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McStas: ILL_H22_D1B Instrument at ILL

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

The ILL_H22_D1B Instrument

The D1B diffractometer on the H22 curved thermal guide at the ILL


  • Site: ILL
  • Author: FARHI Emmanuel ( and SANCHEZ Javier (
  • Origin:ILL
  • Date: June, 2008
  • Version:(Unknown)


The D1B diffractometer on the H22 curved thermal guide at the ILL.

D1B is a two-axis spectrometer dedicated to diffraction experiments requesting a
high neutron flux. A great number of experiments performed on D1B concern the
determination of magnetic structures. At small angles where the magnetic peaks
are expected, a high spatial resolution can be achieved, the FWHM reaches 0.2°
(for a sample with = 8 mm). Three pyrolitic graphite monochromators focusing
onto the sample position provide a flux of 6.5·106 n cm-2s-1. A second
wavelength with = 1.28 Å is available by using a germanium monochromator. D1B is
equipped with 3He/Xe position-sensitive detector composed of a system of
multi-electrodes with 400 cells, which span a 2 range of 80°. The detector can
be moved so that an angular range of 2°<2<130° can be covered. The specially
designed cryostat is known for its low background crucial for some experiments
with small intensity changes. Because of its high flux at = 2.52 Å together with
the large multi-detector, surface studies such as adsorbed phases as well as
real-time diffraction experiments are possible. Collecting a diffraction pattern
with sufficient statistics in minutes (1-5 min) even seconds allows in situ
studies of reaction kinetics. A fast detection of phase transitions can also be
obtained by scanning the temperature. A complete thermal variation of the
diffraction patterns (1.5 - 300 K) can be achieved in few hours (3-5h).

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
lambda AA mean incident wavelength. 2.52
dlambda AA wavelength full width. 0.03
DM 0
Powder str File name for powder description, LAZ/LAU/Fullprof "Na2Ca3Al2F14.laz"
RV m Monochromator vertical curvature, 0 for flat, -1 for automatic setting 2.2
L1 m Source-Monochromator distance 0.25
L2 m Monochromator-Sample distance 3.0
L3 m Sample-Detector distance 1.500
TRAS_X m Additional monochromator translation along X, left/righ w.r.t beam -0
TRAS_Z m Additional monochromator translation along Z, along guide 0
TILT deg Monochromator additional tilt, for rocking curves 0
THETA_M 22.11
R_pitch deg Angular pitch between the absorbing blades .42
R_ri m Inner radius of the collimator 0.324
R_ro m Outer radius of the collimator 0.419
R_h m Height of the collimator 0.090
R_ttmin deg Lower scattering angle limit -130
R_ttmax deg Higher scattering angle limit -2
R_present 1 Presence flag for the radial collimator. 0: unactivate component. 1
verbose 1 Print DIF configuration. 0 to be quiet 1
Inc_Cryo 1 Cryostat incoherent fraction 0.02
Trans_Cryo 1 Cryostat event transmission 0.85
Trans_Spl 1 Sample event transmission 0.2
Inc_Spl 1 Sample incoherent fraction 0.05


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

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