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[videbaek <videbaek AT bnl.gov>]

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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--
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

Attachment: RDO2_50V_08112021.png
Description: PNG image

Attachment: RDO2_140V_08172021.png
Description: PNG image