[Dsg-hallc_nps] [EXTERNAL] Re: EEL 108 noise/grounding

[Robert Michaels]

On Friday evening we removed the aluminum shielding, so if you would please recycle or recover the material from room 108 I’d appreciate it.  Our conclusions and what we’re doing is in the NPS logbook.  It was worth a try.

Thanks

Bob

________________________________
From: Brad Sawatzky <brads at jlab.org>
Sent: Thursday, December 1, 2022 5:14:02 PM
To: Robert Michaels <rom at jlab.org>; Aaron Brown <ambrown at jlab.org>
Cc: Dsg-hallc_nps at jlab.org <dsg-hallc_nps at jlab.org>
Subject: [EXTERNAL] Re: [Dsg-hallc_nps] EEL 108 noise/grounding

To answer Aaron: the scheme is to ground the internals to the tank and
the tank to the (clean) rack ground.  At the moment the tank-to-rack
ground is effectively being accomplished through the 200+ ground braids
on the connected signal cables (along with the HV shroud cable shroud).

A more direct connection between the NPS tank and the racks (and other
ground points) has been previously tested using the 00-gauge ground
cable with no effect on the noise.  The same cable has also been pulled
in the access rear door (with HV off, of course) and used to directly
tie the internal LV distribution boards to ground.  Also with no visible
effect on the oscillations (unfortunately).

In the Hall, the NPS tank (which is aluminum-lined all around, with the
current exception of the front face) is electrically isolated from the
SHMS carriage and will be explicitly tied to the Hall clean ground with
a 00 gauge (or heavier) ground cable.


I definitely think there is value in revisiting tests with the internal
grounding of the LV boards (ie. dragging in the heavy grounding cable
and touching off on ground points inside the tank to see if that now has
an effect on the oscillations seen now.  (These oscillation amplitudes
are considerably smaller than in the past, so perhaps improved internal
grounding may make a notable difference this time.)

-- Brad

On Thu, 01 Dec 2022, Robert Michaels via Dsg-hallc_nps wrote:

> Thank you for trying this.  I'm not aware of a grounding diagram but
> I'll see if we can generate one as a point of discussion.  Improved
> grounding is one of the ideas that I most frequently hear mentioned
> when discussing this problem.
>
> Again, thanks
> Bob
> Get Outlook for iOS
>
> ----------------------------------------------------------------------------
>


> From: Dsg-hallc_nps <dsg-hallc_nps-bounces at jlab.org> on behalf of Aaron
> Brown via Dsg-hallc_nps <dsg-hallc_nps at jlab.org>
> Sent: Thursday, December 1, 2022 3:11:00 PM
> To: Dsg-hallc_nps at jlab.org <dsg-hallc_nps at jlab.org>
> Subject: [Dsg-hallc_nps] EEL 108 noise/grounding
>
> Hi Bob et al.,
> We've added thick aluminum foil to cover the front and back of the
> detector (see attached).  Looking at the scope it appears as though
> this did not help mitigate the noise.  Can anyone point me to a
> grounding schematic for the test setup in EEL 108 (if one exists)?
> Thanks,
> Aaron
>
> References
>
>    Visible links
>    . https://urldefense.proofpoint.com/v2/url?u=https-3A__aka.ms_o0ukef&d=DwIBAg&c=CJqEzB1piLOyyvZjb8YUQw&r=niPpw-PoOQn3jt3nn_-lSw&m=FvXosJ8sDtbr83pfcjCiOJUhbSkI09rOPQIVRW4OSKNRLsfSXb52bMhlSprW2NIc&s=WoeYkQOuAh8SxVRCb0BZ1wDblL7CsiDnudLpAWiwQoc&e=

--
Brad Sawatzky (he/him), PhD <brads at jlab.org> -<>- Jefferson Lab/SciComp/F272
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov
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