[Halld-tagger] NMR control

[Alexander Somov]

I would also contact with Paul Brindza and check with him.
The Hall-B dipole magnet was operated at a lower field of
~1.1 T as far as I remember (though I am not 100% sure).
Could the magnet cooling become an issue for us ?

Cheers,
       Alex



On Thu, 8 Oct 2009, Tim Whitlatch wrote:

> Hi All,
>
> We plan on having an NMR probe (actually 2). The power supply will be stable 
> to 10ppm. I spoke with Stepan from Hall B and they are not using feedback and 
> have not had the need. They have a 0.1% energy resolution requirement.They 
> periodically look at the Hall probe data and have not seen any changes that 
> would affect their resolution.
> Shall we get rid of our feedback/control requirement?
>
> Tim
>
> Richard Jones wrote:
>> Response from Dan Sober,
>>> Richard,
>>> Hall B lived without a field probe for a long time, just trusting the 
>>> current setting procedure and monitoring the current -- seemed to be 
>>> consistent to much better than 10^-3. Eventually (in 2004) a Hall probe 
>>> was installed, but I think it is just read out into the data base, not 
>>> used for feedback.  If the current regulation is good, then I don't think 
>>> field feedback is necessary, unless new operating experience tells us 
>>> otherwise.
>>> Dan
>>> 
>> 
>> 
>> Alexander Somov wrote:
>>> Hi,
>>> 
>>> Do you know whether the Hall-B used a feedback in their magnet ?
>>> 
>>> Is it a temperature variation in the magnet that leads to the
>>> field variation for the constant current/voltage (I would talk to the 
>>> magnet experts and try to find out the magnitude of the field
>>> instability) ? ( would Paul Brindza be the right person to discuss ? )
>>> 
>>> Cheers,
>>>         Alex
>>> 
>>> P.S. On the other hand $20k is not an extreme amount.
>>>   Perhaps it's better to have the feedback system...
>>> 
>>> 
>>> 
>>> 
>>> On Wed, 7 Oct 2009, Tim Whitlatch wrote:
>>>
>>> 
>>>> Hi Gents,
>>>> 
>>>> Have we decided whether or not we can live without an NMR controller on 
>>>> the tagger magnet power supply? I know we want to know the field with the 
>>>> probes but do we need to have the feedback to automatically adjust? This 
>>>> may determine whether or not we can get a rebuilt controller from JLAB 
>>>> for about $20K.
>>>> 
>>>> Tim
>>>> 
>>>> 
>>>>
>>>>
>>> 
>> 
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