3 // Author: Anders Vestbo <mailto:vestbo$fi.uib.no>, Uli Frankenfeld <mailto:franken@fi.uib.no>
4 //*-- Copyright © ALICE HLT Group
6 #include "AliL3StandardIncludes.h"
8 #include "AliL3RootTypes.h"
9 #include "AliL3Logging.h"
10 #include "AliL3Track.h"
11 #include "AliL3Transform.h"
12 #include "AliL3Vertex.h"
13 #include "AliL3SpacePointData.h"
21 //_____________________________________________________________
26 //<img src="track_coordinates.gif">
34 AliL3Track::AliL3Track()
44 ComesFromMainVertex(false);
58 memset(fHitNumbers,0,159*sizeof(UInt_t));
62 void AliL3Track::Set(AliL3Track *tpt)
65 SetRowRange(tpt->GetFirstRow(),tpt->GetLastRow());
66 SetPhi0(tpt->GetPhi0());
67 SetKappa(tpt->GetKappa());
68 SetNHits(tpt->GetNHits());
69 SetFirstPoint(tpt->GetFirstPointX(),tpt->GetFirstPointY(),tpt->GetFirstPointZ());
70 SetLastPoint(tpt->GetLastPointX(),tpt->GetLastPointY(),tpt->GetLastPointZ());
72 SetPsi(tpt->GetPsi());
73 SetTgl(tpt->GetTgl());
74 SetCharge(tpt->GetCharge());
75 SetHits(tpt->GetNHits(),(UInt_t *)tpt->GetHitNumbers());
77 SetMCid(tpt->GetMCid());
79 SetPID(tpt->GetPID());
80 SetSector(tpt->GetSector());
83 Int_t AliL3Track::Compare(const AliL3Track *track) const
86 if(track->GetNHits() < GetNHits()) return 1;
87 if(track->GetNHits() > GetNHits()) return -1;
91 AliL3Track::~AliL3Track()
96 Double_t AliL3Track::GetP() const
98 // Returns total momentum.
99 return fabs(GetPt())*sqrt(1. + GetTgl()*GetTgl());
102 Double_t AliL3Track::GetPseudoRapidity() const
104 return 0.5 * log((GetP() + GetPz()) / (GetP() - GetPz()));
108 Double_t AliL3Track::GetEta() const
110 return GetPseudoRapidity();
114 Double_t AliL3Track::GetRapidity() const
117 const Double_t m_pi = 0.13957;
118 return 0.5 * log((m_pi + GetPz()) / (m_pi - GetPz()));
121 void AliL3Track::Rotate(Int_t slice,Bool_t tolocal)
123 //Rotate track to global parameters
124 //If flag tolocal is set, the track is rotated
125 //to local coordinates.
127 Float_t psi[1] = {GetPsi()};
129 AliL3Transform::Local2GlobalAngle(psi,slice);
131 AliL3Transform::Global2LocalAngle(psi,slice);
134 first[0] = GetFirstPointX();
135 first[1] = GetFirstPointY();
136 first[2] = GetFirstPointZ();
138 AliL3Transform::Local2Global(first,slice);
140 AliL3Transform::Global2LocHLT(first,slice);
141 //AliL3Transform::Global2Local(first,slice,kTRUE);
143 SetFirstPoint(first[0],first[1],first[2]);
145 last[0] = GetLastPointX();
146 last[1] = GetLastPointY();
147 last[2] = GetLastPointZ();
149 AliL3Transform::Local2Global(last,slice);
151 AliL3Transform::Global2LocHLT(last,slice);
152 //AliL3Transform::Global2Local(last,slice,kTRUE);
153 SetLastPoint(last[0],last[1],last[2]);
155 Float_t center[3] = {GetCenterX(),GetCenterY(),0};
157 AliL3Transform::Local2Global(center,slice);
159 AliL3Transform::Global2LocHLT(center,slice);
160 //AliL3Transform::Global2Local(center,slice,kTRUE);
161 SetCenterX(center[0]);
162 SetCenterY(center[1]);
164 SetPhi0(atan2(fFirstPoint[1],fFirstPoint[0]));
165 SetR0(sqrt(fFirstPoint[0]*fFirstPoint[0]+fFirstPoint[1]*fFirstPoint[1]));
173 void AliL3Track::CalculateHelix()
175 //Calculate Radius, CenterX and CenterY from Psi, X0, Y0
176 fRadius = fPt / (AliL3Transform::GetBFieldValue());
177 if(fRadius) fKappa = -fQ*1./fRadius;
178 else fRadius = 999999; //just zero
179 Double_t trackPhi0 = fPsi + fQ * AliL3Transform::PiHalf();
181 fCenterX = fFirstPoint[0] - fRadius * cos(trackPhi0);
182 fCenterY = fFirstPoint[1] - fRadius * sin(trackPhi0);
184 SetPhi0(atan2(fFirstPoint[1],fFirstPoint[0]));
185 SetR0(sqrt(fFirstPoint[0]*fFirstPoint[0]+fFirstPoint[1]*fFirstPoint[1]));
188 Double_t AliL3Track::GetCrossingAngle(Int_t padrow,Int_t slice)
190 //Calculate the crossing angle between track and given padrow.
