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McStas: ILL_H22_D1A Instrument at ILL

[ Identification | Description | Input parameters | Output parameters | Links ]

The ILL_H22_D1A Instrument

Simple monochromator Diffractometer for powders (D1A) installed on H22, with container/sample environment and radial collimator.


  • Site: ILL
  • Author: E. Farhi
  • Origin: ILL
  • Date: 13 Apr 2006
  • Version:(Unknown)


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.

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
lambda Angs Wavelength at monochromator 1.911
dlambda 0.03
DM Angs d-spacing of monochromator. Use DM=0 to compute the values from the requested wavelength. 0
RV -1
powder str File name for powder sample description "Na2Ca3Al2F14.laz"
container str File name for container decription in Al cryostat/furnace "V.laz"


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <> / Wed Jan 12 15:13:21 2022

Last Modified: Wednesday, 12-Jan-2022 16:13:21 CET
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