[Halld-offline] [EXTERNAL] Re: Software versions and simulation issues

[Sean Dobbs]

Hi all,

As discussed in the last meeting, the implementation of the FCAL smearing
that I approved had a design flaw, and backwards compatibility should have
been supported.  I checked in a change which was merged today that resolves
this issue, along with a modification of CCDB.  Basically, the values for
the mc variation of /FCAL/digi_scales were restored for backward
compatibility, and appropriate values for the new smearing scheme were put
in a new table,  /FCAL/MC/digi_scales. This is not as elegant as was hoped
for, but properly backward compatible, and hopefully more clear what all of
the MC factors mean.

A new halld_sim version should be tagged, presumably with a version number
of 4.8.0.

What does this mean for users?  Here are some guidelines depending on which
halld_sim version one is using (n.b. the latest version is also
recommended, but not available in all cases):
latest (4.8.0?):  the current CCDB constants are fine
4.6.0 and 4.7.0:  use a CCDB timestamp between 2019-07-27 and 2019-09-25
4.5.0 and earlier:  the current CCDB constants are fine


Cheers,
Sean

On Tue, Sep 17, 2019 at 10:36 AM Sean Dobbs <sdobbs at fsu.edu> wrote:

> Hi all,
>
> I've been working on tracking down some problems that were reported to me
> about poor simulation yields which seem to have exposed some issues in how
> we're dealing with the interaction of software and the CCDB in the current
> frame work.  Thanks to all who helped in tracking this down.
>
> The issue started on July 26, when some modifications to the CCDB were
> made to support changes made to mcsmear to improve the FCAL smearing.  A
> new halld_sim version was rolled out at this point.  The CCDB changes were
> not necessarily backward compatible to older halld_im versions, or at least
> weren't checked - which is fine, that's how our system has been designed so
> far - but the changes were not announced widely enough, which is a mea
> culpa,
>
> For people who were generating simulations themselves, they are usually
> using the latest CCDB and the straightforward fix is to use the latest
> version of halld_sim (or a version >= 4.6.0)
>
> For the centralized submission page, the situation is more problematic.
> The default for generating simulations for 2017 data is halld_sim 4.2.0,
> which is outdated, although there are newer versions that are built.  For
> other data sets, no up-to-date version of halld_sim exists.  Also, there is
> no ability in the form to set a CCDB timestamp that would give a version of
> constants that would work with these older constants.
>
> So, we should probably discuss this in some more detail in our software
> meeting this afternoon, and see if there are ways we can improve our
> defaults and communication to avoid such issues in the future.
>
> Cheers,
> Sean
>
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