track is rotated |
122 | //to local coordinates. | |
0391971c | 123 | |
0391971c | 124 | |
125 | Float_t psi[1] = {GetPsi()}; | |
203925a9 | 126 | if(!tolocal) |
494fad94 | 127 | AliL3Transform::Local2GlobalAngle(psi,slice); |
203925a9 | 128 | else |
494fad94 | 129 | AliL3Transform::Global2LocalAngle(psi,slice); |
0391971c | 130 | SetPsi(psi[0]); |
131 | Float_t first[3]; | |
132 | first[0] = GetFirstPointX(); | |
133 | first[1] = GetFirstPointY(); | |
134 | first[2] = GetFirstPointZ(); | |
203925a9 | 135 | if(!tolocal) |
494fad94 | 136 | AliL3Transform::Local2Global(first,slice); |
203925a9 | 137 | else |
5a31e9df | 138 | AliL3Transform::Global2LocHLT(first,slice); |
139 | //AliL3Transform::Global2Local(first,slice,kTRUE); | |
203925a9 | 140 | |
0391971c | 141 | SetFirstPoint(first[0],first[1],first[2]); |
142 | Float_t last[3]; | |
143 | last[0] = GetLastPointX(); | |
144 | last[1] = GetLastPointY(); | |
145 | last[2] = GetLastPointZ(); | |
203925a9 | 146 | if(!tolocal) |
494fad94 | 147 | AliL3Transform::Local2Global(last,slice); |
203925a9 | 148 | else |
5a31e9df | 149 | AliL3Transform::Global2LocHLT(last,slice); |
150 | //AliL3Transform::Global2Local(last,slice,kTRUE); | |
0391971c | 151 | SetLastPoint(last[0],last[1],last[2]); |
203925a9 | 152 | |
6d4f1901 | 153 | Float_t center[3] = {GetCenterX(),GetCenterY(),0}; |
154 | if(!tolocal) | |
494fad94 | 155 | AliL3Transform::Local2Global(center,slice); |
6d4f1901 | 156 | else |
5a31e9df | 157 | AliL3Transform::Global2LocHLT(center,slice); |
158 | //AliL3Transform::Global2Local(center,slice,kTRUE); | |
6d4f1901 | 159 | SetCenterX(center[0]); |
160 | SetCenterY(center[1]); | |
161 | ||
3e87ef69 | 162 | SetPhi0(atan2(fFirstPoint[1],fFirstPoint[0])); |
163 | SetR0(sqrt(fFirstPoint[0]*fFirstPoint[0]+fFirstPoint[1]*fFirstPoint[1])); | |
164 | ||
203925a9 | 165 | if(!tolocal) |
166 | fIsLocal=kFALSE; | |
167 | else | |
168 | fIsLocal=kTRUE; | |
0391971c | 169 | } |
170 | ||
108615fc | 171 | void AliL3Track::CalculateHelix(){ |
eeddc64d | 172 | //Calculate Radius, CenterX and CenterY from Psi, X0, Y0 |
108615fc | 173 | // |
174 | ||
5a31e9df | 175 | fRadius = fPt / (AliL3Transform::GetBFieldValue()); |
3ceb3fe1 | 176 | if(fRadius) fKappa = -fQ*1./fRadius; |
108615fc | 177 | else fRadius = 999999; //just zero |
5a31e9df | 178 | Double_t trackPhi0 = fPsi + fQ * AliL3Transform::PiHalf(); |
108615fc | 179 | |
180 | fCenterX = fFirstPoint[0] - fRadius * cos(trackPhi0); | |
181 | fCenterY = fFirstPoint[1] - fRadius * sin(trackPhi0); | |
3e87ef69 | 182 | |
183 | SetPhi0(atan2(fFirstPoint[1],fFirstPoint[0])); | |
184 | SetR0(sqrt(fFirstPoint[0]*fFirstPoint[0]+fFirstPoint[1]*fFirstPoint[1])); | |
108615fc | 185 | } |
186 | ||
3e87ef69 | 187 | Double_t AliL3Track::GetCrossingAngle(Int_t padrow,Int_t slice) |
0391971c | 188 | { |
189 | //Calculate the crossing angle between track and given padrow. | |
