[ Identification | Description | Input parameters | Output parameters | Links ]
FermiChopper_ILL
ComponentModels a fermi chopper with optional supermirror coated blades supermirror facilities may be disabled by setting m = 0, R0=0 Slit packages are straight. Chopper slits are separated by an infinitely thin absorbing material. The effective transmission (resulting from fraction of the transparent material and its transmission) may be specified. The chopper slit package width may be specified through the total width 'width' of the full package or the width 'w' of each single slit. The other parameter is calculated by: width = Nslit*w. The chopper needs a default velocity to calculate the initial value for an iterative calculation of TOF values. This can be specified by its velocity, energy, wavelength or wavevector. Example: FermiChopper_ILL(phase=-50.0, rad=0.04, nu=100, ymin=-0.04, ymax=0.04, w=0.00022475, Nslit=200.0, R0=0.0, Qc=0.02176, alpham=2.33, m=0.0, Vi=1000, slit=0.012, eff=0.95, zero_time=0) Markus PoehlmannWARNING: This is a contributed Component.Christian Carbogno and Helmut Schober %VALIDATION Apr 2005: extensive external test, most problems solved (cf. 'Bugs') Validated by: K. Lieutenant limitations: no blade width used %BUGS - overestimates peak width for long wavelengths - does not give the right pulse position, shape and width for slit widths below 0.1 mm
Name | Unit | Description | Default |
---|---|---|---|
filename | str | optional file name to write component statistics (debuging) | 0 |
phase | deg | chopper phase at t=0 | 0 |
rad | m | chopper cylinder radius | 0.04 |
nu | Hz | chopper frequency | 100 |
ymin | m | lower y bound of cylinder | -0.04 |
ymax | m | upper y bound of cylinder | 0.04 |
w | m | width of one chopper slit | 0.00022475 |
Nslit | 1 | number of chopper slits | 200.0 |
R0 | 1 | low-angle reflectivity | 0.0 |
Qc | AA-1 | critical scattering vector | 0.02176 |
alpham | AA | slope of reflectivity | 2.33 |
m | 1 | m-value of material. Zero means completely absorbing. | 0.0 |
Wi | AA-1 | width of supermirror cut-off | 2e-3 |
Vi | m/s | velocity of prototype neutron. Use 0 for automatic mode | 0 |
slit | m | channel length of the Fermi chopper | 0.012 |
eff | 1 | efficiency = transmission x fraction of transparent material | 0.95 |
zero_time | 1 | set time to zero: 0: no 1: once per half cycle | 0 |
Ei | meV | optional mean energy of prototype neutron | 0 |
lambda | Angs | optional mean wavelength of prototype neutron | 0 |
Ki | Angs-1 | optional mean wavevector of prototype neutron | 0 |
width | m | optional total width of slit package | 0 |
Name | Unit | Description | Default |
---|---|---|---|
FCVars | - | structure containing many neutron counters for the data in 'filename', mean velocities, angular frequency of the chopper etc. |
FermiChopper_ILL.comp
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[ Identification | Description | Input parameters | Output parameters | Links ]
Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Mon Feb 7 13:18:37 2011