News
- peak fitting code is separated in a new script:
cxif5315/fit-peaks-2017-03-08.py
- code is cleaned, purified, straight-forwarded and brought to "standard-command-line-interface" style
- formalism for peak coordinate y(x,phi,beta,...) is checked.
- It looks correct for l=0
- for l=1 I am still doubt about 1-st equation. Other than that it is correct.
- Sign conventions: sign of angle phi and beta returned by the fit to n peaks and saved in the peak list is the same as from direct angles evaluation using 2 peaks in equatorial plane from equations:
tan(phi) = (y2*d1-y1*d2) / (x1*d2-x2*d1)
tan(beta)= x*sin(phi) + y*cos(phi) / d
where x=px/R, y=py/R, d=sqrt(1+x*x+y*y) - 1, px,py
-peak coordinates andR
-sample to detector distance in the same units aspx,py
.
Significant code changes
- sign of angle
beta
is changed for saving in the list pf peaks. - fit is considered not-completed if covariance matrix contains inf or fit returns non-changed input parameters for angles.
Fit results
Consumed time (sec) : 29.693 Events processed : 9735 Events fitted : 3517
EQU
Pre-selected event peak statistics
Angles evaluated for 2-peak events
Angles from n-peak fit
Fit quality
Event selection based on fit quality
fit probability > 0.1 Error on phi < 2 deg Error on beta < 10 deg |dphi| < 10 deg |dphi| < 20 deg
Difference between n-peak fit and 2-peak evaluation for 2-peak in EQU events
Small difference between two algorithms of angles evaluation confirms that
- signs are selected correctly,
- complicated n-peak fit algorithm produces the same results as simple 2-peak formulas.
___________________________________________________________________________
ARC (is not used for now)
Angles from the fit for 2-peak
ARC fit quality
Difference between fit in ARC (2-peak) and EQU (2-4-peak) regions
Again: not quite sure in formalism for ARC region
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