TOPAS full axial model

[Łukasz Kruszewski]

Hello to all! 

My name's Lukasz Kruszewski, my interest recently is the mineralogy of 
burning coal dumps. I'm trying to obtain the unit cell parameters of some 
members of the alunite group, analysed on Bruker D5005 diffractometer (Co 
Ka, Bragg-Brentano, RS = 0.6mm wide, FDS = 1 deg.) with use for an article. 
I pack powdered samples as thin layer on a glass slide with limiters. I 
would like to kindly ask for help in understanding well the FULL AXIAL MODEL 
in the INSTRUMENT section of TOPAS program. I know that the SOURCE LENGTH, 
SAMPLE LENGTH and RS length should be FIXED, but I don't know actually does 
the SAMPLE LENGHT means. Do I understand well that its the length of the 
beam focusation area only, or the whole length of the glass slide, or the 
'working' distance between source and detector? 

I would be grateful for any tips (-: 

With best regards, 

Lukasz Kruszewski
Instutite of Geochemistry, Mineralogy and Petrology
Faculty of Geology
University of Warsaw