These symbols will be used below to coordinate datasets with the same shape. Most MX x-ray detectors will produce two-dimensional images. Some will produce three-dimensional images, using one of the indices to select a detector module. rank of the ``data`` field number of scan points number of detector pixels in the slowest direction number of detector pixels in the second slowest direction number of detector pixels in the third slowest direction number of channels in the incident beam spectrum, if known functional application definition for macromolecular crystallography Note, it is recommended that ``file_name`` and ``file_time`` are included as attributes at the root of a file that includes :ref:`NXmx`. See :ref:`NXroot`. ISO 8601 time/date of the first data point collected in UTC, using the Z suffix to avoid confusion with local time. Note that the time zone of the beamline should be provided in NXentry/NXinstrument/time_zone. ISO 8601 time/date of the last data point collected in UTC, using the Z suffix to avoid confusion with local time. Note that the time zone of the beamline should be provided in NXentry/NXinstrument/time_zone. This field should only be filled when the value is accurately observed. If the data collection aborts or otherwise prevents accurate recording of the end_time, this field should be omitted. ISO 8601 time/date of the last data point collected in UTC, using the Z suffix to avoid confusion with local time. Note that the time zone of the beamline should be provided in NXentry/NXinstrument/time_zone. This field may be filled with a value estimated before an observed value is available. NeXus NXDL schema to which this file conforms For a dimension-2 detector, the rank of the data array will be 3. For a dimension-3 detector, the rank of the data array will be 4. This allows for the introduction of the frame number as the first index. Descriptive name of sample This is a requirement to describe for any scan experiment. The axis on which the sample position depends may be stored anywhere, but is normally stored in the NXtransformations group within the NXsample group. If there is no goniometer, e.g. with a jet, depends_on should be set to "." This is the recommended location for sample goniometer and other related axes. This is a requirement to describe for any scan experiment. The reason it is optional is mainly to accommodate XFEL single shot exposures. Use of the depends_on field and the NXtransformations group is strongly recommended. As noted above this should be an absolute requirement to have for any scan experiment. The reason it is optional is mainly to accommodate XFEL single shot exposures. Name of instrument. Consistency with the controlled vocabulary beamline naming in http://mmcif.wwpdb.org /dictionaries/mmcif_pdbx_v50.dic/Items /_diffrn_source.pdbx_synchrotron_beamline.html and http://mmcif.wwpdb.org/dictionaries/mmcif_pdbx_v50.dic /Items/_diffrn_source.type.html} is highly recommended. Short name for instrument, perhaps the acronym. ISO 8601 time_zone offset from UTC. Optional logical grouping of detector elements. Each detector element is represented as an NXdetector group with its own detector data array. Each detector data array may be further decomposed into array sections by use of NXdetector_module groups. The names are given in the group names field. The groups are defined hierarchically, with names given in the group_names field, unique identifiing indices given in the field group_index, and the level in the hierarchy given in the group_parent field. For example if an x-ray detector, DET, consists of four elements in a rectangular array:: DTL DTR DLL DLR We could have:: group_names: ["DET", "DTL", "DTR", "DLL", "DLR"] group_index: [1, 2, 3, 4, 5] group_parent: [-1, 1, 1, 1, 1] An array of the names of the detector elements or hierarchical groupings of detector elements. Specified in the base classes as comma separated list of names, but new code should use an array of names as quoted strings. An array of unique indices for detector elements or groupings of detector elements. Each element is a unique ID for the corresponding group named in the field group_names. The IDs are positive integers starting with 1. An array of the hierarchical levels of the parents of detector elements or groupings of detector elements. A top-level element or grouping has parent level -1. Normally the detector group will have the name ``detector``. However, in the case of multiple detector elements, each element needs a uniquely named NXdetector group. NeXus path to the detector positioner axis that most directly supports the detector. In the case of a single-module detector, the detector axis chain may start here. Location for axes (transformations) to do with the detector. In the case of a single-module detector, the axes of the detector axis chain may be stored here. Suggested container for detailed non-standard detector information like corrections applied automatically or performance settings. For a dimension-2 detector, the rank of the data array will be 3. For a dimension-3 detector, the rank of the data array will be 4. This allows for the introduction of the frame number as the first index. name/manufacturer/model/etc. information. For a time-of-flight detector this is the scaling factor to convert from the numeric value reported to the flight time for a given measurement. Many detectors consist of multiple smaller modules that are operated in sync and store their data in a common dataset. To allow consistent parsing of the experimental geometry, this application definiton requires all detectors to define a detector module, even if there is only one. This group specifies the hyperslab of data in the data array associated with the detector that contains the data for this module. If the module is associated with a full data array, rather than with a hyperslab within a larger array, then a single module should be defined, spanning the entire array. 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 :ref:`order <Design-ArrayStorageOrder>` of indices (i, j or i, j, k) is slow to fast. 