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"
37 ClassImp(AliMUONTrackParam) // Class implementation in ROOT context
39 //_________________________________________________________________________
40 AliMUONTrackParam::AliMUONTrackParam()
45 fInverseBendingMomentum = 0;
53 //_________________________________________________________________________
55 AliMUONTrackParam::operator=(const AliMUONTrackParam& theMUONTrackParam)
58 if (this == &theMUONTrackParam)
61 // base class assignement
62 TObject::operator=(theMUONTrackParam);
64 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
65 fBendingSlope = theMUONTrackParam.fBendingSlope;
66 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
67 fZ = theMUONTrackParam.fZ;
68 fBendingCoor = theMUONTrackParam.fBendingCoor;
69 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
73 //_________________________________________________________________________
74 AliMUONTrackParam::AliMUONTrackParam(const AliMUONTrackParam& theMUONTrackParam)
75 : TObject(theMUONTrackParam)
78 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
79 fBendingSlope = theMUONTrackParam.fBendingSlope;
80 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
81 fZ = theMUONTrackParam.fZ;
82 fBendingCoor = theMUONTrackParam.fBendingCoor;
83 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
86 //_________________________________________________________________________
87 void AliMUONTrackParam::GetParamFrom(const AliESDMuonTrack& esdMuonTrack)
89 // assigned value form ESD track.
90 fInverseBendingMomentum = esdMuonTrack.GetInverseBendingMomentum();
91 fBendingSlope = TMath::Tan(esdMuonTrack.GetThetaY());
92 fNonBendingSlope = TMath::Tan(esdMuonTrack.GetThetaX());
93 fZ = esdMuonTrack.GetZ();
94 fBendingCoor = esdMuonTrack.GetBendingCoor();
95 fNonBendingCoor = esdMuonTrack.GetNonBendingCoor();
98 //_________________________________________________________________________
99 void AliMUONTrackParam::SetParamFor(AliESDMuonTrack& esdMuonTrack)
101 // assigned value form ESD track.
102 esdMuonTrack.SetInverseBendingMomentum(fInverseBendingMomentum);
103 esdMuonTrack.SetThetaX(TMath::ATan(fNonBendingSlope));
104 esdMuonTrack.SetThetaY(TMath::ATan(fBendingSlope));
105 esdMuonTrack.SetZ(fZ);
106 esdMuonTrack.SetBendingCoor(fBendingCoor);
107 esdMuonTrack.SetNonBendingCoor(fNonBendingCoor);
110 //__________________________________________________________________________
111 void AliMUONTrackParam::ExtrapToZ(Double_t Z)
113 // Track parameter extrapolation to the plane at "Z".
114 // On return, the track parameters resulting from the extrapolation
115 // replace the current track parameters.
116 if (this->fZ == Z) return; // nothing to be done if same Z
117 Double_t forwardBackward; // +1 if forward, -1 if backward
118 if (Z < this->fZ) forwardBackward = 1.0; // spectro. z<0
119 else forwardBackward = -1.0;
120 Double_t vGeant3[7], vGeant3New[7]; // 7 in parameter ????
121 Int_t iGeant3, stepNumber;
122 Int_t maxStepNumber = 5000; // in parameter ????
123 // For safety: return kTRUE or kFALSE ????
124 // Parameter vector for calling EXTRAP_ONESTEP
125 SetGeant3Parameters(vGeant3, forwardBackward);
126 // sign of charge (sign of fInverseBendingMomentum if forward motion)
127 // must be changed if backward extrapolation
128 Double_t chargeExtrap = forwardBackward *
129 TMath::Sign(Double_t(1.0), this->fInverseBendingMomentum);
130 Double_t stepLength = 6.0; // in parameter ????
131 // Extrapolation loop
133 while (((-forwardBackward * (vGeant3[2] - Z)) <= 0.0) && // spectro. z<0
134 (stepNumber < maxStepNumber)) {
136 // Option for switching between helix and Runge-Kutta ????
137 //ExtrapOneStepRungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
138 ExtrapOneStepHelix(chargeExtrap, stepLength, vGeant3, vGeant3New);
139 if ((-forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z spectro. z<0
140 // better use TArray ????
141 for (iGeant3 = 0; iGeant3 < 7; iGeant3++)
142 {vGeant3[iGeant3] = vGeant3New[iGeant3];}
144 // check maxStepNumber ????
145 // Interpolation back to exact Z (2nd order)
146 // should be in function ???? using TArray ????
