3.3.1.9. NXcollimator

Status:

base class, extends NXobject

Description:

A beamline collimator.

Symbols:

No symbol table

Groups cited:

NXgeometry, NXlog, NXoff_geometry, NXtransformations

Structure:

@default: (optional) NX_CHAR

Declares which child group contains a path leading to a NXdata group.

It is recommended (as of NIAC2014) to use this attribute to help define the path to the default dataset to be plotted. See https://www.nexusformat.org/2014_How_to_find_default_data.html for a summary of the discussion.

type: (optional) NX_CHAR

Any of these values: Soller | radial | oscillating | honeycomb

soller_angle: (optional) NX_FLOAT {units=NX_ANGLE}

Angular divergence of Soller collimator

divergence_x: (optional) NX_FLOAT {units=NX_ANGLE}

divergence of collimator in local x direction

divergence_y: (optional) NX_FLOAT {units=NX_ANGLE}

divergence of collimator in local y direction

frequency: (optional) NX_FLOAT {units=NX_FREQUENCY}

Frequency of oscillating collimator

blade_thickness: (optional) NX_FLOAT {units=NX_LENGTH}

blade thickness

blade_spacing: (optional) NX_FLOAT {units=NX_LENGTH}

blade spacing

absorbing_material: (optional) NX_CHAR

name of absorbing material

transmitting_material: (optional) NX_CHAR

name of transmitting material

depends_on: (optional) NX_CHAR

NeXus positions components by applying a set of translations and rotations to apply to the component starting from 0, 0, 0. The order of these operations is critical and forms what NeXus calls a dependency chain. The depends_on field defines the path to the top most operation of the dependency chain or the string “.” if located in the origin. Usually these operations are stored in a NXtransformations group. But NeXus allows them to be stored anywhere.

Assuming a collimator with a “flat” entry surface, the reference plane is the plane which contains this surface. The reference point of the collimator in the x and y axis is the centre of the collimator entry surface on that plane. The reference plane is orthogonal to the z axis and the location of this plane is the reference point on the z axis. The collimator faces negative z values.

../../_images/collimator.png

GEOMETRY: (optional) NXgeometry

DEPRECATED: Use the field depends_on and NXtransformations to position the collimator and NXoff_geometry to describe its shape instead

position, shape and size

frequency_log: (optional) NXlog

Log of frequency

OFF_GEOMETRY: (optional) NXoff_geometry

This group describes the shape of the beam line component

TRANSFORMATIONS: (optional) NXtransformations

This is the group recommended for holding the chain of translation and rotation operations necessary to position the component within the instrument. The dependency chain may however traverse similar groups in other component groups.

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/nexusformat/definitions/blob/main/base_classes/NXcollimator.nxdl.xml