2.3.3.1.31. NXmoderator

Status:

base class, extends NXobject

Description:

A neutron moderator

Symbols:

No symbol table

Groups cited:

NXdata, NXgeometry, NXlog, 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.

distance: (optional) NX_FLOAT {units=NX_LENGTH}

Effective distance as seen by measuring radiation. ...

Effective distance as seen by measuring radiation. Note, it is recommended to use NXtransformations instead.

type: (optional) NX_CHAR

Any of these values:

  • H20

  • D20

  • Liquid H2

  • Liquid CH4

  • Liquid D2

  • Solid D2

  • C

  • Solid CH4

  • Solid H2

poison_depth: (optional) NX_FLOAT {units=NX_LENGTH}

coupled: (optional) NX_BOOLEAN

whether the moderator is coupled

coupling_material: (optional) NX_CHAR

The material used for coupling. Usually Cd.

poison_material: (optional) NX_CHAR

Any of these values: Gd | Cd

temperature: (optional) NX_FLOAT {units=NX_TEMPERATURE}

average/nominal moderator temperature

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.

The reference point of the moderator is its center in the x and y axis. The reference point on the z axis is the surface of the moderator pointing towards the source (the negative part of the z axis).

../../_images/moderator.png

GEOMETRY: (optional) NXgeometry

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

“Engineering” position of moderator

temperature_log: (optional) NXlog

log file of moderator temperature

pulse_shape: (optional) NXdata

moderator pulse shape

OFF_GEOMETRY: (optional) NXoff_geometry

This group describes the shape of the moderator

TRANSFORMATIONS: (optional) NXtransformations

Hypertext Anchors

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

NXDL Source:

https://github.com/FAIRmat-NFDI/nexus_definitions/tree/fairmat/base_classes/NXmoderator.nxdl.xml