[ Identification | Description | Input parameters | Links ]

The ILL_H22_D1B Instrument

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

Identification

• Site: ILL
• Author: FARHI Emmanuel (farhi@ill.fr) and SANCHEZ Javier (sanchez-montero@ill.fr)
• Origin: ILL
• Date: June, 2008

Description

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	AA	Mono lattice spacing	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	deg	Mono takeoff angle	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

Links

• Source code for ILL_H22_D1B.instr.

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[ Identification | Description | Input parameters | Links ]

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

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Last Modified: Tuesday, 17-Sep-2024 05:31:13 CEST