[ 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 ]

Generated for mcstas 3.5.32

---

Last Modified: Monday, 30-Jun-2025 11:05:10 CEST