191 //Take the dot product of the tangent vector of the track, and
192 //vector perpendicular to the padrow.
193 //In order to do this, we need the tangent vector to the track at the
194 //point. This is done by rotating the radius vector by 90 degrees;
195 //rotation matrix: ( 0 1 )
198 Float_t angle=0;//Angle perpendicular to the padrow in local coordinates
199 if(slice>=0)//Global coordinates
201 AliL3Transform::Local2GlobalAngle(&angle,slice);
202 if(!CalculateReferencePoint(angle,AliL3Transform::Row2X(padrow)))
203 cerr<<"AliL3Track::GetCrossingAngle : Track does not cross line in slice "<<slice<<" row "<<padrow<<endl;
205 else //should be in local coordinates
208 GetCrossingPoint(padrow,xyz);
216 tangent[0] = (fPoint[1] - GetCenterY())/GetRadius();
217 tangent[1] = -1.*(fPoint[0] - GetCenterX())/GetRadius();
219 Double_t perp_padrow[2] = {cos(angle),sin(angle)};
221 Double_t cos_beta = fabs(tangent[0]*perp_padrow[0] + tangent[1]*perp_padrow[1]);
222 if(cos_beta > 1) cos_beta=1;
223 return acos(cos_beta);
226 Bool_t AliL3Track::GetCrossingPoint(Int_t padrow,Float_t *xyz)
228 //Assumes the track is given in local coordinates
232 cerr<<"GetCrossingPoint: Track is given on global coordinates"<<endl;
236 Double_t xHit = AliL3Transform::Row2X(padrow);
239 Double_t aa = (xHit - GetCenterX())*(xHit - GetCenterX());
240 Double_t r2 = GetRadius()*GetRadius();
244 Double_t aa2 = sqrt(r2 - aa);
245 Double_t y1 = GetCenterY() + aa2;
246 Double_t y2 = GetCenterY() - aa2;
248 if(fabs(y2) < fabs(y1)) xyz[1] = y2;
250 Double_t yHit = xyz[1];
251 Double_t angle1 = atan2((yHit - GetCenterY()),(xHit - GetCenterX()));
252 if(angle1 < 0) angle1 += 2.*AliL3Transform::Pi();
253 Double_t angle2 = atan2((GetFirstPointY() - GetCenterY()),(GetFirstPointX() - GetCenterX()));
254 if(angle2 < 0) angle2 += AliL3Transform::TwoPi();
255 Double_t diff_angle = angle1 - angle2;
256 diff_angle = fmod(diff_angle,AliL3Transform::TwoPi());
257 if((GetCharge()*diff_angle) > 0) diff_angle = diff_angle - GetCharge()*AliL3Transform::TwoPi();
258 Double_t s_tot = fabs(diff_angle)*GetRadius();
259 Double_t zHit = GetFirstPointZ() + s_tot*GetTgl();
266 Bool_t AliL3Track::CalculateReferencePoint(Double_t angle,Double_t radius)
268 // Global coordinate: crossing point with y = ax+ b;
269 // a=tan(angle-AliL3Transform::PiHalf());
271 const Double_t rr=radius; //position of reference plane
272 const Double_t xr = cos(angle) * rr;
273 const Double_t yr = sin(angle) * rr;
275 Double_t a = tan(angle-AliL3Transform::PiHalf());
276 Double_t b = yr - a * xr;
278 Double_t pp=(fCenterX+a*fCenterY-a*b)/(1+pow(a,2));
279 Double_t qq=(pow(fCenterX,2)+pow(fCenterY,2)-2*fCenterY*b+pow(b,2)-pow(fRadius,2))/(1+pow(a,2));
281 Double_t racine = pp*pp-qq;
282 if(racine<0) return IsPoint(kFALSE); //no Point
284 Double_t rootRacine = sqrt(racine);
285 Double_t x0 = pp+rootRacine;
286 Double_t x1 = pp-rootRacine;
287 Double_t y0 = a*x0 + b;
288 Double_t y1 = a*x1 + b;
290 Double_t diff0 = sqrt(pow(x0-xr,2)+pow(y0-yr,2));
291 Double_t diff1 = sqrt(pow(x1-xr,2)+pow(y1-yr,2));
302 Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX);
303 Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX);
304 if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){
305 if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi();
306 else pointPhi0 += AliL3Transform::TwoPi();
308 Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ;
309 fPoint[2] = fFirstPoint[2] + stot * fTanl;
311 fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf();
