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

The Source_div Component

Neutron source with Gaussian or uniform divergence

Identification

Description

The routine is a rectangular neutron source, which has a gaussian or uniform
divergent output in the forward direction.
The neutron energy is uniformly distributed between E0-dE and E0+dE or
a wavelength is uniformly distributed between Lambda0-dLambda and Lambda0+dLambda.
If energy and wavelength are given, energy is used.
In the case of uniform distribution (gauss=0), angles are uniformly distributed
between -hdiv and +hdiv as well as -vdiv and +vdiv. For Gaussian distribution
(gauss=1), 'hdiv' and 'vdiv' define the FWHM of a Gauss'schen distribution,

Example: Source_div(width=0.1, height=0.1, hdiv=2, vdiv=2, E0=14, dE=2, gauss=0)

%VALIDATION
Feb 2005: tested by Kim Lefmann    (o.k.)
Apr 2005: energy distribution used in external tests of Fermi choppers (o.k.)
Jun 2005: wavelength distribution used in external tests of velocity selectors (o.k.)
Validated by: K. Lieutenant

%BUGS
distribution is uniform in (hor. and vert.) angle (relative to moderator normal),
therefore not suited for large angles

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
width m Width of source  
height m Height of source  
hdiv deg FWHM (Gaussian) or maximal (uniform) horizontal divergence  
vdiv deg FWHM (Gaussian) or maximal (uniform) vertical divergence  
E0 meV Mean energy of neutrons. 0.0
dE meV Energy spread of neutrons. 0.0
Lambda0 Ang Mean wavelength of neutrons (only relevant for E0=0) 0.0
dLambda Ang Wavelength spread of neutrons. 0.0
gauss - Criterion: 0: uniform, 1: Gaussian distribution (default) 1

Output parameters

Name Unit Description Default
sigmah rad parameter 'sigma' of the Gaussian distribution for horizontal divergence  
sigmav rad parameter 'sigma' of the Gaussian distribution for vertical divergence  
p_init - normalisation factor 1/'neutron_count'  

Links


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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Tue Sep 30 19:37:37 2008