sPHENIX HCal discussion

[John Haggerty <haggerty AT bnl.gov>]

Hello,

Jin, Nils, and Alan have put together an excellent forum for making 
forward progress on the simulation, and there are quite a few people 
interested in understanding the HCAL.  Fortunately, Chris and Jin have 
taken some important steps to make possible the next steps.  Chris was 
concerned about some off behavior with the azimuthal matscan, but with 
the help of the tutorials, I was able to see that the behavior comes 
from the EMCAL, and on closer examination, Jin found that this was due 
to precise channeling of geantinos down the fibers.  For real particles 
which multiple scattering, this is unlikely to be a problem, so the way 
is open to use the new geometry for the next round of studies.  I 
attached the depths in radiation lengths and absorption lengths from 
Chris's macro, where I had only one calorimeter section turned on at a time.

Standing around the blackboard with Sarah, Ron, Xiaochun, Chris, Jin, 
Abhisek and others, we thought the next step for the HCAL would be to 
run single particles (mu/e/pi/p) with a few thousand events per tower 
over 3 towers in phi in a few eta bins (like 0-0.1, 0.3-0.4, 0.6-0.7, 
0.9-1.0) so we can do the next level of reality checking.  We concluded 
that we need events with the field on, and a vertex distributed in +/- 
10 cm, and all three calorimeter compartments and the nominal tilt angle.

We think it would be possible to generate a similar sample with zero 
tilt angle, which would allow us to quantify the merits of the chosen 
tilt angle, although this is just a warm-up and basic check-out of the 
machinery, which will be exercised with jet reconstruction.

If you can't join us in person, please join us by email or phone over 
the next few days, we'll try and keep this list updated with our 
thinking.  I think you'll find the tutorials on the Indico web site as 
informative as I did, as well.

--
John Haggerty
email: haggerty AT bnl.gov
cell: 631 741 3358

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