diff --git a/DDRec/include/DDRec/DetectorData.h b/DDRec/include/DDRec/DetectorData.h
index 287b54ae974ed6a713fa3f5bc5f6291c046954c5..8bf146dcd6c6f516e3a365f6678452a9548499e6 100644
--- a/DDRec/include/DDRec/DetectorData.h
+++ b/DDRec/include/DDRec/DetectorData.h
@@ -389,7 +389,7 @@ namespace DD4hep {
 	
 	Layer() :
 	  distance(0),
-	  thickness(0),
+	  phi0(0),
 	  absorberThickness(0),
 	  inner_nRadiationLengths(0),
 	  inner_nInteractionLengths(0),        
@@ -405,10 +405,10 @@ namespace DD4hep {
 	/// distance from Origin (or the z-axis) to the inner-most face of the layer
 	double distance;
         
-	/// DEPRECATED: total thickness of the layer. Use inner/outer thicknesses instead
-	double thickness ;
+	/// phi0 of layer: potential rotation around normal to absorber plane, e.g. if layers are 'staggered' in phi in fwd. calos 
+	double phi0 ;
 	
-        /// DEPRECATED: thickness of the absorber part of the layer. Use instead number of X0, lambdaI in and out
+        /// thickness of the absorber part of the layer. Consider using inner/outer_nRadiationLengths and inner/outer_nInteractionLengths
 	double absorberThickness ;
         
         ///Absorber material in front of sensitive element in the layer, units of radiation lengths
diff --git a/DDRec/include/DDRec/Material.h b/DDRec/include/DDRec/Material.h
index ecdd3abc8b01591b9f26b09ae491b4a9eaf513b6..077f7aa34d273602962564804a75875c2d1987c7 100644
--- a/DDRec/include/DDRec/Material.h
+++ b/DDRec/include/DDRec/Material.h
@@ -84,8 +84,20 @@ namespace DD4hep {
 					    _x0( m.radiationLength() ),
 					    _lambda( m.interactionLength() ) {}
       
+      /// copy assignement
+       MaterialData& operator=(const MaterialData& m){
+        if ( this != &m )  {
+          _name = m._name ;
+          _Z = m._Z ;
+          _A = m._A  ;
+          _rho = m._rho ;
+          _x0 = m._x0 ;
+          _lambda = m._lambda ;
+        }
+        return *this ;
+      }
 
-      /// assignment from Geometry::Material
+     /// assignment from Geometry::Material
       MaterialData& operator=(const IMaterial& m){
         if ( this != &m )  {
           _name = m.name() ;