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. Two or three values for the stride of the module in pixels in each direction. By default the stride is [1,1] or [1,1,1], and this is the most likely case. This optional field is included for completeness. Offset of the module in regards to the origin of the detector in an arbitrary direction. Values along the direction of :ref:`fastest varying <Design-ArrayStorageOrder>` pixel direction. The direction itself is given through the vector attribute. Values along the direction of :ref:`slowest varying <Design-ArrayStorageOrder>` pixel direction. The direction itself is given through the vector attribute. Distance from the sample to the beam center. Normally this value is for guidance only, the proper geometry can be found following the depends_on axis chain, But in appropriate cases where the dectector distance to the sample is observable independent of the axis chain, that may take precedence over the axis chain calculation. Boolean to indicate if the distance is a derived, rather than a primary observation. If distance_derived true or is not specified, the distance is assumed to be derived from delector axis specifications. Detector dead time. Elapsed actual counting time. Boolean to indicate if the distance is a derived, rather than a primary observation. If true or not provided, that value of beam_center_derived is assumed to be true. This is the x position where the direct beam would hit the detector. This is a length and can be outside of the actual detector. The length can be in physical units or pixels as documented by the units attribute. Normally, this should be derived from the axis chain, but the direct specification may take precendence if it is not a derived quantity. This is the y position where the direct beam would hit the detector. This is a length and can be outside of the actual detector. The length can be in physical units or pixels as documented by the units attribute. Normally, this should be derived from the axis chain, but the direct specification may take precendence if it is not a derived quantity. True when the angular calibration has been applied in the electronics, false otherwise. Angular calibration data. True when the flat field correction has been applied in the electronics, false otherwise. Flat field correction data. If provided, it is recommended that is be compressed. Errors of the flat field correction data. If provided, it is recommended that it be compressed. True when the pixel mask correction has been applied in the electronics, false otherwise. The 32-bit pixel mask for the detector. Can be either one mask for the whole dataset (i.e. an array with indices i, j) or each frame can have its own mask (in which case it would be an array with indices np, i, j). Contains a bit field for each pixel to signal dead, blind, high or otherwise unwanted or undesirable pixels. They have the following meaning: * bit 0: gap (pixel with no sensor) * bit 1: dead * bit 2: under-responding * bit 3: over-responding * bit 4: noisy * bit 5: -undefined- * bit 6: pixel is part of a cluster of problematic pixels (bit set in addition to others) * bit 7: -undefined- * bit 8: user defined mask (e.g. around beamstop) * bits 9-30: -undefined- * bit 31: virtual pixel (corner pixel with interpolated value) Normal data analysis software would not take pixels into account when a bit in (mask & 0x0000FFFF) is set. Tag bit in the upper two bytes would indicate special pixel properties that normally would not be a sole reason to reject the intensity value (unless lower bits are set. If the full bit depths is not required, providing a mask with fewer bits is permissible. If needed, additional pixel masks can be specified by including additional entries named pixel_mask_N, where N is an integer. For example, a general bad pixel mask could be specified in pixel_mask that indicates noisy and dead pixels, and an additional pixel mask from experiment-specific shadowing could be specified in pixel_mask_2. The cumulative mask is the bitwise OR of pixel_mask and any pixel_mask_N entries. If provided, it is recommended that it be compressed. True when a count-rate correction has already been applied in the data recorded here, false otherwise. How many bits the electronics record per pixel. Time it takes to read the detector (typically milliseconds). This is important to know for time resolved experiments. This is time for each frame. This is exposure_time + readout time. The gain setting of the detector. This influences background. The value at which the detector goes into saturation. Data above this value is known to be invalid. For example, given a saturation_value and an underload_value, the valid pixels are those less than or equal to the saturation_value and greater than or equal to the underload_value. The lowest value at which pixels for this detector would be reasonably be measured. For example, given a saturation_value and an underload_value, the valid pixels are those less than or equal to the saturation_value and greater than or equal to the underload_value. At times, radiation is not directly sensed by the detector. Rather, the detector might sense the output from some converter like a scintillator. This is the name of this converter material. At times, radiation is not directly sensed by the detector. Rather, the detector might sense the output from some converter like a scintillator. This is the thickness of this converter material. Single photon counter detectors can be adjusted for a certain energy range in which they work optimally. This is the energy setting for this. If the detector supports multiple thresholds, this is an array. Description of type such as scintillator, ccd, pixel, image plate, CMOS, ... In the case of a monchromatic beam this is the scalar wavelength. Several other use cases are permitted, depending on the presence or absence of other incident_wavelength_X fields. In the case of a polychromatic beam this is an array of length **m** of wavelengths, with the relative weights in incident_wavelength_weight. In the case of a monochromatic beam that varies shot- to-shot, this is an array of wavelengths, one for each recorded shot. Here, incident_wavelength_weight and incident_wavelength_spread are not set. In the case of a polychromatic beam that varies shot-to- shot, this is an array of length **m** with the relative weights in incident_wavelength_weight as a 2D array. In the case of a polychromatic beam that varies shot-to- shot and where the channels also vary, this is a 2D array of dimensions **np** by **m** (slow to fast) with the relative weights in incident_wavelength_weight as a 2D array. In the case of a polychromatic beam this is an array of length **m** of the relative weights of the corresponding wavelengths in incident_wavelength. In the case of a polychromatic beam that varies shot-to- shot, this is a 2D array of dimensions **np** by **m** (slow to fast) of the relative weights of the corresponding wavelengths in incident_wavelength. The wavelength spread FWHM for the corresponding wavelength(s) in incident_wavelength. Flux density incident on beam plane area in photons per second per unit area. In the case of a beam that varies in flux shot-to-shot, this is an array of values, one for each recorded shot. Flux incident on beam plane in photons per second. In the case of a beam that varies in total flux shot-to-shot, this is an array of values, one for each recorded shot. Two-element array of FWHM (if Gaussian or Airy function) or diameters (if top hat) or widths (if rectangular) of the beam in the order x, y The beam profile, Gaussian, Airy function, top-hat or rectangular. The profile is given in the plane of incidence of the beam on the sample. The neutron or x-ray storage ring/facility. Note, the NXsource base class has many more fields available, but at present we only require the name. Name of source. Consistency with the naming in http://mmcif.wwpdb.org/dictionaries/mmcif_pdbx_v50.dic/Items /_diffrn_source.pdbx_synchrotron_site.html controlled vocabulary is highly recommended. short name for source, perhaps the acronym