[Halld-tagger] NMR control

[Tim Whitlatch]

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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