GlueX Software meeting +minutes

[David Lawrence <davidl@jlab.org>]

Hi byte-riders,

    We will be having a software meeting again tomorrow. If you have any 
agenda items, please send them to me. (So far, we will be hearing from 
Richard on Rad-phi event generators.)

Find below the minutes from last week's software meeting.

Regards,
-David

==Minutes==

Attendees: David L.(chair), Mike W., Mark I., Elliott W., Simon T., 
Eugene C., Elton S.,

Phone: Andrei S., Benni Z., Alex O. , Richard J.

===Announcments===

* The program ''pythiagen'' is now in the repository and can be used to 
to produce HDDM files. Not all information is copied into the HDDM file 
right now since the data model doesn't currently support it. More will 
be presented on this at a future meeting.

* Elliott suggested moving the action items to another page since this 
will archive them better, even after they are completed.

== FDC Lorentz deflection/correction ==

Simon presented the current status of his efforts to include the Lorentz 
effect in the simulation and account for it in the reconstruction. He 
put the effect in some time ago, but the reconstruction is proving the 
larger portion of the work. The difficulty is that the sign of the 
correction depends on whether the track passed on the left side or right 
side of the wire. The only way to know this from the data is by looking 
at tracks formed by multiple hits. A considerable amount of work has 
been done on track finding which incorporates a Riemann fit to get the 
parameters for a segment which are then used to apply the Lorentz 
correction. The current algorithm correctly resolves the left-right 
ambiguity 70-75% of the time. Much of the inefficiency, however, may be 
coming from the region at the edge of the cell or in the region closer 
to the wire where the Lorentz effect is less important. This will be 
looked at in more detail in the future.

Residuals and momentum and angular resoultion were also presented. These 
were from single segment fits with and without the Lorentz correction. 
The momentum resolution showed significant improvement, but the angular 
resolution does not appear to be very sensitive to this effect at all.

Finally, some work was reported on segment linking to form track 
candidates than can be fit later. Some discussion was had on being more 
flexible on linking segments with a different charge which could 
possibly improve the efficiency over what was presented. This will be 
looked at.

== Wiki Authentication ==
Mark proposed removing the password protection on the Wiki required to 
simply read the pages. At the same time, the ability to have anyone 
create their own account would have to be removed. The new system would 
require them to request an account from the wiki master(s) who would 
create it for them. A vote was taken as to whether to adopt this change 
and it was unanimously accepted. Mark will implement the change.

==Action Items==

# Remove read-only password for Wiki
# Complete "Version 4" Simulation geometry document. (David, Simon)
# Put updated collaboration list in DocDB and commit list to repository 
(Zisis)
# Develop system for incorporating alternative b-fields in simulation  
(Richard and David)
# <s>Look at recent FDC geometry changes</s> (Richard)
# <s>Create an easy way to produce radiation length plots and document 
it</s> (David)
# Review the digitization scheme(s) we have now and figure out how to 
make them more coherent (??)
# <s>Remove "default" from calibration file directory path</s>(David)
# Tie HDGeant and DANA constants to single source (David)
# Output configuration parameters database from DANA

-- 

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  David Lawrence Ph.D.
  Staff Scientist                 Office: (757)269-5567   [[[  [   [ [       
  Jefferson Lab                   Pager:  (757)584-5567   [  [ [ [ [ [   
  http://www.jlab.org/~davidl     davidl@jlab.org         [[[  [[ [[ [[[
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