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McStas: RITA_II Instrument at PSI

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

The RITA_II Instrument

RITA type triple-axis spectrometer (TAS)

Identification

Description

This instrument is model of RITA-II at the RNR13 guide at SINQ, PSI as of 2009. The energy and q-resolution as been verified against measured data in 2- and 3-axis modes. See Udby et al., Nuclear Instruments and Methods 634 (2011) s138-.
The model is based on the following components in downstream order
  • The SINQ source in 2009 - tested up to Ei=15 meV versus measurements. The spectrum of genereated rays is controlled by the BPL and BPH parameters.
  • The RNR13 guide with average m-value based on color-codes on guide pieces and gaps as measured/from technical drawings.
  • The Druckal monochromator: 5 slabs of PG(002) with vertically focusing option. The horizontal rotation angle (A1) and scattering angle (A2) can either be set by user input or calculated automatically from EI/KI.
  • Optional filter after the monochromator, before the sample.
  • Variable linear collimator after the monochromator, before the sample.
  • Optional perspex attenuation.
  • Inbound Diaphagm slit.
  • Sample: Incoherent scatterer, powder or single crystal from reflection list.
  • Outbound Diaphragm slit.
  • Optional filter after the sample, with radial collimator.
  • 9 - blade analyser: Base-rotation (AA5) and individual blade angles (C1-C9) can either be set by user or calculated automatically from EF/KF.
  • Coarse collimator: Removes cross-talk by allowing only passage of scattered neutrons from specified blade in each channel.
  • Detector: PSD detector with 100% efficiency and specified point-spread function from measurements.
  • Windows: Monitors the neutrons in each electronically specified window [XWinMin,XWinMax;YWinMin,YWinMax].
EXAMPLES
  • Generating a virtual source
  • mcrun RITA-II.instr -n3e6 BPL=0.97 BPH=1.03 EI=5 EF=5 COLL_MS=40 SAMPLE=1 OUTFILTER=0 REP=10 VIRTUALOUT=1 -d RITA-II_Vsource40
  • Vanadium sample, no filters, seeing 1st-3rd order neutrons
  • mcrun RITA-II.instr -n3e6 BPL=0.30 BPH=1.03 EI=5 EF=5 SAMPLE=1 INFILTER=0 OUTFILTER=0 REP=10 -d RITA-II_Vanadium
  • Powder sample (default sapphire), simulation 1) through entire instrument or 2)from virtual source 3) in 2-axis mode, with particular slit settings scaling the source yield to 2008 values
  • 1) mcrun RITA-II.instr -n3e6 EF=5 EN=0 SAMPLE=2 COLL_MS=40 SAMPLEFILE="Al2O3_sapphire.lau" BARNS=0 SOURCEFILE="RITA-II_Vsource40/Vin_default.dat" REP=10 -d RITA-II_40_powder
    2) mcrun RITA-II.instr EI=5 EF=5 SAMPLE=2 SAMPLEFILE="Al2O3_sapphire.lau" BARNS=0 SOURCEFILE="RITA-II_Vsource40/Vin_default.dat" VIRTUALIN=1 REP=3 -d RITA-II_VINsource40_powder
    3) mcrun RITA-II.instr -n 1e7 ITAR=0.71 COLL_MS=19.6 BPL=0.97 BPH=1.03 EI=5 EF=5 QH=0 QK=0 QL=0 QM=1 A3=0.001 A4=-71 AA5=-90 A6=1e-3 MST=25 MSB=25 MSL=10 MSR=10 SAMPLE=2 SAMPLEFILE="Al2O3_sapphire.lau" SST=25 SSB=25 SSL=10 SSR=10 OUTFILTER=0 OUTFILTERFILE=Be.trm COARSE=1 REP=5 LC=6 RC=4 REP=1 BARNS=0 ANAFORCE=1 -d RITA-II_Al2O3_2axis
  • Single crystal sample. Define first lattice vector (a) along -x (to the right) , second lattice vector (b) along z (forward), third lattice vector (c) along y (up).
  • mcrun RITA-II.instr -n1e6 BPL=0.97 BPH=1.03 EI=5 EF=5 SAMPLE=3 REP=10 QH=2 QM=0 AS=4.95 BS=4.95 CS=4.95 AAX=-4.95 BBZ=4.95 CCY=4.95 AH=0 AK=1 AL=0 BH=1 BK=0 BL=0 SAMPLEFILE="Pb.laz" -d RITA-II_SXPb200
  • Phonon sample, inelastic scattering, no Bragg peaks in sample
  • mcrun RITA-II.instr -n1e6 L0=3.418 BPL=0.97 BPH=1.03 EI=7 EF=5 SAMPLE=4 REP=10 QH=2 QK=0.16 QM=0 AS=4.95 BS=4.95 CS=4.95 AAX=-4.95 BBZ=4.95 CCY=4.95 AH=0 AK=1 AL=0 BH=1 BK=0 BL=0 SAMPLEFILE="Pb.laz" -d RITA-II_SXPb200_2meV

