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

# The `Guide` Component

Neutron guide.

## Identification

- Author: Kristian Nielsen
- Origin: Risoe
- Date: September 2 1998
- Version: 1.24

## Description

    Models a rectangular guide tube centered on the Z axis. The entrance lies
    in the X-Y plane.
    For details on the geometry calculation see the description in the McStas
    reference manual.

    Example: Guide(w1=0.1, h1=0.1, w2=0.1, h2=0.1, l=2.0,
              R0=0.99, Qc=0.021, alpha=6.07, m=2, W=0.003

    %VALIDATION
    May 2005: extensive internal test, no bugs found
    Validated by: K. Lieutenant

    %BUGS
    This component does not work with gravitation on. Use component Guide_gravity then.

    Example values: m=4 Qc=0.0219 W=1/300 alpha=6.49 R0=1

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
w1 | m | Width at the guide entry |
h1 | m | Height at the guide entry |
w2 | m | Width at the guide exit |
h2 | m | Height at the guide exit |
l | m | length of guide |
R0 | 1 | Low-angle reflectivity | 0.99
Qc | AA-1 | Critical scattering vector | 0.0219
alpha | AA | Slope of reflectivity | 6.07
m | 1 | m-value of material. Zero means completely absorbing. | 2
W | AA-1 | Width of supermirror cut-off | 0.003

## Links

- Source code for `Guide.comp`.

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