312 if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi();
313 fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi());
315 return IsPoint(kTRUE);
318 Bool_t AliL3Track::CalculateEdgePoint(Double_t angle)
320 // Global coordinate: crossing point with y = ax; a=tan(angle);
322 Double_t rmin=AliL3Transform::Row2X(AliL3Transform::GetFirstRow(-1)); //min Radius of TPC
323 Double_t rmax=AliL3Transform::Row2X(AliL3Transform::GetLastRow(-1)); //max Radius of TPC
325 Double_t a = tan(angle);
326 Double_t pp=(fCenterX+a*fCenterY)/(1+pow(a,2));
327 Double_t qq=(pow(fCenterX,2)+pow(fCenterY,2)-pow(fRadius,2))/(1+pow(a,2));
328 Double_t racine = pp*pp-qq;
329 if(racine<0) return IsPoint(kFALSE); //no Point
330 Double_t rootRacine = sqrt(racine);
331 Double_t x0 = pp+rootRacine;
332 Double_t x1 = pp-rootRacine;
336 Double_t r0 = sqrt(pow(x0,2)+pow(y0,2));
337 Double_t r1 = sqrt(pow(x1,2)+pow(y1,2));
338 //find the right crossing point:
339 //inside the TPC modules
343 if(r0>rmin&&r0<rmax){
344 Double_t da=atan2(y0,x0);
345 if(da<0) da+=AliL3Transform::TwoPi();
346 if(fabs(da-angle)<0.5)
349 if(r1>rmin&&r1<rmax){
350 Double_t da=atan2(y1,x1);
351 if(da<0) da+=AliL3Transform::TwoPi();
352 if(fabs(da-angle)<0.5)
355 if(!(ok0||ok1)) return IsPoint(kFALSE); //no Point
358 Double_t diff0 = sqrt(pow(fFirstPoint[0]-x0,2)+pow(fFirstPoint[1]-y0,2));
359 Double_t diff1 = sqrt(pow(fFirstPoint[0]-x1,2)+pow(fFirstPoint[1]-y1,2));
360 if(diff0<diff1) ok1 = kFALSE; //use ok0
361 else ok0 = kFALSE; //use ok1
363 if(ok0){fPoint[0]=x0; fPoint[1]=y0;}
364 else {fPoint[0]=x1; fPoint[1]=y1;}
366 Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX);
367 Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX);
368 if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){
369 if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi();
370 else pointPhi0 += AliL3Transform::TwoPi();
372 Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ;
373 fPoint[2] = fFirstPoint[2] + stot * fTanl;
375 fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf();
376 if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi();
377 fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi());
379 return IsPoint(kTRUE);
382 Bool_t AliL3Track::CalculatePoint(Double_t xplane)
384 // Local coordinate: crossing point with x plane
386 Double_t racine = pow(fRadius,2)-pow(xplane-fCenterX,2);
387 if(racine<0) return IsPoint(kFALSE);
388 Double_t rootRacine = sqrt(racine);
390 Double_t y0 = fCenterY + rootRacine;
391 Double_t y1 = fCenterY - rootRacine;
392 //Double_t diff0 = sqrt(pow(fFirstPoint[0]-xplane)+pow(fFirstPoint[1]-y0));
393 //Double_t diff1 = sqrt(pow(fFirstPoint[0]-xplane)+pow(fFirstPoint[1]-y1));
394 Double_t diff0 = fabs(y0-fFirstPoint[1]);
395 Double_t diff1 = fabs(y1-fFirstPoint[1]);
398 if(diff0<diff1) fPoint[1]=y0;
401 Double_t pointPhi0 = atan2(fPoint[1]-fCenterY,fPoint[0]-fCenterX);
402 Double_t trackPhi0 = atan2(fFirstPoint[1]-fCenterY,fFirstPoint[0]-fCenterX);
403 if(fabs(trackPhi0-pointPhi0)>AliL3Transform::Pi()){
404 if(trackPhi0<pointPhi0) trackPhi0 += AliL3Transform::TwoPi();
405 else pointPhi0 += AliL3Transform::TwoPi();
407 Double_t stot = -fQ * (pointPhi0-trackPhi0) * fRadius ;
408 fPoint[2] = fFirstPoint[2] + stot * fTanl;
410 fPointPsi = pointPhi0 - fQ * AliL3Transform::PiHalf();
411 if(fPointPsi<0.) fPointPsi+= AliL3Transform::TwoPi();
412 fPointPsi = fmod(fPointPsi, AliL3Transform::TwoPi());
414 return IsPoint(kTRUE);
417 void AliL3Track::UpdateToFirstPoint()
419 //Update track parameters to the innermost point on the track.
