[esa-t474] spectrometer uncertainty

[Bino Maiheu]

	Dear All,

I've started some studies concerning the uncertainty and the overall
layout of the chicane. I wanted to make some plots first of all in the
style of Karl-Heinz Hiller ( see LC-DET-2004-031 ), but for a 4 magnet
chicane. I think it's important that we have a think about how to
calculate the energy in a 4 magnet chicane and that we fix the formalism
for later studies. So I've started a small writeup, which you can see in
attachment. 

I also included a plots which shows the \Delta E/E versus \Delta B/B,
distance between the first 2 magnets, distance between the central BPM
and the second magnet ( as these are the 2 independent variables ! ) and
the uncertainty on these quantities, for BPM resolutions of 1um, 500,
100 and 50 nm. There is more explanation in what I have written so far,
which are nothing more than some initial thoughts, but I wanted to
distribute this already now for early feedback. 

My plan next is to extrapolate these plots for ILC chicane and
subsequently use a full Geant 4 simulation with real fieldmaps to
reproduce and study these curves more in detail as a function of
magnetic field uniformity and misalignments of BPMs and Magnets.

Questions and sort of drafting of a TODO list are welcome. 

Bino


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