[Solid_software] GEMC benefits and larger frameworks

[Richard S. Holmes]

On Thu, Mar 3, 2016 at 5:28 PM, Maurizio Ungaro <ungaro at jlab.org> wrote:

> - FADC output - mode 1 right now but mode 5 and 7 coming soon. This is a
> 4ns sampled signal, same as real life.
>

This isn't something I know a lot about; is it applicable to SoLID?


> - Documentation is getting there ;-) gemc.jlab.org
>

I wasn't aware of the new site, looks good so far.

- Coming next week: merging of background events into generator
>

Potentially significant for us I think.


> This is indeed a limitation. Currently in clas12 we do use the same
> parameters as reconstruction, because they come from a common DB. The
> calculations of parameters are done using the reconstruction java library.
> If the reconstruction is in C++ this can be achieved with the plugin
> capability of gemc - using a shared library that is used in reconstruction
> as well.
>

This is something I'd like to know more about.


> Having said that, it’s not feasible to include in reconstruction ALL the
> passive volumes.
>

I don't think there's any need to.


> If the mysql DB is used in the API, the geometry is run and variation
> indexed. So it’s uniquely associated with an output (where run, variation
> and ALL geometry parameters are stored).
>

I need a few more words about this. Given an output file, how does one
determine the parameters and the Perl script versions used to create the
geometry?

> Also note: GEMC does not allow (I think) taking advantage of GEANT4's
> ability to replicate logical volumes; e.g. each calorimeter module must be
> a separately-defined entry in the database.
>
> Replicas are there. Copies are there.
>

They are? Are we using GEMC wrong? Currently our Perl scripts generate, for
instance, 30 copies of each baffle block, one for each sector, rather than
one logical volume that's instantiated as 30 physical volumes.

Admittedly gemc was not designed to be part of a framework, however a
> partial re-design is in process that could help in that regard. For
> example, using plugins for hit processes, for generator and output
> mechanisms.
>

That sounds promising.

-- 
- Richard S. Holmes
  Physics Department
  Syracuse University
  Syracuse, NY 13244
  315-443-5977
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