420 //This means that the parameters of the track will be given in the point
421 //of closest approach to the first innermost point, i.e. the point
422 //lying on the track fit (and not the coordinates of the innermost point itself).
423 //This function assumes that fFirstPoint is already set to the coordinates of the innermost
426 //During the helix-fit, the first point on the track is set to the coordinates
427 //of the innermost assigned cluster. This may be ok, if you just want a fast
428 //estimate of the "global" track parameters; such as the momentum etc.
429 //However, if you later on want to do more precise local calculations, such
430 //as impact parameter, residuals etc, you need to give the track parameters
431 //according to the actual fit.
433 Double_t xc = GetCenterX() - GetFirstPointX();
434 Double_t yc = GetCenterY() - GetFirstPointY();
436 Double_t dist_x1 = xc*(1 + GetRadius()/sqrt(xc*xc + yc*yc));
437 Double_t dist_y1 = yc*(1 + GetRadius()/sqrt(xc*xc + yc*yc));
438 Double_t distance1 = sqrt(dist_x1*dist_x1 + dist_y1*dist_y1);
440 Double_t dist_x2 = xc*(1 - GetRadius()/sqrt(xc*xc + yc*yc));
441 Double_t dist_y2 = yc*(1 - GetRadius()/sqrt(xc*xc + yc*yc));
442 Double_t distance2 = sqrt(dist_x2*dist_x2 + dist_y2*dist_y2);
444 //Choose the closest:
446 if(distance1 < distance2)
448 point[0] = dist_x1 + GetFirstPointX();
449 point[1] = dist_y1 + GetFirstPointY();
453 point[0] = dist_x2 + GetFirstPointX();
454 point[1] = dist_y2 + GetFirstPointY();
457 Double_t pointpsi = atan2(point[1]-GetCenterY(),point[0]-GetCenterX());
458 pointpsi -= GetCharge()*AliL3Transform::PiHalf();
459 if(pointpsi < 0) pointpsi += AliL3Transform::TwoPi();
461 //Update the track parameters
462 SetR0(sqrt(point[0]*point[0]+point[1]*point[1]));
463 SetPhi0(atan2(point[1],point[0]));
464 SetFirstPoint(point[0],point[1],GetZ0());
469 void AliL3Track::GetClosestPoint(AliL3Vertex *vertex,Double_t &closest_x,Double_t &closest_y,Double_t &closest_z)
471 //Calculate the point of closest approach to the vertex
472 //This function calculates the minimum distance from the helix to the vertex, and choose
473 //the corresponding point lying on the helix as the point of closest approach.
475 Double_t xc = GetCenterX() - vertex->GetX();
476 Double_t yc = GetCenterY() - vertex->GetY();
478 Double_t dist_x1 = xc*(1 + GetRadius()/sqrt(xc*xc + yc*yc));
479 Double_t dist_y1 = yc*(1 + GetRadius()/sqrt(xc*xc + yc*yc));
480 Double_t distance1 = sqrt(dist_x1*dist_x1 + dist_y1*dist_y1);
482 Double_t dist_x2 = xc*(1 - GetRadius()/sqrt(xc*xc + yc*yc));
483 Double_t dist_y2 = yc*(1 - GetRadius()/sqrt(xc*xc + yc*yc));
484 Double_t distance2 = sqrt(dist_x2*dist_x2 + dist_y2*dist_y2);
486 //Choose the closest:
487 if(distance1 < distance2)
489 closest_x = dist_x1 + vertex->GetX();
490 closest_y = dist_y1 + vertex->GetY();
494 closest_x = dist_x2 + vertex->GetX();
495 closest_y = dist_y2 + vertex->GetY();
498 //Get the z coordinate:
499 Double_t angle1 = atan2((closest_y-GetCenterY()),(closest_x-GetCenterX()));
500 if(angle1 < 0) angle1 = angle1 + AliL3Transform::TwoPi();
502 Double_t angle2 = atan2((GetFirstPointY()-GetCenterY()),(GetFirstPointX()-GetCenterX()));
503 if(angle2 < 0) angle2 = angle2 + AliL3Transform::TwoPi();
505 Double_t diff_angle = angle1 - angle2;
506 diff_angle = fmod(diff_angle,AliL3Transform::TwoPi());
508 if((GetCharge()*diff_angle) < 0) diff_angle = diff_angle + GetCharge()*AliL3Transform::TwoPi();
509 Double_t s_tot = fabs(diff_angle)*GetRadius();
511 closest_z = GetFirstPointZ() - s_tot*GetTgl();