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

The Collimator_radial Component

A radial Soller collimator.

Identification

Description

Radial Soller collimator with rectangular opening and specified length.
The collimator is made of many rectangular channels stacked radially.
Each channel is a set of transmitting layers, separated by an absorbing
material, the whole stuff is inside an absorbing housing.
The component should be positioned at the radius center.
When specifying the divergence parameter, the transmission function is an
average (triangular approximation) and does not utilize knowledge of
the actual neutron trajectory.
On the other hand, when specifying the number of blades, model is exact,
but statistics is lowered by a factor 2.
A zero divergence disables collimation (then the component works as a double
slit). If the input/output (w1, w2) width are 0, then a perfect collimator
is assumed (no slit check except for the total angular range and height).
The component can be made oscillating (usual on diffractometers and TOF
machines) with the 'roc' parameter.
The neutron beam outside the collimator area is transmitted unaffected.

Example: Contains shadow parts due to radial geometry
       Collimator_radial(w1=0.015, h1=.3, w2=0.015, h2=.3, len=.35,
                  divergence=40,transmission=1,
                  theta_min=5, theta_max=165, nchan=128, radius=0.9)

Ideal: Collimator_radial(w1=0, h1=.3, w2=0, h2=.3, len=.35,
                  divergence=40,transmission=1,
                  theta_min=5, theta_max=165, radius=0.9)

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
w1 m Input window width 0.015
h1 m Input window height .3
w2 m Output window width 0.015
h2 m Output window height .3
len m Length/Distance between slits .35
divergence min of arc Divergence angle. May also be specified with the nblades parameter 40
transmission 1 Transmission of Soller (0<=t<=1) 1
theta_min deg Minimum Theta angle for the radial setting 5
theta_max deg Maximum Theta angle for the radial setting 165
nchan 1 Number of channels in the theta range 128
radius m Radius of the collimator (to entry window) 0
nblades 1 Number of blades composing each Soller. Overrides the divergence parameter 0
roc 1 Enable oscillation of collimator with an amplitude of 'roc' times a single soller size (w1). 0
verbose 0/1 Gives additional information 0

Output parameters

Name Unit Description Default
soller_theta1  
soller_theta2  
window_theta  
use_approx  
ideal  

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