0391971c | 190 | //Take the dot product of the tangent vector of the track, and |
191 | //vector perpendicular to the padrow. | |
dab230b2 | 192 | //In order to do this, we need the tangent vector to the track at the |
193 | //point. This is done by rotating the radius vector by 90 degrees; | |
194 | //rotation matrix: ( 0 1 ) | |
195 | // ( -1 0 ) | |
3e87ef69 | 196 | |
197 | Float_t angle=0;//Angle perpendicular to the padrow in local coordinates | |
198 | if(slice>=0)//Global coordinates | |
199 | { | |
200 | AliL3Transform::Local2GlobalAngle(&angle,slice); | |
201 | if(!CalculateReferencePoint(angle,AliL3Transform::Row2X(padrow))) | |
202 | cerr<<"AliL3Track::GetCrossingAngle : Track does not cross line in slice "<<slice<<" row "<<padrow<<endl; | |
203 | } | |
204 | else //should be in local coordinates | |
205 | { | |
206 | Float_t xyz[3]; | |
207 | GetCrossingPoint(padrow,xyz); | |
208 | fPoint[0] = xyz[0]; | |
209 | fPoint[1] = xyz[1]; | |
210 | fPoint[2] = xyz[2]; | |
211 | } | |
212 | ||
0391971c | 213 | Double_t tangent[2]; |
dab230b2 | 214 | |
3e87ef69 | 215 | tangent[0] = (fPoint[1] - GetCenterY())/GetRadius(); |
216 | tangent[1] = -1.*(fPoint[0] - GetCenterX())/GetRadius(); | |
217 | ||
218 | Double_t perp_padrow[2] = {cos(angle),sin(angle)}; | |
23f26160 | 219 | |
0391971c | 220 | Double_t cos_beta = fabs(tangent[0]*perp_padrow[0] + tangent[1]*perp_padrow[1]); |
23f26160 | 221 | if(cos_beta > 1) cos_beta=1; |
0391971c | 222 | return acos(cos_beta); |
0391971c | 223 | } |
224 | ||
3e87ef69 | 225 | Bool_t AliL3Track::GetCrossingPoint(Int_t padrow,Float_t *xyz) |
0391971c | 226 | { |
227 | //Assumes the track is given in local coordinates | |
3e87ef69 | 228 | |
0391971c | 229 | if(!IsLocal()) |
230 | { | |
3e87ef69 | 231 | cerr<<"GetCrossingPoint: Track is given on global coordinates"<<endl; |
0391971c | 232 | return false; |
233 | } | |
234 | ||
494fad94 | 235 | Double_t xHit = AliL3Transform::Row2X(padrow); |
0391971c | 236 | |
237 | xyz[0] = xHit; | |
238 | Double_t aa = (xHit - GetCenterX())*(xHit - GetCenterX()); | |
239 | Double_t r2 = GetRadius()*GetRadius(); | |
240 | if(aa > r2) | |
241 | return false; | |
242 | ||
243 | Double_t aa2 = sqrt(r2 - aa); | |
244 | Double_t y1 = GetCenterY() + aa2; | |
245 | Double_t y2 = GetCenterY() - aa2; | |
246 | xyz[1] = y1; | |
247 | if(fabs(y2) < fabs(y1)) xyz[1] = y2; | |
3e87ef69 | 248 | |
0391971c | 249 | Double_t yHit = xyz[1]; |
250 | Double_t angle1 = atan2((yHit - GetCenterY()),(xHit - GetCenterX())); | |
9ca67380 | 251 | if(angle1 < 0) angle1 += 2.*AliL3Transform::Pi(); |
0391971c | 252 | Double_t angle2 = atan2((GetFirstPointY() - GetCenterY()),(GetFirstPointX() - GetCenterX())); |
5a31e9df | 253 | if(angle2 < 0) angle2 += AliL3Transform::TwoPi(); |
0391971c | 254 | Double_t diff_angle = angle1 - angle2; |
5a31e9df | 255 | diff_angle = fmod(diff_angle,AliL3Transform::TwoPi()); |
