# 3.3.2.28. NXxbase¶

Status:

application definition, extends NXobject

Description:

This definition covers the common parts of all monochromatic single crystal raw data application definitions.

Symbols:

No symbol table

Groups cited:

Structure:

entry: (required) NXentry

title: (required) NX_CHAR

start_time: (required) NX_DATE_TIME

definition: (required) NX_CHAR

Official NeXus NXDL schema to which this file conforms

Obligatory value: NXxbase

instrument: (required) NXinstrument

source: (required) NXsource

type: (required) NX_CHAR

name: (required) NX_CHAR

probe: (required) NX_CHAR

Any of these values: neutron | x-ray | electron

monochromator: (required) NXmonochromator

wavelength: (required) NX_FLOAT {units=NX_WAVELENGTH}

detector: (required) NXdetector

The name of the group is detector if there is only one detector, if there are several, names have to be detector1, detector2, …detectorn.

data[np, number of x pixels, number of y pixels]: (required) NX_INT

The area detector data, the first dimension is always the number of scan points, the second and third are the number of pixels in x and y. The origin is always assumed to be in the center of the detector. maxOccurs is limited to the the number of detectors on your instrument.

@signal: (required) NX_POSINT

Obligatory value: 1

x_pixel_size: (required) NX_FLOAT {units=NX_LENGTH}

y_pixel_size: (required) NX_FLOAT {units=NX_LENGTH}

distance: (required) NX_FLOAT {units=NX_LENGTH}

frame_start_number: (required) NX_INT

This is the start number of the first frame of a scan. In PX one often scans a couple of frames on a give sample, then does something else, then returns to the same sample and scans some more frames. Each time with a new data file. This number helps concatenating such measurements.

sample: (required) NXsample

name: (required) NX_CHAR

Descriptive name of sample

orientation_matrix[3, 3]: (required) NX_FLOAT

The orientation matrix according to Busing and Levy conventions. This is not strictly necessary as the UB can always be derived from the data. But let us bow to common usage which includes the UB nearly always.

unit_cell[6]: (required) NX_FLOAT

The unit cell, a, b, c, alpha, beta, gamma. Again, not strictly necessary, but normally written.

temperature[NP]: (required) NX_FLOAT

The sample temperature or whatever sensor represents this value best

x_translation: (required) NX_FLOAT {units=NX_LENGTH}

Translation of the sample along the X-direction of the laboratory coordinate system

y_translation: (required) NX_FLOAT {units=NX_LENGTH}

Translation of the sample along the Y-direction of the laboratory coordinate system

distance: (required) NX_FLOAT {units=NX_LENGTH}

Translation of the sample along the Z-direction of the laboratory coordinate system

control: (required) NXmonitor

mode: (required) 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: (required) NX_FLOAT

preset value for time or monitor

integral: (required) NX_FLOAT {units=NX_ANY}

Total integral monitor counts

DATA: (required) NXdata

The name of this group id data if there is only one detector; if there are several the names will be data1, data2, data3 and will point to the corresponding detector groups in the instrument hierarchy.

data –> /NXentry/NXinstrument/NXdetector/data

NXDL Source:

https://github.com/nexusformat/definitions/blob/master/applications/NXxbase.nxdl.xml