[Halld-offline] HDGeant4 Meeting Minutes, April 21, 2020

[Mark Ito]

Colleagues,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_April_21,_2020#Minutes> 
and below.

   -- Mark


    HDGeant4 Meeting, April 21, 2020, Minutes

Present: Mark Dalton, Sean Dobbs, Mark Ito (chair), Igal Jaegle, Naomi 
Jarvis, Richard Jones, Simon Taylor

There is a recording of this meeting <https://bluejeans.com/s/kCBOV/> on 
the BlueJeans site. Use your JLab credentials to get access.


      Review of minutes from the last Meeting

We went over the minutes from March 24 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_March_24,_2020#Minutes> 
without comment.


      BCAL structure in E/p distributions for kaons

We went over Issue #149 
<https://github.com/JeffersonLab/HDGeant4/issues/149>, recently 
submitted by Peter Pauli. He sees sharp features in the distribution of 
E/p in the BCAL for K^− s in hdgeant4 and not in data. They are present 
both in the simulation of his reaction and in the single particle gun. 
The discussion went on for quite a while as we worked our way through 
the plots and comments in the issue. Please see the recording and the 
postings in the issue for all the details. In summary:

 1. We thought one way to untangle the various features that Peter has
    pointed out might be by turning on and off (a) decays and (b)
    hadronic interactions. Note that at Beni's suggestion, Peter has
    already looked at decays.
 2. Richard is suspicious that there might be a problem in the treatment
    of kaons stopping in the BCAL. If energy released by capture of
    stopped kaons is not accounted for in the Monte Carlo, then that
    could explain the difference Peter observes between MC and data.
    Richard thought that before Peter spends time on item(1), he
    (Richard) should take a look at this.


      Reports from UConn

  * Richard has some students working on MC. They have discovered some
    issues, including seg faults, that they have reported to Richard. At
    this point they have not been submitted as GitHub issues.
  * Richard raised the issue of upgrading our version of Geant4.
      o We are at 10.02.p02, released June 29, 2016. The latest release
        is 10.06.p01, released February 14, 2020. That is a big gap.
      o About half of the custom fixes from Richard that we needed for
        10.02.p02 are incorporated in 10.06.p01. He has produced the
        correspondingly reduced set of custom fixes need for this latest
        release, as well as fixes need for other releases since 10.02.p02.
      o Going to 10.02.p02 requires GCC 5.x. We are using 4.8.5 on RHEL7
        and CentOS7. Past experience tells us that this is no small deal.
      o There is a start-up delay with G4 10.02.p02 that was not present
        in 10.02.p02 due to "voxelation". There is an option to skip
        this step, at a possible cost in execution speed.
  * When working remotely, there is a package called VirtualGL
    <https://www.virtualgl.org/> that will allow graphics commands to be
    executed on the local graphics card. This speeds things up considerably.

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  * This page was last modified on 21 April 2020, at 20:05.

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