mfisch
Hi Alan
I would like to use the absorption edge macro.
If I refine from a standard material (Corundum) k-beta, I obtain a very small value (2%), which should not affect my lambda list too much (it is no longer 100% when I add k-beta but in this case 102%).
When I then add the absorption edge macro, the same value (2% k beta) now refines to 20%...
Can you please explain a little more what this macro exactly does?
What are the parameters a_white and b_white and a_erf, edge_extra? Are there meaningful values?
Thanks,
Martin
alancoelho
Hi Martin
The absorption edge macro is defined in TOPAS.INC as:
macro Absorption_Edge_Correction_Eqn(& edge, & a_white, & b_white, & a_erf, & edge_extra)
{
modify_peak_eqn =
(
Get(current_peak) + ' Line 1
a_white Exp(- b_white (Get(current_peak_x) - edge)^2) / Tan(Th) ' Line 2
)
(edge_extra + 0.5 (1 + Erf_Approx( a_erf (Get(current_peak_x) - edge))) ); ' Line 3
}
Get(current_peak) is an emission profile line, lets call this EML. EML therefore has a Gaussian added to it; the Gaussian is defined in Line 2. This Gaussian represents the white radiation.
The Gaussian is divided by Tan(Th) in order to preserve intensity such that I dTh = I dLamda.
The (EML + Gaussian) is then multiplied by a filter (Line 3). The filter is simply a step function as defined by the error function. You can plot this filter using Excel for example.
edge_extra is supposed to indicate the amount of intensity that gets through the Ni filter. Typically its set to zero.
cheers
alan
mfisch
Thanks!!
So, there is a high correlation between edge_extra and a refined k-beta intensty, I guess.
K-beta needs to be determined w/o the abs. edge macro...