147 Double_t dZ12 = vGeant3New[2] - vGeant3[2]; // 1->2
148 if (TMath::Abs(dZ12) > 0) {
149 Double_t dZ1i = Z - vGeant3[2]; // 1-i
150 Double_t dZi2 = vGeant3New[2] - Z; // i->2
151 Double_t xPrime = (vGeant3New[0] - vGeant3[0]) / dZ12;
153 ((vGeant3New[3] / vGeant3New[5]) - (vGeant3[3] / vGeant3[5])) / dZ12;
154 Double_t yPrime = (vGeant3New[1] - vGeant3[1]) / dZ12;
156 ((vGeant3New[4] / vGeant3New[5]) - (vGeant3[4] / vGeant3[5])) / dZ12;
157 vGeant3[0] = vGeant3[0] + xPrime * dZ1i - 0.5 * xSecond * dZ1i * dZi2; // X
158 vGeant3[1] = vGeant3[1] + yPrime * dZ1i - 0.5 * ySecond * dZ1i * dZi2; // Y
160 Double_t xPrimeI = xPrime - 0.5 * xSecond * (dZi2 - dZ1i);
161 Double_t yPrimeI = yPrime - 0.5 * ySecond * (dZi2 - dZ1i);
162 // (PX, PY, PZ)/PTOT assuming forward motion
164 1.0 / TMath::Sqrt(1.0 + xPrimeI * xPrimeI + yPrimeI * yPrimeI); // PZ/PTOT
165 vGeant3[3] = xPrimeI * vGeant3[5]; // PX/PTOT
166 vGeant3[4] = yPrimeI * vGeant3[5]; // PY/PTOT
168 AliWarning(Form("Extrap. to Z not reached, Z = %f",Z));
170 // Track parameters from Geant3 parameters,
171 // with charge back for forward motion
172 GetFromGeant3Parameters(vGeant3, chargeExtrap * forwardBackward);
175 //__________________________________________________________________________
176 void AliMUONTrackParam::SetGeant3Parameters(Double_t *VGeant3, Double_t ForwardBackward)
178 // Set vector of Geant3 parameters pointed to by "VGeant3"
179 // from track parameters in current AliMUONTrackParam.
180 // Since AliMUONTrackParam is only geometry, one uses "ForwardBackward"
181 // to know whether the particle is going forward (+1) or backward (-1).
182 VGeant3[0] = this->fNonBendingCoor; // X
183 VGeant3[1] = this->fBendingCoor; // Y
184 VGeant3[2] = this->fZ; // Z
185 Double_t pYZ = TMath::Abs(1.0 / this->fInverseBendingMomentum);
187 pYZ / TMath::Sqrt(1.0 + this->fBendingSlope * this->fBendingSlope);
189 TMath::Sqrt(pYZ * pYZ +
190 pZ * pZ * this->fNonBendingSlope * this->fNonBendingSlope); // PTOT
191 VGeant3[5] = -ForwardBackward * pZ / VGeant3[6]; // PZ/PTOT spectro. z<0
192 VGeant3[3] = this->fNonBendingSlope * VGeant3[5]; // PX/PTOT
193 VGeant3[4] = this->fBendingSlope * VGeant3[5]; // PY/PTOT
196 //__________________________________________________________________________
197 void AliMUONTrackParam::GetFromGeant3Parameters(Double_t *VGeant3, Double_t Charge)
199 // Get track parameters in current AliMUONTrackParam
200 // from Geant3 parameters pointed to by "VGeant3",
201 // assumed to be calculated for forward motion in Z.
202 // "InverseBendingMomentum" is signed with "Charge".
203 this->fNonBendingCoor = VGeant3[0]; // X
204 this->fBendingCoor = VGeant3[1]; // Y
205 this->fZ = VGeant3[2]; // Z
206 Double_t pYZ = VGeant3[6] * TMath::Sqrt(1.0 - VGeant3[3] * VGeant3[3]);
207 this->fInverseBendingMomentum = Charge / pYZ;
208 this->fBendingSlope = VGeant3[4] / VGeant3[5];
209 this->fNonBendingSlope = VGeant3[3] / VGeant3[5];
212 //__________________________________________________________________________
213 void AliMUONTrackParam::ExtrapToStation(Int_t Station, AliMUONTrackParam *TrackParam)
215 // Track parameters extrapolated from current track parameters ("this")
216 // to both chambers of the station(0..) "Station"
217 // are returned in the array (dimension 2) of track parameters
218 // pointed to by "TrackParam" (index 0 and 1 for first and second chambers).
