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Removing obsolete classes (Chrstian)
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a9e2aefa 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
88cb7938 16/* $Id$ */
a9e2aefa 17
3831f268 18///////////////////////////////////////////////////
19//
20// Track parameters
21// in
22// ALICE
23// dimuon
24// spectrometer
a9e2aefa 25//
3831f268 26///////////////////////////////////////////////////
a9e2aefa 27
58443fe3 28//#include <Riostream.h>
3831f268 29#include "AliMUON.h"
a9e2aefa 30#include "AliMUONTrackParam.h"
06c11448 31#include "AliMUONConstants.h"
a9e2aefa 32#include "AliRun.h"
94de3818 33#include "AliMagF.h"
8c343c7c 34#include "AliLog.h"
a9e2aefa 35
36ClassImp(AliMUONTrackParam) // Class implementation in ROOT context
37
61adb9bd 38 //_________________________________________________________________________
30178c30 39AliMUONTrackParam::AliMUONTrackParam()
40 : TObject()
41{
42// Constructor
43
44 fInverseBendingMomentum = 0;
45 fBendingSlope = 0;
46 fNonBendingSlope = 0;
47 fZ = 0;
48 fBendingCoor = 0;
49 fNonBendingCoor = 0;
50}
61adb9bd 51
30178c30 52 //_________________________________________________________________________
53AliMUONTrackParam&
54AliMUONTrackParam::operator=(const AliMUONTrackParam& theMUONTrackParam)
61adb9bd 55{
58443fe3 56 // Asignment operator
30178c30 57 if (this == &theMUONTrackParam)
61adb9bd 58 return *this;
59
30178c30 60 // base class assignement
61 TObject::operator=(theMUONTrackParam);
62
63 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
64 fBendingSlope = theMUONTrackParam.fBendingSlope;
65 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
66 fZ = theMUONTrackParam.fZ;
67 fBendingCoor = theMUONTrackParam.fBendingCoor;
68 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
61adb9bd 69
70 return *this;
71}
72 //_________________________________________________________________________
30178c30 73AliMUONTrackParam::AliMUONTrackParam(const AliMUONTrackParam& theMUONTrackParam)
74 : TObject(theMUONTrackParam)
61adb9bd 75{
58443fe3 76 // Copy constructor
30178c30 77 fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
78 fBendingSlope = theMUONTrackParam.fBendingSlope;
79 fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
80 fZ = theMUONTrackParam.fZ;
81 fBendingCoor = theMUONTrackParam.fBendingCoor;
82 fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
61adb9bd 83}
a9e2aefa 84
a9e2aefa 85 //__________________________________________________________________________
86void AliMUONTrackParam::ExtrapToZ(Double_t Z)
87{
88 // Track parameter extrapolation to the plane at "Z".
89 // On return, the track parameters resulting from the extrapolation
90 // replace the current track parameters.
a9e2aefa 91 if (this->fZ == Z) return; // nothing to be done if same Z
92 Double_t forwardBackward; // +1 if forward, -1 if backward
5b64e914 93 if (Z < this->fZ) forwardBackward = 1.0; // spectro. z<0
a9e2aefa 94 else forwardBackward = -1.0;
a6f03ddb 95 Double_t vGeant3[7], vGeant3New[7]; // 7 in parameter ????
a9e2aefa 96 Int_t iGeant3, stepNumber;
97 Int_t maxStepNumber = 5000; // in parameter ????
98 // For safety: return kTRUE or kFALSE ????
a6f03ddb 99 // Parameter vector for calling EXTRAP_ONESTEP
a9e2aefa 100 SetGeant3Parameters(vGeant3, forwardBackward);
956019b6 101 // sign of charge (sign of fInverseBendingMomentum if forward motion)
a6f03ddb 102 // must be changed if backward extrapolation
956019b6 103 Double_t chargeExtrap = forwardBackward *
104 TMath::Sign(Double_t(1.0), this->fInverseBendingMomentum);
a9e2aefa 105 Double_t stepLength = 6.0; // in parameter ????
106 // Extrapolation loop
107 stepNumber = 0;
5b64e914 108 while (((-forwardBackward * (vGeant3[2] - Z)) <= 0.0) && // spectro. z<0
a9e2aefa 109 (stepNumber < maxStepNumber)) {
110 stepNumber++;
a6f03ddb 111 // Option for switching between helix and Runge-Kutta ????
4d03a78e 112 //ExtrapOneStepRungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
113 ExtrapOneStepHelix(chargeExtrap, stepLength, vGeant3, vGeant3New);
5b64e914 114 if ((-forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z spectro. z<0
a9e2aefa 115 // better use TArray ????
116 for (iGeant3 = 0; iGeant3 < 7; iGeant3++)
117 {vGeant3[iGeant3] = vGeant3New[iGeant3];}
118 }
119 // check maxStepNumber ????
a9e2aefa 120 // Interpolation back to exact Z (2nd order)
121 // should be in function ???? using TArray ????
