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[ Identification | Description | Input parameters | Links ]

The SNS_BASIS Instrument


  • Site: SNS
  • Author: N.Tsapatsaris ( and Peter K. Wilendrup (
  • Origin: NBI
  • Date: 2013-2015


The approximative, analytic SNS Source description of this instrument is realised
by use of the ESS_moderator_short model, but weighted due to the opposite moderator
arrangement at the SNS and at the once-planned ESS short pluse facility. The correct
SNS Source File to use with SNS_Source is source_sct091_tu_02_1.dat.

The instrument serves as a test instrument for the components
Spherical_Backscattering_Analyser, also written by by Niko Tsapatsaris with help from
Peter Willendrup and Guide_m by Niko Tsapatsaris.

The instrument is based on models initially written by
A) REL ( and HNB ( with contributions
from Johan Jacobsen (
B) G. Granroth

A virtual experiment on BASIS i.e. a comparison with real and simulation results were
published in AIP conference,DOI: 10.1051/epjconf/20158303015 and RSI, DOI: 10.1063/1.4961569

Instrument geometry parameters etc. were taken from the publication:
"A time-of-flight backscattering spectrometer at the Spallation Neutron Source, BASIS" by
Mamontov, E.;   Herwig, K. W.; Neutron Scattering Science Division, Oak Ridge National Laboratory,
Oak Ridge, Tennessee 37831, USA, in Review of Scientific Instruments,82(8),085109 - 085109-10, 2011

This simulation uses the sample component Isotropic_Sqw. We are using the description for a Vanadium
hollow cylindrical sample. One Arm Component is used to place the Analyser Component at an angle
defined as ROT1.

Input parameters

Parameters in boldface are required; the others are optional.
LamAAWavelength selected by the chopper system6.4
Lambda_minAAMinimum wavelength produced at the source5
Lambda_maxAAMaximum wavelength produced at the source7
RadCurvmRadius of Curvature of the guide system1000
omega1HzFrequency of the first DiskChopper60
omega2HzFrequency of the second DiskChopper60
omega3HzFrequency of the third DiskChopper60
ch1_opendegAngular opening of the first Diskchopper51.4
ch2_opendegAngular opening of the second Diskchopper57.6
ch3_opendegAngular opening of the third Diskchopper171.1
ROT1degPositioning of central analyser wrt. the incoming beam, in the scattering plane90
AN_ROTdegOut-of-plane rotation of analysers wrt. scattering plane2
TOTAL_LENGTHmTotal length of the guide system84
dROTdegPositioning of neighbouring analysers wrt. central analyser11


  • Source code for SNS_BASIS.instr.
  • A reference/HTML link for more information

[ Identification | Description | Input parameters | Links ]

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

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