3.3.1.21. NXfermi_chopper

Status:

base class, extends NXobject

Description:

A Fermi chopper, possibly with curved slits.

Symbols:

No symbol table

Groups cited:

NXgeometry, NXoff_geometry, NXtransformations

Structure:

@default: (optional) NX_CHAR

Declares which child group contains a path leading ...

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

Fermi chopper type

rotation_speed: (optional) NX_FLOAT {units=NX_FREQUENCY}

chopper rotation speed

radius: (optional) NX_FLOAT {units=NX_LENGTH}

radius of chopper

slit: (optional) NX_FLOAT {units=NX_LENGTH}

width of an individual slit

r_slit: (optional) NX_FLOAT {units=NX_LENGTH}

radius of curvature of slits

number: (optional) NX_INT {units=NX_UNITLESS}

number of slits

height: (optional) NX_FLOAT {units=NX_LENGTH}

input beam height

width: (optional) NX_FLOAT {units=NX_LENGTH}

input beam width

distance: (optional) NX_FLOAT {units=NX_LENGTH}

distance. Note, it is recommended to use NXtransformations instead.

wavelength: (optional) NX_FLOAT {units=NX_WAVELENGTH}

Wavelength transmitted by chopper

energy: (optional) NX_FLOAT {units=NX_ENERGY}

energy selected

absorbing_material: (optional) NX_CHAR

absorbing material

transmitting_material: (optional) NX_CHAR

transmitting material

depends_on: (optional) NX_CHAR

NeXus positions components by applying a set of translations and rotations ...

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.

GEOMETRY: (optional) NXgeometry

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

geometry of the fermi chopper

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 ...

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/NXfermi_chopper.nxdl.xml