122 Double_t dZ12 = vGeant3New[2] - vGeant3[2]; // 1->2
1e2b8bb7 123 if (TMath::Abs(dZ12) > 0) {
124 Double_t dZ1i = Z - vGeant3[2]; // 1-i
125 Double_t dZi2 = vGeant3New[2] - Z; // i->2
126 Double_t xPrime = (vGeant3New[0] - vGeant3[0]) / dZ12;
127 Double_t xSecond =
128 ((vGeant3New[3] / vGeant3New[5]) - (vGeant3[3] / vGeant3[5])) / dZ12;
129 Double_t yPrime = (vGeant3New[1] - vGeant3[1]) / dZ12;
130 Double_t ySecond =
131 ((vGeant3New[4] / vGeant3New[5]) - (vGeant3[4] / vGeant3[5])) / dZ12;
132 vGeant3[0] = vGeant3[0] + xPrime * dZ1i - 0.5 * xSecond * dZ1i * dZi2; // X
133 vGeant3[1] = vGeant3[1] + yPrime * dZ1i - 0.5 * ySecond * dZ1i * dZi2; // Y
134 vGeant3[2] = Z; // Z
135 Double_t xPrimeI = xPrime - 0.5 * xSecond * (dZi2 - dZ1i);
136 Double_t yPrimeI = yPrime - 0.5 * ySecond * (dZi2 - dZ1i);
137 // (PX, PY, PZ)/PTOT assuming forward motion
138 vGeant3[5] =
139 1.0 / TMath::Sqrt(1.0 + xPrimeI * xPrimeI + yPrimeI * yPrimeI); // PZ/PTOT
140 vGeant3[3] = xPrimeI * vGeant3[5]; // PX/PTOT
141 vGeant3[4] = yPrimeI * vGeant3[5]; // PY/PTOT
142 } else {
143 AliWarning(Form("Extrap. to Z not reached, Z = %f",Z));
144 }
956019b6 145 // Track parameters from Geant3 parameters,
146 // with charge back for forward motion
147 GetFromGeant3Parameters(vGeant3, chargeExtrap * forwardBackward);
a9e2aefa 148}
149
150 //__________________________________________________________________________
151void AliMUONTrackParam::SetGeant3Parameters(Double_t *VGeant3, Double_t ForwardBackward)
152{
153 // Set vector of Geant3 parameters pointed to by "VGeant3"
154 // from track parameters in current AliMUONTrackParam.
155 // Since AliMUONTrackParam is only geometry, one uses "ForwardBackward"
156 // to know whether the particle is going forward (+1) or backward (-1).
157 VGeant3[0] = this->fNonBendingCoor; // X
158 VGeant3[1] = this->fBendingCoor; // Y
159 VGeant3[2] = this->fZ; // Z
160 Double_t pYZ = TMath::Abs(1.0 / this->fInverseBendingMomentum);
161 Double_t pZ =
162 pYZ / TMath::Sqrt(1.0 + this->fBendingSlope * this->fBendingSlope);
163 VGeant3[6] =
164 TMath::Sqrt(pYZ * pYZ +
165 pZ * pZ * this->fNonBendingSlope * this->fNonBendingSlope); // PTOT
5b64e914 166 VGeant3[5] = -ForwardBackward * pZ / VGeant3[6]; // PZ/PTOT spectro. z<0
a9e2aefa 167 VGeant3[3] = this->fNonBendingSlope * VGeant3[5]; // PX/PTOT
168 VGeant3[4] = this->fBendingSlope * VGeant3[5]; // PY/PTOT
169}
170
171 //__________________________________________________________________________
172void AliMUONTrackParam::GetFromGeant3Parameters(Double_t *VGeant3, Double_t Charge)
173{
174 // Get track parameters in current AliMUONTrackParam
956019b6 175 // from Geant3 parameters pointed to by "VGeant3",
176 // assumed to be calculated for forward motion in Z.
a9e2aefa 177 // "InverseBendingMomentum" is signed with "Charge".
178 this->fNonBendingCoor = VGeant3[0]; // X
179 this->fBendingCoor = VGeant3[1]; // Y
180 this->fZ = VGeant3[2]; // Z
181 Double_t pYZ = VGeant3[6] * TMath::Sqrt(1.0 - VGeant3[3] * VGeant3[3]);
182 this->fInverseBendingMomentum = Charge / pYZ;
183 this->fBendingSlope = VGeant3[4] / VGeant3[5];
184 this->fNonBendingSlope = VGeant3[3] / VGeant3[5];
185}
186
187 //__________________________________________________________________________
188void AliMUONTrackParam::ExtrapToStation(Int_t Station, AliMUONTrackParam *TrackParam)
189{
190 // Track parameters extrapolated from current track parameters ("this")
191 // to both chambers of the station(0..) "Station"
192 // are returned in the array (dimension 2) of track parameters
193 // pointed to by "TrackParam" (index 0 and 1 for first and second chambers).
194 Double_t extZ[2], z1, z2;
ecfa008b 195 Int_t i1 = -1, i2 = -1; // = -1 to avoid compilation warnings
a9e2aefa 196 // range of Station to be checked ????
06c11448 197 z1 = AliMUONConstants::DefaultChamberZ(2 * Station);
198 z2 = AliMUONConstants::DefaultChamberZ(2 * Station + 1);
a9e2aefa 199 // First and second Z to extrapolate at
200 if ((z1 > this->fZ) && (z2 > this->fZ)) {i1 = 0; i2 = 1;}
201 else if ((z1 < this->fZ) && (z2 < this->fZ)) {i1 = 1; i2 = 0;}
202 else {
8c343c7c 203 AliError(Form("Starting Z (%f) in between z1 (%f) and z2 (%f) of station(0..)%d",this->fZ,z1,z2,Station));
204// cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
205// cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
206// ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
a9e2aefa 207 }
208 extZ[i1] = z1;
209 extZ[i2] = z2;
210 // copy of track parameters
211 TrackParam[i1] = *this;
212 // first extrapolation
213 (&(TrackParam[i1]))->ExtrapToZ(extZ[0]);
214 TrackParam[i2] = TrackParam[i1];
215 // second extrapolation
216 (&(TrackParam[i2]))->ExtrapToZ(extZ[1]);
217 return;
218}
219
04b5ea16 220 //__________________________________________________________________________
889a0215 221void AliMUONTrackParam::ExtrapToVertex(Double_t xVtx, Double_t yVtx, Double_t zVtx)
04b5ea16 222{
223 // Extrapolation to the vertex.
