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

# The `Bender` Component

Models a curved neutron guide.

## Identification

- Author: Philipp Bernhardt
- Origin: Uni. Erlangen (Germany)
- Date: Februar 7 1999
- Version: 1.13

## Description

    Models a curved neutron guide with cylindrical walls.

    Bender radius, entrance width and height are necessary input data. To define
    the bender, you may either enter the deviation angle 'Win' or the length 'l'.
    The bender may consist of 'k' vertical channels, separated by partitioning walls
    of thickness 'd'. Three different reflectivity profiles can be given: for outer
    walls, for inner walls and for the top and bottom walls. The partitioning walls
    have the same coating as the exterior walls.

    The entrance lies in the X-Y plane, centered on the Z axis. The neutrons will
    also leave the bender in the X-Y plane at the z-value l=r*Win, i.e. they are
    centred on (0,0,r*Win); they have an (average) flight direction along the z-axis.
    Therefore, the following component is adjacent, if positioned AT (0,0,r*Win)
    without rotation.
    So, seen from outside, it behaves like a straight guide along the Z axis. As a
    consequence, it is shown straight in 'mcdisplay'.
    This behaviour results from a co-ordinate transformation inside the component.
    It is done to facilitate its use. Neither rotation nor shift along the x-axis
    need to be calculated; a new arm is not necessary. Internally, the bender is
    bent to the negative X axis;

    Example:
    Bender of 120 mm height, 50 mm width, 250 m radius and 0.04 rad (or 2.292 deg) curvature
    not channeled, with a standard m=2 coating on

    Bender(w=0.05,h=0.12,r=250,Win=0.04,
           R0a=0.99,Qca=0.021,alphaa=6.07,ma=2,Wa=0.003,
           R0i=0.99,Qci=0.021,alphai=6.07,mi=2,Wi=0.003,
           R0s=0.99,Qcs=0.021,alphas=6.07,ms=2,Ws=0.003)

    %BUGS
    Some users have reported potentially strange behaviours with this component.
    This component does not work with gravitation on.

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
w | m | Width at the bender entry and exit |
h | m | Height at the bender entry and exit |
r | m | Radius of the bender |
Win | rad | Angle of the deflection of the whole bender | 0.04
k | 1 | Number of channels inside the bender | 1
d | m | Thickness of one blade separating the channels | 0.001
R0a | 1 | Low-angle reflectivity at the outer side of the bender | 0.99
Qca | AA-1 | Critical scattering vector | 0.021
alphaa | AA | Slope of reflectivity | 6.07
ma | 1 | m-value of material | 2
Wa | AA-1 | Width of supermirror cut-off | 0.003
R0i | 1 | Low-angle reflectivity at the inner side of the bender | 0.99
Qci | AA-1 | Critical scattering vector | 0.021
alphai | AA | Slope of reflectivity | 6.07
mi | 1 | m-value of material | 2
Wi | AA-1 | Width of supermirror cut-off | 0.003
R0s | 1 | Low-angle reflectivity at the top and bottom side of the bender | 0.99
Qcs | AA-1 | Critical scattering vector | 0.021
alphas | AA | Slope of reflectivity | 6.07
ms | 1 | m-value of material | 2
Ws | AA-1 | Width of supermirror cut-off | 0.003
l | m | length of bender l=r*Win | 0

## Output parameters

Name | Unit | Description | Default
--- | --- | --- | ---
bk | m | Width of 1 channel + 1 separating blade |
mWin | rad | Angle of the deflection of the whole bender |

## Links

- Source code for `Bender.comp`.
- Additional note from Philipp Bernhardt.

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