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McStas: RITA_II

[ Identification | Description | Input 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.
NameUnitDescriptionDefault
ITARmARelative neutron yield from the spallation target. Value relative to 20091.0
L0AngsCentre of generated wavelength distribution from source4.045
BPLBand 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
BPHBand 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_N1Order of reflection used on mono1
MONOFORCE1If set, monochromator is flat0
MONO_MOS_HminMonochromator, horizontal mosaicity37
MONO_MOS_VminMonochromator, vertical mosaicity37
EImeVIncoming neutron energy. Also used to set range of energy monitors0
EFmeVOutgoing neutron energy. Also used to set range of energy monitors0
ENmeVEnergy transferred in crystal0
SM11
SS1Scattering configuration signs. 'W' is SM=1,SS=-1,SA=1-1
SA11
QHrluMeasurement QH position in crystal0
QKrluMeasurement QK position in crystal0
QLrluMeasurement QL position in crystal0
QMAngs-1Wavevector transferred in sample, use QM=0 if (QH,QK,QL) is specified1.8051
ASAngsSample lattice parameter A4.95
BSAngsSample lattice parameter B4.95
CSAngsSample lattice parameter C4.95
AAdegAngle between lattice vectors B,C90
BBdegAngle between lattice vectors C,A90
CCdegAngle between lattice vectors A,B90
AHrluFirst reciprocal lattice vector in scattering plane, X0
AKrluFirst reciprocal lattice vector in scattering plane, Y1
ALrluFirst reciprocal lattice vector in scattering plane, Z0
BHrluSecond reciprocal lattice vector in scattering plane, X1
BKrluSecond reciprocal lattice vector in scattering plane, Y0
BLrluSecond reciprocal lattice vector in scattering plane, Z0
INFILTER1Flag to indicate if mono-block filter is in or out0
INFILTERFILEstringAn input file of wavevector vs transmission to use with incoming filter"Be.trm"
COLL_MSdegPrimary collimator max divergence80
MSTmMonochromator TOP slit40
MSBmMonochromator BOTTOM slit40
MSLmMonochromator LEFT slit40
MSRmMonochromator RIGHT slit40
PTHICKmThickness of perspex attenuator1e-3
PERSPEX1Flag to indicate if perspex attenuator is in or out0
SAMPLE11 is incoherent scatterer, 2 is powder, 3 is single crystal.1
SAMPLEFILEstringName of samplefile (with reflectionlist etc)"default"
MOSIsotropic 'mosaicity' of single crystal100
DD_Dspead of lattice parameter1e-3
SAMPLESIZEmLength, height and width of single crystal sample, or radius and height of phonon sample0.01
BARNS1If set the flag indicates that reflection list structure factors are in units of barns, otherwise fm^21
AAX-4.95
AAYOrientation vector of unit cell, single_crystal0
AAZ0
BBX0
BBYOrientation vector of unit cell, single_crystal0
BBZ4.95
CCX0
CCYOrientation vector of unit cell, single_crystal4.95
CCZ0
A1degMonohromator rotation angle0
A2degMonohromator take-off angle0
A3degSample rotation angle0
A4degSample take-off angle0
A6degAnalyzer take-off angle0
TILTdegTilt angle out of plane of the sample scattering vector out of plane (rotation around z of the A3 arm)0
SSTmSample TOP slit100
SSBmSample BOTTOM slit100
SSLmSample LEFT slit100
SSRmSample RIGHT slit100
OUTFILTER1Flag to indicate if the outbound filter is in or out1
OUTFILTERFILEstringAn input file of wavevector vs transmission to use with outgoing filter"Be.trm"
ANAFORCE1If set the analyzer is forced flat0
AA5degAnalyzer rack rotation angle0
C1degAnalyzer blade 1 position0
C2degAnalyzer blade 2 position0
C3degAnalyzer blade 3 position0
C4degAnalyzer blade 4 position0
C5degAnalyzer blade 5 position0
C6degAnalyzer blade 6 position0
C7degAnalyzer blade 7 position0
C8degAnalyzer blade 8 position0
C9degAnalyzer blade 9 position0
COARSE1Flag to indicate if Detector collimator is in or out1
LCdegDetector-collimator angle of the leftmost blade4
RCdegDetector-collimator angle of the rightmost blade3
REP1Repetition factor of virtual_input or Monochromator/Sample/Analyzer SPLITs1
VIRTUALOUT1If set, flag indicates that a Virtual source is created after the monochromator collimator0
VIRTUALIN1If set, flag to indicates that Virtual source is used after the monochromator collimator0
SOURCEFILEstringName of file to be used/genereated as virtual input/output"Vin_default.dat"
verbose1print TAS configuration. 0 to be quiet1

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 | Links ]

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


Last Modified: Wednesday, 03-Jan-2024 19:59:10 CET
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