1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 ///////////////////////////////////////////////////
26 ///////////////////////////////////////////////////
28 //#include <Riostream.h>
30 #include "AliMUONTrackParam.h"
31 #include "AliMUONConstants.h"
32 #include "AliESDMuonTrack.h"
35 #include "AliTracker.h"
36 #include "AliMUONHitForRec.h"
38 ClassImp(AliMUONTrackParam) // Class implementation in ROOT context
40 //_________________________________________________________________________
41 AliMUONTrackParam::AliMUONTrackParam()
43 fInverseBendingMomentum(0.),
53 // get field from outside
54 fkField = AliTracker::GetFieldMap();
55 if (!fkField) AliWarning("No field available");
58 //_________________________________________________________________________
59 AliMUONTrackParam::AliMUONTrackParam(const AliMUONTrackParam& theMUONTrackParam)
60 : TObject(theMUONTrackParam),
61 fInverseBendingMomentum(theMUONTrackParam.fInverseBendingMomentum),
62 fBendingSlope(theMUONTrackParam.fBendingSlope),
63 fNonBendingSlope(theMUONTrackParam.fNonBendingSlope),
64 fZ(theMUONTrackParam.fZ),
65 fBendingCoor(theMUONTrackParam.fBendingCoor),
66 fNonBendingCoor(theMUONTrackParam.fNonBendingCoor),
67 fkField(theMUONTrackParam.fkField),
68 fHitForRecPtr(theMUONTrackParam.fHitForRecPtr)
74 //_________________________________________________________________________
75 AliMUONTrackParam& AliMUONTrackParam::operator=(const AliMUONTrackParam& theMUONTrackParam)
78 if (this == &theMUONTrackParam)
81 // base class assignement
82 TObject::operator=(theMUONTrackParam);
84 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
85 fBendingSlope = theMUONTrackParam.fBendingSlope;
86 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
87 fZ = theMUONTrackParam.fZ;
88 fBendingCoor = theMUONTrackParam.fBendingCoor;
89 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
90 fkField = theMUONTrackParam.fkField;
91 fHitForRecPtr = theMUONTrackParam.fHitForRecPtr;
96 //__________________________________________________________________________
97 AliMUONTrackParam::~AliMUONTrackParam()
100 /// Update the number of TrackHit's connected to the attached HitForRec if any
101 if (fHitForRecPtr) fHitForRecPtr->SetNTrackHits(fHitForRecPtr->GetNTrackHits() - 1); // decrement NTrackHits of hit
104 //__________________________________________________________________________
105 void AliMUONTrackParam::SetTrackParam(AliMUONTrackParam& theMUONTrackParam)
107 /// Set track parameters from "TrackParam" leaving pointer to fHitForRecPtr unchanged
108 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
109 fBendingSlope = theMUONTrackParam.fBendingSlope;
110 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
111 fZ = theMUONTrackParam.fZ;
112 fBendingCoor = theMUONTrackParam.fBendingCoor;
113 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
117 //__________________________________________________________________________
118 AliMUONHitForRec* AliMUONTrackParam::GetHitForRecPtr(void) const
120 /// return pointer to HitForRec attached to the current TrackParam
121 /// this method should not be called when fHitForRecPtr == NULL
122 if (!fHitForRecPtr) AliWarning("AliMUONTrackParam::GetHitForRecPtr: fHitForRecPtr == NULL");
123 return fHitForRecPtr;
126 //__________________________________________________________________________
127 Int_t AliMUONTrackParam::Compare(const TObject* TrackParam) const
129 /// "Compare" function to sort with decreasing Z (spectro. muon Z <0).
130 /// Returns 1 (0, -1) if Z of current TrackHit
131 /// is smaller than (equal to, larger than) Z of TrackHit
132 if (fHitForRecPtr->GetZ() < ((AliMUONTrackParam*)TrackParam)->fHitForRecPtr->GetZ()) return(1);
133 else if (fHitForRecPtr->GetZ() == ((AliMUONTrackParam*)TrackParam)->fHitForRecPtr->GetZ()) return(0);
137 //_________________________________________________________________________
138 void AliMUONTrackParam::GetParamFrom(const AliESDMuonTrack& esdMuonTrack)
140 // assigned value form ESD track.
141 fInverseBendingMomentum = esdMuonTrack.GetInverseBendingMomentum();
142 fBendingSlope = TMath::Tan(esdMuonTrack.GetThetaY());
143 fNonBendingSlope = TMath::Tan(esdMuonTrack.GetThetaX());
144 fZ = esdMuonTrack.GetZ();
145 fBendingCoor = esdMuonTrack.GetBendingCoor();
146 fNonBendingCoor = esdMuonTrack.GetNonBendingCoor();
149 //_________________________________________________________________________
150 void AliMUONTrackParam::SetParamFor(AliESDMuonTrack& esdMuonTrack)
152 // assigned value form ESD track.