219 Double_t extZ[2], z1, z2;
220 Int_t i1 = -1, i2 = -1; // = -1 to avoid compilation warnings
221 // range of Station to be checked ????
222 z1 = AliMUONConstants::DefaultChamberZ(2 * Station);
223 z2 = AliMUONConstants::DefaultChamberZ(2 * Station + 1);
224 // First and second Z to extrapolate at
225 if ((z1 > this->fZ) && (z2 > this->fZ)) {i1 = 0; i2 = 1;}
226 else if ((z1 < this->fZ) && (z2 < this->fZ)) {i1 = 1; i2 = 0;}
228 AliError(Form("Starting Z (%f) in between z1 (%f) and z2 (%f) of station(0..)%d",this->fZ,z1,z2,Station));
229 // cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
230 // cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
231 // ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
235 // copy of track parameters
236 TrackParam[i1] = *this;
237 // first extrapolation
238 (&(TrackParam[i1]))->ExtrapToZ(extZ[0]);
239 TrackParam[i2] = TrackParam[i1];
240 // second extrapolation
241 (&(TrackParam[i2]))->ExtrapToZ(extZ[1]);
245 //__________________________________________________________________________
246 void AliMUONTrackParam::ExtrapToVertex(Double_t xVtx, Double_t yVtx, Double_t zVtx)
248 // Extrapolation to the vertex.
249 // Returns the track parameters resulting from the extrapolation,
250 // in the current TrackParam.
251 // Changes parameters according to Branson correction through the absorber
253 Double_t zAbsorber = -503.0; // to be coherent with the Geant absorber geometry !!!!
255 // Extrapolates track parameters upstream to the "Z" end of the front absorber
256 ExtrapToZ(zAbsorber); // !!!
257 // Makes Branson correction (multiple scattering + energy loss)
258 BransonCorrection(xVtx,yVtx,zVtx);
259 // Makes a simple magnetic field correction through the absorber
260 FieldCorrection(zAbsorber);
264 // Keep this version for future developments
265 //__________________________________________________________________________
266 // void AliMUONTrackParam::BransonCorrection()
268 // // Branson correction of track parameters
269 // // the entry parameters have to be calculated at the end of the absorber
270 // Double_t zEndAbsorber, zBP, xBP, yBP;
271 // Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
273 // // Would it be possible to calculate all that from Geant configuration ????
274 // // and to get the Branson parameters from a function in ABSO module ????
275 // // with an eventual contribution from other detectors like START ????
276 // // Radiation lengths outer part theta > 3 degres
277 // static Double_t x01[9] = { 18.8, // C (cm)
278 // 10.397, // Concrete (cm)
279 // 0.56, // Plomb (cm)
280 // 47.26, // Polyethylene (cm)
281 // 0.56, // Plomb (cm)
282 // 47.26, // Polyethylene (cm)
283 // 0.56, // Plomb (cm)
284 // 47.26, // Polyethylene (cm)
285 // 0.56 }; // Plomb (cm)
286 // // inner part theta < 3 degres
287 // static Double_t x02[3] = { 18.8, // C (cm)
288 // 10.397, // Concrete (cm)
290 // // z positions of the materials inside the absober outer part theta > 3 degres
291 // static Double_t z1[10] = { 90, 315, 467, 472, 477, 482, 487, 492, 497, 502 };
292 // // inner part theta < 3 degres
293 // static Double_t z2[4] = { 90, 315, 467, 503 };
294 // static Bool_t first = kTRUE;
295 // static Double_t zBP1, zBP2, rLimit;
296 // // Calculates z positions of the Branson's planes: zBP1 for outer part and zBP2 for inner part (only at the first call)
299 // Double_t aNBP = 0.0;
300 // Double_t aDBP = 0.0;
303 // for (iBound = 0; iBound < 9; iBound++) {
305 // (z1[iBound+1] * z1[iBound+1] * z1[iBound+1] -
306 // z1[iBound] * z1[iBound] * z1[iBound] ) / x01[iBound];
308 // (z1[iBound+1] * z1[iBound+1] - z1[iBound] * z1[iBound] ) / x01[iBound];
310 // zBP1 = (2.0 * aNBP) / (3.0 * aDBP);
313 // for (iBound = 0; iBound < 3; iBound++) {
315 // (z2[iBound+1] * z2[iBound+1] * z2[iBound+1] -
316 // z2[iBound] * z2[iBound ] * z2[iBound] ) / x02[iBound];
318 // (z2[iBound+1] * z2[iBound+1] - z2[iBound] * z2[iBound]) / x02[iBound];
320 // zBP2 = (2.0 * aNBP) / (3.0 * aDBP);
321 // rLimit = z2[3] * TMath::Tan(3.0 * (TMath::Pi()) / 180.);
