[Halld-pid] [EXTERNAL] TOF shielding

[Timothy Whitlatch]

Hi Paul,

Thanks for the  tamped down version. As was pointed out two weeks ago, the offset light guide/pmt was noticed before we started fitting any brackets. As a result of this, Beni came and checked the signal and all is nominal on that module.  The "broken" module joint feels the same as any other module joint and does not feel "Broken". There are 8 areas with the same design and the other 7 are fine. We will need to modify the  1 bracket mount to make sure we support the pmt shield without stressing the pmt/light guide.  This should be no problem. The assembly should be completed by Wednesday and installed by the end of the week.

We can touch up the paint on the frames....garnet or blue/orange...your call.

Regards,


Tim Whitlatch

Hall D Engineer

Jefferson Lab

757-269-5087

________________________________
From: Halld-pid <halld-pid-bounces at jlab.org> on behalf of Paul Eugenio <peugenio at fsu.edu>
Sent: Saturday, October 5, 2019 10:58 AM
To: Hall D PID Mailing List <halld-pid at jlab.org>
Subject: Re: [Halld-pid] [EXTERNAL] TOF shielding

Dear Tim,

I want to follow up to my earlier email (now that I got over the initial shock that my baby is not perfect).   First, the Hall D crew are top notch highly competent profession technicians, and as I reread my email, I want to say that I should not couple the bracket problems with the broken module joint.   While we have some challenges with the last inner mounting brackets (and may need to change them), it is likely that the module joint failure was due to plethora of possibilities including a bad glue joint.  Seeing many people poking and prodding the TOF yesterday was a bit nerve-racking.   We should talk more about the inner brackets this coming week.  I also wanted to discuss touching up the paint on the main TOF frames, but I’m afraid to ask as it may end up orange and blue.

Yours very truly,

Paul

--
Prof. Paul Eugenio
Florida State University
Department of Physics
Tallahassee, Florida,  USA 32306

(850) 325-0314
peugenio at fsu.edu<mailto:peugenio at fsu.edu>

On Oct 4, 2019, at 4:42 PM, Paul Eugenio <peugenio at fsu.edu<mailto:peugenio at fsu.edu>> wrote:

Dear Tim,

Beni pointed out the broken module today.   I am alarmed that this happened.  While adjusting the brackets in the central region is challenging, there should be NO force placed on the module PMT ends.    I want to really stress this point.   If we have a problem with the mounting then we should better design the central brackets.  I’m thinking that we should replace the double bracket with a new design going back to a single bracket adjustment.  This could likely be done with a redesigned collar which has a central tab for bracket connection.  This way we could use a much narrower brackets.


Paul


--
Prof. Paul Eugenio
Florida State University
Department of Physics
Tallahassee, Florida,  USA 32306

(850) 325-0314
peugenio at fsu.edu<mailto:peugenio at fsu.edu>

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