[Clas12_software] geometry service meeting

[Mac Mestayer]

Hello CLAS12 software group;

Last week, I met with Yelena and Johann to discuss
algorithm issues involving the geometry of the drift chambers.
We identified a number of issues:

1- the drift chambers were designed and manufactured using
"nominal parameters": distance to the 1st wire plane, angle
to the mid-point of the 1st wire in the 1st plane, nominal
forward tilt angle of the wire planes, etc.  We realized that
there were 2 nominal angles that were implicitly set to
zero, the nominal rotation about the x and z axes.  We will
make these values explicit and set them to 0.

2- we expanded the customer pool of the drift chamber service
to include surveyors: if they enter survey numbers for the
various survey points on the chamber, the geom. service will
calculate the three displacement coordinates and the three
misalignment angles.

3- subsequent to that meeting, we decided that we would not
change the nominal parameters when new survey or alignment run
data is generated, but that we would adjust the volume, plane
and/or wire-end coordinates that we send to our various
customers: gemc, ced, TRAC

 		questions? comments? - regards, Mac

"mestayer at jlab.org", (757)-269-7252