324 // pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
326 // if (fInverseBendingMomentum < 0) sign = -1;
327 // pZ = pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope));
328 // pX = pZ * fNonBendingSlope;
329 // pY = pZ * fBendingSlope;
330 // pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
331 // xEndAbsorber = fNonBendingCoor;
332 // yEndAbsorber = fBendingCoor;
333 // radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
335 // if (radiusEndAbsorber2 > rLimit*rLimit) {
336 // zEndAbsorber = z1[9];
339 // zEndAbsorber = z2[3];
343 // xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
344 // yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
346 // // new parameters after Branson and energy loss corrections
347 // pZ = pTotal * zBP / TMath::Sqrt(xBP * xBP + yBP * yBP + zBP * zBP);
348 // pX = pZ * xBP / zBP;
349 // pY = pZ * yBP / zBP;
350 // fBendingSlope = pY / pZ;
351 // fNonBendingSlope = pX / pZ;
353 // pT = TMath::Sqrt(pX * pX + pY * pY);
354 // theta = TMath::ATan2(pT, pZ);
356 // TotalMomentumEnergyLoss(rLimit, pTotal, theta, xEndAbsorber, yEndAbsorber);
358 // fInverseBendingMomentum = (sign / pTotal) *
360 // fBendingSlope * fBendingSlope +
361 // fNonBendingSlope * fNonBendingSlope) /
362 // TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
364 // // vertex position at (0,0,0)
365 // // should be taken from vertex measurement ???
366 // fBendingCoor = 0.0;
367 // fNonBendingCoor = 0;
371 void AliMUONTrackParam::BransonCorrection(Double_t xVtx,Double_t yVtx,Double_t zVtx)
373 // Branson correction of track parameters
374 // the entry parameters have to be calculated at the end of the absorber
375 // simplified version: the z positions of Branson's planes are no longer calculated
376 // but are given as inputs. One can use the macros MUONTestAbso.C and DrawTestAbso.C
377 // to test this correction.
378 // Would it be possible to calculate all that from Geant configuration ????
379 // and to get the Branson parameters from a function in ABSO module ????
380 // with an eventual contribution from other detectors like START ????
381 //change to take into account the vertex postition (real, reconstruct,....)
383 Double_t zBP, xBP, yBP;
384 Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
386 static Bool_t first = kTRUE;
387 static Double_t zBP1, zBP2, rLimit, thetaLimit, zEndAbsorber;
388 // zBP1 for outer part and zBP2 for inner part (only at the first call)
392 zEndAbsorber = -503; // spectro (z<0)
393 thetaLimit = 3.0 * (TMath::Pi()) / 180.;
394 rLimit = TMath::Abs(zEndAbsorber) * TMath::Tan(thetaLimit);
395 zBP1 = -450; // values close to those calculated with EvalAbso.C
399 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
401 if (fInverseBendingMomentum < 0) sign = -1;
405 pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
406 xEndAbsorber = fNonBendingCoor;
407 yEndAbsorber = fBendingCoor;
408 radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
410 if (radiusEndAbsorber2 > rLimit*rLimit) {
416 xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
417 yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
419 // new parameters after Branson and energy loss corrections
420 // Float_t zSmear = zBP - gRandom->Gaus(0.,2.); // !!! possible smearing of Z vertex position
422 Float_t zSmear = zBP ;
424 pZ = pTotal * (zSmear-zVtx) / TMath::Sqrt((xBP-xVtx) * (xBP-xVtx) + (yBP-yVtx) * (yBP-yVtx) +( zSmear-zVtx) * (zSmear-zVtx) );
425 pX = pZ * (xBP - xVtx)/ (zSmear-zVtx);
426 pY = pZ * (yBP - yVtx) / (zSmear-zVtx);
427 fBendingSlope = pY / pZ;
428 fNonBendingSlope = pX / pZ;
431 pT = TMath::Sqrt(pX * pX + pY * pY);
432 theta = TMath::ATan2(pT, TMath::Abs(pZ));
433 pTotal = TotalMomentumEnergyLoss(thetaLimit, pTotal, theta);
435 fInverseBendingMomentum = (sign / pTotal) *
437 fBendingSlope * fBendingSlope +
438 fNonBendingSlope * fNonBendingSlope) /
439 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
441 // vertex position at (0,0,0)
442 // should be taken from vertex measurement ???
