sPHENIX HCal discussion

[John Lajoie <lajoie AT iastate.edu>]

Hi Ron, Edward, Abhisek:

    OK, I can sleep better knowing that this tile was previously known to have issues.

    I agree with Abhisek's comment about unwrapping tiles thought to good to see what you find.

John

On 4/21/2017 8:47 AM, Abhisek Sen wrote:

Hi Ron,

    Looks like Uniplast already marked some of those effects in the data sheet they provided. That particular tile 116.92.197 failed the thickness test and has comment about the fiber issue. You can the excel sheet in docdb (https://docdb.sphenix.bnl.gov/cgi-bin/private/ShowDocument?docid=34). It will be good to unwrap more tiles and see if you find anything issue on those tiles which they claimed good. 

     We performed cosmic test on the individual towers after assembly only, not individual tiles in last beam test. The response had much less variation than last set of tiles they sent us. So I still think the quality has improved. See what you can find more after autopsy.

Cheers,

Abhisek

     

On Fri, Apr 21, 2017 at 8:12 AM Edouard Kistenev <kistenev AT bnl.gov> wrote:

This tile came to BNL as an illustration of what may happen if QC does not work. It works. We tried to understand what and how happened by intentionally creating similar defects (fortunately it has threshold character -immediate dramatic light loss)  - what breaks is the core not the cladding,  Unfortunately the effect is global light loss so "simple" solution like measuring muon impact point in the tile tester are not helpful, but human eyes or total muon response do marvels. Anyway  -problem is well known and not forgotten. 

Edward

Sent from my iPhone

On Apr 20, 2017, at 6:05 PM, Ron Belmont <ron.belmont AT colorado.edu> wrote:

Hi All,

It seems like the attachment was rejected (too large maybe).  Here's a link: https://www.dropbox.com/s/2ifz75bfsjaw3b9/higheta.pdf?dl=0

Regards,

Ron

On Thu, Apr 20, 2017 at 4:02 PM, Ron Belmont <ron.belmont AT colorado.edu> wrote:

Dear HCal-ers,

Attached is a short set slides we made made to show the scan of the high eta outer HCal tile we've done.  The fiber is cracked near the SiPM, which spoils the scan.  The shipping box has a bit of a gash in it, but it was packed extremely carefully with lots of foam, and there was no visible damage on any of the tiles during the unpacking process.

If there aren't any objections, we will unwrap more tiles to test them.  We're hopeful that analysis of the 2017 Tile Mapper will help shed some light when the damage to the fiber may have occurred on this particular tile (before or after the 2017 beam test).

Regards,

Sebastian and Ron

--

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Ron Belmont
Postdoctoral Research Associate
University of Colorado, Boulder
ron.belmont AT colorado.edu
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Ron Belmont
Postdoctoral Research Associate
University of Colorado, Boulder
ron.belmont AT colorado.edu
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John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

Contact me: john.lajoie