[ Identification | Description | Input parameters | Links ]

# The `Source_div_quasi` Component

Quasi-stochastic neutron source with Gaussian or uniform divergence

## Identification

- Site:
- Author: Mads Carlsen and Erik Bergbäck Knudsen (erkn@fysik.dtu.dk)
- Origin: DTU Physics
- Date: Jan 22

## Description

    A flat rectangular surface source with uniform or Gaussian divergence profile and focussing.
    If the parametere gauss is not set (the default) the divergence profile is flat
    in the range [-focus_ax,focus_ay]. If gauss is set, the focux_ax,focus_ay is considered
    the standard deviation of the gaussian profile.
    Currently focussing is only active for flat profile. The "focus window" is defined by focus_xw,focus_yh and dist.
    The spectral intensity profile is uniformly distributed in the energy interval defined by e0+-dE/2 or
    by wavelength lambda0+-dlambda/2

    The phase space spanned by the generated neutrons is sampled by means of Halton-sequences, instead of regular
    pseudo random numbers. This ensures that samples are evenly distributed within the phase space region of interest.

    Example: Source_div_quasi(xwidth=0.1, yheight=0.1, focus_aw=2, focus_ah=2, E0=14, dE=2, gauss=0)

    %VALIDATION

    %BUGS

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
spectrum_file |  | File from which to read the spectral intensity profile | "" |
xwidth | m | Width of source | 0 |
yheight | m | Height of source | 0 |
focus_xw | m | Width of sampling window | 0 |
focus_yh | m | Height of sampling window | 0 |
dist | m | Downstream distance to place sampling target window | 0 |
focus_aw | rad | Std. dev. (Gaussian) or maximal (uniform) horz. width divergence. focus_xw overrrides if it is more restrictive. | 0 |
focus_ah | rad | Std. dev. (Gaussian) or maximal (uniform) vert. height divergence. focus_yh overrrides if it is more restrictive. | 0 |
E0 | meV | Mean energy of neutrons. | 0 |
dE | meV | Energy spread of neutrons. | 0 |
lambda0 | AA | Mean wavelength of neutrons (only relevant for E0=0) | 0 |
dlambda | AA | Wavelength half spread of neutrons. | 0 |
flux | 1/(s*cm**2*st*energy unit) | Flux per energy unit, Angs or meV | 0 |
gauss | 1 | Criterion: 0: uniform, 1: Gaussian distribution of energy/wavelength | 0 |
gauss_a | 1 | Criterion: 0: uniform, 1: Gaussian divergence distribution | 0 |
randomphase |  | When=1, the X-ray phase is randomised | 1 |
phase |  | Set to finite value to define X-ray phase (0:2 pi) | 0 |
verbose |  | Generate more output on the console. | 1 |

AT ( | , | , |  | ) RELATIVE |  |
ROTATED ( | , | , |  | ) RELATIVE |

## Links

- Source code for `Source_div_quasi.comp`.

[ Identification | Description | Input parameters | Links ]