Transcript xBSM Analysis - Dan Peterson 2011-02-18

xBSM Analysis - Dan Peterson 2011-02-18
At previous meetings:
2011-01-28 CesrTA general meeting
2011-02-01 Collaboration meeting
reported on progress on xBSM data analysis
using all 3 optics : GAP. FZP, CA,
using parameterized fitting in all cases.
2011-02-18 an update
modifications to the functions
comparison of results from optics, for same conditions
comparison with the template-based fitting
New fits: GAP - unchanged, using a gap size of 21μm referred to the source.
4 parameters: gaussian + flat background
FZP - out-of-focus width and fraction have been calibrated
using the smallest beam size available.
Introduced a slope to the background.
4 parameters: narrow gaussian + background slope
D. Peterson
2011-02-18
( Wide gaussian position, width,
and fractional area are fixed.
Constant background is fixed in
a preliminary fit. )
CA - adjusted peak positions ( 2) and strengths (3) .
There were changes to 5 of the 36 constants.
Intrinsic widths at σ=0 μm beam size are derived from the sum: ∑ exp(i 2π P(x) /λ T(x) )
For this approach to work, it is necessary only to have a function for σ=0 μm beam size
and parameterization for σ≠0 μm beam size .
Remember, it does not matter how I obtain the function.
3 parameters: width, position, height
The position motion is
now reported at the
source.
J. Flanagan template fitting
D. Peterson parameterized fitting
GAP
FZP
CA
FZP
16 μm
40 μm
20 μm
50 μm
30 μm
“57 μm”
The out-of-focus part is has a width of σ=84 μm, and is 87% of the signal.
Precision is lost when the beam size exceeds about σ=45 μm.
Coded Aperture
16 μm
20 μm
45 μm
When the beam size exceeds
about σ=55 μm,
the dip between the two major peaks
has less influence on the fit
relative to trying to fit the wings.
Even though the fit range is cut off
with larger beam motion
(so that non-pixels are not added to
the average),
the fit is not good on the wings.
50 μm
“60 μm”