[Hps] ECal geometry

[McCormick, Jeremy I.]

Hi,

Just wanted to double check some of these ECal survey/alignment numbers that have gone into our latest detector description...

ECal front face --> distance in Z to front of ECal crystals
152.4 cm

ECal dX --> displacement of ECal along X axis
4.127 cm

Flange front face --> distance in Z to front of vacuum flange
137.0 cm

For the last one (distance to flange), I am not certain the information I have is being interpretted correctly, so that one could use tweaking.
 
The coordinate origin is the center of the target for electron running, which wasn't actually present in the test run.  But as I understand it, all the numbers going into the geometry are based on this reference point.

Here are a few snapshots from Geant4 of this geometry...

http://www.slac.stanford.edu/~jeremym/hps/new_flange2.png
http://www.slac.stanford.edu/~jeremym/hps/new_flange.png

Here is the reference doc sent around earlier with some ECal numbers...

http://www.slac.stanford.edu/~jeremym/hps/ecal_alignment_position.pdf

Once these numbers are verified, we'd like to make a stable geometry definition to be used in simulations for PAC results.

If there are any corrections or questions, please just reply to the HPS list, not just me.

Thanks.

--Jeremy