Simple monochromator Diffractometer for powders (D1A) installed on H22, with
container/sample environment and radial collimator.
Author: E. Farhi
Date: 13 Apr 2006
D1A is a reliable diffractometer for standard crystallographic problems. It gives
excellent results with the Rietveld method owing to its near perfect Gaussian
peak-shape in the 2θ-range 30° to 150°.
Special features include
a high fixed take-off angle of 122 deg, giving high resolution at large
scattering angles (up to 160 deg);
a bank of 25 high efficiency collimators and counters;
an anisotropically squashed germanium monochromator focussing a 250
mm high beam onto only 30 mm;
a wide choice of wavelengths, from 1.39 Angs to 2.99 Angs, quickly available by
simple rotation of the focussing monochromator;
The large monochromator take-off angle means that the diffraction pattern is
focussed for the parallel geometry shown (2θ = 122°). The counter can be swept
through 0 deg to 2θ = 160° deg for the highest angle counter, usually in steps
of 0.05 deg.
Monochromator Neutron wavelength
Ge 117 DM=0.7946 AA 1.390
Ge 335 DM=0.8655 AA 1.514
Ge 115 DM=1.0925 AA 1.911 (optimal)
Ge 113 DM=1.712 AA 2.994
The sample is a powder, in a container can, all positioned in an
Al environment (e.g. cryostat/furnace shield).
This instrument was installed on the H22 guide.
Parameters in boldface are required;
the others are optional.
Wavelength at monochromator
d-spacing of monochromator. Use DM=0 to compute the values from the requested wavelength.
File name for powder sample description
File name for container decription in Al cryostat/furnace