224 // Returns the track parameters resulting from the extrapolation,
225 // in the current TrackParam.
956019b6 226 // Changes parameters according to Branson correction through the absorber
04b5ea16 227
5b64e914 228 Double_t zAbsorber = -503.0; // to be coherent with the Geant absorber geometry !!!!
229 // spectro. (z<0)
04b5ea16 230 // Extrapolates track parameters upstream to the "Z" end of the front absorber
b45fd22b 231 ExtrapToZ(zAbsorber); // !!!
5b64e914 232 // Makes Branson correction (multiple scattering + energy loss)
889a0215 233 BransonCorrection(xVtx,yVtx,zVtx);
5b64e914 234 // Makes a simple magnetic field correction through the absorber
b45fd22b 235 FieldCorrection(zAbsorber);
04b5ea16 236}
237
43af2cb6 238
239// Keep this version for future developments
04b5ea16 240 //__________________________________________________________________________
43af2cb6 241// void AliMUONTrackParam::BransonCorrection()
242// {
243// // Branson correction of track parameters
244// // the entry parameters have to be calculated at the end of the absorber
245// Double_t zEndAbsorber, zBP, xBP, yBP;
246// Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
247// Int_t sign;
248// // Would it be possible to calculate all that from Geant configuration ????
249// // and to get the Branson parameters from a function in ABSO module ????
250// // with an eventual contribution from other detectors like START ????
251// // Radiation lengths outer part theta > 3 degres
252// static Double_t x01[9] = { 18.8, // C (cm)
253// 10.397, // Concrete (cm)
254// 0.56, // Plomb (cm)
255// 47.26, // Polyethylene (cm)
256// 0.56, // Plomb (cm)
257// 47.26, // Polyethylene (cm)
258// 0.56, // Plomb (cm)
259// 47.26, // Polyethylene (cm)
260// 0.56 }; // Plomb (cm)
261// // inner part theta < 3 degres
262// static Double_t x02[3] = { 18.8, // C (cm)
263// 10.397, // Concrete (cm)
264// 0.35 }; // W (cm)
265// // z positions of the materials inside the absober outer part theta > 3 degres
266// static Double_t z1[10] = { 90, 315, 467, 472, 477, 482, 487, 492, 497, 502 };
267// // inner part theta < 3 degres
268// static Double_t z2[4] = { 90, 315, 467, 503 };
269// static Bool_t first = kTRUE;
270// static Double_t zBP1, zBP2, rLimit;
271// // Calculates z positions of the Branson's planes: zBP1 for outer part and zBP2 for inner part (only at the first call)
272// if (first) {
273// first = kFALSE;
274// Double_t aNBP = 0.0;
275// Double_t aDBP = 0.0;
276// Int_t iBound;
277
278// for (iBound = 0; iBound < 9; iBound++) {
279// aNBP = aNBP +
280// (z1[iBound+1] * z1[iBound+1] * z1[iBound+1] -
281// z1[iBound] * z1[iBound] * z1[iBound] ) / x01[iBound];
282// aDBP = aDBP +
283// (z1[iBound+1] * z1[iBound+1] - z1[iBound] * z1[iBound] ) / x01[iBound];
284// }
285// zBP1 = (2.0 * aNBP) / (3.0 * aDBP);
286// aNBP = 0.0;
287// aDBP = 0.0;
288// for (iBound = 0; iBound < 3; iBound++) {
289// aNBP = aNBP +
290// (z2[iBound+1] * z2[iBound+1] * z2[iBound+1] -
291// z2[iBound] * z2[iBound ] * z2[iBound] ) / x02[iBound];
292// aDBP = aDBP +
293// (z2[iBound+1] * z2[iBound+1] - z2[iBound] * z2[iBound]) / x02[iBound];
294// }
295// zBP2 = (2.0 * aNBP) / (3.0 * aDBP);
296// rLimit = z2[3] * TMath::Tan(3.0 * (TMath::Pi()) / 180.);
297// }
298
299// pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
300// sign = 1;
301// if (fInverseBendingMomentum < 0) sign = -1;
302// pZ = pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope));
303// pX = pZ * fNonBendingSlope;
304// pY = pZ * fBendingSlope;
305// pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
306// xEndAbsorber = fNonBendingCoor;
307// yEndAbsorber = fBendingCoor;
308// radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
309
310// if (radiusEndAbsorber2 > rLimit*rLimit) {
311// zEndAbsorber = z1[9];
312// zBP = zBP1;
313// } else {
314// zEndAbsorber = z2[3];
315// zBP = zBP2;
316// }
317
318// xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
319// yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
320
321// // new parameters after Branson and energy loss corrections
322// pZ = pTotal * zBP / TMath::Sqrt(xBP * xBP + yBP * yBP + zBP * zBP);
323// pX = pZ * xBP / zBP;
324// pY = pZ * yBP / zBP;
325// fBendingSlope = pY / pZ;
326// fNonBendingSlope = pX / pZ;
327
328// pT = TMath::Sqrt(pX * pX + pY * pY);
329// theta = TMath::ATan2(pT, pZ);
330// pTotal =
331// TotalMomentumEnergyLoss(rLimit, pTotal, theta, xEndAbsorber, yEndAbsorber);
332
333// fInverseBendingMomentum = (sign / pTotal) *
334// TMath::Sqrt(1.0 +
335// fBendingSlope * fBendingSlope +
336// fNonBendingSlope * fNonBendingSlope) /
337// TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
338
339// // vertex position at (0,0,0)
340// // should be taken from vertex measurement ???
