Import Geant4 10.5.1 source tree

source/processes/electromagnetic/xrays/History

@@ -16,6 +16,10 @@ committal in the CVS repository !
      * Reverse chronological order (last date on top), please *
      ----------------------------------------------------------
 
+15 March 19: D. Sawkey (xrays-V10-04-06)
+- G4Cerenkov: increase protection against infinite loops
+    (backport of xrays-V10-05-00)
+
 20 September 18: D. Sawkey (xrays-V10-04-05)
 - G4Cerenkov, G4Scintillation. Reset fNumPhotons to 0 correctly each step.
   Fixes bug 2056.

source/processes/electromagnetic/xrays/src/G4Cerenkov.cc

@@ -552,8 +552,9 @@ G4double G4Cerenkov::PostStepGetPhysicalInteractionLength(
   G4double Step = Range - RangeMin;
 
   // If the step is smaller than 1e-16 mm, it may happen that the particle
-  // does not move. See bug 1992. 
-  if (Step < 1.e-16*mm) return StepLimit;
+  // does not move. See bug 1992.
+  //  2019-03-11: change to 1e-15
+  if (Step < 1.e-15*mm) return StepLimit;
 
   if (Step < StepLimit) StepLimit = Step; 
   // If user has defined an average maximum number of photons to