445 fNonBendingCoor = yVtx;
450 //__________________________________________________________________________
451 Double_t AliMUONTrackParam::TotalMomentumEnergyLoss(Double_t thetaLimit, Double_t pTotal, Double_t theta)
453 // Returns the total momentum corrected from energy loss in the front absorber
454 // One can use the macros MUONTestAbso.C and DrawTestAbso.C
455 // to test this correction.
456 // Momentum energy loss behaviour evaluated with the simulation of single muons (april 2002)
457 Double_t deltaP, pTotalCorrected;
459 // Parametrization to be redone according to change of absorber material ????
460 // See remark in function BransonCorrection !!!!
461 // The name is not so good, and there are many arguments !!!!
462 if (theta < thetaLimit ) {
464 deltaP = 2.5938 + 0.0570 * pTotal - 0.001151 * pTotal * pTotal;
466 deltaP = 3.0714 + 0.011767 *pTotal;
468 deltaP *= 0.75; // AZ
471 deltaP = 2.1207 + 0.05478 * pTotal - 0.00145079 * pTotal * pTotal;
473 deltaP = 2.6069 + 0.0051705 * pTotal;
477 pTotalCorrected = pTotal + deltaP / TMath::Cos(theta);
478 return pTotalCorrected;
481 //__________________________________________________________________________
482 void AliMUONTrackParam::FieldCorrection(Double_t Z)
485 // Correction of the effect of the magnetic field in the absorber
486 // Assume a constant field along Z axis.
490 Double_t pYZ,pX,pY,pZ,pT;
491 Double_t pXNew,pYNew;
494 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
495 c = TMath::Sign(1.0,fInverseBendingMomentum); // particle charge
500 pT = TMath::Sqrt(pX*pX+pY*pY);
502 if (TMath::Abs(pZ) <= 0) return;
504 x[0] = x[2]*fNonBendingSlope;
505 x[1] = x[2]*fBendingSlope;
507 // Take magn. field value at position x.
508 gAlice->Field()->Field(x, b);
511 // Transverse momentum rotation
512 // Parameterized with the study of DeltaPhi = phiReco - phiGen as a function of pZ.
513 Double_t phiShift = c*0.436*0.0003*bZ*Z/pZ;
514 // Rotate momentum around Z axis.
515 pXNew = pX*TMath::Cos(phiShift) - pY*TMath::Sin(phiShift);
516 pYNew = pX*TMath::Sin(phiShift) + pY*TMath::Cos(phiShift);
518 fBendingSlope = pYNew / pZ;
519 fNonBendingSlope = pXNew / pZ;
521 fInverseBendingMomentum = c / TMath::Sqrt(pYNew*pYNew+pZ*pZ);
524 //__________________________________________________________________________
525 Double_t AliMUONTrackParam::Px() const
527 // return px from track paramaters
528 Double_t pYZ, pZ, pX;
530 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
531 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
532 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
533 pX = pZ * fNonBendingSlope;
536 //__________________________________________________________________________
537 Double_t AliMUONTrackParam::Py() const
539 // return px from track paramaters
540 Double_t pYZ, pZ, pY;
542 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
543 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
544 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
545 pY = pZ * fBendingSlope;
548 //__________________________________________________________________________
549 Double_t AliMUONTrackParam::Pz() const
551 // return px from track paramaters
554 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
555 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
556 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
559 //__________________________________________________________________________
560 Double_t AliMUONTrackParam::P() const
562 // return p from track paramaters
565 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
566 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