256 | if((GetCharge()*diff_angle) > 0) diff_angle = diff_angle - GetCharge()*AliL3Transform::TwoPi(); | |
0391971c | 257 | Double_t s_tot = fabs(diff_angle)*GetRadius(); |
258 | Double_t zHit = GetFirstPointZ() + s_tot*GetTgl(); | |
259 | xyz[2] = zHit; | |
3e87ef69 | 260 | |
0391971c | 261 | return true; |
3e87ef69 | 262 | |
0391971c | 263 | } |
264 | ||
6d4f1901 | 265 | Bool_t AliL3Track::CalculateReferencePoint(Double_t angle,Double_t radius){ |
5a31e9df | 266 | // Global coordinate: crossing point with y = ax+ b; |
267 | // a=tan(angle-AliL3Transform::PiHalf()); | |
108615fc | 268 | // |
5a31e9df | 269 | const Double_t rr=radius; //position of reference plane |
eeddc64d | 270 | const Double_t xr = cos(angle) * rr; |
271 | const Double_t yr = sin(angle) * rr; | |
6d4f1901 | 272 | |
5a31e9df | 273 | Double_t a = tan(angle-AliL3Transform::PiHalf()); |
108615fc | 274 | Double_t b = yr - a * xr; |
275 | ||
276 | Double_t pp=(fCenterX+a*fCenterY-a*b)/(1+pow(a,2)); | |
277 | Double_t qq=(pow(fCenterX,2)+pow(fCenterY,2)-2*fCenterY*b+pow(b,2)-pow(fRadius,2))/(1+pow(a,2)); | |
278 | ||
279 | Double_t racine = pp*pp-qq; | |
280 | if(racine<0) return IsPoint(kFALSE); //no Point | |
281 | ||
282 | Double_t rootRacine = sqrt(racine); | |
283 | Double_t x0 = pp+rootRacine; | |
284 | Double_t x1 = pp-rootRacine; | |
285 | Double_t y0 = a*x0 + b; | |
286 | Double_t y1 = a*x1 + b; | |
287 | ||
288 | Double_t diff0 = sqrt(pow(x0-xr,2)+pow(y0-yr,2)); | |
289 | Double_t diff1 = sqrt(pow(x1-xr,2)+pow(y1-yr,2)); | |
290 | ||
291 | if(diff0<diff1){ | |
292 | fPoint[0]=x0; | |
293 | fPoint[1]=y0; | |
294 | } | |
295 | else{ | |
296 | fPoint[0]=x1; | |
297 | fPoint[1]=y1; | |
298 | } | |
299 | ||
300 | Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX); | |
301 | Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX); | |
5a31e9df | 302 | if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){ |
303 | if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi(); | |
304 | else pointPhi0 += AliL3Transform::TwoPi(); | |
108615fc | 305 | } |
306 | Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ; | |
307 | fPoint[2] = fFirstPoint[2] + stot * fTanl; | |
308 | ||
5a31e9df | 309 | fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf(); |
310 | if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi(); | |
311 | fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi()); | |
108615fc | 312 | |
313 | return IsPoint(kTRUE); | |
314 | } | |
315 | ||
316 | Bool_t AliL3Track::CalculateEdgePoint(Double_t angle){ | |
317 | // Global coordinate: crossing point with y = ax; a=tan(angle); | |
318 | // | |
4a0bee4e | 319 | Double_t rmin=AliL3Transform::Row2X(AliL3Transform::GetFirstRow(-1)); //min Radius of TPC |
320 | Double_t rmax=AliL3Transform::Row2X(AliL3Transform::GetLastRow(-1)); //max Radius of TPC | |
108615fc | 321 | |
