impoved num precision
[u/mrichter/AliRoot.git] / HMPID / AliHMPIDtrack.cxx
CommitLineData
83253968 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#include "AliESDtrack.h"
17#include "AliTracker.h"
18#include "AliHMPIDtrack.h"
19
20ClassImp(AliHMPIDtrack)
21
22//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
23AliHMPIDtrack::AliHMPIDtrack():AliKalmanTrack()
24{
25 //
26 // def. ctor
27 //
28}
29//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
30AliHMPIDtrack::AliHMPIDtrack(const AliHMPIDtrack& t):AliKalmanTrack(t)
31{
32 //
33 // cctor.
34 //
35 }
36//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
37AliHMPIDtrack::AliHMPIDtrack(const AliESDtrack& t):AliKalmanTrack()
38{
39 //
40 // Constructor from AliESDtrack
41 //
42 SetLabel(t.GetLabel());
43 SetChi2(0.);
44 SetMass(t.GetMass());
45
46 Set(t.GetX(),t.GetAlpha(),t.GetParameter(),t.GetCovariance());
47
48 if ((t.GetStatus()&AliESDtrack::kTIME) == 0) return;
49 StartTimeIntegral();
50 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
51 SetIntegratedLength(t.GetIntegratedLength());
52}
53//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
54AliHMPIDtrack& AliHMPIDtrack::operator=(const AliHMPIDtrack &/*source*/)
55{
56 // ass. op.
57
58 return *this;
59}
60//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
61Bool_t AliHMPIDtrack::PropagateTo(Double_t xk, Double_t xx0, Double_t xrho)
62{
63 //
64 // Propagates this track to a reference plane defined by "xk" [cm]
65 // correcting for the mean crossed material.
66 // Arguments:
67 // "xx0" - thickness/rad.length [units of the radiation length]
68 // "xrho" - thickness*density [g/cm^2]
69 // Returns: kTRUE if the track propagates to plane, else kFALSE
70
71 if (xk == GetX()) {
72 return kTRUE;
73 }
87a6d94b 74 Double_t b[3]; GetBxByBz(b);
75 if (!AliExternalTrackParam::PropagateToBxByBz(xk,b)) {
83253968 76 return kFALSE;
77 }
78 if (!AliExternalTrackParam::CorrectForMeanMaterial(xx0,xrho,GetMass())) {
79 return kFALSE;
80 }
81 return kTRUE;
82}//PropagateTo()
83//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
84Bool_t AliHMPIDtrack::Rotate(Double_t alpha, Bool_t absolute)
85{
86 //
87 // Rotates track parameters in R*phi plane
88 // if absolute rotation alpha is in global system
89 // otherwise alpha rotation is relative to the current rotation angle
90 //
91
92 if (absolute) {
93 alpha -= GetAlpha();
94 }
95
96
97 return AliExternalTrackParam::Rotate(GetAlpha()+alpha);
98
99}
100//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
101Int_t AliHMPIDtrack::GetProlongation(Double_t xk, Double_t &y, Double_t &z)
102{
103 //
104 // Find a prolongation at given x
105 // Return 0 if it does not exist
106 //
107
87a6d94b 108 Double_t bz = GetBz();
83253968 109
110 if (!AliExternalTrackParam::GetYAt(xk,bz,y)) {
111 return 0;
112 }
113 if (!AliExternalTrackParam::GetZAt(xk,bz,z)) {
114 return 0;
115 }
116
117 return 1;
118
119}
120
121//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
496c71b0 122Bool_t AliHMPIDtrack::PropagateToR(Double_t r,Double_t step)
83253968 123{
124 //
125 // Propagate track to the radial position
126 // Rotation always connected to the last track position
127 //
128
129 Double_t xyz0[3];
130 Double_t xyz1[3];
131 Double_t y;
