NXsource

Status:

base class, extends NXobject

Description:

The neutron or x-ray storage ring/facility.

Symbols:

The symbols used in the schema to specify e.g. dimensions of arrays

nx: Number of points in a spectrum

Groups cited:

NXdata, NXgeometry, NXnote

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.

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

  • arc lamp

  • halogen lamp

  • LED

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 or other material used to generate light, e.g. He, Ar gas for lasers, Xe or Hg/Cd vapor for arc lamps, etc.

Any of these values:

  • Ta

  • W

  • depleted_U

  • enriched_U

  • Hg

  • Pb

  • C

  • Ar

  • He

  • Xe

  • Hg/Cd

  • H

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_CHAR

Date and time of the most recent injection.

photon_energy: (optional) NX_FLOAT {units=NX_ENERGY}

The center photon energy of the source, before it is monochromatized or converted

center_wavelength: (optional) NX_FLOAT {units=NX_WAVELENGTH}

The center wavelength of the source, before it is monochromatized or converted

pulse_energy: (optional) NX_FLOAT {units=NX_ENERGY}

For pulsed sources, the energy of a single pulse

peak_power: (optional) NX_FLOAT {units=NX_POWER}

For pulsed sources, the pulse energy divided by the pulse duration

bunch_number_start: (optional) NX_INT

Some facilities tag each bunch. First bunch of the measurement

bunch_number_end: (optional) NX_INT

Last bunch of the measurement

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

‘Engineering’ location of source

distribution: (optional) NXdata

The wavelength or energy distribution of the source

Hypertext Anchors

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

NXDL Source:

https://github.com/FAIRmat-Experimental/nexus_definitions/tree/fairmat/contributed_definitions/NXsource.nxdl.xml