[Poltarg12] No meeting today

[Christopher Keith]

Hello everyone,
I apologize for the extremely late notification, but you had probably 
guessed it anyway.  There will not be a meeting today. We'll have a 
meeting four weeks from now.

Here's an exhaustive update about the target:

*_NMR:_*
James Maxwell is assembling the latest version of the NMR Q-meter, 
designed by himself and Hai Dong.  James has also completed his overhaul 
of the NMR software controls.  The newest version completely replaces 
LabView w/ James' homebrewed Python code. I've seen screenshots, and it 
looks pretty good. We'll try both of these during the next cool-down.

*_Target Cart:_*
The support frame for the target cryostat has been fabricated and 
mounted to the electronics cart in the EEL. It needs to be painted and 
aligned.  Dave Griffith is installing all the electronics cables on the 
cart now and running them through a retractable cable tray attached to 
the cart.  The tray will track with the cryostat as it rolls over the 
cart, keeping the cables and some some small vacuum hoses neatly in place.

*_Cryostat:_***
James Brock and Casey Flanagan disassembled the cryostat for 
modifications for the next cool-down.  We'll add a small tube inside the 
refrigerator that should give us a more accurate measurement of the 
vapor pressure over the liquid helium bath. This is needed for accurate 
calibration of the NMR signal.  Mark Hoegerl will weld attachment points 
on the back of the cryostat for hanging it from the above-mentioned 
support frame.  James Brock is doing a major overhaul of the NMR & 
microwave insert.  This will include a new microwave horn/reflector on 
the underside of the bath.  He and I did some simple measurements on a 
variety of different horn shapes last week.  They do a nice job of 
distributing microwave power over the 2 cm width of a target sample, but 
not quite its full 4 cm length.  James will have some new designs 3D 
printed soon.

*_Installation:_*
We still seem to be on Hall B's unofficial schedule for 2022. When 
asked, I told Stepan Stepanyan that two months would be required to 
install and get the target fully functional in Hall B.  James Brock and 
myself met with Hall B's engineer and designer, Bob Miller and Cyril 
Wiggins, to discuss the installation.  Bob agreed to move the 500 liter 
buffer dewar of liquid helium from its current location to the same 
level as the target cryostat.  This will permit us to use a shorter and 
more efficient transfer line to the target refrigerator.   Bob will 
design and construct a small platform with handrails so we can access 
the cryostat for loading and unloading ammonia samples while the target 
is inside the central detector.    Cyril will design a support frame for 
the downstream raster magnet that attaches to the same rails on the 
target electronics cart as the cryostat.  Finally, we discussed the 
location of the vacuum valve and thin window between the cryostat and 
beam line.

*_Cool-down:_*
We are on track for a cool in late November.  Its primary focus will be 
DNP of butanol and deuterated butanol samples and loading and unloading 
same with the latest version of James Brock's retraction mechanism.  
James Maxwell has been preparing the samples.

I think that's about all.  Let me know if you have any questions.

Best regards,
Chris


-- 
______________________________________________________
Christopher D. Keith, PhD
Jefferson Lab, Suite 6          email: ckeith at jlab.org
12000 Jefferson Ave.            ph: 757-269-5878
Newport News VA 23606           fax: 757-269-5235
______________________________________________________

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