153 esdMuonTrack.SetInverseBendingMomentum(fInverseBendingMomentum);
154 esdMuonTrack.SetThetaX(TMath::ATan(fNonBendingSlope));
155 esdMuonTrack.SetThetaY(TMath::ATan(fBendingSlope));
156 esdMuonTrack.SetZ(fZ);
157 esdMuonTrack.SetBendingCoor(fBendingCoor);
158 esdMuonTrack.SetNonBendingCoor(fNonBendingCoor);
161 //__________________________________________________________________________
162 void AliMUONTrackParam::ExtrapToZ(Double_t Z)
164 // Track parameter extrapolation to the plane at "Z".
165 // On return, the track parameters resulting from the extrapolation
166 // replace the current track parameters.
167 if (this->fZ == Z) return; // nothing to be done if same Z
168 Double_t forwardBackward; // +1 if forward, -1 if backward
169 if (Z < this->fZ) forwardBackward = 1.0; // spectro. z<0
170 else forwardBackward = -1.0;
171 Double_t vGeant3[7], vGeant3New[7]; // 7 in parameter ????
172 Int_t iGeant3, stepNumber;
173 Int_t maxStepNumber = 5000; // in parameter ????
174 // For safety: return kTRUE or kFALSE ????
175 // Parameter vector for calling EXTRAP_ONESTEP
176 SetGeant3Parameters(vGeant3, forwardBackward);
177 // sign of charge (sign of fInverseBendingMomentum if forward motion)
178 // must be changed if backward extrapolation
179 Double_t chargeExtrap = forwardBackward *
180 TMath::Sign(Double_t(1.0), this->fInverseBendingMomentum);
181 Double_t stepLength = 6.0; // in parameter ????
182 // Extrapolation loop
184 while (((-forwardBackward * (vGeant3[2] - Z)) <= 0.0) && // spectro. z<0
185 (stepNumber < maxStepNumber)) {
187 // Option for switching between helix and Runge-Kutta ????
188 //ExtrapOneStepRungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
189 ExtrapOneStepHelix(chargeExtrap, stepLength, vGeant3, vGeant3New);
190 if ((-forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z spectro. z<0
191 // better use TArray ????
192 for (iGeant3 = 0; iGeant3 < 7; iGeant3++)
193 {vGeant3[iGeant3] = vGeant3New[iGeant3];}
195 // check maxStepNumber ????
196 // Interpolation back to exact Z (2nd order)
197 // should be in function ???? using TArray ????
198 Double_t dZ12 = vGeant3New[2] - vGeant3[2]; // 1->2
199 if (TMath::Abs(dZ12) > 0) {
200 Double_t dZ1i = Z - vGeant3[2]; // 1-i
201 Double_t dZi2 = vGeant3New[2] - Z; // i->2
202 Double_t xPrime = (vGeant3New[0] - vGeant3[0]) / dZ12;
204 ((vGeant3New[3] / vGeant3New[5]) - (vGeant3[3] / vGeant3[5])) / dZ12;
205 Double_t yPrime = (vGeant3New[1] - vGeant3[1]) / dZ12;
207 ((vGeant3New[4] / vGeant3New[5]) - (vGeant3[4] / vGeant3[5])) / dZ12;
208 vGeant3[0] = vGeant3[0] + xPrime * dZ1i - 0.5 * xSecond * dZ1i * dZi2; // X
209 vGeant3[1] = vGeant3[1] + yPrime * dZ1i - 0.5 * ySecond * dZ1i * dZi2; // Y
211 Double_t xPrimeI = xPrime - 0.5 * xSecond * (dZi2 - dZ1i);
212 Double_t yPrimeI = yPrime - 0.5 * ySecond * (dZi2 - dZ1i);
213 // (PX, PY, PZ)/PTOT assuming forward motion
215 1.0 / TMath::Sqrt(1.0 + xPrimeI * xPrimeI + yPrimeI * yPrimeI); // PZ/PTOT
216 vGeant3[3] = xPrimeI * vGeant3[5]; // PX/PTOT
217 vGeant3[4] = yPrimeI * vGeant3[5]; // PY/PTOT
219 AliWarning(Form("Extrap. to Z not reached, Z = %f",Z));
221 // Track parameters from Geant3 parameters,
222 // with charge back for forward motion
223 GetFromGeant3Parameters(vGeant3, chargeExtrap * forwardBackward);
226 //__________________________________________________________________________
227 void AliMUONTrackParam::SetGeant3Parameters(Double_t *VGeant3, Double_t ForwardBackward)
229 // Set vector of Geant3 parameters pointed to by "VGeant3"
230 // from track parameters in current AliMUONTrackParam.
231 // Since AliMUONTrackParam is only geometry, one uses "ForwardBackward"
232 // to know whether the particle is going forward (+1) or backward (-1).
