[Halld-cal] Minutes from yesterday's meeting

[Timothy Whitlatch]

Hi All,

In looking back at the archive data, there is only 1 time the hall reached above 80F this spring through fall. October 12 the temp reached 84F and was above 80F for about 12 hours. This is when the overhead door was left open after a tour.

Cheers,


Tim Whitlatch

Hall D Engineer

Jefferson Lab

757-269-5087

________________________________
From: Halld-cal <halld-cal-bounces at jlab.org> on behalf of Alexander Somov <somov at jlab.org>
Sent: Friday, November 15, 2019 6:57 PM
To: Fernando Barbosa <barbosa at jlab.org>; halld-cal at jlab.org <halld-cal at jlab.org>
Subject: Re: [Halld-cal] Minutes from yesterday's meeting

Hi Fernando,

As we have discussed, the temperature accident happened
not the first time. After the first accident, when we
melted a CTP module by running a fan speed at ~2000 rpms,
I took many trigger-related (and other) crates from the
PID control and ran them at 4500+ rpm.

After the overheating problems during last year, Hai Dong
suggested to run the fan at about 5000 rpm for the sake of
CTPs, and I agree with him. There should be enough margin
to cool the crate down if the temperature in the hall
increases.


The CCAL crate,  positioned on the same FCAL platform
runs at about 5000 rpm for more than a year, I didn't
have any problems with it so far.


I belive that the PID fan threshold should be set to at
least 4500 rpm for all crates (indeed it's a choice of
sub-detector groups, who should be responsible for
damaged electronics as well).



Cheers,
       Sasha


P.S. Indeed, there could be other not temperature-related
issues, but this is the most likely one.


Rad damage can be an issue as well, but then modules should
fail "continuously" during the run, likely with various symptoms,
which seems to be not the case. We got 5 modules dead after
the run. The rad dose in the tagger hall is also significantly
larger than in Hall D; I haven't seen such problems with fadcs
there.








On 11/15/19 3:10 PM, Fernando Barbosa wrote:

Hello Elton, all,



Some notes regarding the paragraph below:

a)       The overheating is not an issue unless the hall temperature increases significantly above the specs. For a full description, refer to GlueX-doc-2752. My recommendation has always been to operate the fans fixed at 4,000 RPM or in the 3,000 RPM to 5,000 RPM range under PID control.

b)      During the Summer, we experienced some unexplained failures. Nick recently informed me that there were two instances when the temperature in the hall was excessive duw to HVAC failures or door open for long periods of time. Nick has suggested some additional interlock controls. It would be instructive if someone could check the environmental logs and others since the end of the Spring run.

c)       The last sentence is not correct. Spreading the modules apart will not provide better cooling as the thermal radiative losses are insignificant compared to the convective cooling efficiency.

d)      There is also the possibility of radiation damage on the D2 platform due to changing experimental conditions (prototype tests of the COMCAL and others). This was also brought up by CAEN during maintenance of failed HV controllers. I have Alexandre D. to look into this in detail from logs of radiation detectors he manages.



Best regards,

Fernando







[cid:part1.F33BECE0.568A109A at jlab.org]



-----Original Message-----
From: Halld-cal <halld-cal-bounces at jlab.org><mailto:halld-cal-bounces at jlab.org> On Behalf Of Elton Smith
Sent: Friday, November 15, 2019 1:25 PM
To: halld-cal at jlab.org<mailto:halld-cal at jlab.org>
Subject: [Halld-cal] Minutes from yesterday's meeting



Dear collaborators,



I have posted the minutes from yesterday's meeting on the wiki at https://halldweb.jlab.org/wiki/index.php/Nov_14,_2019_Calorimeter#Minutes.



Cheers, Elton.



--

Elton Smith

Jefferson Lab MS 12H3

12000 Jefferson Ave STE 4

Newport News, VA 23606

(757)269-7625

(757)269-6331 fax



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