Import Geant4 11.2.2 source tree

source/processes/optical/History

@@ -6,6 +6,14 @@ It must **not** be used as a substitute for writing good git commit messages!
 
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+## 2024-05-24 Daren Sawkey (op-V11-01-01)
+- G4OpBoundaryProcess: Calculate Fresnel reflection/refraction correctly when
+  material property TRANSMITTANCE is specified. The ratio of Fresnel
+  reflection/refraction now does not change when a non-zero transmission is
+  specified. Previously, if transmission of X% was specified, there would be
+  transmission of X% as expected, but the ratio of Fresnel refraction to
+  Fresnel reflection would be set to X%. Addressing bug 2578.
+
 ## 2023-10-27 Daren Sawkey (op-V11-01-00)
 - G4OpBoundaryProcess: verbosity of 0 silences run-time warnings
 

source/processes/optical/src/G4OpBoundaryProcess.cc

@@ -1206,9 +1206,15 @@ leap:
       E2_total = E2_perp * E2_perp + E2_parl * E2_parl;
       s2       = fRindex2 * cost2 * E2_total;
 
-      if(fTransmittance > 0.)
-        transCoeff = fTransmittance;
-      else if(cost1 != 0.0)
+      // D.Sawkey, 24 May 24
+      // Transmittance has already been taken into account in PostStepDoIt.
+      // For e.g. specular surfaces, the ratio of Fresnel refraction to
+      // reflection should be given by the math, not material property
+      // TRANSMITTANCE
+      //if(fTransmittance > 0.)
+      //  transCoeff = fTransmittance;
+      //else if(cost1 != 0.0)
+      if(cost1 != 0.0)
         transCoeff = s2 / s1;
       else
         transCoeff = 0.0;