At present the monochromator operation is controlled by the IN1's computer under IN1BeF configuration. The control program is MAD and can only be used by the instrument responsible or the local contact. In the future, the monochromator should be controlled by the D4 computer and NOMAD

There is a dedicated computer (d4.ill.fr) for data acquisition, under Linux and running NOMAD. This program allows you to control the sample environment, the detector scans and to produce the raw data (numors).

There is a dedicated computer (d4lnx.ill.fr) for data treatment under Linux. In this computer you have a set of programs allowing you to produce a single diffractogramme from a series of numors, and to perform simple calculations. As output you obtain a three-columns ASCII diffractogram, in scattering angle (2θ) or modulus of the scattering vector (Q).

The word "numor" means "NUMber Of Run", and the numor files have filenames which are simply the 6 digits of the numor (with padded leading zeros). In the following the outpout files will be named regfiles.

Starting a session

To start a session at d4lnx.ill.fr you need the login and password for the d4 account (this information is written near the computer). Then the system will ask you your surname; in fact this is the name you give to your experiment and will be the name of your working directory.

Caution: Please do not modify files outside your personal sub-directories.

Note: You can always return to this home directory (/home/vis/d4/yourname) with the simple command 'cd' .

D4 software

d4creg: reads raw data (numors) and produces a single diffractogramme

d4cget: reads raw data and extract information as function of numors (or any other parameter)

gnuplot: plots and prints the diffractogrammes

d4opr: performs simple operations with regrouped files (regfiles)

d4rebin: performs a rebinning of a regfiles (in angle or in Q)

d4nifit: fits Ni diffractogramme for calibration (based on polyfit)

Script files

In general, it is advantageous to put the d4creg commands (along with other commands for processing D4c data) in a Linux/UNIX script file (by convention at D4c, the filenames of these scripts begin with "do_" and they are called "dofiles").  In this way, the user doesn't need to keep typing the 6-digit numors nor continue to remember the numor range for each scan.

These script files can contain all Linux commands and should be executed using the "source" command. For example, for a dofile named "do_sample" the command should be:

    prompt> source do_sample

The lines starting with # are comments in script files, so the dofiles with proper comments could also serve as logfiles for your experiment.

In this step the diffractogrammes should be corrected by inelasticity, multiple scattering, absorption, instrumental resolution and background. This part of the data treatment is under the responsability of the users, but there is a running version of the program CORRECT allowing to perform all these corrections.

d4fou: performs the Fourier transformation of the srtucture factor

polyfit: performs fittings on experimental data

lorgaun: is a version of polyfit dedicated to fit a convolution of a Lorentzian and a Gaussian

correct: performs multiple scattering, absorption and inelasticity corrections, plus absolute scale normalization