[Shms_users] Hall C 12 GeV software update (mailing list & request for additional info)

[Brad Sawatzky]

On Tue, 23 Aug 2011, Rolf Ent wrote:

> >       - compare track reconstruction event-by-event
> >         - It would be disconcerting if there are significant
> >         differences between what the "Hall A" tracking algorithms
> >         generate and what the FORTRAN analyzer ends up with.  I
> >         would like to think there is minimal special case "magic" in
> >         either tracking codes.
> >
> >Keep in mind that the tracking algorithm for the Hall A HRS has been
> >specifically written for our set of VDCs. I don't think you have VDC
> >reconstruction in your Fortran analyzer, or do you? Even if you do, I
> >do think there may very well be "special case magic". I doubt such a
> >comparison would work out of the box. But yes, we did the same thing,
> >we compared Fortran and C++ tracking output in exhaustive detail -
> >after we wrote the C++ tracking code from scratch.
> 
> Ole is correct, it is a non-starter to assume the tracking codes will
> give similar results given that the Hall A setup uses VDCs. Even more,
> the Hall C tracking analysis has been painstakingly optimized with
> various "pruning" additions to have a well-known tracking efficiency
> for very high rates within the spectrometer, with many bells and
> whistles how to check it.  Given this, my point of view would be that
> the starting point to optimize for the precision L/T program in Hall C
> should be the robust Hall C tracking algorithm. Maybe one could argue
> we should update the documentation if for instance Eric Christy's
> tracking note is not readily accessible, and adding sections from
> Vladas Tvaskis' thesis.  Don Geesaman did a good job doing the initial
> documentation.

Fair enough.  I had been thinking of using the new algorithm Ole first
implemented for BigBite as a starting point, but whatever works.  Bottom
line is that we need to make sure any new code matches the output of the
old code (or, at least, that any differences are understood).

It would be very helpful to get pointers/links to any tracking notes and
other docs posted to one or both of these pages, if only to get them in
one place.
  https://hallcweb.jlab.org/wiki/index.php/Hall_c_soft_main
  https://hallcweb.jlab.org/analysis_documentation/

-- Brad

-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov