Component Manual for the Neutron Ray-Tracing Package McStas, version 3.8.6

14.13  The Guide_four_side McStas Component

Guide with four side walls

Identification

Description

This component models a guide with four side walls. As user you can controll the properties of every wall separatly. All togther you have up to 8 walls: 4 inner walls and 4 outer walls.

Every single wall can have a elliptic, parabolic or straight shape. All four sides of the guide are independent from each other. In the elliptic case the side wall shape follows the equation x^2/b^2+(z+z0)^2/a^2=1 (the center of the ellipse is located at (0,-z0)). In the parabolic case the side wall shape follows the equation z=b-ax^2;mc In the straight case the side wall shape follows the equation z=l/(w2-w1)*x-w1.

The shape selection is done by the focal points. The focal points are located at the z-axis and are defined by their distance to the entrance or exit window of the guide (in the following called ’focal length’).

If both focal lengths for one wall are zero it will be a straight wall (entrance and exit width have to be given in the beginning).

If one of the focal lengths is not zero the shape will be parabolic (only the entrance width given in the beginning is recognized; exit width will be calculated). If the the entrance focal length is zero the guide will be a focusing devise. If the exit focal length is zero it will be defocusing devise.

If both focals are non zero the shape of the wall will be elliptic (only the entrance width given in the beginning is recognized; exit width will be calculated).

Notice: 1.)The focal points are in general located outside the guide (positive focal lengths). Focal points inside the guide need to have negative focal lengths. 2.)The exit width parameters (w2r, w2l, h2u,h2d) are only taken into account if the walls have a linear shape. In the ellitic or parabolic case they will be ignored.

For the inner channel: the outer side of each wall is calculated by the component in depentence of the wallthickness and the shape of the inner side.

Each of walls can have a own indepenting reflecting layer (defined by an input file) or it can be a absorber or it can be transparent.

The reflectivity properties can be given by an input file (Format [q(Å-1) R(0-1)]) or by parameters (Qc, alpha, m, W).

%BUGS This component does not work with gravitation on.

This component does not work correctly in GROUP-modus.

Input parameters

Parameters in boldface are required; the others are optional.

Name

Unit

Description

Default

RIreflect

(str) Name of relfectivity file for the right inner wall.

0

LIreflect

(str) Name of relfectivity file for the left inner wall.

0

UIreflect

(str) Name of relfectivity file for the top inner wall.

0

DIreflect

(str) Name of relfectivity file for the bottom inner wall.

0

ROreflect

(str) Name of relfectivity file for the right outer wall.

0

LOreflect

(str) Name of relfectivity file for the left outer wall.

0

UOreflect

(str) Name of relfectivity file for the top outer wall.

0

DOreflect

(str) Name of relfectivity file for the bottom outer wall.

0

w1l

m

Width at the left guide entry (positive x-axis)

0.002

w2l

m

Width at the left guide exit (positive x-axis)

0.002

linwl

m

left horizontal wall: distance of 1st focal point

0

loutwl

m

left horizontal wall: distance of 2nd focal point

0

w1r

m

Width at the right guide entry (negative x-axis)

0.002

w2r

m

Width at the right guide exit (negative x-axis)

0.002

linwr

m

right horizontal wall: distance of 1st focal point

0.0

loutwr

m

right horizontal wall: distance of 2nd focal point

0

h1u

m

Height at the top guide entry (positive y-axis)

0.002

h2u

m

Height at the top guide entry (positive y-axis)

0.002

linhu

m

upper vertical wall: distance of 1st focal point

0.0

louthu

m

upper vertical wall: distance of 2nd focal point

0

h1d

m

Height at the bottom guide entry (negative y-axis)

0.002

h2d

m

Height at the bottom guide entry (negative y-axis)

0.002

linhd

m

lower vertical wall: distance of 1st focal point

0.0

louthd

m

lower vertical wall: distance of 2nd focal point

0

l

m

length of guide (DEFAULT = 0)

0

R0

1

Low-angle reflectivity (DEFAULT = 0.99)

0.99

Qcxl

Å\(^{-1}\)

Critical scattering vector for left vertical

0.0217

Qcxr

Å\(^{-1}\)

Critical scattering vector for right vertical

0.0217

Qcyu

Å\(^{-1}\)

Critical scattering vector for top inner wall

0.0217

Qcyd

Å\(^{-1}\)

Critical scattering vector for bottom inner wall

0.0217

alphaxl

Å

Slope of reflectivity for left vertical

6.07

alphaxr

Å

Slope of reflectivity for right vertical

6.07

alphayu

Å

Slope of reflectivity for top inner wall

6.07

alphayd

Å

Slope of reflectivity for bottom inner wall

6.07

Wxr

Å\(^{-1}\)

Width of supermirror cut-off for right inner wall

0.003

Wxl

Å\(^{-1}\)

Width of supermirror cut-off for left inner wall

0.003

Wyu

Å\(^{-1}\)

Width of supermirror cut-off for top inner wall

0.003

Wyd

Å\(^{-1}\)

Width of supermirror cut-off for bottom inner wall

0.003

mxr

1

m-value of material for right vertical inner wall.

3.6

mxl

1

m-value of material for left vertical inner wall.

3.6

myu

1

m-value of material for top inner wall

3.6

myd

1

m-value of material for bottom inner wall

3.6

QcxrOW

Å\(^{-1}\)

Critical scattering vector for right vertical

0.0217

QcxlOW

Å\(^{-1}\)

Critical scattering vector for left vertical

0.0217

QcyuOW

Å\(^{-1}\)

Critical scattering vector for top outer wall

0.0217

QcydOW

Å\(^{-1}\)

Critical scattering vector for bottom outer wall

0.0217

alphaxlOW

Å

Slope of reflectivity for left vertical

6.07

alphaxrOW

Å

Slope of reflectivity for right vertical

6.07

alphayuOW

Å

Slope of reflectivity for top outer wall

6.07

alphaydOW

Å

Slope of reflectivity for bottom outer wall

6.07

WxrOW

Å\(^{-1}\)

Width of supermirror cut-off for right outer wall

0.003

WxlOW

Å\(^{-1}\)

Width of supermirror cut-off for left outer wall

0.003

WyuOW

Å\(^{-1}\)

Width of supermirror cut-off for top outer wall

0.003

WydOW

Å\(^{-1}\)

Width of supermirror cut-off for bottom outer wall

0.003

mxrOW

1

m-value of material for right vertical outer wall

0

mxlOW

1

m-value of material for left vertical outer wall

0

myuOW

1

m-value of material for top outer wall

0

mydOW

1

m-value of material for bottom outer wall

0

rwallthick

m

thickness of the right wall (DEFAULT = 0.001 m)

0.001

lwallthick

m

thickness of the left wall (DEFAULT = 0.001 m)

0.001

uwallthick

m

thickness of the top wall (DEFAULT = 0.001 m)

0.001

dwallthick

m

thickness of the bottom wall(DEFAULT = 0.001 m)

0.001

Links