567 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
569 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope + fNonBendingSlope * fNonBendingSlope);
573 //__________________________________________________________________________
574 void AliMUONTrackParam::ExtrapOneStepHelix(Double_t charge, Double_t step,
575 Double_t *vect, Double_t *vout) const
577 // ******************************************************************
579 // * Performs the tracking of one step in a magnetic field *
580 // * The trajectory is assumed to be a helix in a constant field *
581 // * taken at the mid point of the step. *
584 // * STEP =arc length of the step asked *
585 // * VECT =input vector (position,direction cos and momentum) *
586 // * CHARGE= electric charge of the particle *
588 // * VOUT = same as VECT after completion of the step *
590 // * ==>Called by : <USER>, GUSWIM *
591 // * Author m.hansroul ********* *
592 // * modified s.egli, s.v.levonian *
593 // * modified v.perevoztchikov
595 // ******************************************************************
598 // modif: everything in double precision
600 Double_t xyz[3], h[4], hxp[3];
601 Double_t h2xy, hp, rho, tet;
602 Double_t sint, sintt, tsint, cos1t;
603 Double_t f1, f2, f3, f4, f5, f6;
608 const Int_t kipx = 3;
609 const Int_t kipy = 4;
610 const Int_t kipz = 5;
611 const Int_t kipp = 6;
613 const Double_t kec = 2.9979251e-4;
615 // ------------------------------------------------------------------
617 // units are kgauss,centimeters,gev/c
619 vout[kipp] = vect[kipp];
620 if (TMath::Abs(charge) < 0.00001) {
621 for (Int_t i = 0; i < 3; i++) {
622 vout[i] = vect[i] + step * vect[i+3];
623 vout[i+3] = vect[i+3];
627 xyz[0] = vect[kix] + 0.5 * step * vect[kipx];
628 xyz[1] = vect[kiy] + 0.5 * step * vect[kipy];
629 xyz[2] = vect[kiz] + 0.5 * step * vect[kipz];
631 //cmodif: call gufld (xyz, h) changed into:
634 h2xy = h[0]*h[0] + h[1]*h[1];
635 h[3] = h[2]*h[2]+ h2xy;
637 for (Int_t i = 0; i < 3; i++) {
638 vout[i] = vect[i] + step * vect[i+3];
639 vout[i+3] = vect[i+3];
643 if (h2xy < 1.e-12*h[3]) {
644 ExtrapOneStepHelix3(charge*h[2], step, vect, vout);
647 h[3] = TMath::Sqrt(h[3]);
653 hxp[0] = h[1]*vect[kipz] - h[2]*vect[kipy];
654 hxp[1] = h[2]*vect[kipx] - h[0]*vect[kipz];
655 hxp[2] = h[0]*vect[kipy] - h[1]*vect[kipx];
657 hp = h[0]*vect[kipx] + h[1]*vect[kipy] + h[2]*vect[kipz];
659 rho = -charge*h[3]/vect[kipp];
662 if (TMath::Abs(tet) > 0.15) {
663 sint = TMath::Sin(tet);
665 tsint = (tet-sint)/tet;
666 cos1t = 2.*(TMath::Sin(0.5*tet))*(TMath::Sin(0.5*tet))/tet;
669 sintt = (1. - tsint);
676 f3 = step * tsint * hp;
679 f6 = tet * cos1t * hp;
681 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0] + f3*h[0];
682 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1] + f3*h[1];
683 vout[kiz] = vect[kiz] + f1*vect[kipz] + f2*hxp[2] + f3*h[2];
685 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0] + f6*h[0];
686 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1] + f6*h[1];
687 vout[kipz] = vect[kipz] + f4*vect[kipz] + f5*hxp[2] + f6*h[2];
692 //__________________________________________________________________________
693 void AliMUONTrackParam::ExtrapOneStepHelix3(Double_t field, Double_t step,
694 Double_t *vect, Double_t *vout) const
697 // ******************************************************************
699 // * Tracking routine in a constant field oriented *
701 // * Tracking is performed with a conventional *
702 // * helix step method *
704 // * ==>Called by : <USER>, GUSWIM *
705 // * Authors R.Brun, M.Hansroul ********* *
706 // * Rewritten V.Perevoztchikov
