[BTeam] [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Fri Aug 28 14:19:30 EDT 2020

Can anyone tell me whether we can scan the beam across the vacuum window to determine whether there are any oil droplets (or polymerized residues) on the window?  If we have several mm of clearance, we can make this scan and consider whether there is any kind of suspicious structure.

Michael Tiefenback

________________________________
From: mhattawy at odu.edu <mohammad.hattawy at gmail.com>
Sent: Friday, August 28, 2020 13:44
To: Eugene Pasyuk <pasyuk at jlab.org>
Cc: Brian Freeman <bfreeman at jlab.org>; Bob Miller <rmiller at jlab.org>; David Hamlette <hamlette at jlab.org>; Dennis Turner <dturner at jlab.org>; Eric Christy <meric.christy at gmail.com>; HyeKyoung Park <hkpark at jlab.org>; Michael Tiefenback <tiefen at jlab.org>; Paul Vasilauskis <vasilaus at jlab.org>; Sebastian Kuhn <kuhn at jlab.org>; Stepan Stepanyan <stepanya at jlab.org>; Valery Kubarovsky <vpk at jlab.org>; bteam at jlab.org <bteam at jlab.org>
Subject: Re: [BTeam] [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Hello Eugene,
   If you are asking about the window foil before the target entrance, then we dont know. Answering this question would take 24 hours of work to get there ( disassembling beamline components, pull back the CVT cart, unplug BONuS cables to reach the region to release the beamline pipe from that side)

Mohammad.

On Fri, Aug 28, 2020 at 1:31 PM Eugene Pasyuk <pasyuk at jlab.org<mailto:pasyuk at jlab.org>> wrote:

Do you see any deposits on the window foil?

-Eugene

From: mhattawy at odu.edu<mailto:mhattawy at odu.edu> <mohammad.hattawy at gmail.com<mailto:mohammad.hattawy at gmail.com>>
Sent: Friday, August 28, 2020 13:27
To: Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>>
Cc: Bob Miller <rmiller at jlab.org<mailto:rmiller at jlab.org>>; David Hamlette <hamlette at jlab.org<mailto:hamlette at jlab.org>>; Dennis Turner <dturner at jlab.org<mailto:dturner at jlab.org>>; Eric Christy <meric.christy at gmail.com<mailto:meric.christy at gmail.com>>; Eugene Pasyuk <pasyuk at jlab.org<mailto:pasyuk at jlab.org>>; HyeKyoung Park <hkpark at jlab.org<mailto:hkpark at jlab.org>>; Michael Tiefenback <tiefen at jlab.org<mailto:tiefen at jlab.org>>; Paul Vasilauskis <vasilaus at jlab.org<mailto:vasilaus at jlab.org>>; Sebastian Kuhn <kuhn at jlab.org<mailto:kuhn at jlab.org>>; Stepan Stepanyan <stepanya at jlab.org<mailto:stepanya at jlab.org>>; Valery Kubarovsky <vpk at jlab.org<mailto:vpk at jlab.org>>; bteam at jlab.org<mailto:bteam at jlab.org>
Subject: Re: [BTeam] [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Hello Brian and all,

    We did take out that portion of the beam pipe. It is not as clean as needed. Check the first picture. The second picture shows inside the beam pipe on the other side ( right side of 2H01) which is quite clean. Bob Miller will go ahead and clean it up and ensemble the beamline again.  We were expecting to see larger oil drops or something bigger than the dust we see there. Will see if this will improve the situation, if not we will continue the additional tests you have in mind.

Mohammad Hattawy.

[cid:1743628abd74ce8e91]

[cid:1743628abd75b006a2]

On Fri, Aug 28, 2020 at 12:58 Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>> wrote:

Bob, Stepan, Mohammad,

I would like to thank you folks for the extensive check of the beam line. Please know that we are still internally listing other possibilities, and have several other checks to be made if nothing is found.

Again thanks for taking this opportunity to check things out. It will greatly help our efforts.

