sPHENIX HCal discussion

["Lajoie, John G [PHYSA]" <lajoie AT iastate.edu>]

Hi Chris,

 

Very interesting results. If I am interpreting this correctly it looks like the “bad” tiles are consistent with a lower overall light yield. I’m not sure how to reconcile that with the observation of a different apparent angular distribution of the light exiting the fibers, but perhaps this has more to do with the lower light yield coupled with the logarithmic response of the human eye.

 

What really worries me is that in addition to the overall light yield there is some additional variation in the tile. I’d like to see if there is a way to quantify this. I was thinking you could normalize each measurement in a tile by the average for that tile and then make a 1D plot of that ratio. The width of this distribution tells you something about the relative fluctuations in response for that tile as a function of location, and I wonder of we would see any significant differences between the two classes of tiles.

 

And finally – many thanks to everyone involved for the extremely fast response!!

 

Regards,

John

 

From: Christopher McGinn <chmc7718 AT colorado.edu>
Sent: Friday, March 13, 2020 8:27 PM
To: sphenix-hcal-l AT lists.bnl.gov
Cc: James L Nagle <naglej AT colorado.edu>; Megan Elizabeth Connors <mconnors AT gsu.edu>; Lajoie, John G [PHYSA] <lajoie AT iastate.edu>
Subject: HCal Tile Testing at Boulder

 

Hello all,

We have completed a first pass of four of the eight tiles (with a lot of help from Ron Belmont, Megan Connors, and Dan Richford to get our test area up and running) and plan to show the full eight in the upcoming HCal meeting. I have attached the skeleton of the full presentation w/ figures detailing the LED tested tiles. Label sizes will be fixed and more info will be available Tuesday, but thought it was worth sending, as we confirmed the reduced light output in two of the four (semi-blind as we knew 2 out of 4 were reduced output, but not which specific tiles).

Please let me know if there are any questions or comments. Tile five  is completed, and six currently running, so we are close to a first pass on all eight.

Thanks,

Chris McGinn