708 // ******************************************************************
712 Double_t h4, hp, rho, tet;
713 Double_t sint, sintt, tsint, cos1t;
714 Double_t f1, f2, f3, f4, f5, f6;
719 const Int_t kipx = 3;
720 const Int_t kipy = 4;
721 const Int_t kipz = 5;
722 const Int_t kipp = 6;
724 const Double_t kec = 2.9979251e-4;
727 // ------------------------------------------------------------------
729 // units are kgauss,centimeters,gev/c
731 vout[kipp] = vect[kipp];
734 hxp[0] = - vect[kipy];
735 hxp[1] = + vect[kipx];
739 rho = -h4/vect[kipp];
741 if (TMath::Abs(tet) > 0.15) {
742 sint = TMath::Sin(tet);
744 tsint = (tet-sint)/tet;
745 cos1t = 2.* TMath::Sin(0.5*tet) * TMath::Sin(0.5*tet)/tet;
748 sintt = (1. - tsint);
755 f3 = step * tsint * hp;
758 f6 = tet * cos1t * hp;
760 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0];
761 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1];
762 vout[kiz] = vect[kiz] + f1*vect[kipz] + f3;
764 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0];
765 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1];
766 vout[kipz] = vect[kipz] + f4*vect[kipz] + f6;
770 //__________________________________________________________________________
771 void AliMUONTrackParam::ExtrapOneStepRungekutta(Double_t charge, Double_t step,
772 Double_t* vect, Double_t* vout) const
775 // ******************************************************************
777 // * Runge-Kutta method for tracking a particle through a magnetic *
778 // * field. Uses Nystroem algorithm (See Handbook Nat. Bur. of *
779 // * Standards, procedure 25.5.20) *
781 // * Input parameters *
782 // * CHARGE Particle charge *
783 // * STEP Step size *
784 // * VECT Initial co-ords,direction cosines,momentum *
785 // * Output parameters *
786 // * VOUT Output co-ords,direction cosines,momentum *
787 // * User routine called *
788 // * CALL GUFLD(X,F) *
790 // * ==>Called by : <USER>, GUSWIM *
791 // * Authors R.Brun, M.Hansroul ********* *
792 // * V.Perevoztchikov (CUT STEP implementation) *
795 // ******************************************************************
798 Double_t h2, h4, f[4];
799 Double_t xyzt[3], a, b, c, ph,ph2;
800 Double_t secxs[4],secys[4],seczs[4],hxp[3];
801 Double_t g1, g2, g3, g4, g5, g6, ang2, dxt, dyt, dzt;
802 Double_t est, at, bt, ct, cba;
803 Double_t f1, f2, f3, f4, rho, tet, hnorm, hp, rho1, sint, cost;
813 Double_t maxit = 1992;
814 Double_t maxcut = 11;
816 const Double_t kdlt = 1e-4;
817 const Double_t kdlt32 = kdlt/32.;
818 const Double_t kthird = 1./3.;
819 const Double_t khalf = 0.5;
820 const Double_t kec = 2.9979251e-4;
822 const Double_t kpisqua = 9.86960440109;
826 const Int_t kipx = 3;
827 const Int_t kipy = 4;
828 const Int_t kipz = 5;
831 // *. ------------------------------------------------------------------
833 // * this constant is for units cm,gev/c and kgauss
837 for(Int_t j = 0; j < 7; j++)
840 Double_t pinv = kec * charge / vect[6];
848 if (TMath::Abs(h) > TMath::Abs(rest)) h = rest;
849 //cmodif: call gufld(vout,f) changed into:
854 // * start of integration
867 secxs[0] = (b * f[2] - c * f[1]) * ph2;
868 secys[0] = (c * f[0] - a * f[2]) * ph2;
869 seczs[0] = (a * f[1] - b * f[0]) * ph2;
870 ang2 = (secxs[0]*secxs[0] + secys[0]*secys[0] + seczs[0]*seczs[0]);
871 if (ang2 > kpisqua) break;
873 dxt = h2 * a + h4 * secxs[0];
874 dyt = h2 * b + h4 * secys[0];
875 dzt = h2 * c + h4 * seczs[0];
880 // * second intermediate point
883 est = TMath::Abs(dxt) + TMath::Abs(dyt) + TMath::Abs(dzt);
885 if (ncut++ > maxcut) break;
894 //cmodif: call gufld(xyzt,f) changed into:
901 secxs[1] = (bt * f[2] - ct * f[1]) * ph2;
902 secys[1] = (ct * f[0] - at * f[2]) * ph2;