132 Double_t z;
133
134 Double_t radius = TMath::Sqrt(GetX()*GetX() + GetY()*GetY());
135 // Direction +-
136 Double_t dir = (radius > r) ? -1.0 : 1.0;
137
138 for (Double_t x = radius+dir*step; dir*x < dir*r; x += dir*step) {
139
140 GetXYZ(xyz0);
141 Double_t alpha = TMath::ATan2(xyz0[1],xyz0[0]);
142 Rotate(alpha,kTRUE);
143 GetXYZ(xyz0);
6d256146 144 if (!GetProlongation(x,y,z)) return kFALSE;
83253968 145 xyz1[0] = x * TMath::Cos(alpha) + y * TMath::Sin(alpha);
146 xyz1[1] = x * TMath::Sin(alpha) - y * TMath::Cos(alpha);
147 xyz1[2] = z;
148 Double_t param[7];
149 AliTracker::MeanMaterialBudget(xyz0,xyz1,param);
150 if (param[1] <= 0) {
151 param[1] = 100000000;
152 }
153 PropagateTo(x,param[1],param[0]*param[4]);
154
155 }
156
157 GetXYZ(xyz0);
158 Double_t alpha = TMath::ATan2(xyz0[1],xyz0[0]);
159 Rotate(alpha,kTRUE);
160 GetXYZ(xyz0);
6d256146 161 if (!GetProlongation(r,y,z)) return kFALSE;
83253968 162 xyz1[0] = r * TMath::Cos(alpha) + y * TMath::Sin(alpha);
163 xyz1[1] = r * TMath::Sin(alpha) - y * TMath::Cos(alpha);
164 xyz1[2] = z;
165 Double_t param[7];
166 AliTracker::MeanMaterialBudget(xyz0,xyz1,param);
167
168 if (param[1] <= 0) {
169 param[1] = 100000000;
170 }
496c71b0 171
172 return PropagateTo(r,param[1],param[0]*param[4]);
83253968 173}
174//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
175Double_t AliHMPIDtrack::GetPredictedChi2(const AliCluster3D *c) const {
176 //
177 // Arguments: AliCluster3D
178 // Returns: Chi2 of track for the cluster
179 Double_t p[3]={c->GetX(), c->GetY(), c->GetZ()};
180 Double_t covyz[3]={c->GetSigmaY2(), c->GetSigmaYZ(), c->GetSigmaZ2()};
181 Double_t covxyz[3]={c->GetSigmaX2(), c->GetSigmaXY(), c->GetSigmaXZ()};
182 return AliExternalTrackParam::GetPredictedChi2(p, covyz, covxyz);
183}//GetPredictedChi2()
184//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
185Bool_t AliHMPIDtrack::PropagateTo(const AliCluster3D *c) {
186 //
187 // Arguments: AliCluster3D
188 // Returns: kTRUE if the track propagates to the plane of the cluster
189 Double_t oldX=GetX(), oldY=GetY(), oldZ=GetZ();
190 Double_t p[3]={c->GetX(), c->GetY(), c->GetZ()};
191 Double_t covyz[3]={c->GetSigmaY2(), c->GetSigmaYZ(), c->GetSigmaZ2()};
192 Double_t covxyz[3]={c->GetSigmaX2(), c->GetSigmaXY(), c->GetSigmaXZ()};
5b147198 193 Double_t bz=-GetBz();
87a6d94b 194
83253968 195 if(!AliExternalTrackParam::PropagateTo(p, covyz, covxyz, bz)) return kFALSE;
196 if(IsStartedTimeIntegral())
197 {
198 Double_t d = TMath::Sqrt((GetX()-oldX)*(GetX()-oldX) + (GetY()-oldY)*(GetY()-oldY) + (GetZ()-oldZ)*(GetZ()-oldZ));
199 if (GetX()<oldX) d=-d;
200 AddTimeStep(d);
87a6d94b 201 }
83253968 202 return kTRUE;
203}//PropagateTo()
97a4d538 204//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
205Bool_t AliHMPIDtrack::Intersect(Double_t pnt[3], Double_t norm[3]) const {
83253968 206 //+++++++++++++++++++++++++++++++++++++++++
207 // Origin: K. Shileev (Kirill.Shileev@cern.ch)
208 // Finds point of intersection (if exists) of the helix with the plane.
209 // Stores result in fX and fP.
210 // Arguments: planePoint,planeNorm - the plane defined by any plane's point
211 // and vector, normal to the plane
212 // Returns: kTrue if helix intersects the plane, kFALSE otherwise.