322 | Double_t a = tan(angle); | |
323 | Double_t pp=(fCenterX+a*fCenterY)/(1+pow(a,2)); | |
324 | Double_t qq=(pow(fCenterX,2)+pow(fCenterY,2)-pow(fRadius,2))/(1+pow(a,2)); | |
325 | Double_t racine = pp*pp-qq; | |
326 | if(racine<0) return IsPoint(kFALSE); //no Point | |
327 | Double_t rootRacine = sqrt(racine); | |
328 | Double_t x0 = pp+rootRacine; | |
329 | Double_t x1 = pp-rootRacine; | |
330 | Double_t y0 = a*x0; | |
331 | Double_t y1 = a*x1; | |
332 | ||
333 | Double_t r0 = sqrt(pow(x0,2)+pow(y0,2)); | |
334 | Double_t r1 = sqrt(pow(x1,2)+pow(y1,2)); | |
335 | //find the right crossing point: | |
336 | //inside the TPC modules | |
337 | Bool_t ok0 = kFALSE; | |
338 | Bool_t ok1 = kFALSE; | |
472d9e24 | 339 | |
108615fc | 340 | if(r0>rmin&&r0<rmax){ |
341 | Double_t da=atan2(y0,x0); | |
5a31e9df | 342 | if(da<0) da+=AliL3Transform::TwoPi(); |
108615fc | 343 | if(fabs(da-angle)<0.5) |
344 | ok0 = kTRUE; | |
345 | } | |
346 | if(r1>rmin&&r1<rmax){ | |
472d9e24 | 347 | Double_t da=atan2(y1,x1); |
5a31e9df | 348 | if(da<0) da+=AliL3Transform::TwoPi(); |
108615fc | 349 | if(fabs(da-angle)<0.5) |
350 | ok1 = kTRUE; | |
351 | } | |
352 | if(!(ok0||ok1)) return IsPoint(kFALSE); //no Point | |
353 | ||
354 | if(ok0&&ok1){ | |
355 | Double_t diff0 = sqrt(pow(fFirstPoint[0]-x0,2)+pow(fFirstPoint[1]-y0,2)); | |
356 | Double_t diff1 = sqrt(pow(fFirstPoint[0]-x1,2)+pow(fFirstPoint[1]-y1,2)); | |
357 | if(diff0<diff1) ok1 = kFALSE; //use ok0 | |
358 | else ok0 = kFALSE; //use ok1 | |
359 | } | |
360 | if(ok0){fPoint[0]=x0; fPoint[1]=y0;} | |
361 | else {fPoint[0]=x1; fPoint[1]=y1;} | |
362 | ||
363 | Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX); | |
364 | Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX); | |
5a31e9df | 365 | if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){ |
366 | if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi(); | |
367 | else pointPhi0 += AliL3Transform::TwoPi(); | |
108615fc | 368 | } |
369 | Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ; | |
370 | fPoint[2] = fFirstPoint[2] + stot * fTanl; | |
371 | ||
5a31e9df | 372 | fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf(); |
373 | if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi(); | |
374 | fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi()); | |
108615fc | 375 | |
376 | return IsPoint(kTRUE); | |
377 | } | |
378 | ||
379 | Bool_t AliL3Track::CalculatePoint(Double_t xplane){ | |
380 | // Local coordinate: crossing point with x plane | |
381 | // | |
382 | Double_t racine = pow(fRadius,2)-pow(xplane-fCenterX,2); | |
383 | if(racine<0) return IsPoint(kFALSE); | |
384 | Double_t rootRacine = sqrt(racine); | |
385 | ||
386 | Double_t y0 = fCenterY + rootRacine; | |
387 | Double_t y1 = fCenterY - rootRacine; | |
388 | //Double_t diff0 = sqrt(pow(fFirstPoint[0]-xplane)+pow(fFirstPoint[1]-y0)); | |
