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

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
>> > _______________________________________________
>> > Star-fst-l mailing list
>> > Star-fst-l AT lists.bnl.gov
>> > https://lists.bnl.gov/mailman/listinfo/star-fst-l
>>
>> --
>> Flemming Videbaek
>> senior scientist
>> videbaek @ bnl.gov
>> Brookhaven National Lab
>> Physics Department
>> Bldg 510D
>> Upton, NY 11973
>>
>> phone: 631-344-4106
>> cell     :  631-681-1596
>
> _______________________________________________
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