# 3.3.1.15. NXdetector_module¶

Status:

base class, extends NXobject

Description:

Geometry and logical description of a detector module.

Many detectors consist of multiple smaller modules. Sometimes it is important to know the exact position of such modules. This is the purpose of this group. It is a child group to NXdetector.

Note, the pixel size is given as values in the array fast_pixel_direction and slow_pixel_direction.

Symbols:

No symbol table

Groups cited:

none

Structure:

data_origin: (optional) NX_INT

A dimension-2 or dimension-3 field which gives the indices of the origin of the hyperslab of data for this module in the main area detector image in the parent NXdetector module.

The data_origin is 0-based.

The frame number dimension (np) is omitted. Thus the data_origin field for a dimension-2 dataset with indices (np, i, j) will be an array with indices (i, j), and for a dimension-3 dataset with indices (np, i, j, k) will be an array with indices (i, j, k).

The order of indices (i, j or i, j, k) is slow to fast.

data_size: (optional) NX_INT

Two or three values for the size of the module in pixels in each direction. Dimensionality and order of indices is the same as for data_origin.

module_offset: (optional) NX_NUMBER {units=NX_LENGTH}

Offset of the module in regards to the origin of the detector in an arbitrary direction.

@transformation_type: (optional) NX_CHAR

Obligatory value: translation

@vector: (optional) NX_NUMBER

Three values that define the axis for this transformation

@offset: (optional) NX_NUMBER

A fixed offset applied before the transformation (three vector components).

@offset_units: (optional) NX_CHAR

Units of the offset.

@depends_on: (optional) NX_CHAR

Points to the path of the next element in the geometry chain.

fast_pixel_direction: (optional) NX_NUMBER {units=NX_LENGTH}

Values along the direction of fastest varying pixel direction. Each value in this array is the size of a pixel in the units specified. Alternatively, if only one value is given, all pixels in this direction have the same value. The direction itself is given through the vector attribute.

@transformation_type: (optional) NX_CHAR

Obligatory value: translation

@vector: (optional) NX_NUMBER

Three values that define the axis for this transformation

@offset: (optional) NX_NUMBER

A fixed offset applied before the transformation (three vector components).

@offset_units: (optional) NX_CHAR

Units of the offset.

@depends_on: (optional) NX_CHAR

Points to the path of the next element in the geometry chain.

slow_pixel_direction: (optional) NX_NUMBER {units=NX_LENGTH}

Values along the direction of slowest varying pixel direction. Each value in this array is the size of a pixel in the units specified. Alternatively, if only one value is given, all pixels in this direction have the same value. The direction itself is given through the vector attribute.

@transformation_type: (optional) NX_CHAR

Obligatory value: translation

@vector: (optional) NX_NUMBER

Three values that define the axis for this transformation

@offset: (optional) NX_NUMBER

A fixed offset applied before the transformation (three vector components).

@offset_units: (optional) NX_CHAR

Units of the offset.

@depends_on: (optional) NX_CHAR

Points to the path of the next element in the geometry chain.

NXDL Source:

https://github.com/nexusformat/definitions/blob/master/base_classes/NXdetector_module.nxdl.xml