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 //  Author:                                                                  //
  22 //    Bogdan Vulpescu                                                        //
  23 //                                                                           //
  24 ///////////////////////////////////////////////////////////////////////////////
  25
  26 #include <TMath.h>
  27
  28 #include "AliTRDltuTracklet.h"
  29
  30 ClassImp(AliTRDltuTracklet)
  31
  32 //_____________________________________________________________________________
  33 AliTRDltuTracklet::AliTRDltuTracklet()
  34   :TObject()
  35   ,fX(0)
  36   ,fY(0)
  37   ,fSlope(0)
  38   ,fRowz(0)
  39   ,fDetector(0)
  40   ,fRow(0)
  41   ,fNclusters(0)
  42   ,fLabel(0)
  43   ,fQ(0)
  44 {
  45   //
  46   // AliTRDltuTracklet default constructor
  47   //
  48
  49 }
  50
  51 //_____________________________________________________________________________
  52 AliTRDltuTracklet::AliTRDltuTracklet(Int_t det, Int_t row, Float_t rowz
  53                                    , Float_t slope, Float_t offset, Float_t time
  54                                    , Int_t ncl, Int_t label, Float_t q)
  55   :TObject()
  56   ,fX(time)
  57   ,fY(offset)
  58   ,fSlope(slope)
  59   ,fRowz(rowz)
  60   ,fDetector(det)
  61   ,fRow(row)
  62   ,fNclusters(ncl)
  63   ,fLabel(label)
  64   ,fQ(q)
  65 {
  66   //
  67   // AliTRDltuTracklet constructor
  68   //
  69
  70 }
  71
  72 //_____________________________________________________________________________
  73 AliTRDltuTracklet::~AliTRDltuTracklet()
  74 {
  75   //
  76   // Destructor
  77   //
  78
  79 }
  80
  81 //_____________________________________________________________________________
  82 Float_t AliTRDltuTracklet::GetPt(Float_t field) const
  83 {
  84   //
  85   // Transverse momentum calculation
  86   // Curvature R = (fX*fX + fY*fY) / (2 * sin(alpha))
  87   // alpha = angle deviation from "infinite momentum"
  88   //
  89   // Consistent with AliTRDmcmTracklet::GetPt(...)
  90   //
  91
  92   Float_t infSlope = TMath::ATan(fY/fX) / TMath::Pi()*180.0;
  93   Float_t alpha    = fSlope - infSlope;
  94   Float_t r        = TMath::Sqrt(fX*fX + fY*fY)
  95                    / (2.0 * TMath::Sin(alpha/180.0*TMath::Pi()));
  96
  97   Float_t pt       = 0.3 * field * 0.01 * r;
  98
  99   return pt;
 100
 101 }
 102
 103 //_____________________________________________________________________________
 104 Int_t AliTRDltuTracklet::Compare(const TObject *o) const
 105 {
 106   //
 107   // compare two LTU tracklets according to the intercept point Y1
 108   //
 109
 110   AliTRDltuTracklet *ltutrk = (AliTRDltuTracklet *) o;
 111
 112   if (fRow      != ltutrk->fRow) {
 113     return +1;
 114   }
 115   if (fDetector != ltutrk->fDetector) {
 116     return +1;
 117   }
 118
 119   if (fY <  ltutrk->fY) {
 120     return -1;
 121   }
 122   if (fY == ltutrk->fY) {
 123     return  0;
 124   }
 125
 126   return 1;
 127
 128 }
 129
 130 //_____________________________________________________________________________
 131 Float_t AliTRDltuTracklet::GetYproj(Float_t xpl) const
 132 {
 133   //
 134   // y-projection (bending plane) onto the median plane
 135   //
 136
 137   Float_t yproj = fY + TMath::Tan(fSlope/180.0*TMath::Pi()) * (xpl - fX);
 138
 139   return yproj;
 140
 141 }
 142
 143 //_____________________________________________________________________________
 144 Float_t AliTRDltuTracklet::GetZproj(Float_t xpl) const
 145 {
 146   //
 147   // z-projection (using pad row center) onto the median plane
 148   //
 149
 150   Float_t zproj = fRowz * xpl / fX;
 151
 152   return zproj;
 153
 154 }
 155