233 VGeant3[0] = this->fNonBendingCoor; // X
234 VGeant3[1] = this->fBendingCoor; // Y
235 VGeant3[2] = this->fZ; // Z
236 Double_t pYZ = TMath::Abs(1.0 / this->fInverseBendingMomentum);
238 pYZ / TMath::Sqrt(1.0 + this->fBendingSlope * this->fBendingSlope);
240 TMath::Sqrt(pYZ * pYZ +
241 pZ * pZ * this->fNonBendingSlope * this->fNonBendingSlope); // PTOT
242 VGeant3[5] = -ForwardBackward * pZ / VGeant3[6]; // PZ/PTOT spectro. z<0
243 VGeant3[3] = this->fNonBendingSlope * VGeant3[5]; // PX/PTOT
244 VGeant3[4] = this->fBendingSlope * VGeant3[5]; // PY/PTOT
247 //__________________________________________________________________________
248 void AliMUONTrackParam::GetFromGeant3Parameters(Double_t *VGeant3, Double_t Charge)
250 // Get track parameters in current AliMUONTrackParam
251 // from Geant3 parameters pointed to by "VGeant3",
252 // assumed to be calculated for forward motion in Z.
253 // "InverseBendingMomentum" is signed with "Charge".
254 this->fNonBendingCoor = VGeant3[0]; // X
255 this->fBendingCoor = VGeant3[1]; // Y
256 this->fZ = VGeant3[2]; // Z
257 Double_t pYZ = VGeant3[6] * TMath::Sqrt(1.0 - VGeant3[3] * VGeant3[3]);
258 this->fInverseBendingMomentum = Charge / pYZ;
259 this->fBendingSlope = VGeant3[4] / VGeant3[5];
260 this->fNonBendingSlope = VGeant3[3] / VGeant3[5];
263 //__________________________________________________________________________
264 void AliMUONTrackParam::ExtrapToStation(Int_t Station, AliMUONTrackParam *TrackParam)
266 // Track parameters extrapolated from current track parameters ("this")
267 // to both chambers of the station(0..) "Station"
268 // are returned in the array (dimension 2) of track parameters
269 // pointed to by "TrackParam" (index 0 and 1 for first and second chambers).
270 Double_t extZ[2], z1, z2;
271 Int_t i1 = -1, i2 = -1; // = -1 to avoid compilation warnings
272 // range of Station to be checked ????
273 z1 = AliMUONConstants::DefaultChamberZ(2 * Station);
274 z2 = AliMUONConstants::DefaultChamberZ(2 * Station + 1);
275 // First and second Z to extrapolate at
276 if ((z1 > this->fZ) && (z2 > this->fZ)) {i1 = 0; i2 = 1;}
277 else if ((z1 < this->fZ) && (z2 < this->fZ)) {i1 = 1; i2 = 0;}
279 AliError(Form("Starting Z (%f) in between z1 (%f) and z2 (%f) of station(0..)%d",this->fZ,z1,z2,Station));
280 // cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
281 // cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
282 // ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
286 // copy of track parameters
287 TrackParam[i1] = *this;
288 // first extrapolation
289 (&(TrackParam[i1]))->ExtrapToZ(extZ[0]);
290 TrackParam[i2] = TrackParam[i1];
291 // second extrapolation
292 (&(TrackParam[i2]))->ExtrapToZ(extZ[1]);
296 //__________________________________________________________________________
297 void AliMUONTrackParam::ExtrapToVertex(Double_t xVtx, Double_t yVtx, Double_t zVtx)
299 // Extrapolation to the vertex.
300 // Returns the track parameters resulting from the extrapolation,
301 // in the current TrackParam.
302 // Changes parameters according to Branson correction through the absorber
304 Double_t zAbsorber = -503.0; // to be coherent with the Geant absorber geometry !!!!
306 // Extrapolates track parameters upstream to the "Z" end of the front absorber
307 ExtrapToZ(zAbsorber); // !!!
308 // Makes Branson correction (multiple scattering + energy loss)
309 BransonCorrection(xVtx,yVtx,zVtx);
310 // Makes a simple magnetic field correction through the absorber
311 FieldCorrection(zAbsorber);
315 // Keep this version for future developments
316 //__________________________________________________________________________
317 // void AliMUONTrackParam::BransonCorrection()
319 // // Branson correction of track parameters
320 // // the entry parameters have to be calculated at the end of the absorber
321 // Double_t zEndAbsorber, zBP, xBP, yBP;
322 // Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
324 // // Would it be possible to calculate all that from Geant configuration ????
325 // // and to get the Branson parameters from a function in ABSO module ????
326 // // with an eventual contribution from other detectors like START ????
