Method to translate TOF cluster to nominal sector frame

Author: shahor02

DataFormats/Detectors/TOF/include/DataFormatsTOF/Cluster.h

@@ -49,14 +49,19 @@ class Cluster : public o2::BaseCluster<float>
          kDownRight = 4, // 2^4, 5th bit
          kDown = 5,      // 2^5, 6th bit
          kDownLeft = 6,  // 2^6, 7th bit
-         kLeft = 7 };    // 2^7, 8th bit
+         kLeft = 7,      // 2^7, 8th bit
+         //
+         FrameBit = 6 }; // this bit set means that the cluster is in the nominal (alpha=20*sector+10 deg.) sector frame rather than aligned
 
   Cluster() = default;
 
   Cluster(std::int16_t sensid, float x, float y, float z, float sy2, float sz2, float syz, double timeRaw, double time, float tot, int L0L1latency, int deltaBC, float geanttime = 0.0, double t0 = 0.0);
 
   ~Cluster() = default;
 
+  bool isInNominalSector() const { return isBitSet(FrameBit); }
+  void setInNominalSector() { setBit(FrameBit); }
+
   std::int8_t getSector() const { return getCount(); }
   void setSector(std::int8_t value) { setCount(value); }
 

Detectors/TOF/base/include/TOFBase/Geo.h

@@ -66,6 +66,8 @@ class Geo
   static void antiRotateToSector(Float_t* xyz, Int_t isector);
   static void antiRotateToStrip(Float_t* xyz, Int_t iplate, Int_t istrip, Int_t isector);
 
+  static void alignedToNominalSector(Float_t* xyz, Int_t isector);
+
   static void antiRotate(Float_t* xyz, Double_t rotationAngles[6]);
   static void getDetID(Float_t* pos, Int_t* det);
   static Int_t getIndex(const Int_t* detId);               // Get channel index from det Id (for calibration mainly)

Detectors/TOF/base/src/Geo.cxx

@@ -988,6 +988,7 @@ void Geo::translate(Float_t* xyz, Float_t translationVector[3])
 
   return;
 }
+
 void Geo::translate(Float_t& x, Float_t& y, Float_t& z, Float_t translationVector[3])
 {
   //
@@ -1045,6 +1046,18 @@ void Geo::rotateToSector(Float_t* xyz, Int_t isector)
   return;
 }
 
+void Geo::alignedToNominalSector(Float_t* xyz, Int_t isector)
+{
+  // rotate from the aligned sector frame coordinates to nominal ones (i.e. alpha=20*sector+10 deg.)
+  constexpr float CS[18] = {.848077e-01, 8.660254e-01, 6.427876e-01, 3.420202e-01, -4.371139e-08, -3.420201e-01, -6.427876e-01, -8.660254e-01, -9.848077e-01, -9.848077e-01, -8.660254e-01, -6.427875e-01, -3.420201e-01, 1.192488e-08, 3.420201e-01, 6.427875e-01, 8.660253e-01, 9.848078e-01};
+  constexpr float SN[18] = {1.736482e-01, 5.000000e-01, 7.660444e-01, 9.396926e-01, 1.000000e+00, 9.396926e-01, 7.660444e-01, 5.000001e-01, 1.736483e-01, -1.736482e-01, -5.000000e-01, -7.660446e-01, -9.396927e-01, -1.000000e+00, -9.396926e-01, -7.660445e-01, -5.000002e-01, -1.736480e-01};
+  Float_t xyzDummy[3] = {xyz[1], xyz[2], xyz[0]};      // go to twisted coordinates...
+  o2::tof::Geo::antiRotateToSector(xyzDummy, isector); // lab coordinates
+  xyz[0] = xyzDummy[0] * CS[isector] + xyzDummy[1] * SN[isector];
+  xyz[1] = -xyzDummy[0] * SN[isector] + xyzDummy[1] * CS[isector];
+  xyz[2] = xyzDummy[2];
+}
+
 void Geo::antiRotateToStrip(Float_t* xyz, Int_t iplate, Int_t istrip, Int_t isector)
 {
   Float_t xyzDummy[3] = {0., 0., 0.};