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Hello,

Along with Sho, I was looking at the "new" HPS ECal flange model that was created by one of Maurik's students, and it seems there are a number of problems with it that we've identified:

1) The back plate is missing.
2) There is an additional top plate that is also missing.  (Sho has more info on this.)
3) There is a small gap between the photon tube and the plate it sits alongside, at the back of the flange.
4) The connector between the photon and electron tubes seems to have an overlap with the electron box.
5) The angles between the electron box, which has some angle to it that increases in the beam direction, do not seem to exactly match those of some of the components that sit alongside it, which could explain some of these other issues.

This could be hard to understand in description, so I've attached some files, including two screenshots and the VRML file I used to take them.

I used the Deep View VRML viewer to look at the file.

Sho has looked in detail at the GDML file, but we're not sure exactly how to go about fixing it in order to make it match the CAD or "as built" version.  Any suggestions would be welcome.  I'm not sure either of us has the necessary time to do this right now.

I would actually like to get more information from Maurik on how this file was generated, as the GDML does not look hand-generated.  Was there some kind of script used?  If so, would it be possible to get a copy?

My feeling is that #1 and #2 could have an impact on the simulation, as extra dead material could lead to increased showering and backsplash into the calorimeter.  The other minor geometric errors are not likely to have as much effect, though overlaps should be avoided as they can lead to strange and sometimes wrong behavior in the Geant4 tracking  engine when the geometry is simulated.

Let me know if you have any questions or comments.

And please make sure to keep hps-software in the reply list so everyone can participate in this discussion.  Thanks.

--Jeremy

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