[Halld-cal] FCAL pmt mag shield

[Matthew Shepherd]

Hi Tim,

Thanks -- this is great news and seems to imply that 200 G is just  
beyond the saturation point of the mu metal.

Is it true the Floyd's 143G figure is the maximum magnitude of the  
field in any direction?  (Presumably in practice we also only care  
about the transverse component which is likely smaller than 143 G.)

An updated quote would be great and we can then include that in the  
contract.

Thanks again!

-Matt

On Oct 7, 2009, at 10:13 AM, Tim Whitlatch wrote:

> Hi Matt,
>
> Attached is a spreadsheet showing the magnetic field inside the  
> short shield with .014 in mu metal . The ID of the steel pipe is 1.5  
> in.. The mu metal is 1.35 inched ID (need to ensure this clears all  
> the pmts). The space between the mu metal and steel was filled with  
> mylar sheets (approx. .06 in thk). It shows that there is a  
> threshold just under 200G that the shield works (ie below 0.5G). At  
> 185G the shield performs as desired. After getting with Floyd, it  
> looks like the worst case fringe field (from ANSYS model) in the PMT  
> area is about 143G (no cladding on solenoid). This is good news. It  
> looks like standard 1.5 in. pipe can be used. I have asked Amuneal  
> for a new quote for the present mu metal dimensions.
>
> Cheers,
>
>      Tim
> <Short FCAL steel - .014 mu metal -SEP 2009 ( RUN  
> 2 ).xlsx>_______________________________________________
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