341// fBendingCoor = 0.0;
342// fNonBendingCoor = 0;
343// fZ= 0;
344// }
345
889a0215 346void AliMUONTrackParam::BransonCorrection(Double_t xVtx,Double_t yVtx,Double_t zVtx)
04b5ea16 347{
348 // Branson correction of track parameters
349 // the entry parameters have to be calculated at the end of the absorber
43af2cb6 350 // simplified version: the z positions of Branson's planes are no longer calculated
351 // but are given as inputs. One can use the macros MUONTestAbso.C and DrawTestAbso.C
352 // to test this correction.
04b5ea16 353 // Would it be possible to calculate all that from Geant configuration ????
956019b6 354 // and to get the Branson parameters from a function in ABSO module ????
355 // with an eventual contribution from other detectors like START ????
889a0215 356 //change to take into account the vertex postition (real, reconstruct,....)
357
43af2cb6 358 Double_t zBP, xBP, yBP;
359 Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
360 Int_t sign;
04b5ea16 361 static Bool_t first = kTRUE;
b45fd22b 362 static Double_t zBP1, zBP2, rLimit, thetaLimit, zEndAbsorber;
43af2cb6 363 // zBP1 for outer part and zBP2 for inner part (only at the first call)
04b5ea16 364 if (first) {
365 first = kFALSE;
43af2cb6 366
5b64e914 367 zEndAbsorber = -503; // spectro (z<0)
b45fd22b 368 thetaLimit = 3.0 * (TMath::Pi()) / 180.;
5b64e914 369 rLimit = TMath::Abs(zEndAbsorber) * TMath::Tan(thetaLimit);
370 zBP1 = -450; // values close to those calculated with EvalAbso.C
371 zBP2 = -480;
04b5ea16 372 }
373
374 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
375 sign = 1;
b8dc484b 376 if (fInverseBendingMomentum < 0) sign = -1;
377 pZ = Pz();
378 pX = Px();
379 pY = Py();
04b5ea16 380 pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
381 xEndAbsorber = fNonBendingCoor;
382 yEndAbsorber = fBendingCoor;
383 radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
384
385 if (radiusEndAbsorber2 > rLimit*rLimit) {
04b5ea16 386 zBP = zBP1;
387 } else {
04b5ea16 388 zBP = zBP2;
389 }
390
391 xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
392 yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
393
394 // new parameters after Branson and energy loss corrections
b45fd22b 395// Float_t zSmear = zBP - gRandom->Gaus(0.,2.); // !!! possible smearing of Z vertex position
889a0215 396
397 Float_t zSmear = zBP ;
b45fd22b 398
889a0215 399 pZ = pTotal * (zSmear-zVtx) / TMath::Sqrt((xBP-xVtx) * (xBP-xVtx) + (yBP-yVtx) * (yBP-yVtx) +( zSmear-zVtx) * (zSmear-zVtx) );
400 pX = pZ * (xBP - xVtx)/ (zSmear-zVtx);
401 pY = pZ * (yBP - yVtx) / (zSmear-zVtx);
04b5ea16 402 fBendingSlope = pY / pZ;
403 fNonBendingSlope = pX / pZ;
5b64e914 404
04b5ea16 405
406 pT = TMath::Sqrt(pX * pX + pY * pY);
5b64e914 407 theta = TMath::ATan2(pT, TMath::Abs(pZ));
b45fd22b 408 pTotal = TotalMomentumEnergyLoss(thetaLimit, pTotal, theta);
04b5ea16 409
410 fInverseBendingMomentum = (sign / pTotal) *
411 TMath::Sqrt(1.0 +
412 fBendingSlope * fBendingSlope +
413 fNonBendingSlope * fNonBendingSlope) /
414 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
415
416 // vertex position at (0,0,0)
417 // should be taken from vertex measurement ???
889a0215 418
419 fBendingCoor = xVtx;
420 fNonBendingCoor = yVtx;
421 fZ= zVtx;
422
04b5ea16 423}
b45fd22b 424
04b5ea16 425 //__________________________________________________________________________
b45fd22b 426Double_t AliMUONTrackParam::TotalMomentumEnergyLoss(Double_t thetaLimit, Double_t pTotal, Double_t theta)
04b5ea16 427{
428 // Returns the total momentum corrected from energy loss in the front absorber
43af2cb6 429 // One can use the macros MUONTestAbso.C and DrawTestAbso.C
430 // to test this correction.
b45fd22b 431 // Momentum energy loss behaviour evaluated with the simulation of single muons (april 2002)
04b5ea16 432 Double_t deltaP, pTotalCorrected;
433
b45fd22b 434 // Parametrization to be redone according to change of absorber material ????
956019b6 435 // See remark in function BransonCorrection !!!!
