The `Elliptic_guide_gravity` Component

Perfect elliptic guide which allows for simulations with gravity. The guide mirrors can be divided into segments with individual m-values. Parabolic guide components can also be simulated.

Identification

Author: Henrik Bo Hoffmann Carlsen and Mads Bertelsen
Origin: NBI
Date: 27 Aug 2012

Description

The Elliptic_guide_gravity component models a true elliptic guide, with separate
ellipses in the vertical (top/bottom) and horizontal (left/right) directions,
allowing gravity to be simulated.

The guide is centered along the z-axis, with entry and exit planes parallel to the
xy-plane. The guide entry is at z=0 (in line with other guide components).
By default, the ellipses are defined by specifying their focal points as
distances from the guide entry (linxw, loutxw, linyh, loutyh). In addition,
it is possible to directly define the ellipse through the parameter set:
majorAxisxw, minorAxisxw, majorAxisyh, minorAxisyh, together with
majorAxisoffsetxw and majorAxisoffsetyh, where the offset parameters place the
ellipse centers respectively.
Further, it is possible to approximate the ellipses through parabolas, or as
half ellipses.

m-values for the guides may be specified independently for each of the four walls,
as a scalar value for the entire wall, or as a vector distributing the m-values
evenly (seglength left unset) or according to the vector seglength.

Example 1, Elliptical definition using focal points:

Elliptic_guide_gravity(
l=50,
linxw=5,linyh=5,loutxw=10,loutyh=10,
xwidth=0.05,yheight=0.05,
R0=0.99,Qc=0.0219,alpha=6.07,m=1.0,W=0.003
)

Example 2: Half elliptical definition:

Elliptic_guide_gravity(
l=50,
linxw=5,linyh=5,loutxw=10,loutyh=10,
xwidth=0.1,yheight=0.1,
R0=0.99,Qc=0.0219,alpha=6.07,m=1.0,W=0.003,
option = "halfEllipse",
dimensionsAt = "entrance"
)

Example 3: Parabolic approximation:

Elliptic_guide_gravity(
l=50,
linxw=5,linyh=5,loutxw=1e6,loutyh=1e6, // values larger than 1e8 may cause erroneous results
xwidth=0.1,yheight=0.1,
R0 = 0.99,Qc=0.0219,alpha=6.07,m=1.0,W=0.003,
dimensionsAt = "exit"
)

Example 4: Elliptical definition with varying m-values:

Elliptic_guide_gravity(
l=50,
linxw=5,linyh=5,loutxw=10,loutyh=10,
xwidth=0.1,yheight=0.1,
R0 = 0.99,Qc=0.0219,alpha=6.07,m=1.0,W=0.003,
mvaluesright=marray,mvaluesleft=marray,mvaluestop=marray,mvaluesbottom=marray
)

where marray is initialized as
for(iter=0; iter < 50; iter++){ marray[iter] = 2; }
And Declared as
double mValues[50];
If you are using the array-based coating-specification, you **must** give nSegments a compatible value.

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
xwidth	m	width at the guide entry, mid or exit (see dimensionsAt)	0
yheight	m	height at the guide entry, mid or exit (see dimensionsAt)	0
l	m	length of the guide
linxw	m	distance from 1st focal point to guide entrance - left and right horizontal mirrors	0
loutxw	m	distance from 2nd focal point to guide exit - left and right horizontal mirrors	0
linyh	m	distance from 1st focal point to guide entrance - top and bottom vertical mirrors	0
loutyh	m	distance from 2nd focal point to guide exit - top and bottom vertical mirrors	0
majorAxisxw	m	Direct definition of the guide geometry, will ignore linxw, loutxw, linyh, and loutyh if this is nonzero. Length of the axis parallel to z for the horizontal ellipse.	0
minorAxisxw	m	Direct definition of the guide geometry, will ignore linxw, loutxw, linyh, and loutyh if this is nonzero. Length of the axis perpendicular to z for the horizontal ellipse.	0
majorAxisyh	m	Direct definition of the guide geometry, will ignore linxw, loutxw, linyh, and loutyh if this is nonzero. Length of the axis parallel to z for the vertical ellipse.	0
minorAxisyh	m	Direct definition of the guide geometry, will ignore linxw, loutxw, linyh, and loutyh if this is nonzero. Length of the axis perpendicular to z for the vertical ellipse.	0
majorAxisoffsetxw	m	Direct definition of the guide geometry, distance between the center of the horizontal ellipse and the guide entrance.	0
majorAxisoffsetyh	m	Direct definition of the guide geometry, distance between the center of the vertical ellipse and the guide entrance.	0
dimensionsAt	string	Define whether xwidth and yheight sets the size of the opening, minor axis or the end of the guide.	"entrance"
option	string	Options are 'ellipse' and 'halfEllipse'. Ellipse is defined by both the focal points, while halfEllipse locked the center of the ellipse either the entrance or exit of the guide, and use the focal point of the other end to define the ellipse	"ellipse"
R0	1	Low-angle reflectivity	0.99
Qc	AA^-1	Critical scattering vector	0.0218
alpha	AA	Slope of reflectivity	6.07
m	1	m-value of material for all mirrors, zero means complete absorption.	2
W	AA^-1	Width of supermirror cut-off	0.003
alpharight	AA	Slope of reflectivity for right vertical mirror	-1
mright	1	m-value of material for right vertical mirror	-1
alphaleft	AA	Slope of reflectivity for left vertical mirror	-1
mleft	1	m-value of material for left vertical mirror	-1
alphatop	AA	Slope of reflectivity for top horizontal mirror, overwrites alpha	-1
mtop	1	m-value of material for top horizontal mirror, overwrites m	-1
alphabottom	AA	Slope of reflectivity for bottom horizontal mirror	-1
mbottom	1	m-value of material for bottom horizontal mirror	-1
verbose	bool	Give extra information about calculations	"on"
enableGravity	m	Flag to select propagation with gravity.	1.0
curvature	m	Simulate horizontal radius of curvature by centripetal force added to the gravity. Note: Does not curve the guide in mcdisplay but "curves the neutron". Has opposite sign definition of Guide_curved.	0
nSegments	m	Must be used to specify number of guide segments, i.e. when giving inputs mvaluesright ... etc.	-1
mvaluesright	pointer	Pointer to array of m-values, right mirror	NULL
mvaluesleft	pointer	- same, left mirror	NULL
mvaluestop	pointer	- same, top mirror	NULL
mvaluesbottom	pointer	- same, bottom mirror	NULL
seglength	pointer	Pointer to array of segment lengths for discrete mirror description	NULL

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

The Elliptic_guide_gravity Component

Identification

Description

Input parameters

Links

The `Elliptic_guide_gravity` Component