327 // // Radiation lengths outer part theta > 3 degres
328 // static Double_t x01[9] = { 18.8, // C (cm)
329 // 10.397, // Concrete (cm)
330 // 0.56, // Plomb (cm)
331 // 47.26, // Polyethylene (cm)
332 // 0.56, // Plomb (cm)
333 // 47.26, // Polyethylene (cm)
334 // 0.56, // Plomb (cm)
335 // 47.26, // Polyethylene (cm)
336 // 0.56 }; // Plomb (cm)
337 // // inner part theta < 3 degres
338 // static Double_t x02[3] = { 18.8, // C (cm)
339 // 10.397, // Concrete (cm)
341 // // z positions of the materials inside the absober outer part theta > 3 degres
342 // static Double_t z1[10] = { 90, 315, 467, 472, 477, 482, 487, 492, 497, 502 };
343 // // inner part theta < 3 degres
344 // static Double_t z2[4] = { 90, 315, 467, 503 };
345 // static Bool_t first = kTRUE;
346 // static Double_t zBP1, zBP2, rLimit;
347 // // Calculates z positions of the Branson's planes: zBP1 for outer part and zBP2 for inner part (only at the first call)
350 // Double_t aNBP = 0.0;
351 // Double_t aDBP = 0.0;
354 // for (iBound = 0; iBound < 9; iBound++) {
356 // (z1[iBound+1] * z1[iBound+1] * z1[iBound+1] -
357 // z1[iBound] * z1[iBound] * z1[iBound] ) / x01[iBound];
359 // (z1[iBound+1] * z1[iBound+1] - z1[iBound] * z1[iBound] ) / x01[iBound];
361 // zBP1 = (2.0 * aNBP) / (3.0 * aDBP);
364 // for (iBound = 0; iBound < 3; iBound++) {
366 // (z2[iBound+1] * z2[iBound+1] * z2[iBound+1] -
367 // z2[iBound] * z2[iBound ] * z2[iBound] ) / x02[iBound];
369 // (z2[iBound+1] * z2[iBound+1] - z2[iBound] * z2[iBound]) / x02[iBound];
371 // zBP2 = (2.0 * aNBP) / (3.0 * aDBP);
372 // rLimit = z2[3] * TMath::Tan(3.0 * (TMath::Pi()) / 180.);
375 // pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
377 // if (fInverseBendingMomentum < 0) sign = -1;
378 // pZ = pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope));
379 // pX = pZ * fNonBendingSlope;
380 // pY = pZ * fBendingSlope;
381 // pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
382 // xEndAbsorber = fNonBendingCoor;
383 // yEndAbsorber = fBendingCoor;
384 // radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
386 // if (radiusEndAbsorber2 > rLimit*rLimit) {
387 // zEndAbsorber = z1[9];
390 // zEndAbsorber = z2[3];
394 // xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
395 // yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
397 // // new parameters after Branson and energy loss corrections
398 // pZ = pTotal * zBP / TMath::Sqrt(xBP * xBP + yBP * yBP + zBP * zBP);
399 // pX = pZ * xBP / zBP;
400 // pY = pZ * yBP / zBP;
401 // fBendingSlope = pY / pZ;
402 // fNonBendingSlope = pX / pZ;
404 // pT = TMath::Sqrt(pX * pX + pY * pY);
405 // theta = TMath::ATan2(pT, pZ);
407 // TotalMomentumEnergyLoss(rLimit, pTotal, theta, xEndAbsorber, yEndAbsorber);
409 // fInverseBendingMomentum = (sign / pTotal) *
411 // fBendingSlope * fBendingSlope +
412 // fNonBendingSlope * fNonBendingSlope) /
413 // TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
415 // // vertex position at (0,0,0)
416 // // should be taken from vertex measurement ???
417 // fBendingCoor = 0.0;
418 // fNonBendingCoor = 0;
422 void AliMUONTrackParam::BransonCorrection(Double_t xVtx,Double_t yVtx,Double_t zVtx)
424 // Branson correction of track parameters
425 // the entry parameters have to be calculated at the end of the absorber
426 // simplified version: the z positions of Branson's planes are no longer calculated
427 // but are given as inputs. One can use the macros MUONTestAbso.C and DrawTestAbso.C
428 // to test this correction.
429 // Would it be possible to calculate all that from Geant configuration ????
430 // and to get the Branson parameters from a function in ABSO module ????
431 // with an eventual contribution from other detectors like START ????
432 //change to take into account the vertex postition (real, reconstruct,....)