04b5ea16 436 // The name is not so good, and there are many arguments !!!!
b45fd22b 437 if (theta < thetaLimit ) {
438 if (pTotal < 20) {
439 deltaP = 2.5938 + 0.0570 * pTotal - 0.001151 * pTotal * pTotal;
04b5ea16 440 } else {
b45fd22b 441 deltaP = 3.0714 + 0.011767 *pTotal;
04b5ea16 442 }
443 } else {
b45fd22b 444 if (pTotal < 20) {
445 deltaP = 2.1207 + 0.05478 * pTotal - 0.00145079 * pTotal * pTotal;
04b5ea16 446 } else {
b45fd22b 447 deltaP = 2.6069 + 0.0051705 * pTotal;
04b5ea16 448 }
449 }
450 pTotalCorrected = pTotal + deltaP / TMath::Cos(theta);
451 return pTotalCorrected;
452}
453
b45fd22b 454 //__________________________________________________________________________
455void AliMUONTrackParam::FieldCorrection(Double_t Z)
456{
457 //
458 // Correction of the effect of the magnetic field in the absorber
459 // Assume a constant field along Z axis.
460
461 Float_t b[3],x[3];
462 Double_t bZ;
463 Double_t pYZ,pX,pY,pZ,pT;
464 Double_t pXNew,pYNew;
465 Double_t c;
466
467 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
468 c = TMath::Sign(1.0,fInverseBendingMomentum); // particle charge
469
b8dc484b 470 pZ = Pz();
471 pX = Px();
472 pY = Py();
b45fd22b 473 pT = TMath::Sqrt(pX*pX+pY*pY);
474
5b64e914 475 if (TMath::Abs(pZ) <= 0) return;
b45fd22b 476 x[2] = Z/2;
477 x[0] = x[2]*fNonBendingSlope;
478 x[1] = x[2]*fBendingSlope;
479
480 // Take magn. field value at position x.
481 gAlice->Field()->Field(x, b);
482 bZ = b[2];
483
484 // Transverse momentum rotation
485 // Parameterized with the study of DeltaPhi = phiReco - phiGen as a function of pZ.
5b64e914 486 Double_t phiShift = c*0.436*0.0003*bZ*Z/pZ;
b45fd22b 487 // Rotate momentum around Z axis.
488 pXNew = pX*TMath::Cos(phiShift) - pY*TMath::Sin(phiShift);
489 pYNew = pX*TMath::Sin(phiShift) + pY*TMath::Cos(phiShift);
490
491 fBendingSlope = pYNew / pZ;
492 fNonBendingSlope = pXNew / pZ;
493
494 fInverseBendingMomentum = c / TMath::Sqrt(pYNew*pYNew+pZ*pZ);
495
b8dc484b 496}
497 //__________________________________________________________________________
498Double_t AliMUONTrackParam::Px()
499{
500 // return px from track paramaters
501 Double_t pYZ, pZ, pX;
502 pYZ = 0;
503 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
504 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
505 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
506 pX = pZ * fNonBendingSlope;
507 return pX;
508}
509 //__________________________________________________________________________
510Double_t AliMUONTrackParam::Py()
511{
512 // return px from track paramaters
513 Double_t pYZ, pZ, pY;
514 pYZ = 0;
515 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
516 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
517 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
518 pY = pZ * fBendingSlope;
519 return pY;
520}
521 //__________________________________________________________________________
522Double_t AliMUONTrackParam::Pz()
523{
524 // return px from track paramaters
525 Double_t pYZ, pZ;
526 pYZ = 0;
527 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
528 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
529 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
530 return pZ;
531}
532 //__________________________________________________________________________
533Double_t AliMUONTrackParam::P()
534{
535 // return p from track paramaters
536 Double_t pYZ, pZ, p;
537 pYZ = 0;
538 if ( TMath::Abs(fInverseBendingMomentum) > 0 )
539 pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
540 pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
541 p = TMath::Abs(pZ) *
542 TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope + fNonBendingSlope * fNonBendingSlope);
543 return p;
544
b45fd22b 545}
4d03a78e 546 //__________________________________________________________________________
547void AliMUONTrackParam::ExtrapOneStepHelix(Double_t charge, Double_t step,
f161a467 548 Double_t *vect, Double_t *vout) const
4d03a78e 549{
550// ******************************************************************
551// * *
552// * Performs the tracking of one step in a magnetic field *
553// * The trajectory is assumed to be a helix in a constant field *
554// * taken at the mid point of the step. *
555// * Parameters: *
556// * input *
557// * STEP =arc length of the step asked *
