# 3.3.1.13. NXdetector_group¶

Status:

base class, extends NXobject, version 1.0

Description:

Logical grouping of detector elements.

This class is used to allow a logical grouping of detector elements (e.g. which tube, bank or group of banks) to be recorded in the file. As well as allowing you to e.g just select the “left” or “east” detectors, it may also be useful for determining which elements belong to the same PSD tube and hence have e.g. the same dead time.

For example, if we had “bank1” composed of “tube1”, “tube2” and “tube3” then group_names would be the string “bank1, bank1/tube1, bank1/tube2,bank1/tube3” group_index would be {1,2,3,4} group_parent would be {-1,1,1,1}

The mapping array is interpreted as group 1 is a top level group containing groups 2, 3 and 4

A group_index array in NXdetector gives the base group for a detector element.

Symbols:

No symbol table
Groups cited:
none

Structure:

group_names: (optional) NX_CHAR

Comma separated list of name

group_index[i]: (optional) NX_INT

Unique ID for group. A group_index array in NXdetector gives the base group for a detector element.

group_parent[ref(group_index)]: (optional) NX_INT

Index of group parent in the hierarchy: -1 means no parent (i.e. a top level) group

group_type[ref(group_index)]: (optional) NX_INT

Code number for group type, e.g. bank=1, tube=2 etc.
NXDL Source:
https://github.com/nexusformat/definitions/blob/master/base_classes/NXdetector_group.nxdl.xml