434 Double_t zBP, xBP, yBP;
435 Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
437 static Bool_t first = kTRUE;
438 static Double_t zBP1, zBP2, rLimit, thetaLimit, zEndAbsorber;
439 // zBP1 for outer part and zBP2 for inner part (only at the first call)
443 zEndAbsorber = -503; // spectro (z<0)
444 thetaLimit = 3.0 * (TMath::Pi()) / 180.;
445 rLimit = TMath::Abs(zEndAbsorber) * TMath::Tan(thetaLimit);
446 zBP1 = -450; // values close to those calculated with EvalAbso.C
450 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
452 if (fInverseBendingMomentum < 0) sign = -1;
456 pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
457 xEndAbsorber = fNonBendingCoor;
458 yEndAbsorber = fBendingCoor;
459 radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
461 if (radiusEndAbsorber2 > rLimit*rLimit) {
467 xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
468 yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
470 // new parameters after Branson and energy loss corrections
471 // Float_t zSmear = zBP - gRandom->Gaus(0.,2.); // !!! possible smearing of Z vertex position
473 Float_t zSmear = zBP ;
475 pZ = pTotal * (zSmear-zVtx) / TMath::Sqrt((xBP-xVtx) * (xBP-xVtx) + (yBP-yVtx) * (yBP-yVtx) +( zSmear-zVtx) * (zSmear-zVtx) );
476 pX = pZ * (xBP - xVtx)/ (zSmear-zVtx);
477 pY = pZ * (yBP - yVtx) / (zSmear-zVtx);
478 fBendingSlope = pY / pZ;
479 fNonBendingSlope = pX / pZ;
482 pT = TMath::Sqrt(pX * pX + pY * pY);
483 theta = TMath::ATan2(pT, TMath::Abs(pZ));
484 pTotal = TotalMomentumEnergyLoss(thetaLimit, pTotal, theta);
486 fInverseBendingMomentum = (sign / pTotal) *
488 fBendingSlope * fBendingSlope +
489 fNonBendingSlope * fNonBendingSlope) /
490 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
492 // vertex position at (0,0,0)
493 // should be taken from vertex measurement ???
496 fNonBendingCoor = yVtx;
501 //__________________________________________________________________________
502 Double_t AliMUONTrackParam::TotalMomentumEnergyLoss(Double_t thetaLimit, Double_t pTotal, Double_t theta)
504 // Returns the total momentum corrected from energy loss in the front absorber
505 // One can use the macros MUONTestAbso.C and DrawTestAbso.C
506 // to test this correction.
507 // Momentum energy loss behaviour evaluated with the simulation of single muons (april 2002)
508 Double_t deltaP, pTotalCorrected;
510 // Parametrization to be redone according to change of absorber material ????
511 // See remark in function BransonCorrection !!!!
512 // The name is not so good, and there are many arguments !!!!
513 if (theta < thetaLimit ) {
515 deltaP = 2.5938 + 0.0570 * pTotal - 0.001151 * pTotal * pTotal;
517 deltaP = 3.0714 + 0.011767 *pTotal;
519 deltaP *= 0.75; // AZ
522 deltaP = 2.1207 + 0.05478 * pTotal - 0.00145079 * pTotal * pTotal;
524 deltaP = 2.6069 + 0.0051705 * pTotal;
528 pTotalCorrected = pTotal + deltaP / TMath::Cos(theta);
529 return pTotalCorrected;
532 //__________________________________________________________________________
533 void AliMUONTrackParam::FieldCorrection(Double_t Z)
536 // Correction of the effect of the magnetic field in the absorber
537 // Assume a constant field along Z axis.
541 Double_t pYZ,pX,pY,pZ,pT;
542 Double_t pXNew,pYNew;
545 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
546 c = TMath::Sign(1.0,fInverseBendingMomentum); // particle charge
551 pT = TMath::Sqrt(pX*pX+pY*pY);
553 if (TMath::Abs(pZ) <= 0) return;
555 x[0] = x[2]*fNonBendingSlope;
556 x[1] = x[2]*fBendingSlope;
558 // Take magn. field value at position x.
559 fkField->Field(x, b);
562 // Transverse momentum rotation
563 // Parameterized with the study of DeltaPhi = phiReco - phiGen as a function of pZ.
564 Double_t phiShift = c*0.436*0.0003*bZ*Z/pZ;
565 // Rotate momentum around Z axis.
