[Olympus] Fwd: BPMs, magnetic field, MIE, etc

[Axel Schmidt]

Begin forwarded message:

> From: Alexander Kiselev <kisselev at mail.desy.de>
> Subject: BPMs, magnetic field, MIE, etc
> Date: August 30, 2016 at 17:25:56 EDT
> To: <schmidta at mit.edu>
> 
>  Hi Axel,
> 
>  first, congratulations with your defence. Second (being myself a 12 degree monitor person), let me challenge your 0.27% MIE method systematic
> uncertainty estimate. Starting with a simple question: was BPM data
> "corrected" in some sort for the non-vanishing magnetic field along the beam line between BPM#1 and BPM#2?
> 
>  I mean ~10-20um match between e+ and e- data sounds a bit of a stretch to me, far beyond the capability of a rather simplistic detector we had in hands. With ~1mT residual fields (perhaps not precisely accounted), ~1.5m BPM#1->BPM#2 distance and 2 GeV/c energy you can easily get far off beyond
> that when comparing electron and positron *beams*. Which IMHO happens *before* the situation you considered in section 6.4 (fig.6-15).
> 
>  By the way, MIE method itself with all the machinery you developed looks fine to me. I just doubt the absolute luminosity ratio normalization
> accuracy one can get from it.
> 
>  Unrelated, concerning fig.8-9: does it mean, that you had to waste ~1/4 or so of the raw data (or do I misinterpret the plot)?
> 
>  Cheers,
>    Alexander.
> 

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