sPHENIX HCal discussion

[Megan Connors <meganeconnors AT gmail.com>]

Dear Edward,

Sorry for the delayed reply to Chris. It took some time to dig out the GSU photo between meetings. The ~20% difference is precisely what we saw at GSU and what forms the double peak structure in the B25 distribution. Again the only reason why the double peak is not as pronounced in the Uniplast data is because they changed out the reference tile at some point which caused the higher performing tiles to give a PR closer to 1. I think the Colorado results confirm the conclusions that we made at GSU. There is no evidence of time induced luminosity lost during shipments. The PR value for tile B25.2095.5867 from the Uniplast data is 0.577511 so it was low the whole time.

Best,

-Megan

On Fri, Aug 7, 2020 at 11:13 AM Kistenev, Edouard <kistenev AT bnl.gov> wrote:

Hi, Chris,

look very "correct" - I mean measurements. Have you tried to pump light into fibers and identify emission (crazing) points - check if they are in the same locations as per LED scanning. This will be a good answer - checking for emission points when fiber is positioned in groove but not yet  epoxied is how fiber rejection is done today. Looks like it needs to be repeated after epoxy is cured and fibers polished.

Hi, Megan,

can't you comment on  how and when these tiles got to GSU. Would be nice to know if we have reasons to suspect that these two tiles lost luminosity while in transit between two measurements (slow release of internal forces in plastic fiber) or that Uniplast measurements were simply wrong. I wander if we should use this mishap as an indication that all cases when GSU-UNIPLAST comparison shows more then 20% drop in luminosity in time between measurements need special attention.

Edward

---

From: sPHENIX-HCal-l <sphenix-hcal-l-bounces AT lists.bnl.gov> on behalf of Lajoie, John G [PHYSA] <lajoie AT iastate.edu>
Sent: Thursday, August 6, 2020 7:50 PM
To: Christopher McGinn <chmc7718 AT colorado.edu>; 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,

 

Many thanks for sending these results. It really looks like B25.2095.5867 has a broken fiber at more than one location.

 

John

 

John Lajoie

he, him, his

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

 

From: sPHENIX-HCal-l <sphenix-hcal-l-bounces AT lists.bnl.gov> On Behalf Of Christopher McGinn
Sent: Thursday, August 06, 2020 1:07 PM
To: sphenix-hcal-l AT lists.bnl.gov
Subject: [Sphenix-hcal-l] Follow-up (Complete) Analysis of HCal Tiles w/ Boulder Test Stand

 

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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