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McStas: ILL_H10_IN8

[ Identification | Description | Input parameters | Links ]

The ILL_H10_IN8 Instrument

Thermal neutron three-axis spectrometer IN8@ILL



IN8 is installed on beamtube H10 (diameter F = 200 mm).
The incident wavelength selection is obtained through a double focusing
monochromator , which has three faces equipped with PG002, Cu200 and bent
perfect Si111 crystals, respectively. Horizontal focusing allows increasing the
monochromatic flux at the expense of momentum but not energy resolution when
the horizontal virtual source (an adjustable entrance slit) is introduced at a
distance before the monochromator which matches the monochromator-sample

The aperture of the horizontal virtual source can be varied but is typically
kept below 50 mm. This reduces the background level of the instrument.
Converging collimators as well as diaphragms can be placed in the beam path
before and after the monochromator to optimize the beam dimension and
definition. For special high-resolution experiments using a flat monochromator,
Soller collimators are available.

The shielding drum allows varying the monochromator take-off angle in the range
10 < 2theta_m < 90. The secondary spectrometer has heavy borated polyethylene
shielding installed around the analyzer and detector elements. The scattering
angle at the sample position is in the range 0 < 2theta_s < 130 independent of
the monochromator take-off angle.

In this TAS configuration, Cu200 is used as monochromator and Cu111 as
analyser, with a single type detector.

Input parameters

Parameters in boldface are required; the others are optional.
KFAngs-1Outgoing neutron wavevector5
KIAngs-1Incoming neutron wavevector0
QMAngs-1Wavevector transfer in crystal0.5
ENmeVEnergy transfer in crystal0
verbose1print TAS configuration. 0 to be quiet1
WMmWidth of monochromator0.233
HMmHeight of monochromator0.197
RMHmMonochromator horizontal curvature, 0 for flat, -1 for automatic setting-1
RMVmMonochromator vertical curvature, 0 for flat, -1 for automatic setting-1
DMAngsMonochromator d-spacing1.807
NHM1Number of horizontal slabs composing the monochromator15
NVM1Number of vertical slabs composing the monochromator15
WAmWidth of analyzer0.16
HAmHeight of analyzer0.08
RAHmAnalyzer horizontal curvature, 0 for flat, -1 for automatic setting-1
RAVmAnalyzer vertical curvature, 0 for flat, -1 for automatic setting-1
DAAngsAnalyzer d-spacing2.087
NHA1Number of horizontal slabs composing the analyzer15
NVA1Number of vertical slabs composing the analyzer15
L1mSource-Monochromator distance. Contains 1st Collimator of length 5.342.3
ALF1arc minHorizontal collimation from Source to Monochromator60
ALF2arc minHorizontal collimation from Monochromator to Sample A60
ALF3arc minHorizontal collimation from Sample to Analyzer60
ALF4arc minHorizontal collimation from Analyzer to Detector60
BET1arc minVertical collimation from Source to Monochromator120
BET2arc minVertical collimation from Monochromator to Sample A120
BET3arc minVertical collimation from Sample to Analyzer120
BET4arc minVertical collimation from Analyzer to Detector120


  • Source code for ILL_H10_IN8.instr.
  • Rescal for Matlab at
  • Restrax at

[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43

Last Modified: Tuesday, 16-Apr-2024 20:05:21 CEST
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