3.3.2.12. NXsasΒΆ

Status:

application definition, extends NXobject, version 1.0b

Description:

raw data from 2-D monochromatic SAS data with an area detector

This is an application definition for raw data (not processed or reduced data) from a 2-D small angle scattering instrument collected with a monochromatic beam and an area detector. It is meant to be suitable both for neutron SANS and X-ray SAXS data.

It covers all raw data from all SAS techniques: SAS, WSAS, grazing incidence, GISAS

Symbols:

No symbol table
Groups cited:
NXcollimator, NXdata, NXdetector, NXentry, NXgeometry, NXinstrument, NXmonitor, NXmonochromator, NXsample, NXshape, NXsource

Structure:

(entry): NXentry

@entry: NX_CHAR

NeXus convention is to use entry1, entry2, ... for analysis software to locate each entry

title: NX_CHAR

start_time: NX_DATE_TIME

end_time: NX_DATE_TIME

definition: NX_CHAR

Official NeXus NXDL schema to which this file conforms

Obligatory value: NXsas

instrument: NXinstrument

name: NX_CHAR

Name of the instrument actually used to perform the experiment

source: NXsource

type: NX_CHAR

type of radiation source

name: NX_CHAR

Name of the radiation source

probe: NX_CHAR

Any of these values: neutron | x-ray

monochromator: NXmonochromator

wavelength: NX_FLOAT {units=NX_WAVELENGTH}

The wavelength of the radiation

wavelength_spread: NX_FLOAT

delta_lambda/lambda (): Important for resolution calculations

collimator: NXcollimator

geometry: NXgeometry

shape: NXshape

shape: NX_CHAR

Any of these values: nxcylinder | nxbox

size: NX_FLOAT {units=NX_LENGTH}

The collimation length

detector: NXdetector

data[nXPixel, nYPixel]: NX_NUMBER

This is area detector data, of number of x-pixel versus number of y-pixels. Since the beam center is to be determined as a step of data reduction, it is not necessary to document or assume the position of the beam center in acquired data.

distance: NX_FLOAT {units=NX_LENGTH}

The distance between detector and sample

x_pixel_size: NX_FLOAT {units=NX_LENGTH}

Physical size of a pixel in x-direction

y_pixel_size: NX_FLOAT {units=NX_LENGTH}

Size of a pixel in y direction

polar_angle: NX_FLOAT {units=NX_ANGLE}

azimuthal_angle: NX_FLOAT {units=NX_ANGLE}

rotation_angle: NX_FLOAT {units=NX_ANGLE}

aequatorial_angle: NX_FLOAT {units=NX_ANGLE}

beam_center_x: NX_FLOAT {units=NX_LENGTH}

This is the x position where the direct beam would hit the detector. This is a length, not a pixel position, and can be outside of the actual detector.

beam_center_y: NX_FLOAT {units=NX_LENGTH}

This is the y position where the direct beam would hit the detector. This is a length, not a pixel position, and can be outside of the actual detector.

sample: NXsample

name: NX_CHAR

Descriptive name of sample

aequatorial_angle: NX_FLOAT {units=NX_ANGLE}

control: NXmonitor

mode: NX_CHAR

Count to a preset value based on either clock time (timer) or received monitor counts (monitor).

Any of these values: monitor | timer

preset: NX_FLOAT

preset value for time or monitor

integral: NX_FLOAT {units=NX_ANY}

Total integral monitor counts

data: NXdata

data –> /NXentry/NXinstrument/NXdetector/data
NXDL Source:
https://github.com/nexusformat/definitions/blob/master/applications/NXsas.nxdl.xml