sPHENIX EMCal discussion

["Frantz, Justin" <frantz AT ohio.edu>]

Hi all,

Here is the email we were discussing today.  At the software meeting I 
already presented some answers to some of the questions Chris posed there 
(see the software meeting agenda), but the main core of question is as I 
mentioned today:  previously we made some limits on the frequency  that was 
needed for various types of the calibration, such as  LED gain tracing and 
our tower slope calibration, ranging from maximally frequent (every 5 
minutes, was our previous estimate) to minimally frequent (~once per fill or 
less), can we determine more exactly a more realistic expectation within that 
range?  His comment about number of events exceeding our data capacity  was a 
misunderstanding by him that was clarified at the meeting.  

So it's something we can continue the discussion on next week at the emcal 
meeting, I will present some of those slides and others next week.

-Justin

----------------------------------------------
Justin Frantz, Ph. D.  he
RHIC UEC/Diversity Working Group
Brookhaven National Lab, sPHENIX Experiment
Associate Professor
Ohio University Dept. Of Physics and Astronomy   
frantz AT ohio.edu   
646-228-2539  
PERSONAL ZOOM MEETING:  369-910-7530   Password:  1  
https://urldefense.com/v3/__https://us02web.zoom.us/j/3699107530?pwd=TkZLeU1MY2d5eUpqeTJ5WUJTRHlVUT09__;!!P4SdNyxKAPE!U8DkLz2itiOIWzbLGYlYXm9O2I0lyDrmYXleh-ZXl86B2RggbBfG6Gnt5gxrtN8qmmNcDLtXX0Q$
 

-----Original Message-----
From: pinkenburg [mailto:pinkenburg AT bnl.gov] 
Sent: Monday, September 13, 2021 2:18 PM
To: Craig Woody <woody AT bnl.gov>; Frantz, Justin <frantz AT ohio.edu>; eric 
mannel <mannel AT bnl.gov>; Stefan Bathe <bathe AT bnl.gov>; Sickles, Anne M 
<sickles AT illinois.edu>; Jin Huang <jhuang AT bnl.gov>; Camelia Mironov 
<camelia.mironov AT cern.ch>; John Lajoie <lajoie AT iastate.edu>
Subject: calorimeter calibrations

Hi folks,

we need input in terms of envisioned stability and number of events 
needed to calibrate our calorimeters (where we should make a clear 
distinction between monitoring the stability and calibration). The only 
numbers I can find were presented by me at the S&C review in July which 
were based on Justins slides he gave me:

https://indico.bnl.gov/event/12470/contributions/52012/attachments/35971/58967/SCReview_2021July19.pdf

which I kept deliberately vague so we do not invite too many questions 
on this. In my understanding the main effect we need to deal with is the 
stability of the SiPM gains (where I hope radiation damage will not be 
the leading cause for short term changes). I am a bit surprised that the 
numbers quoted here (stability but also number of events needed) is 
vastly different from what we had in PHENIX. There should be some ideas 
from the testing of the hcal and emc sectors we have in hand to give us 
some guidance about what to expect.

The question we basically need to answer is how long do we think the 
calibration is stable? Is the LED gain tracing enough (which we did in 
PHENIX) or do we need tower by tower calibrations done a few times per 
day where the number of events needed seems to exceed our data taking 
capabilities?

I would like to at least start the discussion of this during tomorrows 
software meeting. This does have profound effects on our workflow so the 
earlier we get some clarity the better.

It's short notice but if we can start collecting this information and 
have a first crack at this tomorrow - that would be great.


Thanks
Chris


-- 
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Christopher H. Pinkenburg       ;    pinkenburg AT bnl.gov
                                ;    http://www.phenix.bnl.gov/~pinkenbu

Brookhaven National Laboratory  ;    phone: (631) 344-5692
Physics Department Bldg 510 C   ;    fax:   (631) 344-3253
Upton, NY 11973-5000

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