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McStas: ILL_H22_D1A

[ Identification | Description | Input parameters | Links ]

The ILL_H22_D1A Instrument

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

Identification

  • Site: ILL
  • Author: E. Farhi
  • Origin: ILL
  • Date: 13 Apr 2006

Description

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.
NameUnitDescriptionDefault
lambdaAngsWavelength at monochromator1.911
dlambdaAngsWavelength-spread around lambda at source0.03
DMAngsd-spacing of monochromator. Use DM=0 to compute the values from the requested wavelength.0
RVmRadius of vertical focussing. flat for 0-1
powderstrFile name for powder sample description"Na2Ca3Al2F14.laz"
containerstrFile name for container decription in Al cryostat/furnace"V.laz"

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36


Last Modified: Wednesday, 03-Jan-2024 19:59:10 CET
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