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fixed_incident_beam_profile [2010/10/18 23:59] (current)
rowlesmr created
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 +====== Fixed_Incident_Beam_Footprint_Correction_With_Mixing ======
 +
 +This macro is part of a collection of macros that are used to properly model the effects of a flat plat sample with a fixed angle incident beam.
 +
 +There is a nice overview of their application in [1]. Individual references are given for each macro.
 +
 +[1] Rowles, M. R. & Madsen, I. C. 2010, '​Whole-Pattern Profile Fitting of Powder Diffraction Data Collected in Parallel-Beam Flat-Plate Asymmetric Reflection Geometry',​ Journal of Applied Crystallography,​ vol. 43, no. 3, pp. 632-634.
 +
 +Contributor:​ Matthew Rowles
 +
 +This macro corrects the peak profile for a flat plate in fixed incident beam geometry, assuming a parallel incident beam and no diffracted optics. Theoretically,​ the mixing parameter should be "​1"​ for an incident beam intensity profile of a hat, but realistically,​ there will be some tapering of intensity at the edges, hence the gaussian... This should be used in conjunction with [[fixed_incident_beam|Fixed_Incident_Beam_Thick_Sample_Correction]].\\ ​
 +Ref: Rowles, M. R. & Madsen, I. C. (2010). J. Appl. Cryst. 43, 632-634.
 +<code topas>​macro Fixed_Incident_Beam_Footprint_Correction_With_Mixing { FIBFCWM }
 +macro FIBFCWM(alpha_v,​ beam_v, mix_v) { FIBFCWM(, alpha_v,, beam_v,,​mix_v) }
 +macro FIBFCWM(alpha,​ alpha_v, beam, beam_v, mix, mix_v)
 +{
 +   #​m_argu alpha ''​angle between the incident beam and the flat plate sample (in degrees)
 +   #​m_argu beam  ''​height of the beam in the vertical (in mm)
 +   #​m_argu mix   ''​the mix param between a purely hat and a purely gaussian beam profile -> 1 is pure hat
 +   ​If_Prm_Eqn_Rpt(alpha,​ alpha_v, min 0.0001 max 90)
 +   ​If_Prm_Eqn_Rpt(beam,​ beam_v, min 0.0001 max 10)
 +   ​If_Prm_Eqn_Rpt(mix,​ mix_v, min 0 max 1)
 +
 +   local width_ = (Sin(2 Th - CeV(alpha, alpha_v) Deg) Rad / Rs) (CeV(beam, beam_v) / Sin(CeV(alpha,​ alpha_v) Deg));
 +                 ''​^the width of the footprint as seen from 2Th   ^the actual footprint on the sample
 +
 +   hat = CeV(mix, mix_v) width_;
 +   ​gauss_fwhm = (1-CeV(mix, mix_v)) width_;
 +}</​code>​
  

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