558// * VECT =input vector (position,direction cos and momentum) *
559// * CHARGE= electric charge of the particle *
560// * output *
561// * VOUT = same as VECT after completion of the step *
562// * *
563// * ==>Called by : <USER>, GUSWIM *
564// * Author m.hansroul ********* *
565// * modified s.egli, s.v.levonian *
566// * modified v.perevoztchikov
567// * *
568// ******************************************************************
569//
570
571// modif: everything in double precision
572
573 Double_t xyz[3], h[4], hxp[3];
574 Double_t h2xy, hp, rho, tet;
575 Double_t sint, sintt, tsint, cos1t;
576 Double_t f1, f2, f3, f4, f5, f6;
577
58443fe3 578 const Int_t kix = 0;
579 const Int_t kiy = 1;
580 const Int_t kiz = 2;
581 const Int_t kipx = 3;
582 const Int_t kipy = 4;
583 const Int_t kipz = 5;
584 const Int_t kipp = 6;
4d03a78e 585
58443fe3 586 const Double_t kec = 2.9979251e-4;
4d03a78e 587 //
588 // ------------------------------------------------------------------
589 //
590 // units are kgauss,centimeters,gev/c
591 //
58443fe3 592 vout[kipp] = vect[kipp];
4d03a78e 593 if (TMath::Abs(charge) < 0.00001) {
594 for (Int_t i = 0; i < 3; i++) {
595 vout[i] = vect[i] + step * vect[i+3];
596 vout[i+3] = vect[i+3];
597 }
598 return;
599 }
58443fe3 600 xyz[0] = vect[kix] + 0.5 * step * vect[kipx];
601 xyz[1] = vect[kiy] + 0.5 * step * vect[kipy];
602 xyz[2] = vect[kiz] + 0.5 * step * vect[kipz];
4d03a78e 603
604 //cmodif: call gufld (xyz, h) changed into:
605 GetField (xyz, h);
606
607 h2xy = h[0]*h[0] + h[1]*h[1];
608 h[3] = h[2]*h[2]+ h2xy;
609 if (h[3] < 1.e-12) {
610 for (Int_t i = 0; i < 3; i++) {
611 vout[i] = vect[i] + step * vect[i+3];
612 vout[i+3] = vect[i+3];
613 }
614 return;
615 }
616 if (h2xy < 1.e-12*h[3]) {
617 ExtrapOneStepHelix3(charge*h[2], step, vect, vout);
618 return;
619 }
620 h[3] = TMath::Sqrt(h[3]);
621 h[0] /= h[3];
622 h[1] /= h[3];
623 h[2] /= h[3];
58443fe3 624 h[3] *= kec;
4d03a78e 625
58443fe3 626 hxp[0] = h[1]*vect[kipz] - h[2]*vect[kipy];
627 hxp[1] = h[2]*vect[kipx] - h[0]*vect[kipz];
628 hxp[2] = h[0]*vect[kipy] - h[1]*vect[kipx];
4d03a78e 629
58443fe3 630 hp = h[0]*vect[kipx] + h[1]*vect[kipy] + h[2]*vect[kipz];
4d03a78e 631
58443fe3 632 rho = -charge*h[3]/vect[kipp];
4d03a78e 633 tet = rho * step;
634
635 if (TMath::Abs(tet) > 0.15) {
636 sint = TMath::Sin(tet);
637 sintt = (sint/tet);
638 tsint = (tet-sint)/tet;
639 cos1t = 2.*(TMath::Sin(0.5*tet))*(TMath::Sin(0.5*tet))/tet;
640 } else {
641 tsint = tet*tet/36.;
642 sintt = (1. - tsint);
643 sint = tet*sintt;
644 cos1t = 0.5*tet;
645 }
646
647 f1 = step * sintt;
648 f2 = step * cos1t;
649 f3 = step * tsint * hp;
650 f4 = -tet*cos1t;
651 f5 = sint;
652 f6 = tet * cos1t * hp;
653
58443fe3 654 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0] + f3*h[0];
655 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1] + f3*h[1];
656 vout[kiz] = vect[kiz] + f1*vect[kipz] + f2*hxp[2] + f3*h[2];
4d03a78e 657
58443fe3 658 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0] + f6*h[0];
659 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1] + f6*h[1];
660 vout[kipz] = vect[kipz] + f4*vect[kipz] + f5*hxp[2] + f6*h[2];
4d03a78e 661
662 return;
663}
664
665 //__________________________________________________________________________
666void AliMUONTrackParam::ExtrapOneStepHelix3(Double_t field, Double_t step,
f161a467 667 Double_t *vect, Double_t *vout) const
4d03a78e 668{
669//
670// ******************************************************************
671// * *
672// * Tracking routine in a constant field oriented *
673// * along axis 3 *
674// * Tracking is performed with a conventional *
675// * helix step method *
676// * *
677// * ==>Called by : <USER>, GUSWIM *
678// * Authors R.Brun, M.Hansroul ********* *
679// * Rewritten V.Perevoztchikov
680// * *
681// ******************************************************************
682//
683
684 Double_t hxp[3];
685 Double_t h4, hp, rho, tet;
686 Double_t sint, sintt, tsint, cos1t;
687 Double_t f1, f2, f3, f4, f5, f6;
688
58443fe3 689 const Int_t kix = 0;
690 const Int_t kiy = 1;
691 const Int_t kiz = 2;
692 const Int_t kipx = 3;
693 const Int_t kipy = 4;
694 const Int_t kipz = 5;
695 const Int_t kipp = 6;
4d03a78e 696
58443fe3 697 const Double_t kec = 2.9979251e-4;
4d03a78e 698
699//
