[Frost] APS slides

[Christopher Keith]

Hi Natalie,
I think your slides look good.  My only comment, as you might expect, is 
about the target.  Your description of how it is polarized is misleading.

The 5T magnet does not align the proton spins to 95% at very low 
temperatures.  This implies the old brute-force method of polarization, 
and it's not the method we use.

Instead, the butanol material is doped (before freezing) with the 
paramagnetic radical TEMPO, and the unpaired electrons in this radical 
are polarized to 99.999% using the 5T magnet and a temperature of about 
0.3K.  Microwaves at ~140 GHz are then used to transfer this electronic 
polarization to the free protons in the butanol,  a process called 
dynamic nuclear polarization, or DNP. The microwaves are switched off, 
the target is cooled to about 0.03 K, and a smaller, 0.5T "holding" coil 
is used to maintain the proton polarization during the photon runs.

For brevity, you might want to say something like: "Free proton spins in 
butanol were dynamically polarized up to 95% at 0.3K, using a 5T 
solenoid. For photon runs the target was operated in the frozen spin 
mode at 30 mK, using a 0.5T racetrack coil to rotate and hold the 
polarization in the transverse direction."

Hope this helps, and good luck at the APS.

Chris Keith

On 4/9/13 11:20 PM, natalie at jlab.org wrote:
> Hi everyone,
> I cannot attend tomorrow's meeting, but here are my slides for APS this
> weekend. It is extremely similar to the collaboration meeting. Please let
> me know if you have any suggestions.
>
> http://www.jlab.org/Hall-B/secure/g9/natalie/apsmtg.pdf
>
> Thanks,
> Natalie
>
> _______________________________________________
> Frost mailing list
> Frost at jlab.org
> https://mailman.jlab.org/mailman/listinfo/frost

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