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

The Source_div Component

Neutron source with Gaussian or uniform divergence

Identification

• Author: KL
• Origin: Risoe
• Date: November 20, 1998
• Version: 1.22
• Modification history:
  • KL, 8 October 2001

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

• Source code for Source_div.comp.

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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Feb 10 11:36:23 2012

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Last Modified: Friday, 10-Feb-2012 12:36:23 CET