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

The Guide_gravity Component

Neutron straight guide with gravity. Can be channeled and focusing. Waviness may be specified, as well as side chamfers (on substrate).

Identification

Description

Models a rectangular straight guide tube centered on the Z axis, with
gravitation handling. The entrance lies in the X-Y plane.
The guide can be channeled (k,d,kh parameters). The guide coating
specifications may be entered via different ways (global, or for
each wall m-value).
Waviness (random) may be specified either globally or for each mirror type.
Side chamfers (due to substrate processing) may be specified the same way.
In order to model a realistic straight guide assembly, a long guide of
length 'l' may be splitted into 'nelements' between which chamfers/gaps are
positioned.
For details on the geometry calculation see the description in the McStas
reference manual.

Example: Guide_gravity(w1=0.1, h1=0.1, w2=0.1, h2=0.1, l=12,
          R0=0.99, Qc=0.0219, alpha=6.07, m=1.0, W=0.003, k=1, d=0.0005)

%VALIDATION
May 2005: extensive internal test, all problems solved
Validated by: K. Lieutenant

Example values: m=4 Qc=0.02 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. 1.0
W AA-1 Width of supermirror cut-off 0.003
k 1 Number of vertical channels in the guide (>= 1) (k-1 vertical dividing walls). 1
d m Thicxkness of subdividing walls 0.0005
mleft 1 m-value of material for left. vert. mirror -1
mright 1 m-value of material for right. vert. mirror -1
mtop 1 m-value of material for top. horz. mirror -1
mbottom 1 m-value of material for bottom. horz. mirror -1
kh 1 Number of horizontal channels in the guide (>= 1). (kh-1 horizontal dividing walls). this enables to have k*kh rectangular channels 1
G m/s2 Gravitation norm. 0 value disables G effects. 0
wavy deg Global guide waviness 0
wavy_z deg Partial waviness along propagation axis 0
wavy_tb deg Partial waviness in transverse direction for top/bottom mirrors 0
wavy_lr deg Partial waviness in transverse direction for left/right mirrors 0
chamfers m Global chamfers specifications (in/out/mirror sides). 0
chamfers_z m Input and output chamfers 0
chamfers_lr m Chamfers on left/right mirror sides 0
chamfers_tb m Chamfers on top/bottom mirror sides 0
nelements 1 Number of sections in the guide (length l/nelements). 1

Output parameters

Name Unit Description Default
GVars - .N_reflection: (1) Array of the cumulated Number of reflections. N_reflection[0] total nb of reflections, N_reflection[1,2,3,4] l/r/t/b reflections, N_reflection[5] total nb neutrons exiting guide, N_reflection[6] total nb neutrons entering guide.  

Links


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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Sun Mar 7 13:24:58 2010