Meeting and update to HDGeant (fwd)

[Elton Smith <elton@jlab.org>]

Dear collaborators,

Tomorrow we will meet at 9:00 am and go over Dave's progress on trigger
simulations. It seems that Richard has just put new tags to identify
tracks in the event (see below), which is what we have been waiting for.

See you tomorrow,  Elton.


-- 
Elton Smith
Jefferson Lab
elton@jlab.org
(757) 269-7625

---------- Forwarded message ----------
Date: Tue, 18 Dec 2001 15:54:08 -0500
From: Richard Jones <richard.t.jones@uconn.edu>
To: halld-mc@jlab.org
Subject: update to HDGeant

Dear colleagues,

After taking a look at the model of the Central Drift Chamber (CDC) that
Curtis brought to the November meeting, I knew that my geometry model had
the stereo layers put in wrong.  Since then Curtis sent me a program that
he used to determine the drilling hole positions in the end plates, which
I used to correct the Hall D geometry model.  Unlike before when I tried
to use the description in HDFast.db to guess what it was supposed to look
like, now the layers actually fit without straws overlapping each other.
I have checked in the new geometry into cvs.  To get it you can just do
cvs checkout hdds.  There are now 23 layers instead of 22, the stereo
layers are in a different order, and so on.  Basically things have
changed.

At the meeting I also learned that the cathode strips the HDFast.db has on
the inner and outer CDC windows are not currently a part of the design.
I see that they are still defined in the HDFast geometry.  Has someone
checked to see what happens to our polar angle resolution when these are
removed?  I am not suggesting that we put them back in, but just asking if
the resolution studies are consistent with the current detector design.
If so then it would be helpful to get the working version of HDFast.db
into cvs so we are all looking at the same detector description.

In response to a request from Dave Doughty, I have added a new track
parameter to the <point> and <shower> tags.  They are there to aid in the
development of reconstruction code by giving the "true" values of the
track/plane intersections and shower coordinates.  From the track="int"
parameter you can tell which points go together when stitching track
segments together.  The track number is just the number that Geant assigns
to a final-state particle at the beginning of an event, and gets inherited
by all of its secondaries.  Yes, photons have "track" numbers too.

To get and run the new code, you need to cvs update your hddm and HDGeant
areas in cvs and rebuild hdgeant from sources.

Richard Jones