566 pXNew = pX*TMath::Cos(phiShift) - pY*TMath::Sin(phiShift);
567 pYNew = pX*TMath::Sin(phiShift) + pY*TMath::Cos(phiShift);
569 fBendingSlope = pYNew / pZ;
570 fNonBendingSlope = pXNew / pZ;
572 fInverseBendingMomentum = c / TMath::Sqrt(pYNew*pYNew+pZ*pZ);
575 //__________________________________________________________________________
576 Double_t AliMUONTrackParam::Px() const
578 // return px from track paramaters
579 Double_t pYZ, pZ, pX;
581 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
582 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
583 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
584 pX = pZ * fNonBendingSlope;
587 //__________________________________________________________________________
588 Double_t AliMUONTrackParam::Py() const
590 // return px from track paramaters
591 Double_t pYZ, pZ, pY;
593 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
594 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
595 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
596 pY = pZ * fBendingSlope;
599 //__________________________________________________________________________
600 Double_t AliMUONTrackParam::Pz() const
602 // return px from track paramaters
605 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
606 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
607 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
610 //__________________________________________________________________________
611 Double_t AliMUONTrackParam::P() const
613 // return p from track paramaters
616 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
617 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
618 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
620 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope + fNonBendingSlope * fNonBendingSlope);
624 //__________________________________________________________________________
625 void AliMUONTrackParam::ExtrapOneStepHelix(Double_t charge, Double_t step,
626 Double_t *vect, Double_t *vout) const
628 // ******************************************************************
630 // * Performs the tracking of one step in a magnetic field *
631 // * The trajectory is assumed to be a helix in a constant field *
632 // * taken at the mid point of the step. *
635 // * STEP =arc length of the step asked *
636 // * VECT =input vector (position,direction cos and momentum) *
637 // * CHARGE= electric charge of the particle *
639 // * VOUT = same as VECT after completion of the step *
641 // * ==>Called by : <USER>, GUSWIM *
642 // * Author m.hansroul ********* *
643 // * modified s.egli, s.v.levonian *
644 // * modified v.perevoztchikov
646 // ******************************************************************
649 // modif: everything in double precision
651 Double_t xyz[3], h[4], hxp[3];
652 Double_t h2xy, hp, rho, tet;
653 Double_t sint, sintt, tsint, cos1t;
654 Double_t f1, f2, f3, f4, f5, f6;
659 const Int_t kipx = 3;
660 const Int_t kipy = 4;
661 const Int_t kipz = 5;
662 const Int_t kipp = 6;
664 const Double_t kec = 2.9979251e-4;
666 // ------------------------------------------------------------------
668 // units are kgauss,centimeters,gev/c
670 vout[kipp] = vect[kipp];
671 if (TMath::Abs(charge) < 0.00001) {
672 for (Int_t i = 0; i < 3; i++) {
673 vout[i] = vect[i] + step * vect[i+3];
674 vout[i+3] = vect[i+3];
678 xyz[0] = vect[kix] + 0.5 * step * vect[kipx];
679 xyz[1] = vect[kiy] + 0.5 * step * vect[kipy];
680 xyz[2] = vect[kiz] + 0.5 * step * vect[kipz];
682 //cmodif: call gufld (xyz, h) changed into:
685 h2xy = h[0]*h[0] + h[1]*h[1];
686 h[3] = h[2]*h[2]+ h2xy;
688 for (Int_t i = 0; i < 3; i++) {
689 vout[i] = vect[i] + step * vect[i+3];
690 vout[i+3] = vect[i+3];
694 if (h2xy < 1.e-12*h[3]) {
695 ExtrapOneStepHelix3(charge*h[2], step, vect, vout);
698 h[3] = TMath::Sqrt(h[3]);
704 hxp[0] = h[1]*vect[kipz] - h[2]*vect[kipy];
705 hxp[1] = h[2]*vect[kipx] - h[0]*vect[kipz];
706 hxp[2] = h[0]*vect[kipy] - h[1]*vect[kipx];
708 hp = h[0]*vect[kipx] + h[1]*vect[kipy] + h[2]*vect[kipz];
710 rho = -charge*h[3]/vect[kipp];
713 if (TMath::Abs(tet) > 0.15) {
714 sint = TMath::Sin(tet);
716 tsint = (tet-sint)/tet;