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
ITAR mA Relative neutron yield from the spallation target. Value relative to 2009 1.0
L0 Angs Centre of generated wavelength distribution from source 4.045
BPL - Band Pass Low factor, multiplied on source wavelength L0 to allow neutrons with wavelengths with lambda {BPL*L0,BPH*L0} to be traced from the source. 0.97
BPH - Band Pass High factor, multiplied on source wavelength L0 to allow neutrons with wavelengths with lambda {BPL*L0,BPH*L0} to be traced from the source. 1.03
MONO_N 1 Order of reflection used on mono 1
MONOFORCE 1 If set, monochromator is flat 0
MONO_MOS_H min Monochromator, horizontal mosaicity 37
MONO_MOS_V min Monochromator, vertical mosaicity 37
EI meV Incoming neutron energy. Also used to set range of energy monitors 0
EF meV Outgoing neutron energy. Also used to set range of energy monitors 0
EN meV Energy transferred in crystal 0
SM 1
SS 1 Scattering configuration signs. 'W' is SM=1,SS=-1,SA=1 -1
SA 1
QH rlu Measurement QH position in crystal 0
QK rlu Measurement QK position in crystal 0
QL rlu Measurement QL position in crystal 0
QM Angs-1 Wavevector transferred in sample, use QM=0 if (QH,QK,QL) is specified 1.8051
AS Angs Sample lattice parameter A 4.95
BS Angs Sample lattice parameter B 4.95
CS Angs Sample lattice parameter C 4.95
AA deg Angle between lattice vectors B,C 90
BB deg Angle between lattice vectors C,A 90
CC deg Angle between lattice vectors A,B 90
AH rlu First reciprocal lattice vector in scattering plane, X 0
AK rlu First reciprocal lattice vector in scattering plane, Y 1
AL rlu First reciprocal lattice vector in scattering plane, Z 0
BH rlu Second reciprocal lattice vector in scattering plane, X 1
BK rlu Second reciprocal lattice vector in scattering plane, Y 0
BL rlu Second reciprocal lattice vector in scattering plane, Z 0
INFILTER 1 Flag to indicate if mono-block filter is in or out 0
INFILTERFILE string An input file of wavevector vs transmission to use with incoming filter "Be.trm"
COLL_MS deg Primary collimator max divergence 80
MST m Monochromator TOP slit 40
MSB m Monochromator BOTTOM slit 40
MSL m Monochromator LEFT slit 40
MSR m Monochromator RIGHT slit 40
PTHICK m Thickness of perspex attenuator 1e-3
PERSPEX 1 Flag to indicate if perspex attenuator is in or out 0
SAMPLE 1 1 is incoherent scatterer, 2 is powder, 3 is single crystal. 1
SAMPLEFILE string Name of samplefile (with reflectionlist etc) "default"
MOS - Isotropic 'mosaicity' of single crystal 100
DD_D - spead of lattice parameter 1e-3
SAMPLESIZE m Length, height and width of single crystal sample, or radius and height of phonon sample 0.01
BARNS 1 If set the flag indicates that reflection list structure factors are in units of barns, otherwise fm^2 1
AAX - -4.95
AAY - Orientation vector of unit cell, single_crystal 0
AAZ - 0
BBX - 0
BBY - Orientation vector of unit cell, single_crystal 0
BBZ - 4.95
CCX - 0
CCY - Orientation vector of unit cell, single_crystal 4.95
CCZ - 0
A1 deg Monohromator rotation angle 0
A2 deg Monohromator take-off angle 0
A3 deg Sample rotation angle 0
A4 deg Sample take-off angle 0
AA5 deg Analyzer rack rotation angle 0
A6 deg Analyzer take-off angle 0
TILT deg Tilt angle out of plane of the sample scattering vector out of plane (rotation around z of the A3 arm) 0
SST m Sample TOP slit 100
SSB m Sample BOTTOM slit 100
SSL m Sample LEFT slit 100
SSR m Sample RIGHT slit 100
OUTFILTER 1 Flag to indicate if the outbound filter is in or out 1
OUTFILTERFILE string An input file of wavevector vs transmission to use with outgoing filter "Be.trm"
ANAFORCE 1 If set the analyzer is forced flat 0
AA5 deg Analyzer rack rotation angle 0
C1 deg Analyzer blade 1 position 0
C2 deg Analyzer blade 2 position 0
C3 deg Analyzer blade 3 position 0
C4 deg Analyzer blade 4 position 0
C5 deg Analyzer blade 5 position 0
C6 deg Analyzer blade 6 position 0
C7 deg Analyzer blade 7 position 0
C8 deg Analyzer blade 8 position 0
C9 deg Analyzer blade 9 position 0
COARSE 1 Flag to indicate if Detector collimator is in or out 1
LC deg Detector-collimator angle of the leftmost blade 4
RC deg Detector-collimator angle of the rightmost blade 3
REP 1 Repetition factor of virtual_input or Monochromator/Sample/Analyzer SPLITs 1
VIRTUALOUT 1 If set, flag indicates that a Virtual source is created after the monochromator collimator 0
VIRTUALIN 1 If set, flag to indicates that Virtual source is used after the monochromator collimator 0
SOURCEFILE string Name of file to be used/genereated as virtual input/output "Vin_default.dat"
verbose 1 print TAS configuration. 0 to be quiet 1

Links

  • Source code for RITA_II.instr.
  • Rescal for Matlab at http://www.ill.fr/tas/matlab
  • 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> / Wed Apr 19 10:57:33 2017


Last Modified: Wednesday, 19-Apr-2017 12:57:33 CEST
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