213 //+++++++++++++++++++++++++++++++++++++++++
214 Double_t x0[3]; GetXYZ(x0); //get track position in MARS
83253968 215
216 //estimates initial helix length up to plane
217 Double_t s=(pnt[0]-x0[0])*norm[0] + (pnt[1]-x0[1])*norm[1] + (pnt[2]-x0[2])*norm[2];
218 Double_t dist=99999,distPrev=dist;
97a4d538 219 Double_t p[3],x[3];
83253968 220 while(TMath::Abs(dist)>0.00001){
221 //calculates helix at the distance s from x0 ALONG the helix
97a4d538 222 Propagate(s,x,p);
83253968 223 //distance between current helix position and plane
224 dist=(x[0]-pnt[0])*norm[0]+(x[1]-pnt[1])*norm[1]+(x[2]-pnt[2])*norm[2];
225 if(TMath::Abs(dist) >= TMath::Abs(distPrev)) {return kFALSE;}
226 distPrev=dist;
227 s-=dist;
228 }
229 //on exit pnt is intersection point,norm is track vector at that point,
230 //all in MARS
231 for (Int_t i=0; i<3; i++) {pnt[i]=x[i]; norm[i]=p[i];}
232 return kTRUE;
233}//Intersect()
234//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
97a4d538 235void AliHMPIDtrack::Propagate(Double_t len, Double_t x[3],Double_t p[3]) const {
83253968 236 //+++++++++++++++++++++++++++++++++++++++++
237 // Origin: K. Shileev (Kirill.Shileev@cern.ch)
238 // Extrapolate track along simple helix in magnetic field
239 // Arguments: len -distance alogn helix, [cm]
240 // bz - mag field, [kGaus]
241 // Returns: x and p contain extrapolated positon and momentum
242 // The momentum returned for straight-line tracks is meaningless !
243 //+++++++++++++++++++++++++++++++++++++++++
244 GetXYZ(x);
97a4d538 245 Double_t bField[3];
246 TGeoGlobalMagField::Instance()->Field(x,bField);
5b147198 247 Double_t bz = -bField[2];
83253968 248 if (OneOverPt() < kAlmost0 || TMath::Abs(bz) < kAlmost0Field ){ //straight-line tracks
249 Double_t unit[3]; GetDirection(unit);
250 x[0]+=unit[0]*len;
251 x[1]+=unit[1]*len;
252 x[2]+=unit[2]*len;
253
254 p[0]=unit[0]/kAlmost0;
255 p[1]=unit[1]/kAlmost0;
256 p[2]=unit[2]/kAlmost0;
257 } else {
258 GetPxPyPz(p);
259 Double_t pp=GetP();
260 Double_t a = -kB2C*bz*GetSign(); ////////// what is kB2C
261 Double_t rho = a/pp;
262 x[0] += p[0]*TMath::Sin(rho*len)/a - p[1]*(1-TMath::Cos(rho*len))/a;
263 x[1] += p[1]*TMath::Sin(rho*len)/a + p[0]*(1-TMath::Cos(rho*len))/a;
264 x[2] += p[2]*len/pp;
265 Double_t p0=p[0];
266 p[0] = p0 *TMath::Cos(rho*len) - p[1]*TMath::Sin(rho*len);
267 p[1] = p[1]*TMath::Cos(rho*len) + p0 *TMath::Sin(rho*len);
268 }
269}//Propagate()
270//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
ee2f3539 271Bool_t AliHMPIDtrack::Update(const AliHMPIDCluster *pClu, Double_t /*chisq*/, Int_t /*index*/)
496c71b0 272{
273 //
274 // Arguments: AliCluster3D, chi sq, and clu index
275 // Returns: kTRUE if the track parameters are successfully updated
276 Double_t p[2]={pClu->GetY(), pClu->GetZ()};
277 Double_t cov[3]={pClu->GetSigmaY2(), 0., pClu->GetSigmaZ2()};
278 if (!AliExternalTrackParam::Update(p,cov)) return kFALSE;
279
280 /*
281 AliTracker::FillResiduals(this,p,cov,pClu->GetVolumeId());
282
283 Int_t n=GetNumberOfClusters();
284 fIndex[n]=index;
285 SetNumberOfClusters(n+1);
286 SetChi2(GetChi2()+chisq);
287*/
288 return kTRUE;
289
290}//Update()
291//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++