sPHENIX HCal discussion

[Christopher McGinn <chmc7718 AT colorado.edu>]

Hi Megan,

Thank you for the feedback. I will try to answer bullet by bullet:

•  You are correct - the coating was fine i merely meant the white layer wrapping was open on the SiPM edge (was attempting to distinguish from the black layer). If you folks opened it for a photo, then it was known and no problem - I just noticed so wanted to make a note.
  
  
• B26 definitely has a different shape so I agree that comparison should be taken with a grain of salt. As to a rescan - I have not done one, B26 as included should be the same as the March scans. This could introduce additional discrepancy beyond just the tile shape differences, so if you think it important I could do a rescan of B26 under current conditions.
  
  
• So I'm not 100% certain how to  go about removing the fiber region - but perhaps I can provide versions w/ a z-scale more suited for the bulk?

Let me know if you have more questions/comments/response to above,
Chris

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From: Megan Connors <meganeconnors AT gmail.com>
Sent: Friday, August 7, 2020 12:12 PM
To: Christopher McGinn <chmc7718 AT colorado.edu>
Cc: sphenix-hcal-l AT lists.bnl.gov <sphenix-hcal-l AT lists.bnl.gov>
Subject: Re: [Sphenix-hcal-l] Follow-up (Complete) Analysis of HCal Tiles w/ Boulder Test Stand

 

Hi Chris,

Thanks for the update. The results look as expected. The PRs and photo of the bad tile is below.

I had a couple of comments/questions on your analysis.

-Slide 5 you say the "coating" was undone but you really mean the wrapping right, not that there is damage to the coating on the tile. The wrapping was removed at GSU to make the photo below.

-It's nice to be reminded of the B26 results but we should be careful comparing these since the fibers routing and tile shape are different. Was the B26 tile rescanned with your new SiPM set up?

-Since we really want to see how uniform the tiles themselves are, is there any way to subtract off the fiber so that the scale better reflects any potential changes in the tile?

GSU Measurement reminder:

Tile number         -PR        -MPV

•B25.2095.5867 -0.763476 -362.532

•B25.2042.5710 -1.35517 -615.12

•B25.2043.5712 -1.34392 -610.986

•B25.1229.3275 -1.09085 -507.248

I tried to paste the picture from Saif presentation (https://indico.bnl.gov/event/8781/contributions/38842/attachments/28960/44824/hcal_gsu_062320.pdf) below that shows the crazing at the bends.

Best,

-Megan

On Thu, Aug 6, 2020 at 2:07 PM Christopher McGinn <chmc7718 AT colorado.edu> wrote:

Hello all,

This is a follow-up to the previously sent preliminary analysis of the underperforming HCal tiles that was previously sent to the list (and was discussed partially in the biweekly HCal meeting here: https://indico.bnl.gov/event/9090/). I've attached the final analysis, now correcting the scans taken incorrectly. Analysis shows 2/4 sent tiles have anomalously low light output when compared to the B26 tile sent for testing in March. Please let me know if you have questions or comments,

Chris

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