sPHENIX HCal discussion

[Stefan Bathe <stefan.bathe AT baruch.cuny.edu>]

Dear All, (specifically Xiaochun, Eric, Chris)

Xiaochun asked in today’s HCal Meeting about the HCal channel mapping for his 
Geant simulation.  As far as I can tell, this was last discussed in the 
8/27/19 HCal Meeting:

https://indico.bnl.gov/event/6688/

where both Eric and I gave presentations on our ideas of how to map hardware 
channels to digitizer channels.  I think we basically agreed.  In the end, 
though, I think, it might be up to the software group (Chris?) to decide 
which numbers to assign to the channels.  I guess the two options would be to 
either adopt the digitizer channel numbering (no additional map needed, but 
geometrically more complex) or to have numbers simply increment in z and phi 
(geometrically simple, but additional map needed).
The other open question is where to start counting.  Naturally one would like 
to start counting at phi = 0 (and at the South end, so along the z axis).  
But the sector at phi = 0 (and at phi = 180 degrees) have their outer radius 
combs vertical.  Therefore phi = 0 is in the center of a sector, not at the 
edge.  This would introduce an offset with respect to the digitizer channel 
number, which is ugly.  The answer to this question might also depend on 
which sectors get plugged into which digitizer boards/crates, which Eric and 
Steve would know.  (I’m saying this because it might make sense to start 
counting at channel 0 of a digitizer board.)

Regards,
Stefan
 
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Stefan Bathe
Professor of Physics
Baruch College, CUNY
and RIKEN Visiting Scientist

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