[Primexd] FCAL bad channel status

[Colin Gleason]

Sasha,

There is one dead base in the FCAL (x,y)=(-3,29), crate, slot, channel= 3
BOT, 18, 12. I suggest we look at occupancies and waveforms in LED data to
see if there are other suspicious channels prior to changing this base out.
In my experience, it is not worth the effort to change one dead base on the
edge of the FCAL. If it was from an inner block, things would be different.
I also expect there is one bad fadc channel (this has been a known issue
since before the spring 2018 run). Once we know the complete list of bad
channels, we can check the signal and swap at bases as needed. In my
experience, there is usually one or two cables that need to be repaired in
addition to some bases that need to be changed.

-Colin

On Wed, Nov 28, 2018 at 1:08 PM Alexander Somov <somov at jlab.org> wrote:

>
> Hi,
>
> Yes, I agree with Matt, it is important to understand what's going on with
> these bases
>
> Cheers,
>        Sasha
>
>
>
>
> On Wed, 28 Nov 2018, Shepherd, Matthew wrote:
>
> >
> >> On Nov 28, 2018, at 11:38 AM, Colin Gleason <gleasonc at jlab.org> wrote:
> >
> >>  The base failure rate had dropped to less than 2 per week by the end
> of the run, so we should be able to manage replacements through the rest of
> the Fall run. I think Chris and Nick have been busy with installation, but
> once that is complete we can get them to repair more bases for the spring.
> >
> > We should start targeting bases that have high current draw when HV is
> on and set to operational value but normal current when HV is off.  These
> are likely to be the same bases that have trouble holding HV at the highest
> settings.  The symptoms are different from HV drop, but I believe the
> suspected root cause (poor cleanliness QC by the manufacturer) is the same
> and I think the documented repair will work.  Let's pull 3-5 of these and
> have Nick and Chris rework them and see that the operating current is
> reduced and HV is able to be set high.  If it is, we can gradually begin
> working through those.
> >
> > Matt
> >
> >
>


-- 
Colin Gleason
Postdoctoral Fellow
Indiana University
Department of Physics
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/primexd/attachments/20181129/d2b99122/attachment-0002.html>