McStas: Source_simple Component

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

# The `Source_simple` Component

A circular neutron source with flat energy spectrum and arbitrary flux

## Identification

- Author: Kim Lefmann
- Origin: Risoe
- Date: October 30, 1997
- Version:(Unknown)
- Modification history:
  - KL, October 4, 2001
  - Emmanuel Farhi, October 30, 2001. Serious bug corrected.

## Description

    The routine is a circular neutron source, which aims at a square target
    centered at the beam (in order to improve MC-acceptance rate).  The angular
    divergence is then given by the dimensions of the target.
    The neutron energy is uniformly distributed between lambda0-dlambda and
    lambda0+dlambda or between E0-dE and E0+dE.
    The flux unit is specified in n/cm2/s/st/energy unit (meV or Angs).

    This component replaces Source_flat, Source_flat_lambda,
    Source_flux and Source_flux_lambda.

    Example: Source_simple(radius=0.1, dist=2, focus_xw=.1, focus_yh=.1, E0=14, dE=2)

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
--- | --- | --- | --- | ---
radius | m | Radius of circle in (x,y,0) plane where neutrons are generated. | 0.1 |
yheight | m | Height of rectangle in (x,y,0) plane where neutrons are generated. | 0 |
xwidth | m | Width of rectangle in (x,y,0) plane where neutrons are generated. | 0 |
dist | m | Distance to target along z axis. | 0 |
focus_xw | m | Width of target | .045 |
focus_yh | m | Height of target | .12 |
E0 | meV | Mean energy of neutrons. | 0 |
dE | meV | Energy half spread of neutrons (flat or gaussian sigma). | 0 |
lambda0 | AA | Mean wavelength of neutrons. | 0 |
dlambda | AA | Wavelength half spread of neutrons. | 0 |
flux | 1/(s*cm**2*st*energy unit) | flux per energy unit, Angs or meV if flux=0, the source emits 1 in 4*PI whole space. | 1 |
gauss | 1 | Gaussian (1) or Flat (0) energy/wavelength distribution | 0 |
target_index | 1 | relative index of component to focus at, e.g. next is +1 this is used to compute 'dist' automatically. | +1 |

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

## Links

- Source code for `Source_simple.comp`.

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