717 cos1t = 2.*(TMath::Sin(0.5*tet))*(TMath::Sin(0.5*tet))/tet;
720 sintt = (1. - tsint);
727 f3 = step * tsint * hp;
730 f6 = tet * cos1t * hp;
732 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0] + f3*h[0];
733 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1] + f3*h[1];
734 vout[kiz] = vect[kiz] + f1*vect[kipz] + f2*hxp[2] + f3*h[2];
736 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0] + f6*h[0];
737 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1] + f6*h[1];
738 vout[kipz] = vect[kipz] + f4*vect[kipz] + f5*hxp[2] + f6*h[2];
743 //__________________________________________________________________________
744 void AliMUONTrackParam::ExtrapOneStepHelix3(Double_t field, Double_t step,
745 Double_t *vect, Double_t *vout) const
748 // ******************************************************************
750 // * Tracking routine in a constant field oriented *
752 // * Tracking is performed with a conventional *
753 // * helix step method *
755 // * ==>Called by : <USER>, GUSWIM *
756 // * Authors R.Brun, M.Hansroul ********* *
757 // * Rewritten V.Perevoztchikov
759 // ******************************************************************
763 Double_t h4, hp, rho, tet;
764 Double_t sint, sintt, tsint, cos1t;
765 Double_t f1, f2, f3, f4, f5, f6;
770 const Int_t kipx = 3;
771 const Int_t kipy = 4;
772 const Int_t kipz = 5;
773 const Int_t kipp = 6;
775 const Double_t kec = 2.9979251e-4;
778 // ------------------------------------------------------------------
780 // units are kgauss,centimeters,gev/c
782 vout[kipp] = vect[kipp];
785 hxp[0] = - vect[kipy];
786 hxp[1] = + vect[kipx];
790 rho = -h4/vect[kipp];
792 if (TMath::Abs(tet) > 0.15) {
793 sint = TMath::Sin(tet);
795 tsint = (tet-sint)/tet;
796 cos1t = 2.* TMath::Sin(0.5*tet) * TMath::Sin(0.5*tet)/tet;
799 sintt = (1. - tsint);
806 f3 = step * tsint * hp;
809 f6 = tet * cos1t * hp;
811 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0];
812 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1];
813 vout[kiz] = vect[kiz] + f1*vect[kipz] + f3;
815 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0];
816 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1];
817 vout[kipz] = vect[kipz] + f4*vect[kipz] + f6;
821 //__________________________________________________________________________
822 void AliMUONTrackParam::ExtrapOneStepRungekutta(Double_t charge, Double_t step,
823 Double_t* vect, Double_t* vout) const
826 // ******************************************************************
828 // * Runge-Kutta method for tracking a particle through a magnetic *
829 // * field. Uses Nystroem algorithm (See Handbook Nat. Bur. of *
830 // * Standards, procedure 25.5.20) *
832 // * Input parameters *
833 // * CHARGE Particle charge *
834 // * STEP Step size *
835 // * VECT Initial co-ords,direction cosines,momentum *
836 // * Output parameters *
837 // * VOUT Output co-ords,direction cosines,momentum *
838 // * User routine called *
839 // * CALL GUFLD(X,F) *
841 // * ==>Called by : <USER>, GUSWIM *
842 // * Authors R.Brun, M.Hansroul ********* *
843 // * V.Perevoztchikov (CUT STEP implementation) *
846 // ******************************************************************
849 Double_t h2, h4, f[4];
850 Double_t xyzt[3], a, b, c, ph,ph2;
851 Double_t secxs[4],secys[4],seczs[4],hxp[3];
852 Double_t g1, g2, g3, g4, g5, g6, ang2, dxt, dyt, dzt;
853 Double_t est, at, bt, ct, cba;
854 Double_t f1, f2, f3, f4, rho, tet, hnorm, hp, rho1, sint, cost;
864 Double_t maxit = 1992;
865 Double_t maxcut = 11;
867 const Double_t kdlt = 1e-4;
868 const Double_t kdlt32 = kdlt/32.;
869 const Double_t kthird = 1./3.;
870 const Double_t khalf = 0.5;
871 const Double_t kec = 2.9979251e-4;
873 const Double_t kpisqua = 9.86960440109;
877 const Int_t kipx = 3;
878 const Int_t kipy = 4;
879 const Int_t kipz = 5;
882 // *. ------------------------------------------------------------------
884 // * this constant is for units cm,gev/c and kgauss
888 for(Int_t j = 0; j < 7; j++)
891 Double_t pinv = kec * charge / vect[6];
899 if (TMath::Abs(h) > TMath::Abs(rest)) h = rest;
900 //cmodif: call gufld(vout,f) changed into:
905 // * start of integration
918 secxs[0] = (b * f[2] - c * f[1]) * ph2;