700// ------------------------------------------------------------------
701//
702// units are kgauss,centimeters,gev/c
703//
58443fe3 704 vout[kipp] = vect[kipp];
705 h4 = field * kec;
4d03a78e 706
58443fe3 707 hxp[0] = - vect[kipy];
708 hxp[1] = + vect[kipx];
4d03a78e 709
58443fe3 710 hp = vect[kipz];
4d03a78e 711
58443fe3 712 rho = -h4/vect[kipp];
4d03a78e 713 tet = rho * step;
714 if (TMath::Abs(tet) > 0.15) {
715 sint = TMath::Sin(tet);
716 sintt = (sint/tet);
717 tsint = (tet-sint)/tet;
718 cos1t = 2.* TMath::Sin(0.5*tet) * TMath::Sin(0.5*tet)/tet;
719 } else {
720 tsint = tet*tet/36.;
721 sintt = (1. - tsint);
722 sint = tet*sintt;
723 cos1t = 0.5*tet;
724 }
725
726 f1 = step * sintt;
727 f2 = step * cos1t;
728 f3 = step * tsint * hp;
729 f4 = -tet*cos1t;
730 f5 = sint;
731 f6 = tet * cos1t * hp;
732
58443fe3 733 vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0];
734 vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1];
735 vout[kiz] = vect[kiz] + f1*vect[kipz] + f3;
4d03a78e 736
58443fe3 737 vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0];
738 vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1];
739 vout[kipz] = vect[kipz] + f4*vect[kipz] + f6;
4d03a78e 740
741 return;
742}
743 //__________________________________________________________________________
744void AliMUONTrackParam::ExtrapOneStepRungekutta(Double_t charge, Double_t step,
f161a467 745 Double_t* vect, Double_t* vout) const
4d03a78e 746{
747//
748// ******************************************************************
749// * *
750// * Runge-Kutta method for tracking a particle through a magnetic *
751// * field. Uses Nystroem algorithm (See Handbook Nat. Bur. of *
752// * Standards, procedure 25.5.20) *
753// * *
754// * Input parameters *
755// * CHARGE Particle charge *
756// * STEP Step size *
757// * VECT Initial co-ords,direction cosines,momentum *
758// * Output parameters *
759// * VOUT Output co-ords,direction cosines,momentum *
760// * User routine called *
761// * CALL GUFLD(X,F) *
762// * *
763// * ==>Called by : <USER>, GUSWIM *
764// * Authors R.Brun, M.Hansroul ********* *
765// * V.Perevoztchikov (CUT STEP implementation) *
766// * *
767// * *
768// ******************************************************************
769//
770
771 Double_t h2, h4, f[4];
772 Double_t xyzt[3], a, b, c, ph,ph2;
773 Double_t secxs[4],secys[4],seczs[4],hxp[3];
774 Double_t g1, g2, g3, g4, g5, g6, ang2, dxt, dyt, dzt;
775 Double_t est, at, bt, ct, cba;
776 Double_t f1, f2, f3, f4, rho, tet, hnorm, hp, rho1, sint, cost;
777
778 Double_t x;
779 Double_t y;
780 Double_t z;
781
782 Double_t xt;
783 Double_t yt;
784 Double_t zt;
785
786 Double_t maxit = 1992;
787 Double_t maxcut = 11;
788
58443fe3 789 const Double_t kdlt = 1e-4;
790 const Double_t kdlt32 = kdlt/32.;
791 const Double_t kthird = 1./3.;
792 const Double_t khalf = 0.5;
793 const Double_t kec = 2.9979251e-4;
794
795 const Double_t kpisqua = 9.86960440109;
796 const Int_t kix = 0;
797 const Int_t kiy = 1;
798 const Int_t kiz = 2;
799 const Int_t kipx = 3;
800 const Int_t kipy = 4;
801 const Int_t kipz = 5;
4d03a78e 802
803 // *.
804 // *. ------------------------------------------------------------------
805 // *.
806 // * this constant is for units cm,gev/c and kgauss
807 // *
808 Int_t iter = 0;
809 Int_t ncut = 0;
810 for(Int_t j = 0; j < 7; j++)
811 vout[j] = vect[j];
812
58443fe3 813 Double_t pinv = kec * charge / vect[6];
4d03a78e 814 Double_t tl = 0.;
815 Double_t h = step;
816 Double_t rest;
817
818
819 do {
820 rest = step - tl;
821 if (TMath::Abs(h) > TMath::Abs(rest)) h = rest;
822 //cmodif: call gufld(vout,f) changed into:
823
824 GetField(vout,f);
825
826 // *
827 // * start of integration
828 // *
829 x = vout[0];
830 y = vout[1];
831 z = vout[2];
832 a = vout[3];
833 b = vout[4];
834 c = vout[5];
835
58443fe3 836 h2 = khalf * h;
837 h4 = khalf * h2;
4d03a78e 838 ph = pinv * h;
58443fe3 839 ph2 = khalf * ph;
4d03a78e 840 secxs[0] = (b * f[2] - c * f[1]) * ph2;
841 secys[0] = (c * f[0] - a * f[2]) * ph2;
842 seczs[0] = (a * f[1] - b * f[0]) * ph2;
843 ang2 = (secxs[0]*secxs[0] + secys[0]*secys[0] + seczs[0]*seczs[0]);
58443fe3 844 if (ang2 > kpisqua) break;
4d03a78e 845
846 dxt = h2 * a + h4 * secxs[0];
847 dyt = h2 * b + h4 * secys[0];
848 dzt = h2 * c + h4 * seczs[0];
849 xt = x + dxt;
850 yt = y + dyt;