389 | //Double_t diff1 = sqrt(pow(fFirstPoint[0]-xplane)+pow(fFirstPoint[1]-y1)); | |
390 | Double_t diff0 = fabs(y0-fFirstPoint[1]); | |
391 | Double_t diff1 = fabs(y1-fFirstPoint[1]); | |
392 | ||
393 | fPoint[0]=xplane; | |
394 | if(diff0<diff1) fPoint[1]=y0; | |
395 | else fPoint[1]=y1; | |
396 | ||
397 | Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX); | |
398 | Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX); | |
5a31e9df | 399 | if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){ |
400 | if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi(); | |
401 | else pointPhi0 += AliL3Transform::TwoPi(); | |
108615fc | 402 | } |
403 | Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ; | |
404 | fPoint[2] = fFirstPoint[2] + stot * fTanl; | |
405 | ||
5a31e9df | 406 | fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf(); |
407 | if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi(); | |
408 | fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi()); | |
108615fc | 409 | |
410 | return IsPoint(kTRUE); | |
411 | } | |
412 | ||
3e87ef69 | 413 | void AliL3Track::UpdateToFirstPoint() |
414 | { | |
415 | //Update track parameters to the innermost point on the track. | |
1f1942b8 | 416 | //This means that the parameters of the track will be given in the point |
417 | //of closest approach to the first innermost point, i.e. the point | |
418 | //lying on the track fit (and not the coordinates of the innermost point itself). | |
419 | //This function assumes that fFirstPoint is already set to the coordinates of the innermost | |
420 | //assigned cluster. | |
421 | // | |
422 | //During the helix-fit, the first point on the track is set to the coordinates | |
423 | //of the innermost assigned cluster. This may be ok, if you just want a fast | |
424 | //estimate of the "global" track parameters; such as the momentum etc. | |
425 | //However, if you later on want to do more precise local calculations, such | |
426 | //as impact parameter, residuals etc, you need to give the track parameters | |
427 | //according to the actual fit. | |
3e87ef69 | 428 | |
1f1942b8 | 429 | Double_t xc = GetCenterX() - GetFirstPointX(); |
430 | Double_t yc = GetCenterY() - GetFirstPointY(); | |
3e87ef69 | 431 | |
1f1942b8 | 432 | Double_t dist_x1 = xc*(1 + GetRadius()/sqrt(xc*xc + yc*yc)); |
433 | Double_t dist_y1 = yc*(1 + GetRadius()/sqrt(xc*xc + yc*yc)); | |
434 | Double_t distance1 = sqrt(dist_x1*dist_x1 + dist_y1*dist_y1); | |
3e87ef69 | 435 | |
1f1942b8 | 436 | Double_t dist_x2 = xc*(1 - GetRadius()/sqrt(xc*xc + yc*yc)); |
437 | Double_t dist_y2 = yc*(1 - GetRadius()/sqrt(xc*xc + yc*yc)); | |
438 | Double_t distance2 = sqrt(dist_x2*dist_x2 + dist_y2*dist_y2); | |
3e87ef69 | 439 | |
1f1942b8 | 440 | //Choose the closest: |
441 | Double_t point[2]; | |
442 | if(distance1 < distance2) | |
443 | { | |
444 | point[0] = dist_x1 + GetFirstPointX(); | |
