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

# The `Collimator_radial` Component

A radial Soller collimator.

## Identification

- Author: Emmanuel Farhi <farhi@ill.fr>
- Origin: ILL
- Date: July 2005
- Version: 1.11

## 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 (nslit), separated by an absorbing
    material (infinitely thin), the whole stuff is inside an absorbing housing.
    When using zero as the number of channels (nchan), the collimator is continuous,
    whithout shadowing effect.
    The component should be positioned at the radius center.
    The component can be made oscillating (usual on diffractometers and TOF
    machines) with the 'roc' parameter.
    The neutron beam outside the collimator angular area is transmitted unaffected.

    Example: Channelled radial collimator with shadow parts
           Collimator_radial(xwidth=0.015, yheight=.3, length=.35,
                      divergence=40,transmission=1,
                      theta_min=5, theta_max=165, nchan=128, radius=0.9)
      A continuous radial collimator
           Collimator_radial(yheight=.3, length=.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
--- | --- | --- | ---
xwidth | m | Soller window width, filled with nslit slits. Use 0 value for continuous collimator. | 0
yheight | m | Collimator height. | .3
length | m | Length/Distance between inner and outer slits. | .35
divergence | min of arc | Divergence angle. May also be specified with the nslit parameter. A zero value unactivates component. | 0
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 Soller channels in the theta range. Use 0 value for continuous collimator. | 0
radius | m | Radius of the collimator (to entry window). | 1.3
nslit | 1 | Number of blades composing each Soller. Overrides the divergence parameter. | 0
roc | deg | Amplitude of oscillation of collimator. 0=fixed. | 0
verbose | 0/1 | Gives additional information. | 0
approx | 0/1 | Use Soller triangular transmission approximation. | 0

## Links

- Source code for `Collimator_radial.comp`.

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