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

The Guide_gravity Component

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

Identification

Description

Models a rectangular guide tube centered on the Z axis. The entrance lies
in the X-Y plane. Gravitation applies also when reaching the guide input
window. The guide can be channeled (k,d 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.
The guide section may be splitted into nelements equivalent parts of length
l/nelements. Chamfers do apply in between these parts.
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)

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) [1] (k-1 vertical dividing walls) 1
d m Thicxkness of subdividing walls [0] 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 (kh-1 horizontal dividing walls) this enables to have k*kh rectangular channels -1
kh 1
G -9.81
wavy 0
wavy_z 0
wavy_tb 0
wavy_lr 0
chamfers 0
chamfers_z 0
chamfers_lr 0
chamfers_tb 0
nelements 1

Output parameters

Name Unit Description Default
GVars 1 internal variables 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> / Feb 28 2006