851 zt = z + dzt;
852 // *
853 // * second intermediate point
854 // *
855
856 est = TMath::Abs(dxt) + TMath::Abs(dyt) + TMath::Abs(dzt);
857 if (est > h) {
858 if (ncut++ > maxcut) break;
58443fe3 859 h *= khalf;
4d03a78e 860 continue;
861 }
862
863 xyzt[0] = xt;
864 xyzt[1] = yt;
865 xyzt[2] = zt;
866
867 //cmodif: call gufld(xyzt,f) changed into:
868 GetField(xyzt,f);
869
870 at = a + secxs[0];
871 bt = b + secys[0];
872 ct = c + seczs[0];
873
874 secxs[1] = (bt * f[2] - ct * f[1]) * ph2;
875 secys[1] = (ct * f[0] - at * f[2]) * ph2;
876 seczs[1] = (at * f[1] - bt * f[0]) * ph2;
877 at = a + secxs[1];
878 bt = b + secys[1];
879 ct = c + seczs[1];
880 secxs[2] = (bt * f[2] - ct * f[1]) * ph2;
881 secys[2] = (ct * f[0] - at * f[2]) * ph2;
882 seczs[2] = (at * f[1] - bt * f[0]) * ph2;
883 dxt = h * (a + secxs[2]);
884 dyt = h * (b + secys[2]);
885 dzt = h * (c + seczs[2]);
886 xt = x + dxt;
887 yt = y + dyt;
888 zt = z + dzt;
889 at = a + 2.*secxs[2];
890 bt = b + 2.*secys[2];
891 ct = c + 2.*seczs[2];
892
893 est = TMath::Abs(dxt)+TMath::Abs(dyt)+TMath::Abs(dzt);
894 if (est > 2.*TMath::Abs(h)) {
895 if (ncut++ > maxcut) break;
58443fe3 896 h *= khalf;
4d03a78e 897 continue;
898 }
899
900 xyzt[0] = xt;
901 xyzt[1] = yt;
902 xyzt[2] = zt;
903
904 //cmodif: call gufld(xyzt,f) changed into:
905 GetField(xyzt,f);
906
58443fe3 907 z = z + (c + (seczs[0] + seczs[1] + seczs[2]) * kthird) * h;
908 y = y + (b + (secys[0] + secys[1] + secys[2]) * kthird) * h;
909 x = x + (a + (secxs[0] + secxs[1] + secxs[2]) * kthird) * h;
4d03a78e 910
911 secxs[3] = (bt*f[2] - ct*f[1])* ph2;
912 secys[3] = (ct*f[0] - at*f[2])* ph2;
913 seczs[3] = (at*f[1] - bt*f[0])* ph2;
58443fe3 914 a = a+(secxs[0]+secxs[3]+2. * (secxs[1]+secxs[2])) * kthird;
915 b = b+(secys[0]+secys[3]+2. * (secys[1]+secys[2])) * kthird;
916 c = c+(seczs[0]+seczs[3]+2. * (seczs[1]+seczs[2])) * kthird;
4d03a78e 917
918 est = TMath::Abs(secxs[0]+secxs[3] - (secxs[1]+secxs[2]))
919 + TMath::Abs(secys[0]+secys[3] - (secys[1]+secys[2]))
920 + TMath::Abs(seczs[0]+seczs[3] - (seczs[1]+seczs[2]));
921
58443fe3 922 if (est > kdlt && TMath::Abs(h) > 1.e-4) {
4d03a78e 923 if (ncut++ > maxcut) break;
58443fe3 924 h *= khalf;
4d03a78e 925 continue;
926 }
927
928 ncut = 0;
929 // * if too many iterations, go to helix
930 if (iter++ > maxit) break;
931
932 tl += h;
58443fe3 933 if (est < kdlt32)
4d03a78e 934 h *= 2.;
935 cba = 1./ TMath::Sqrt(a*a + b*b + c*c);
936 vout[0] = x;
937 vout[1] = y;
938 vout[2] = z;
939 vout[3] = cba*a;
940 vout[4] = cba*b;
941 vout[5] = cba*c;
942 rest = step - tl;
943 if (step < 0.) rest = -rest;
944 if (rest < 1.e-5*TMath::Abs(step)) return;
945
946 } while(1);
947
948 // angle too big, use helix
949
950 f1 = f[0];
951 f2 = f[1];
952 f3 = f[2];
953 f4 = TMath::Sqrt(f1*f1+f2*f2+f3*f3);
954 rho = -f4*pinv;
955 tet = rho * step;
956
957 hnorm = 1./f4;
958 f1 = f1*hnorm;
959 f2 = f2*hnorm;
960 f3 = f3*hnorm;
961
58443fe3 962 hxp[0] = f2*vect[kipz] - f3*vect[kipy];
963 hxp[1] = f3*vect[kipx] - f1*vect[kipz];
964 hxp[2] = f1*vect[kipy] - f2*vect[kipx];
4d03a78e 965
58443fe3 966 hp = f1*vect[kipx] + f2*vect[kipy] + f3*vect[kipz];
4d03a78e 967
968 rho1 = 1./rho;
969 sint = TMath::Sin(tet);
58443fe3 970 cost = 2.*TMath::Sin(khalf*tet)*TMath::Sin(khalf*tet);
4d03a78e 971
972 g1 = sint*rho1;
973 g2 = cost*rho1;
974 g3 = (tet-sint) * hp*rho1;
975 g4 = -cost;
976 g5 = sint;
977 g6 = cost * hp;
978
58443fe3 979 vout[kix] = vect[kix] + g1*vect[kipx] + g2*hxp[0] + g3*f1;
980 vout[kiy] = vect[kiy] + g1*vect[kipy] + g2*hxp[1] + g3*f2;
981 vout[kiz] = vect[kiz] + g1*vect[kipz] + g2*hxp[2] + g3*f3;
4d03a78e 982
58443fe3 983 vout[kipx] = vect[kipx] + g4*vect[kipx] + g5*hxp[0] + g6*f1;
984 vout[kipy] = vect[kipy] + g4*vect[kipy] + g5*hxp[1] + g6*f2;
985 vout[kipz] = vect[kipz] + g4*vect[kipz] + g5*hxp[2] + g6*f3;
4d03a78e 986
987 return;
988}
989//___________________________________________________________
f161a467 990 void AliMUONTrackParam::GetField(Double_t *Position, Double_t *Field) const
4d03a78e 991{
992 // interface to "gAlice->Field()->Field" for arguments in double precision
993
994 Float_t x[3], b[3];
995
996 x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
997
998 gAlice->Field()->Field(x, b);
999 Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
1000
1001 return;
1002 }