Seth R. Johnson

Ah excellent, yes you are quite right, we can support reentry like that: we should be able to handle a lot of direction changes "on" the surface without losing tracks...

Next step: - Hardcode global `kREFLECTIVITY` for all surfaces (to be moved into and expanded to SurfacePhysicsParams) - Implement surface interaction with reflection + transmission Later work: * Import G4...

converted to mermaid: ```mermaid flowchart TD A{{Determine Local Normal}} --> B1[Default: Global Normal] A --> B2[UNIFIED sigma_alpha] A --> B3[GliSurface] B1 --> C{{Calculate Reflectivity}} B2 --> C B3 --> C...

From the discussion with @stognini and @hhollenb ## Geometry surface mapping @sethrj Done via GeoParams: - {pv, pv} -> border (interface) -> SurfaceId - {lv} -> skin (boundary) -> SurfaceId...

From Friday morning's discussion: - Support instantiating boundary crossing action twice - Add outward surface normal - Add a "paused" (nomenclature TBD) action ID for being on a surface -...

Notes from our surface discussion today (@hhollenb , @Rashika-Gupta , @amandalund , @stognini , @whokion ): Independent of model: - Reflectivity (depends on neighbor materials, user provided properties) - Applying...

Next steps: 1. Add surface/volume properties to core and optical params (@amandalund ) 2. Extend "init boundary" to look up surface ID and kill (no need for SD check) if...

That's amazing @hhollenb ! Thanks for that.

1. Volume surface selector: map before/after geo state to surface ID (@hhollenb ) 2. Surface model class (without currently inheriting from a step action!) that returns vector of surface layers...

**NAMING** agreed upon by @sethrj @stognini @amandalund @Rashika-Gupta Roughness types: polished, smear [used by GLISUR], gaussian [used by UNIFIED] Reflection types: grid [user defined], analytic [Fresnel equations] Interaction types: DielectricDielectric,...