[Halla_running] No Shift/4PM meeting until Wednesday.

[KiJun Park]

Dear All,

Since there is on-going work of recovering the contaminated CHL2, a U-tube installation is going on during Monday-Tuesday(Apr.6-7).
If thing goes well, they lock up Wednesday(Apr.8, 7:00AM) and try to cool down CHL2 till SWING. Then machine will be setup with lower energy mode.
After talk to Thia, I cancel all shifts till next Wednesday(Apr.8, SWING).
A 4PM experimental meeting is cancelled as well till this time, except Monday(Apr.6) which we may have an update of CHL status.

Sincerely,
Kijun

-----------------------------------------------
Dr. Kijun Park
Physics Dept. Old Dominion University
Thomas Jefferson National Accelerator Facility
Suit 5 Room 12_1/F374
12000 Jefferson Ave.
Newport News VA 23606
Phone 757-269-6989
------------------------------------------------

----- Original Message -----
From: "Kijun Park" <parkkj at jlab.org>
To: "halla running" <halla_running at jlab.org>
Cc: "halla coll" <halla_coll at jlab.org>
Sent: Wednesday, April 1, 2015 9:33:31 AM
Subject: [Halla_running] No Shift until Sunday.

Dear All,

One clear info....
Since accelerator tunnel is opened until Sunday(Apr.05,24:00), we will not have any shift then.
Thanks.

Sincerely,
Kijun(RC)

-----------------------------------------------
Dr. Kijun Park
Physics Dept. Old Dominion University
Thomas Jefferson National Accelerator Facility
Suit 5 Room 12_1/F374
12000 Jefferson Ave.
Newport News VA 23606
Phone 757-269-6989
------------------------------------------------

----- Original Message -----
From: "Kijun Park" <parkkj at jlab.org>
To: "halla running" <halla_running at jlab.org>
Cc: "halla coll" <halla_coll at jlab.org>
Sent: Monday, March 30, 2015 12:20:30 PM
Subject: [Halla_running]  update

Dear All,

Here is more precise info. from the Jay.

https://logbooks.jlab.org/entry/3331242 explains the problems with CHL1
(4K) connected to SCM 2KM cold box. This has been cooling the South
Linac. CC4 was spinning at 500 Hz and came to an abrupt halt.  No one
has a hypothesis which augurs a quick fix.  All the plausible hypotheses
take 3-6 months to fix.

I can't find the clog entry which discusses contamination in the heat
exchanger linking CHL2 (4K) and SCN 2KN cold box.  This combo has been
cooling the North Linac. This system is being warmed to ~90K in the hope
that the contamination is predominantly air, not C02 or H20.  An attempt
will be made to unclog the heat exchanger with warm gas and move the
impurities into the sub-system designed to immobilize them so the box
doesn't have to be warmed all the way to 300K now.  The long term
concern is that the contamination must have entered through systems in
the tunnel or the piping from tunnel to CHL.


Sincerely,
Kijun
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