-Brian

________________________________

From: mhattawy at odu.edu<mailto:mhattawy at odu.edu> <mohammad.hattawy at gmail.com<mailto:mohammad.hattawy at gmail.com>>

Sent: Friday, August 28, 2020 11:47 AM

To: Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>>

Cc: Sebastian Kuhn <kuhn at jlab.org<mailto:kuhn at jlab.org>>; Bob Miller <rmiller at jlab.org<mailto:rmiller at jlab.org>>; David Hamlette <hamlette at jlab.org<mailto:hamlette at jlab.org>>; Eugene Pasyuk <pasyuk at jlab.org<mailto:pasyuk at jlab.org>>; Michael Tiefenback <tiefen at jlab.org<mailto:tiefen at jlab.org>>; Dennis Turner <dturner at jlab.org<mailto:dturner at jlab.org>>; HyeKyoung Park <hkpark at jlab.org<mailto:hkpark at jlab.org>>; bteam at jlab.org<mailto:bteam at jlab.org>

<bteam at jlab.org<mailto:bteam at jlab.org>>; Stepan Stepanyan <stepanya at jlab.org<mailto:stepanya at jlab.org>>; Paul Vasilauskis <vasilaus at jlab.org<mailto:vasilaus at jlab.org>>; Valery Kubarovsky <vpk at jlab.org<mailto:vpk at jlab.org>>

Subject: Re: [BTeam] [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Hello all,

    After talking with Bob Miller and Stepan Stepanyan, we ended up with only one suspicion, that is some oil from the vacuum pump went inside the beam pipe. I spoke with Brian Freeman, crew chief, and informed me that the best estimate for the beam to

be back is around 4 pm, the worst is tomorrow morning as they are still working on the south linac.

   Given the time estimate from Bob Miller for taking out the beam pipe, cleaning it, and putting it back would take about three hours. We will go ahead and clean the beam pipe between the end of the CVT carte and 2H01A.

Mohammad Hattawy.

On Fri, Aug 28, 2020 at 10:43 AM Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>> wrote:

Thank you for all the reply and the good information, these things will help.

-Brian

________________________________

From:

mhattawy at odu.edu<mailto:mhattawy at odu.edu> <mohammad.hattawy at gmail.com<mailto:mohammad.hattawy at gmail.com>>

Sent: Friday, August 28, 2020 9:57 AM

To: Sebastian Kuhn <kuhn at jlab.org<mailto:kuhn at jlab.org>>; Bob Miller <rmiller at jlab.org<mailto:rmiller at jlab.org>>; David Hamlette <hamlette at jlab.org<mailto:hamlette at jlab.org>>;

Eugene Pasyuk <pasyuk at jlab.org<mailto:pasyuk at jlab.org>>

Cc: Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>>; Michael Tiefenback <tiefen at jlab.org<mailto:tiefen at jlab.org>>; Dennis Turner <dturner at jlab.org<mailto:dturner at jlab.org>>;

HyeKyoung Park <hkpark at jlab.org<mailto:hkpark at jlab.org>>;

bteam at jlab.org<mailto:bteam at jlab.org> <bteam at jlab.org<mailto:bteam at jlab.org>>; Stepan Stepanyan <stepanya at jlab.org<mailto:stepanya at jlab.org>>; Paul Vasilauskis <vasilaus at jlab.org<mailto:vasilaus at jlab.org>>

Subject: Re: [BTeam] [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Hello all,

  David Hamlette surveyed the upstream beam pipe, around 9 AM, and did not find any hot spot. The beam has gone at 5:00 AM, so maybe the 4 hours down time did kill all the activation. Bob Miller is in the Hall to cycle the other valve, VBF2H01A, and check

the beamline components once more for any displacement.

Mohammad.

On Fri, Aug 28, 2020 at 9:28 AM Sebastian Kuhn <kuhn at jlab.org<mailto:kuhn at jlab.org>> wrote:

Just a small addition: We have already tried re-centering the beam on the target structure - TWICE - and also changing the angle with which it comes into the Hall. Nothing changed the background, and we could not find any obstructions other than the known

target walls, which we avoid by centering the beam.

- Sebastian

On Aug 28, 2020, at 6:01 AM, Brian Freeman <bfreeman at jlab.org<mailto:bfreeman at jlab.org>> wrote:

  1.  We could simply try angle and position changes into the target ? It looks like things got really noisy after a target change in the hall on the 15th, probably a coincidence (https://logbooks.jlab.org/entry/3835820)

. I believe that the Midstream counters sit around the Target somewhere, and Downstream counters are after CLAS. So perhaps we just have a bad angle going into the Target? ( 1hr )

--

Best regards,

Mohammad Hattawy.

--

Best regards,

Mohammad Hattawy.

--

Best regards,
Mohammad Hattawy.

--
Best regards,
Mohammad Hattawy.
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