sPHENIX EMCal discussion

["W.A. Zajc" <zajc AT nevis.columbia.edu>]

Hello all:

I have conflicts that prevent attendance to the EmCal meetings, so call me an interested non-observer.

I have a question about the EMCal plans for zero suppression in Year-1. This was sparked by a statement from Chris Pinkenburg at Tuesday’s Calibrations meeting that always reading out non-suppressed calorimeters will slow the readout to a crawl (Chris, please correct if I am misquoting you). 

A back-of-the-iPad calculation shows that in central Au+Au, the average energy in a delta-eta x delta-phi = 0.025 x 0.025 is about 50 MeV. Divide this by ~4 for MB. These numbers immediately raise the question of what energy threshold is being considered for zero suppression, and how do various physics signals depend on this threshold?

1) Yes, I know the threshold will be on an ADC value, not an energy. But I think its still useful to phrase the question in terms of truth values.

2) Yes, I know that a central collision does not uniformly illuminate the EmCal with 50 MeV hits; it will be much more granular and concentrated with the average energy per *hit* tower ~ 0.3-0.4 (??) GeV. 

Chi has reminded me that when zero suppressing you are not just throwing away empty words but you are also adding bits to specify the tower ID. So real zero suppression gains have to be determined with non-trivial simulations. Perhaps this has already been done for the EMCal?

Best regards,

Bill 

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W.A. Zajc
I.I. Rabi Professor of Physics
Columbia University
New York, NY 10027

https://blogs.cuit.columbia.edu/waz1/
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On Jun 23, 2022, at 8:22 AM, Craig Woody <woody AT bnl.gov> wrote:

Dear All,
  Just a reminder that we will have our regular EMCAL meeting tomorrow, Friday June 24th starting at 9:00 am EDT. Here's the Indico link: https://indico.bnl.gov/event/16262/

Cheers,
Craig
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