base class, extends NXobject


The neutron or x-ray storage ring/facility.


No symbol table

Groups cited:

NXdata, NXgeometry, NXnote, NXoff_geometry, NXtransformations


@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.

distance: (optional) NX_FLOAT {units=NX_LENGTH}

Effective distance from sample Distance as seen by radiation from sample. This number should be negative to signify that it is upstream of the sample.

name: (optional) NX_CHAR

Name of source

@short_name: (optional) NX_CHAR

short name for source, perhaps the acronym

type: (optional) NX_CHAR

type of radiation source (pick one from the enumerated list and spell exactly)

Any of these values:

  • Spallation Neutron Source

  • Pulsed Reactor Neutron Source

  • Reactor Neutron Source

  • Synchrotron X-ray Source

  • Pulsed Muon Source

  • Rotating Anode X-ray

  • Fixed Tube X-ray

  • UV Laser

  • Free-Electron Laser

  • Optical Laser

  • Ion Source

  • UV Plasma Source

  • Metal Jet X-ray

probe: (optional) NX_CHAR

type of radiation probe (pick one from the enumerated list and spell exactly)

Any of these values:

  • neutron

  • x-ray

  • muon

  • electron

  • ultraviolet

  • visible light

  • positron

  • proton

power: (optional) NX_FLOAT {units=NX_POWER}

Source power

emittance_x: (optional) NX_FLOAT {units=NX_EMITTANCE}

Source emittance (nm-rad) in X (horizontal) direction.

emittance_y: (optional) NX_FLOAT {units=NX_EMITTANCE}

Source emittance (nm-rad) in Y (horizontal) direction.

sigma_x: (optional) NX_FLOAT {units=NX_LENGTH}

particle beam size in x

sigma_y: (optional) NX_FLOAT {units=NX_LENGTH}

particle beam size in y

flux: (optional) NX_FLOAT {units=NX_FLUX}

Source intensity/area (example: s-1 cm-2)

energy: (optional) NX_FLOAT {units=NX_ENERGY}

Source energy. For storage rings, this would be the particle beam energy. For X-ray tubes, this would be the excitation voltage.

current: (optional) NX_FLOAT {units=NX_CURRENT}

Accelerator, X-ray tube, or storage ring current

voltage: (optional) NX_FLOAT {units=NX_VOLTAGE}

Accelerator voltage

frequency: (optional) NX_FLOAT {units=NX_FREQUENCY}

Frequency of pulsed source

period: (optional) NX_FLOAT {units=NX_PERIOD}

Period of pulsed source

target_material: (optional) NX_CHAR

Pulsed source target material

Any of these values:

  • Ta

  • W

  • depleted_U

  • enriched_U

  • Hg

  • Pb

  • C

number_of_bunches: (optional) NX_INT

For storage rings, the number of bunches in use.

bunch_length: (optional) NX_FLOAT {units=NX_TIME}

For storage rings, temporal length of the bunch

bunch_distance: (optional) NX_FLOAT {units=NX_TIME}

For storage rings, time between bunches

pulse_width: (optional) NX_FLOAT {units=NX_TIME}

temporal width of source pulse

mode: (optional) NX_CHAR

source operating mode

Any of these values:

  • Single Bunch: for storage rings

  • Multi Bunch: for storage rings

top_up: (optional) NX_BOOLEAN

Is the synchrotron operating in top_up mode?

last_fill: (optional) NX_NUMBER {units=NX_CURRENT}

For storage rings, the current at the end of the most recent injection.

@time: (optional) NX_DATE_TIME

date and time of the most recent injection.

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.

The reference point of the source plane is its center in the x and y axis. The source is considered infinitely thin in the z axis.


notes: (optional) NXnote

any source/facility related messages/events that occurred during the experiment

bunch_pattern: (optional) NXdata

For storage rings, description of the bunch pattern. This is useful to describe irregular bunch patterns.

title: (optional) NX_CHAR

name of the bunch pattern

pulse_shape: (optional) NXdata

source pulse shape

geometry: (optional) NXgeometry

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

“Engineering” location of source.

OFF_GEOMETRY: (optional) NXoff_geometry

This group describes the shape of the beam line component

distribution: (optional) NXdata

The wavelength or energy distribution of the source

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: