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McStas: ILL_H10_IN8 Instrument at ILL

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

The ILL_H10_IN8 Instrument

Thermal neutron three-axis spectrometer IN8@ILL

Identification

Description

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
distance.

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.
Name Unit Description Default
KF Angs-1 Outgoing neutron wavevector 5
KI Angs-1 Incoming neutron wavevector 0
QM Angs-1 Wavevector transfer in crystal 0.5
EN meV Energy transfer in crystal 0
verbose 1 print TAS configuration. 0 to be quiet 1
WM m Width of monochromator 0.233
HM m Height of monochromator 0.197
RMH m Monochromator horizontal curvature, 0 for flat, -1 for automatic setting -1
RMV m Monochromator vertical curvature, 0 for flat, -1 for automatic setting -1
DM Angs Monochromator d-spacing 1.807
NHM 1 Number of horizontal slabs composing the monochromator 15
NVM 1 Number of vertical slabs composing the monochromator 15
WA m Width of analyzer 0.16
HA m Height of analyzer 0.08
RAH m Analyzer horizontal curvature, 0 for flat, -1 for automatic setting -1
RAV m Analyzer vertical curvature, 0 for flat, -1 for automatic setting -1
DA Angs Analyzer d-spacing 2.087
NHA 1 Number of horizontal slabs composing the analyzer 15
NVA 1 Number of vertical slabs composing the analyzer 15
L1 m Source-Monochromator distance. Contains 1st Collimator of length 5.34 2.3
ALF1 arc min Horizontal collimation from Source to Monochromator 60
ALF2 arc min Horizontal collimation from Monochromator to Sample A 60
ALF3 arc min Horizontal collimation from Sample to Analyzer 60
ALF4 arc min Horizontal collimation from Analyzer to Detector 60
BET1 arc min Vertical collimation from Source to Monochromator 120
BET2 arc min Vertical collimation from Monochromator to Sample A 120
BET3 arc min Vertical collimation from Sample to Analyzer 120
BET4 arc min Vertical collimation from Analyzer to Detector 120

Links

  • Source code for ILL_H10_IN8.instr.
  • Rescal for Matlab at http://www.ill.eu/instruments-support/computing-for-science/cs-software/all-software/matlab-ill/
  • Restrax at http://omega.ujf.cas.cz/restrax/

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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Mar 17 20:40:07 2017


Last Modified: Friday, 17-Mar-2017 21:40:07 CET
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