Add getters for global pos/slope of TRD tracklets

Author: martenole

DataFormats/Detectors/TRD/include/DataFormatsTRD/Constants.h

@@ -42,8 +42,10 @@ constexpr int NCOLMCM = 18;     // the number of pads per MCM
 
 constexpr int NBITSTRKLPOS = 11;                   // number of bits for position in tracklet64 word
 constexpr int NBITSTRKLSLOPE = 8;                  // number of bits for slope in tracklet64 word
-constexpr float GRANULARITYTRKLPOS = 1.f / 75;     // granularity of position in tracklet64 word in pad-widths
-constexpr float GRANULARITYTRKLSLOPE = 1.f / 1000; // granularity of slope in tracklet64 word in pads/timebin
+constexpr float PADGRANULARITYTRKLPOS = 80.f;
+constexpr float PADGRANULARITYTRKLSLOPE = 1000.f;
+constexpr float GRANULARITYTRKLPOS = 1.f / PADGRANULARITYTRKLPOS;     // granularity of position in tracklet64 word in pad-widths
+constexpr float GRANULARITYTRKLSLOPE = 1.f / PADGRANULARITYTRKLSLOPE; // granularity of slope in tracklet64 word in pads/timebin
 
 // OS: Should this not be flexible for example in case of Kr calib?
 constexpr int TIMEBINS = 30; // the number of time bins

DataFormats/Detectors/TRD/include/DataFormatsTRD/Tracklet64.h

@@ -81,6 +81,8 @@ class Tracklet64
   // ----- Getters for tracklet information -----
   int getMCM() const { return 4 * (getPadRow() % 4) + getColumn(); }                                 // returns MCM position on ROB [0..15]
   int getROB() const { return (getHCID() % 2) ? (getPadRow() / 4) * 2 + 1 : (getPadRow() / 4) * 2; } // returns ROB number [0..5] for C0 chamber and [0..7] for C1 chamber
+  float getY() const;                                                                                // translate local position into global y (in cm)
+  float getDy(float nTbDrift = 19.4f) const;                                                         // translate local slope into dy/dx with dx=3m (drift length) and default drift time in time bins (19.4 timebins / 3cm)
 
   // ----- Getters for offline corresponding values -----
   int getDetector() const { return getHCID() / 2; }

DataFormats/Detectors/TRD/src/Tracklet64.cxx

@@ -9,6 +9,7 @@
 // or submit itself to any jurisdiction.
 
 #include "DataFormatsTRD/Tracklet64.h"
+#include "DataFormatsTRD/Constants.h"
 
 #include "fairlogger/Logger.h"
 #include <iostream>
@@ -19,6 +20,37 @@ namespace o2
 namespace trd
 {
 
+using namespace constants;
+
+float Tracklet64::getY() const
+{
+  int padLocalBin = getPosition();
+  int padLocal = 0;
+  if (padLocalBin & (1 << (NBITSTRKLPOS - 1))) {
+    padLocal = -((~(padLocalBin - 1)) & ((1 << NBITSTRKLPOS) - 1));
+  } else {
+    padLocal = padLocalBin & ((1 << NBITSTRKLPOS) - 1);
+  }
+  int mcmCol = (getMCM() % NMCMROBINCOL) + NMCMROBINCOL * (getROB() % 2);
+  float offset = -63.f + ((float)NCOLMCM) * mcmCol;
+  float padWidth = 0.635f + 0.03f * (getDetector() % NLAYER);
+  return (offset + padLocal * GRANULARITYTRKLPOS) * padWidth;
+}
+
+float Tracklet64::getDy(float nTbDrift) const
+{
+  float dy;
+  int dyLocalBin = getSlope();
+  if (dyLocalBin & (1 << (NBITSTRKLSLOPE - 1))) {
+    dy = (~(dyLocalBin - 1)) & ((1 << NBITSTRKLSLOPE) - 1);
+    dy *= -1.f;
+  } else {
+    dy = dyLocalBin & ((1 << NBITSTRKLSLOPE) - 1);
+  }
+  float padWidth = 0.635f + 0.03f * (getDetector() % NLAYER);
+  return dy * GRANULARITYTRKLSLOPE * padWidth * nTbDrift;
+}
+
 void Tracklet64::printStream(std::ostream& stream) const
 {
   stream << "Tracklet64 : 0x" << std::hex << getTrackletWord();

Detectors/TRD/simulation/src/TrapSimulator.cxx

@@ -1920,9 +1920,9 @@ void TrapSimulator::fitTracklet()
   yoffs = yoffs << decPlaces; // holds position of ADC channel 1
 
   // we need to scale the offset since we want to store it in units of 1/80 pad and the calculation is done in 1/256 pad width granularity
-  unsigned int scaleY = (unsigned int)(80. / 256. * shift);
+  unsigned int scaleY = (unsigned int)(PADGRANULARITYTRKLPOS / 256. * shift);
   // the slope is given in units of 1/1000 pads/timebin
-  unsigned long scaleD = (unsigned long)(1000. / 256. * shift);
+  unsigned long scaleD = (unsigned long)(PADGRANULARITYTRKLSLOPE / 256. * shift);
   LOG(debug) << "scaleY : " << scaleY << "  scaleD=" << scaleD << " shift:" << std::hex << shift << std::dec;
   int deflCorr = (int)mTrapConfig->getDmemUnsigned(mgkDmemAddrDeflCorr, mDetector, mRobPos, mMcmPos);
   int ndrift = (int)mTrapConfig->getDmemUnsigned(mgkDmemAddrNdrift, mDetector, mRobPos, mMcmPos);