Content

Analysis of cxif5315

Comments and references to code

2015-05-04 from Kartik Ayyer:

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Fraser transformation in python

Menng's matlab code fraser1.m,  fraser2.m for Fraser transformation is implemented in python fraser.py (download).

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Example of diffraction and transformed images: 

Angles phi and beta using Kartik's code

Using Kartik's formulas for angles phi and beta kartik-2-peak-ev-angles.py.txt one can get distributions:

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• angle phi is evaluated using two peak positions and sample-to-detector distance
• angle beta is evaluated using one !!! peak position and angle phi.
• peak and event selection need to be improved
• it could be nice to have explanation to this formalism...

Angles phi and beta from fit

Solving equation for tan(theta) we may get functional dependence between x and y peak position for angles phi and theta,

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this function presents a solution of quadratic equation which has two roots. The root is selected depending on sign of theta angle...

This function is parameterized catheterized in python script fiber_angles.py and can be plotted for different angles:

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Solutions: y1=-B+sqtr(B^2-C)   and y2=-B-sqtr(B^2-C):

Similar function is used in data processing to fit peak (x,y) positions in equatorial region and use two angles as a fit parameters.

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