[ Identification | Description | Examples | Input parameters | Links ]
SNS_BASIS InstrumentESCRIPTION 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 (ruep.lechner@gmail.com) and HNB (bordallo@nbi.ku.dk) with contributions from Johan Jacobsen (johan.fett@gmail.com) 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.
| Name | Unit | Description | Default |
| Lam | AA | Wavelength selected by the chopper system | 6.4 |
| Lambda_min | AA | Minimum wavelength produced at the source | 5 |
| Lambda_max | AA | Maximum wavelength produced at the source | 7 |
| RadCurv | m | Radius of Curvature of the guide system | 1000 |
| omega1 | Hz | Frequency of the first DiskChopper | 60 |
| omega2 | Hz | Frequency of the second DiskChopper | 60 |
| omega3 | Hz | Frequency of the third DiskChopper | 60 |
| ch1_open | deg | Angular opening of the first Diskchopper | 51.4 |
| ch2_open | deg | Angular opening of the second Diskchopper | 57.6 |
| ch3_open | deg | Angular opening of the third Diskchopper | 171.1 |
| ROT1 | deg | Positioning of central analyser wrt. the incoming beam, in the scattering plane | 90 |
| AN_ROT | deg | Out-of-plane rotation of analysers wrt. scattering plane | 2 |
| TOTAL_LENGTH | m | Total length of the guide system | 84 |
| dROT | deg | Positioning of neighbouring analysers wrt. central analyser | 11 |
SNS_BASIS.instr.
[ Identification | Description | Examples | Input parameters | Links ]
Generated for mcstas 3.8.4