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--- fixed_incident_beam_absorption [2010/10/18 23:04] – rowlesmr
+++ fixed_incident_beam_absorption [2025/09/19 15:18] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Fixed_Incident_Beam_Thick_Sample_Absorption ======
+This macro is part of a collection of macros that are used to 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
+Thick Sample absorption correction for fixed incident beam geometry. There is a typo in the delta function in the original reference. It's correct here.\\
+Ref: Masson, O., Guiebretière, R. & Dauger, A. (1996). J. Appl. Cryst. 29, 540-546.
+<code topas>macro Fixed_Incident_Beam_Thick_Sample_Absorption { FIBTSA }
+macro FIBTSA(alpha_v, mu_v) { FIBTSA(,alpha_v,,mu_v) }
+macro FIBTSA(alpha, alpha_v, mu, mu_v)
+{
+   #m_argu mu    ''in cm^-1
+   #m_argu alpha ''in degrees
+   If_Prm_Eqn_Rpt(mu, mu_v, min 3 max 500)
+   If_Prm_Eqn_Rpt(alpha, alpha_v, min 0.0001 max 90)
+   exp_conv_const = Ln(0.001) (1/((CeV(mu,mu_v) Rs / 10) ((1/Tan(2 Th - CeV(alpha,alpha_v) Deg)) + Tan(Th)))) Rad;
+                  ''^ the Ln(0.001) is because of the definition of the exp func in topas -- see the manual.
+                                                 ''^ the /10 is in there because Rs is in mm and mu is in cm^-1
+}</code>