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McStas: Moderator Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The Moderator Component

A simple pulsed source for time-of-flight.


  • Author: KN, M.Hagen
  • Origin: Risoe
  • Date: August 1998
  • Version: $Revision$


Produces a simple time-of-flight spectrum, with a flat energy distribution

Example: Moderator(radius = 0.0707, dist = 9.035, focus_xw = 0.021, focus_yh = 0.021,
                   Emin = 10, Emax = 15, Ec = 9.0, t0 = 37.15, gamma = 39.1)

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
radius m Radius of source 0.07
Emin meV Lower edge of energy distribution  
Emax meV Upper edge of energy distribution  
dist m Distance from source to the focusing rectangle 0
focus_xw m Width of focusing rectangle 0.02
focus_yh m Height of focusing rectangle 0.02
t0 mus decay constant for low-energy neutrons 37.15
Ec meV Critical energy, below which the flux decay is constant 9.0
gamma meV energy dependence of decay time 39.1
target_index 1 relative index of component to focus at, e.g. next is +1 this is used to compute 'dist' automatically. +1
flux 1/(s*cm**2*st*meV) flux 1

Output parameters

Name Unit Description Default


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <> / Fri Mar 17 20:40:06 2017

Last Modified: Friday, 17-Mar-2017 21:40:06 CET
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