903 seczs[1] = (at * f[1] - bt * f[0]) * ph2;
907 secxs[2] = (bt * f[2] - ct * f[1]) * ph2;
908 secys[2] = (ct * f[0] - at * f[2]) * ph2;
909 seczs[2] = (at * f[1] - bt * f[0]) * ph2;
910 dxt = h * (a + secxs[2]);
911 dyt = h * (b + secys[2]);
912 dzt = h * (c + seczs[2]);
916 at = a + 2.*secxs[2];
917 bt = b + 2.*secys[2];
918 ct = c + 2.*seczs[2];
920 est = TMath::Abs(dxt)+TMath::Abs(dyt)+TMath::Abs(dzt);
921 if (est > 2.*TMath::Abs(h)) {
922 if (ncut++ > maxcut) break;
931 //cmodif: call gufld(xyzt,f) changed into:
934 z = z + (c + (seczs[0] + seczs[1] + seczs[2]) * kthird) * h;
935 y = y + (b + (secys[0] + secys[1] + secys[2]) * kthird) * h;
936 x = x + (a + (secxs[0] + secxs[1] + secxs[2]) * kthird) * h;
938 secxs[3] = (bt*f[2] - ct*f[1])* ph2;
939 secys[3] = (ct*f[0] - at*f[2])* ph2;
940 seczs[3] = (at*f[1] - bt*f[0])* ph2;
941 a = a+(secxs[0]+secxs[3]+2. * (secxs[1]+secxs[2])) * kthird;
942 b = b+(secys[0]+secys[3]+2. * (secys[1]+secys[2])) * kthird;
943 c = c+(seczs[0]+seczs[3]+2. * (seczs[1]+seczs[2])) * kthird;
945 est = TMath::Abs(secxs[0]+secxs[3] - (secxs[1]+secxs[2]))
946 + TMath::Abs(secys[0]+secys[3] - (secys[1]+secys[2]))
947 + TMath::Abs(seczs[0]+seczs[3] - (seczs[1]+seczs[2]));
949 if (est > kdlt && TMath::Abs(h) > 1.e-4) {
950 if (ncut++ > maxcut) break;
956 // * if too many iterations, go to helix
957 if (iter++ > maxit) break;
962 cba = 1./ TMath::Sqrt(a*a + b*b + c*c);
970 if (step < 0.) rest = -rest;
971 if (rest < 1.e-5*TMath::Abs(step)) return;
975 // angle too big, use helix
980 f4 = TMath::Sqrt(f1*f1+f2*f2+f3*f3);
989 hxp[0] = f2*vect[kipz] - f3*vect[kipy];
990 hxp[1] = f3*vect[kipx] - f1*vect[kipz];
991 hxp[2] = f1*vect[kipy] - f2*vect[kipx];
993 hp = f1*vect[kipx] + f2*vect[kipy] + f3*vect[kipz];
996 sint = TMath::Sin(tet);
997 cost = 2.*TMath::Sin(khalf*tet)*TMath::Sin(khalf*tet);
1001 g3 = (tet-sint) * hp*rho1;
1006 vout[kix] = vect[kix] + g1*vect[kipx] + g2*hxp[0] + g3*f1;
1007 vout[kiy] = vect[kiy] + g1*vect[kipy] + g2*hxp[1] + g3*f2;
1008 vout[kiz] = vect[kiz] + g1*vect[kipz] + g2*hxp[2] + g3*f3;
1010 vout[kipx] = vect[kipx] + g4*vect[kipx] + g5*hxp[0] + g6*f1;
1011 vout[kipy] = vect[kipy] + g4*vect[kipy] + g5*hxp[1] + g6*f2;
1012 vout[kipz] = vect[kipz] + g4*vect[kipz] + g5*hxp[2] + g6*f3;
1016 //___________________________________________________________
1017 void AliMUONTrackParam::GetField(Double_t *Position, Double_t *Field) const
1019 // interface to "gAlice->Field()->Field" for arguments in double precision
1023 x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
1025 gAlice->Field()->Field(x, b);
1026 Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
1030 //_____________________________________________-
1031 void AliMUONTrackParam::Print(Option_t* opt) const
1034 // Printing TrackParam information
1035 // "full" option for printing all the information about the TrackParam
1040 if ( sopt.Contains("FULL") ) {
1041 cout << "<AliMUONTrackParam> Bending P=" << setw(5) << setprecision(3) << 1./GetInverseBendingMomentum() <<
1042 ", NonBendSlope=" << setw(5) << setprecision(3) << GetNonBendingSlope()*180./TMath::Pi() <<
1043 ", BendSlope=" << setw(5) << setprecision(3) << GetBendingSlope()*180./TMath::Pi() <<
1044 ", (x,y,z)_IP=(" << setw(5) << setprecision(3) << GetNonBendingCoor() <<
1045 "," << setw(5) << setprecision(3) << GetBendingCoor() <<
1046 "," << setw(5) << setprecision(3) << GetZ() <<
1047 ") cm, (px,py,pz)=(" << setw(5) << setprecision(3) << Px() <<
1048 "," << setw(5) << setprecision(3) << Py() <<
1049 "," << setw(5) << setprecision(3) << Pz() << ") GeV/c" << endl;
1052 cout << "<AliMUONTrackParam>" << endl;