Draft: Fixed AlignmentUseCase when changing ROOT Unit

Changed the DetectorDataService as a "* 10 " had been introduced to convert the units. Not only it should not have been done this way, but I also be;lieve that the DetectorDataService should not play with units itself. @clemenci @jonrob what do you think ?

Core/include/Core/Units.h

@@ -18,22 +18,22 @@
 
 namespace LHCb::Detector::detail {
 
-  inline static constexpr double GaudiCentimeter    = 10.0;
+  inline static constexpr double GaudiCentimeter    = 10.0; // Gaudi/G4 units are mm
   inline static constexpr double DD4hepToLHCbCm     = GaudiCentimeter / dd4hep::centimeter;
   inline static constexpr double LHCbToDD4hepCm     = dd4hep::centimeter / GaudiCentimeter;
-  inline static constexpr double GaudiTeV           = 1.0;
-  inline static constexpr double DD4hepToLHCbEnergy = dd4hep::TeV / GaudiTeV;
+  inline static constexpr double GaudiTeV           = 1.0e6; // Gaudi/G4 units are MeV
+  inline static constexpr double DD4hepToLHCbEnergy = GaudiTeV / dd4hep::TeV;
 
   template <typename TYPE>
-  inline TYPE toLHCbLengthUnits( const TYPE length ) {
+  inline TYPE toLHCbLengthUnits( const TYPE& length ) {
     return DD4hepToLHCbCm * length;
   }
   template <typename TYPE>
-  inline TYPE toLHCbAreaUnits( const TYPE area ) {
+  inline TYPE toLHCbAreaUnits( const TYPE& area ) {
     return DD4hepToLHCbCm * DD4hepToLHCbCm * area;
   }
   template <typename TYPE>
-  inline TYPE toLHCbEnergyUnits( const TYPE energy ) {
+  inline TYPE toLHCbEnergyUnits( const TYPE& energy ) {
     return DD4hepToLHCbEnergy * energy;
   }
   inline ROOT::Math::Transform3D toLHCbLengthUnits( const ROOT::Math::Transform3D& t ) {
@@ -48,8 +48,8 @@ namespace LHCb::Detector::detail {
     t.GetComponents( dx, dy, dz );
     return {toLHCbLengthUnits( dx ), toLHCbLengthUnits( dy ), toLHCbLengthUnits( dz )};
   }
-  inline auto toLHCbLengthUnits( const ROOT::Math::XYZVector& v ) { return DD4hepToLHCbCm * v; }
-  inline auto toDD4hepUnits( const ROOT::Math::XYZVector& v ) { return LHCbToDD4hepCm * v; }
-  inline auto toDD4hepUnits( const ROOT::Math::XYZPoint& p ) { return LHCbToDD4hepCm * p; }
-
+  template <typename T>
+  inline auto toDD4hepUnits( const T& d ) {
+    return LHCbToDD4hepCm * d;
+  }
 } // End namespace LHCb::Detector::detail