[esa-t474] Energy resolution for the ESA spectrometer

[Michele Viti]

Mike Hildreth wrote:
> Hi Yury,
>
> 	Interesting question.  The NMRs we used at CERN to map the LEP 
> spectrometer dipole were better than 1e-4, but that was also at much 
> higher field. We had reproducibility on the integral of the central field 
> where the NMRs locked to a few 1e-6, where the integral was calculated as 
> the piecewise area between successive measurements using the NMR values as 
> the corners of the trapezoid and a precision rule for the distance.  The 
> field itself had fluctuations along the length of almost 1e-3, so it was 
> definitely not a case of averaging out fluctuations.
> 	
> 	cheers,
>
> 		mike
Hi;
I rememebr that the magnetic field at LEP was 0.1 T at 100 GeV...which 
was exactly the magnetic field used in ESA for the magnetic chicane.
The NMR used in magnet 2 and 4 (the ones used for measurements) are type 
2 covering B-field range 0.09 to 0.26 Tesla.
According to the manual the absolute accuracy of better than 5 ppm and a 
resolution is around 10^-7 Tesla....

cheers

Michele