[Halld-offline] Offline Software Meeting Minutes, September 3, 2014

[Mark Ito]

Folks,

Please find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_September_3,_2014#Minutes 
.

   -- Mark
__________________________

GlueX Offline Meeting, September 3, 2014
Minutes

    Present:
      * CMU: Paul Mattione, Curtis Meyer
      * IU: Kei Moriya, Matt Shepherd
      * JLab: Alex Barnes, Mark Dalton, Mark Ito (chair), David Lawrence,
        Will McGinley, Elton Smith, Mike Staib, Simon Taylor
      * MIT: Justin Stevens
      * NU: Sean Dobbs

Collaboration Meeting Agenda

    We took a look at the [27]Collaboration Meeting page. There are
    nominally 4 30-min slots for the offline starting at 4:00 pm Friday.
    Mark will make a proposal.

    David suggested that part of someone's presentation should include a
    list of software projects so that collaborators can volunteer
    themselves or others for needed tasks.

Review of Minutes from the Last Meeting

    We went over the [28]minutes from the August 20 meeting.

    In the context of Ryan's presentation on multi-pion final states, Matt
    commented that he, Ryan, and Paul did a detailed comparison of Ryan's
    software and Paul's analysis library, down to comparing single events.
    With a lot of back and forth to clarify/resolve differences the
    agreement between the two is "perfect in some very difficult to
    reproduce, slightly obscure way".

Tagger Simulation Update

    Richard Jones was in transit to JLab with the tagger microscope and
    could not participate in the meeting, but we noted [29]his email
    announcing the merge from his development branch onto the trunk and
    looked at the [30]long list of files changed on the trunk.

    Sean did some checking with the new code; see his report below.

Simulating the Commissioning Geometry

    Simon is done with putting in the geometry changes associated with the
    commissioning configuration. He as not done a check for overlaps yet.

    Sean is putting together a set of configuration files do drive
    large-scale simulation using this geometry. Simon has done some tests
    as well.

Comparing Simulated HDDM and EVIO Files

    Sean has done comparisons between hit information between simulation
    native output (HDDM format) and EVIO data derived from same using the
    new trunk from Richard (see above). In most cases the agreement is very
    good. An exception is the number of tracks at the wire-based stage
    which shows about twice as many tracks for EVIO. This needs to be
    tracked down.

    For the complete set of comparisons see [31]Sean's slides.

    We discussed a feature of the HDDM to EVIO conversion where a 100 ns
    offset is added to all times so that they come out positive (and thus
    TDC-like). Richard added an offset to each of the appropriate "hit"
    factories in sim-recon to take out this offset to restore times to
    their original values. We discussed alternate solutions to this
    problem, including adding a global offset or putting values in the CCDB
    for the Monte Carlo variation (which Sean has already implemented), but
    decided not to decide until Richard can be included in the discussion.

Calibration Constant Style

    Mark D. raised the issue of a policy on how we implement constants for
    multi-channel systems. There are two styles being used:
     1. One global factor to get all channels "into the ballpark" and
        channel-by-channel factors for fine adjustment.
     2. Channel-by-channel factors only.

    (Not all constants are factors, but this exemplifies the issue.)

    Elton argued that style (1) leads to confusion in the long term since
    the "true meaning" of the global factor can change from generation to
    generation of calibrators, making historical comparisons difficult.
    Mark D. pointed out that for the BCAL, since different layers have
    different "ballpark" factors, style (1) is unwieldy.

    Discussed whether or not we should have a uniform style across all
    detector systems. In the end, we decided that each detector system
    should be able to choose its own style as appropriate. The main
    argument was that either style is workable and we already have a mix of
    both as one goes from system to system.

Refrain from Excessive Use of Cosmetics

    David strongly encouraged us to try and preserve the original style of
    code as much as possible. In particular, indentation, spacing
    conventions, line-break choices should be left in their as-found state.
    Wholesale changes that have no functional effect defeat the "blame"
    feature of Subversion, where one can obtain a line-by-line report of
    the last person to change the code. Purely cosmetic changes cause
    gratuitous blame shifting.

Action Items

     1. Propose an agenda for the Collaboration Meeting. (Mark)
     2. Track down factor of two in wire-based track multiplicity between
        "HDDM" and "EVIO".
     3. Decide on how to handle the 100 ns EVIO conversion shift.

References

   27. 
https://halldweb1.jlab.org/wiki/index.php/GlueX-Collaboration-Oct-2014
   28. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_August_20,_2014#Minutes
   29. 
https://mailman.jlab.org/pipermail/halld-offline/2014-September/001789.html
   30. 
http://clasweb.jlab.org/websvn/prod/listing.php?repname=GlueX&path=%2F&rev=14984&sc=1
   31. https://halldweb1.jlab.org/wiki/images/7/7e/Hddm_evio_comp.pdf

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295