.. auto-generated by script ../../../../utils/nxdl2rst.py from the NXDL source NXattenuator.nxdl.xml

.. index::
    ! NXattenuator (base class)
    ! attenuator (base class)
    see: attenuator (base class); NXattenuator

.. _NXattenuator:

============
NXattenuator
============

**Status**:

  base class, extends :ref:`NXobject`, version 1.0

**Description**:

  A device that reduces the intensity of a beam by attenuation.

  If uncertain whether to use :ref:`NXfilter` (band-pass filter)
  or :ref:`NXattenuator` (reduces beam intensity), then choose 
  :ref:`NXattenuator`.

**Symbols**:

  No symbol table

**Groups cited**:
  none

**Structure**:

  .. index:: distance (field)

  **distance**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Distance from sample

  .. index:: type (field)

  **type**: :ref:`NX_CHAR <NX_CHAR>`

    Type or composition of attenuator, e.g. polythene

  .. index:: thickness (field)

  **thickness**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Thickness of attenuator along beam direction

  .. index:: scattering cross section (field)

  **scattering_cross_section**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_CROSS_SECTION <NX_CROSS_SECTION>`}

    Scattering cross section (coherent+incoherent)

  .. index:: absorption cross section (field)

  **absorption_cross_section**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_CROSS_SECTION <NX_CROSS_SECTION>`}

    Absorption cross section

  .. index:: attenuator transmission (field)

  **attenuator_transmission**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_DIMENSIONLESS <NX_DIMENSIONLESS>`}

    The nominal amount of the beam that gets through
    (transmitted intensity)/(incident intensity)

  .. index:: status (field)

  **status**: :ref:`NX_CHAR <NX_CHAR>`

    In or out or moving of the beam

    Any of these values: ``in`` | ``out`` | ``moving``

    .. index:: time (field attribute)

    **@time**: :ref:`NX_DATE_TIME <NX_DATE_TIME>`

      time stamp for this observation

**NXDL Source**:
  https://github.com/nexusformat/definitions/blob/master/base_classes/NXattenuator.nxdl.xml