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[Aschenauer Elke-Caroline <elke AT bnl.gov>]

okay, to be 100% clear there is now way we can bring the detector back to the clean room.

To extract the detector to add some grounding wire if this is done very careful, is fine. But please make sure to integrate Rahul and Bob in the process, of course this impacts our sTGC installation if Rahul and Bob need to ficus on this now.

Cheers elke

On Aug 18, 2021, at 09:26, Zhenyu Ye <yezhenyu2003 AT gmail.com> wrote:

I would not bring detector back to clean room. It involves operations which in my view too risky for reducing the noise on the outer sections of two modules.

On the contrary, if pulling out the detector and adding grounding wires is low risk, I think it is worth doing it.

Xu and I have discussed the tests with detector at various poisons 1. Fully in 2. Half In (out) 3. Fully out.

Zhenyu

On Aug 18, 2021, at 8:18 AM, Visser, Gerard <gvisser AT indiana.edu> wrote:

Well, I don't know what to say exactly.
If pulling it is low risk I think a test again in out position with as much darkness as possible, followed by some grounding maybe-improvements and test again, is good to do.
The noise seems more than a little high so you may be looking at a choice between going back to cleanroom vs. having no useful tracking from the modules involved. That could be a painful choice, I don't have any info to judge it. At least these two modules are not in a line, right? (Both on inner disk.) Is it good enough to have tracking only from the 2nd & 3rd disks on these sectors?

     Gerard


p.s. If you guys want to have a brief meeting on this matter, I'm available.


From: Xu Sun <sunxuhit AT gmail.com>
Sent: Wednesday, August 18, 2021 9:11 AM
To: Visser, Gerard <gvisser AT indiana.edu>
Cc: Aschenauer Elke-Caroline <elke AT bnl.gov>; Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] High Noise Shown in Module at Disk 1 position 7 and 11

Hi Gerard,

If we could change the purple cable that would be great, but right now it is not possible to do so unless we took the half FST back to the clean room, which we don't want.
And if I understand correctly, putting the grounding between the T-board and aluminum ring is the only operation we are going to do.
If the grounding wire didn't fix it, then we have to leave it and see if we could optimise the noise from the software side.

I am still on hold now, let me know if I should proceed to pull the FST out.

Best,

Xu

On Wed, Aug 18, 2021 at 9:04 AM Visser, Gerard <gvisser AT indiana.edu> wrote:
I am guessing from afar of course but my guess is there is a connection failure somehow relating to the T-board.

However Xu wants to first add some further ground connections between T-board and ring, of course this will be nice if it resolves the issue but I'm not too hopeful on that.

    Gerard



From: Aschenauer Elke-Caroline
Sent: Wednesday, August 18, 2021 8:57 AM
To: Xu Sun
Cc: Aschenauer Elke-Caroline; Visser, Gerard; Star-fst L
Subject: Re: [Star-fst-l] High Noise Shown in Module at Disk 1 position 7 and 11

I ask again, what do you think is causing the noise at the detector and you can fix moving the detector  out.

Cheers elke

On Aug 18, 2021, at 08:55, Xu Sun <sunxuhit AT gmail.com> wrote:

Hi Gerard & all,

I think that they have already swapped cables to rule out PPB or readout system as an issue.

Yes, we swapped the purple cable to another PPB and RO chain and the issue moved with purple cable.

That also (right??) rules out the bias power supply as an issue.

Yes, we also switched the HV cable on ISEG module with a working channel/cable and the issue stays the same.

It seems complicated to take the FST out but Rahul and Bob thinks it is doable as far as I understand.

Best,

Xu

On Wed, Aug 18, 2021 at 8:52 AM Visser, Gerard <gvisser AT indiana.edu> wrote:
hi Elke & all,
  I think that they have already swapped cables to rule out PPB or readout system as an issue.
  That also (right??) rules out the bias power supply as an issue.
  It seems to me that to pull it out is necessary to investigate further. Isn't pulling it out a low risk operation? If it is not low risk then yeah one could decide to just leave this and hope for something to get better on its own or else live with the high noise level.

    Gerard


From: Star-fst-l <star-fst-l-bounces AT lists.bnl.gov> on behalf of Aschenauer Elke-Caroline <elke AT bnl.gov>
Sent: Wednesday, August 18, 2021 8:48 AM
To: Xu Sun <sunxuhit AT gmail.com>
Cc: Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] High Noise Shown in Module at Disk 1 position 7 and 11

Dear All,

are we sure that pulling out the detector is the right way to go.
I would like to see noise tests as function of HV to see if we see this noise turning on at a certain HV.
Also what things have you all swapped to understand where the noise comes from.
What is the working assumption which means you think you need to pull out the detector.

I really think we need to think this a bit more through.

Cheers elke

On Aug 18, 2021, at 08:28, Xu Sun <sunxuhit AT gmail.com> wrote:

Hi Tonko,

Yes. Please go ahead and let me know when you are finished.
On my way to STAR, we could start to pull the detector after you are done.

Best,

Xu

On Wed, Aug 18, 2021 at 8:15 AM Tonko Ljubicic <tonko AT bnl.gov> wrote:
Hello Xu, all,

before you pull the detector out today I would like 15-20 minutes to take a run
regardless of noise. This will give me some data to ponder while you
are checking the noise sources.

Would that be possible? Now?

        -- Tonko

On Wed, Aug 18, 2021 at 1:37 AM Xu Sun <sunxuhit AT gmail.com> wrote:

Hi Flemming,

The bias voltage is different in two tests.
For the test on 08/11/2021, the bias voltage is 50V for both inner and outer. This is because the detector is only half way in and we couldn't block the light.
For the test on 08/17/2021, the bias voltage is 140V for inner and 160V for outer.

Best,

Xu

On Tue, Aug 17, 2021 at 7:34 PM videbaek <videbaek AT bnl.gov> wrote:

Hi Xu,

a question were the bias voltage the same in the two tests or did you go
to 140 for the outer. Just want to make sure I understand what you did.
I am coming in to the lab tomorrow as already planned and will see you
in the hall

flemming

On 2021-08-17 19:11, Xu Sun wrote:

Hi All,

We ramped the whole FST detector to the working HV last night and did
a readout test for all the modules.
There are two modules located at Disk 1 position 7 and Disk 1 position
11 (all belong to RDO2) showing an abnormal noise than the previous
test. The RO test results can be found in the attached file
(RDO2_140V_08172021.png).

Both modules 1-7 and 1-11 were tested with 50V while the FST was half
way in the cone on 08/11/2021. The results then were quite normal and
could be found in the attached file (RDO2_50V_08112021.png).
The only difference between two tests, as far as we are aware, is the
position of the detector: on 08/11/2021 detector was half way in the
cone and on 08/17/2021 detector was at final position.
We have made sure the issue is on the purple cable and module side by
swapping connections through the readout chain.
Similar problems were found in the clean room RO test and were fixed
by adding grounding to the aluminum ring or replacing the purple
cable.

We plan to pull the FST out tomorrow morning and check what happened.
We also plan to add additional grounding of 1-7 and 1-11 to the
aluminum ring instead of  only grounding to the T-board since it is
almost impossible to change the purple cable for Disk 1 (most inner
disk) on the scaffolding.

Best,

Xu
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