TRD/AliTRDltuTracklet.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
   5  * Contributors are mentioned in the code where appropriate.              *
   6  *                                                                        *
   7  * Permission to use, copy, modify and distribute this software and its   *
   8  * documentation strictly for non-commercial purposes is hereby granted   *
   9  * without fee, provided that the above copyright notice appears in all   *
  10  * copies and that both the copyright notice and this permission notice   *
  11  * appear in the supporting documentation. The authors make no claims     *
  12  * about the suitability of this software for any purpose. It is          *
  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 ///////////////////////////////////////////////////////////////////////////////
  17 //                                                                           //
  18 //                                                                           //
  19 //  TRD chamber local track (LTU, tracklet)                                  //
  20 //                                                                           //
  21 //                                                                           //
  22 ///////////////////////////////////////////////////////////////////////////////
  23
  24 #include <TMath.h>
  25
  26 #include "AliTRDltuTracklet.h"
  27
  28 ClassImp(AliTRDltuTracklet)
  29
  30 //_____________________________________________________________________________
  31 AliTRDltuTracklet::AliTRDltuTracklet(Int_t det,
  32                                      Int_t row,
  33                                      Float_t rowz,
  34                                      Float_t slope,
  35                                      Float_t offset,
  36                                      Float_t time,
  37                                      Int_t ncl,
  38                                      Int_t label,
  39                                      Float_t q)
  40 {
  41   //
  42   // AliTRDltuTracklet constructor
  43   //
  44
  45   fDetector  = det;
  46   fRow       = row;
  47   fRowz      = rowz;
  48   fSlope     = slope;
  49   fX         = time;
  50   fY         = offset;
  51   fNclusters = ncl;
  52   fLabel     = label;
  53   fQ         = q;
  54
  55 }
  56
  57 //_____________________________________________________________________________
  58 AliTRDltuTracklet::~AliTRDltuTracklet()
  59 {
  60   //
  61   // destructor
  62   //
  63
  64 }
  65
  66 //_____________________________________________________________________________
  67 Float_t AliTRDltuTracklet::GetPt(Float_t field) const
  68 {
  69   // transverse momentum calculation
  70   // curvature R = (fX*fX + fY*fY) / (2 * sin(alpha))
  71   // alpha = angle deviation from "infinite momentum"
  72   //
  73   // consistent with AliTRDmcmTracklet::GetPt(...)
  74
  75   Float_t infSlope = TMath::ATan(fY/fX)/TMath::Pi()*180.0;
  76   Float_t alpha = fSlope - infSlope;
  77   Float_t r = TMath::Sqrt(fX*fX + fY*fY)/(2.0*TMath::Sin(alpha/180.0*TMath::Pi()));
  78
  79   Float_t pt = 0.3 * field * 0.01 * r;
  80
  81   return pt;
  82
  83 }
  84
  85 //_____________________________________________________________________________
  86 Int_t AliTRDltuTracklet::Compare(const TObject * o) const
  87 {
  88   //
  89   // compare two LTU tracklets according to the intercept point Y1
  90   //
  91
  92   AliTRDltuTracklet *ltutrk = (AliTRDltuTracklet*)o;
  93
  94   if (fRow      != ltutrk->fRow)      return +1;
  95   if (fDetector != ltutrk->fDetector) return +1;
  96
  97   if (fY <  ltutrk->fY) return -1;
  98   if (fY == ltutrk->fY) return  0;
  99
 100   return 1;
 101
 102 }
 103
 104 //_____________________________________________________________________________
 105 Float_t AliTRDltuTracklet::GetYproj(Float_t xpl) const
 106 {
 107   //
 108   // y-projection (bending plane) onto the median plane
 109   //
 110
 111   Float_t yproj;
 112
 113   yproj = fY + TMath::Tan(fSlope/180.0*TMath::Pi()) * (xpl - fX);
 114
 115   return yproj;
 116
 117 }
 118
 119 //_____________________________________________________________________________
 120 Float_t AliTRDltuTracklet::GetZproj(Float_t xpl) const
 121 {
 122   //
 123   // z-projection (using pad row center) onto the median plane
 124   //
 125
 126   Float_t zproj;
 127
 128   zproj = fRowz * xpl / fX;
 129
 130   return zproj;
 131
 132 }
 133