[Halld-offline] changes to the CDC geometry

[Richard Jones]

Hello all,

I just checked in some changes to the CDC geometry. These are small tweaks
to the stereo layer angles, as suggested by Beni at the last collaboration
meeting. He noticed back last winter that the co-alignment of the
closest-packed layer pairs on the stereo layers was off at the level of
0.01 degrees or so. I have corrected this and now the alignment should
agree with ideal closest-packed geometry with accuracy at the level of a
micron or so, assuming that the straw ring radii in hdds were correct.

I have checked the geometry visually in hdgeant, and it looks fine. Just be
aware that this change has gone in, and alert me if any weird
inefficiencies show up in the tracking that you had not seen before.

-Richard J.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/halld-offline/attachments/20140627/7a8dd894/attachment-0002.html>