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["Visser, Gerard" <gvisser AT indiana.edu>]

hi Zhenyu,

    What do you anticipate are the principal risks in withdrawing the detector to the installation rails? I guess it is good to be more explicit about that, but it was not discussed in slides of 2/15 meeting. With a high probability the high bias current issues are all on the detector, but it is possible they are on T-board and that should be diagnosable and if necessary replaceable with the detector withdrawn to the rails. Or at least that was the original idea. I agree with your assessment below but I think we should understand what risks you mean.

      - Gerard

p.s. I would guess a 15% chance to the 1-12 problem may be the grey cable, another 15% chance maybe the PPB. Most likely it is on the detector, ABC board having already been ruled out (right???)

---

From: Star-fst-l <star-fst-l-bounces AT lists.bnl.gov> on behalf of Ye, Zhenyu <yezhenyu AT uic.edu>
Sent: Wednesday, February 23, 2022 9:50 PM
To: flemming videbaek <videbaek AT bnl.gov>
Cc: Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST shutdown work

 

Hi Flemming,

Yes I believe we can visually inspect the soft cooling tubes, at least the parts after the outermost disk, w/o moving the detector at all.
I think there is little risk to move the detector out w/o passing the TPC surface.
The risk will increase but probably still tolerable (?) if we pull the detector completely out of the TPC cone.
Unless it is deemed necessary, I would not consider bringing it down to the clean room.

Zhenyu

> On Feb 23, 2022, at 4:31 PM, videbaek <videbaek AT bnl.gov> wrote:
>
> Hi Zhenyu
>
> Sounds like a good approach.
> For the cooling tubes, are there any way we can visually inspect them w/o pulling out
> ( camera + light). The possible concern is the flowing novec may remove some material, but as all
> parts apart from the tubes is grounded it should be good.
> Just for your info; I will be out of town Saturday-Friday (~6 days).
>
> best F
>
>
>
>
>
> On 2022-02-23 16:14, Ye, Zhenyu wrote:
>> Hi Flemming,
>> We should discuss this next Monday.
>> If I look at slide 3
>> https://urldefense.com/v3/__https://nam04.safelinks.protection.outlook.com/?url="https*3A*2F*2Fdrupal.star.bnl.gov*2FSTAR*2Fsystem*2Ffiles*2FFstHardware_STARColl_Feb2022.pdf&amp;data=04*7C01*7Cyezhenyu*40uic.edu*7C85b0de4618234468dca808d9f71c3020*7Ce202cd477a564baa99e3e3b71a7c77dd*7C0*7C0*7C637812523265774849*7CUnknown*7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0*3D*7C3000&amp;sdata=5uj71xIEyBRTMLn2qDDIZzahA27xKBglivCDbMEmI2M*3D&amp;reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSU!!P4SdNyxKAPE!TEvVeAOEQo6Uv6ZM1O4saVRJHPV-Mpld8MdC3lxojQ3jkfYRIopFIwoILKrPSESL6rAIBNw$
>> It is possible that HV current fluctuation on 1-12 can be fixed by
>> replacing the Grey cable. We will replace the PPB for 3-11. Thus, the
>> maximum gain is 1-6 inner (need to understand its efficiency) and 2-2
>> outer (basically useless). I would call this a small improvement, and
>> certainly I would not advocate to take the detector out only for this
>> due to the huge risk.
>> However, we may want to check the soft cooling tubes. I asked Yu to
>> place some cooling tubes in NOVEC before the run started. I would take
>> a look at those first. I would also check the cooling rack, check for
>> leaks and reassess the leak rate after servicing it before deciding
>> whether to not to take it out.
>> Best,
>> Zhenyu
>>> On Feb 23, 2022, at 2:23 PM, videbaek <videbaek AT bnl.gov> wrote:
>>> I assume you have seen Rahul's call for shutdown work.
>>> I would assume that we would try inversigate and fix the trouble modules, understand the leakage (checking the tubes). So this would imply taking it down. As the shutdown is very long I would assume this is not right after the end of run, but at some time convenient for particular you.
>>> What is your thought on this?
>>> best Flemming
>>> --
>>> 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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>
> --
> 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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