[ Identification | Description | Input parameters | Links ]

# The `Test_Fermi` Instrument

Cross comparison of Fermi Chopper components

## Identification

- Site: Tests_optics
- Author: E. Farhi [farhi@ill.fr]
- Origin: ILL
- Date: Sept 1st, 2008

## Description

    Cross comparison of Fermi Chopper components, using McStas and
    contributed components, as well as rotating collimator approximations. It
    shows that all implementations are equivalent. However, approximating rotating
    guide are 30% faster than McStas Fermi chopper.

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
Fermi | 1 | Choice of Fermi chopper component to test, with 1=FermiChopper, 3=FermiChopper_ILL, 4=rotating Guide_gravity, 5=rotating Guide_channeled | 1
lambda | AA | Mean wavelength from source | 3.39
width_FC | m | total slit pack width | 0.044
height_FC | m | height of FC slit pack | 0.064
length_FC | m | length of FC slit pack | 0.012
FC_Hz | Hz | rotation speed. Omega=2*PI*nu in rad/s, nu*60 in rpm | 100
Nslit_FC |  | Number of slits in FC slit package | 120
d_SF | m | distance from Source to FC center | 3
d_FD | m | distance from FC center to Detector | 3
phase | deg | FC phase. Use -0 for automatic | 271.92
time_to_arrival |  |  | 0
time_window_width |  |  | 0

## Links

- Source code for `Test_Fermi.instr`.

[ Identification | Description | Input parameters | Links ]