445 | point[1] = dist_y1 + GetFirstPointY(); | |
446 | } | |
447 | else | |
448 | { | |
449 | point[0] = dist_x2 + GetFirstPointX(); | |
450 | point[1] = dist_y2 + GetFirstPointY(); | |
451 | } | |
452 | ||
453 | Double_t pointpsi = atan2(point[1]-GetCenterY(),point[0]-GetCenterX()); | |
5a31e9df | 454 | pointpsi -= GetCharge()*AliL3Transform::PiHalf(); |
455 | if(pointpsi < 0) pointpsi += AliL3Transform::TwoPi(); | |
3e87ef69 | 456 | |
1f1942b8 | 457 | //Update the track parameters |
458 | SetR0(sqrt(point[0]*point[0]+point[1]*point[1])); | |
459 | SetPhi0(atan2(point[1],point[0])); | |
460 | SetFirstPoint(point[0],point[1],GetZ0()); | |
461 | SetPsi(pointpsi); | |
3e87ef69 | 462 | |
3e87ef69 | 463 | } |
464 | ||
6d4f1901 | 465 | void AliL3Track::GetClosestPoint(AliL3Vertex *vertex,Double_t &closest_x,Double_t &closest_y,Double_t &closest_z) |
466 | { | |
467 | //Calculate the point of closest approach to the vertex | |
1f1942b8 | 468 | //This function calculates the minimum distance from the helix to the vertex, and choose |
469 | //the corresponding point lying on the helix as the point of closest approach. | |
6d4f1901 | 470 | |
1f1942b8 | 471 | Double_t xc = GetCenterX() - vertex->GetX(); |
6d4f1901 | 472 | Double_t yc = GetCenterY() - vertex->GetY(); |
473 | ||
474 | Double_t dist_x1 = xc*(1 + GetRadius()/sqrt(xc*xc + yc*yc)); | |
475 | Double_t dist_y1 = yc*(1 + GetRadius()/sqrt(xc*xc + yc*yc)); | |
476 | Double_t distance1 = sqrt(dist_x1*dist_x1 + dist_y1*dist_y1); | |
477 | ||
478 | Double_t dist_x2 = xc*(1 - GetRadius()/sqrt(xc*xc + yc*yc)); | |
479 | Double_t dist_y2 = yc*(1 - GetRadius()/sqrt(xc*xc + yc*yc)); | |
480 | Double_t distance2 = sqrt(dist_x2*dist_x2 + dist_y2*dist_y2); | |
481 | ||
482 | //Choose the closest: | |
483 | if(distance1 < distance2) | |
484 | { | |
485 | closest_x = dist_x1 + vertex->GetX(); | |
486 | closest_y = dist_y1 + vertex->GetY(); | |
487 | } | |
488 | else | |
489 | { | |
490 | closest_x = dist_x2 + vertex->GetX(); | |
491 | closest_y = dist_y2 + vertex->GetY(); | |
492 | } | |
493 | ||
494 | //Get the z coordinate: | |
495 | Double_t angle1 = atan2((closest_y-GetCenterY()),(closest_x-GetCenterX())); | |
5a31e9df | 496 | if(angle1 < 0) angle1 = angle1 + AliL3Transform::TwoPi(); |
6d4f1901 | 497 | |
498 | Double_t angle2 = atan2((GetFirstPointY()-GetCenterY()),(GetFirstPointX()-GetCenterX())); | |
5a31e9df | 499 | if(angle2 < 0) angle2 = angle2 + AliL3Transform::TwoPi(); |
6d4f1901 | 500 | |
501 | Double_t diff_angle = angle1 - angle2; | |
5a31e9df | 502 | diff_angle = fmod(diff_angle,AliL3Transform::TwoPi()); |
6d4f1901 | 503 | |
5a31e9df | 504 | if((GetCharge()*diff_angle) < 0) diff_angle = diff_angle + GetCharge()*AliL3Transform::TwoPi(); |
6d4f1901 | 505 | Double_t s_tot = fabs(diff_angle)*GetRadius(); |
506 | ||
507 | closest_z = GetFirstPointZ() - s_tot*GetTgl(); | |
508 | } | |
de3c3890 | 509 |