919 secys[0] = (c * f[0] - a * f[2]) * ph2;
920 seczs[0] = (a * f[1] - b * f[0]) * ph2;
921 ang2 = (secxs[0]*secxs[0] + secys[0]*secys[0] + seczs[0]*seczs[0]);
922 if (ang2 > kpisqua) break;
924 dxt = h2 * a + h4 * secxs[0];
925 dyt = h2 * b + h4 * secys[0];
926 dzt = h2 * c + h4 * seczs[0];
931 // * second intermediate point
934 est = TMath::Abs(dxt) + TMath::Abs(dyt) + TMath::Abs(dzt);
936 if (ncut++ > maxcut) break;
945 //cmodif: call gufld(xyzt,f) changed into:
952 secxs[1] = (bt * f[2] - ct * f[1]) * ph2;
953 secys[1] = (ct * f[0] - at * f[2]) * ph2;
954 seczs[1] = (at * f[1] - bt * f[0]) * ph2;
958 secxs[2] = (bt * f[2] - ct * f[1]) * ph2;
959 secys[2] = (ct * f[0] - at * f[2]) * ph2;
960 seczs[2] = (at * f[1] - bt * f[0]) * ph2;
961 dxt = h * (a + secxs[2]);
962 dyt = h * (b + secys[2]);
963 dzt = h * (c + seczs[2]);
967 at = a + 2.*secxs[2];
968 bt = b + 2.*secys[2];
969 ct = c + 2.*seczs[2];
971 est = TMath::Abs(dxt)+TMath::Abs(dyt)+TMath::Abs(dzt);
972 if (est > 2.*TMath::Abs(h)) {
973 if (ncut++ > maxcut) break;
982 //cmodif: call gufld(xyzt,f) changed into:
985 z = z + (c + (seczs[0] + seczs[1] + seczs[2]) * kthird) * h;
986 y = y + (b + (secys[0] + secys[1] + secys[2]) * kthird) * h;
987 x = x + (a + (secxs[0] + secxs[1] + secxs[2]) * kthird) * h;
989 secxs[3] = (bt*f[2] - ct*f[1])* ph2;
990 secys[3] = (ct*f[0] - at*f[2])* ph2;
991 seczs[3] = (at*f[1] - bt*f[0])* ph2;
992 a = a+(secxs[0]+secxs[3]+2. * (secxs[1]+secxs[2])) * kthird;
993 b = b+(secys[0]+secys[3]+2. * (secys[1]+secys[2])) * kthird;
994 c = c+(seczs[0]+seczs[3]+2. * (seczs[1]+seczs[2])) * kthird;
996 est = TMath::Abs(secxs[0]+secxs[3] - (secxs[1]+secxs[2]))
997 + TMath::Abs(secys[0]+secys[3] - (secys[1]+secys[2]))
998 + TMath::Abs(seczs[0]+seczs[3] - (seczs[1]+seczs[2]));
1000 if (est > kdlt && TMath::Abs(h) > 1.e-4) {
1001 if (ncut++ > maxcut) break;
1007 // * if too many iterations, go to helix
1008 if (iter++ > maxit) break;
1013 cba = 1./ TMath::Sqrt(a*a + b*b + c*c);
1021 if (step < 0.) rest = -rest;
1022 if (rest < 1.e-5*TMath::Abs(step)) return;
1026 // angle too big, use helix
1031 f4 = TMath::Sqrt(f1*f1+f2*f2+f3*f3);
1040 hxp[0] = f2*vect[kipz] - f3*vect[kipy];
1041 hxp[1] = f3*vect[kipx] - f1*vect[kipz];
1042 hxp[2] = f1*vect[kipy] - f2*vect[kipx];
1044 hp = f1*vect[kipx] + f2*vect[kipy] + f3*vect[kipz];
1047 sint = TMath::Sin(tet);
1048 cost = 2.*TMath::Sin(khalf*tet)*TMath::Sin(khalf*tet);
1052 g3 = (tet-sint) * hp*rho1;
1057 vout[kix] = vect[kix] + g1*vect[kipx] + g2*hxp[0] + g3*f1;
1058 vout[kiy] = vect[kiy] + g1*vect[kipy] + g2*hxp[1] + g3*f2;
1059 vout[kiz] = vect[kiz] + g1*vect[kipz] + g2*hxp[2] + g3*f3;
1061 vout[kipx] = vect[kipx] + g4*vect[kipx] + g5*hxp[0] + g6*f1;
1062 vout[kipy] = vect[kipy] + g4*vect[kipy] + g5*hxp[1] + g6*f2;
1063 vout[kipz] = vect[kipz] + g4*vect[kipz] + g5*hxp[2] + g6*f3;
1067 //___________________________________________________________
1068 void AliMUONTrackParam::GetField(Double_t *Position, Double_t *Field) const
1070 // interface for arguments in double precision (Why ? ChF)
1074 x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
1076 fkField->Field(x, b);
1077 Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
1081 //_____________________________________________-
1082 void AliMUONTrackParam::Print(Option_t* opt) const
1085 // Printing TrackParam information
1086 // "full" option for printing all the information about the TrackParam
1091 if ( sopt.Contains("FULL") ) {
1092 cout << "<AliMUONTrackParam> Bending P=" << setw(5) << setprecision(3) << 1./GetInverseBendingMomentum() <<
1093 ", NonBendSlope=" << setw(5) << setprecision(3) << GetNonBendingSlope()*180./TMath::Pi() <<
1094 ", BendSlope=" << setw(5) << setprecision(3) << GetBendingSlope()*180./TMath::Pi() <<
1095 ", (x,y,z)_IP=(" << setw(5) << setprecision(3) << GetNonBendingCoor() <<
1096 "," << setw(5) << setprecision(3) << GetBendingCoor() <<
1097 "," << setw(5) << setprecision(3) << GetZ() <<
1098 ") cm, (px,py,pz)=(" << setw(5) << setprecision(3) << Px() <<
1099 "," << setw(5) << setprecision(3) << Py() <<
1100 "," << setw(5) << setprecision(3) << Pz() << ") GeV/c" << endl;
1103 cout << "<AliMUONTrackParam>" << endl;