XND: Experiment description in the input file.

Introduction

The block has to be repeated for each different experience according to the nExp value declared in the program header; any experience can obviously contain more diagrams and any diagrams more phases. The experiment block contain the following header and variables blocks.

Experiment Header

Natured 0X-ray
1 neutron, single wavelenght
2 anomalous X-ray scattering
3 (neutron, reserved for magnetic structures)
Techn d 0X-ray Bragg-Brentano geometry (symmetric reflection)
0 neutron, single wavelenght (transmission)
1 (reserved for X-ray, asymmetric reflection)
2 (reserved for X-ray, linear detector)
3 (reserved for X-ray, courbed detector)
nDiag d number of diagrams collected in the experience
FileType d file type identifier (see Data File Formats)
nLambda d number of wavelenghts
nBkg d number of points for background definition
TempOrig f origin of polynomial development
Title s title labelling the experience

The following lines are repeated nDiag times. Its content depends on the FileType.
if (FileType=0) (simulation mode, no data to read)
Temp f value of Temp for the simulated diagram
2theta_0 f starting point of the diagram
Delta(2theta) f step
2theta_f f end point of the diagram
if (FileType=20 or 21) (multiples banks)
NPts d number of points on the data file
Temp_min d starting value of Temp
Cumul d 1 or the number of successive diagrams to be cumulated
Skipd 0 or the number of following diagrams to be skipped
NumVard control parameter, Temp is the Numvar parameter in the header
Monod 0 or value of the renormalization monitor
DataName s name of the data file
otherwise
Temp f value of Temp for the actual diagram
NPts d number of points in the data file, these value is only checked when a binary data file is used
Dataname s name of the data file

Wavelength block

Order % kind of developpement of the variables in this standard block
the following group of lines is repeated N\lambda times
lambda @ the value of the wavelength
Int @Intensity of the wavelength
W_l(tan\theta)@ spectral lorentzian width, coefficient of the lorentzian composant varying as tan(theta)-tan(theta_min)
W_g(tan\theta)@ spectral gaussian width, this is the coefficient of the gaussian composant varying as tan(theta)-tan(theta_min)

Background block

Order %kind of developpement of the variables in this standard block
the following group of lines is repeated nBckg times
2theta_i fangle of the selected background point
Int_bkg_i @Intensity of the background at 2theta_i

Alignment block

Order %kind of developpement of the variables in this standard block
Zero @error on the absolute position of 2theta counter in degrees
Polar @correction of polarisation : cos^2(2theta_mono)
0 if neutron or synchrotron radiation data
1 if filtered X-ray data
0.8357 Cu-K_beta radiation, graphite monochromator
t_mono @tangent of the minimum of the spectral distribution (-v/2u of classical Rietveld)
s_Eclair @ intensity correction (rectangular sample) at low angle for illumination

if sin(theta) < s_Eclair the intensities are corrected according to sin(theta)/s_eclair

following are reserved (if Techn > 0)
Zero_{\theta} difference \theta - 2\theta or fixed angle incidence
Abso absorption correction (only if Techn=4)

Instumental profile block

Order %kind of developpement of the variables in this standard block
Wl0 @ constant lorentzian linewidth
Wg0 @ constant gaussian linewidth
Wl_T2 @ lorentzian linewidth varying with 1/tan(2theta) like axial divergency
Wg_T2 @ gaussian linewidth varying with 1/tan(2theta) like axial divergency

Asymmetry block

Order %kind of developpement of the variables in this standard block
the following group of lines is repeated according to mAssym in the program header
A_T2 @ asymmetry coefficient varying with 1/tan(2theta)
A_T @ asymmetry coefficient varying with 1/tan(theta)
AS @ asymmetry coefficient varying with sin(theta)

JFB, June 25th, 1996