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AlignAndFocusPowder dialog.
Table of Contents
Algorithm to focus powder diffraction data into a number of histograms according to a grouping scheme defined in a CalFile.
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| InputWorkspace | Input | MatrixWorkspace | Mandatory | The input workspace |
| OutputWorkspace | Output | MatrixWorkspace | Mandatory | The result of diffraction focussing of InputWorkspace |
| UnfocussedWorkspace | Output | MatrixWorkspace | Treated data in d-spacing before focussing (optional). This will likely need rebinning. | |
| CalFileName | Input | string | The name of the calibration file with offset, masking, and grouping data. Allowed extensions: [‘.h5’, ‘.hd5’, ‘.hdf’, ‘.cal’] | |
| GroupFilename | Input | string | Overrides grouping from CalFileName. Allowed extensions: [‘.xml’, ‘.cal’] | |
| GroupingWorkspace | InOut | GroupingWorkspace | Optional: A GroupingWorkspace giving the grouping info. | |
| CalibrationWorkspace | InOut | TableWorkspace | Optional: A Workspace containing the calibration information. Either this or CalibrationFile needs to be specified. | |
| OffsetsWorkspace | Input | OffsetsWorkspace | Optional: An OffsetsWorkspace giving the detector calibration values. | |
| MaskWorkspace | InOut | MaskWorkspace | Optional: A workspace giving which detectors are masked. | |
| MaskBinTable | Input | TableWorkspace | Optional: A workspace giving pixels and bins to mask. | |
| Params | Input | dbl list | A comma separated list of first bin boundary, width, last bin boundary. Optionally this can be followed by a comma and more widths and last boundary pairs. Negative width values indicate logarithmic binning. | |
| ResampleX | Input | number | 0 | Number of bins in x-axis. Non-zero value overrides “Params” property. Negative value means logarithmic binning. |
| Dspacing | Input | boolean | True | Bin in Dspace. (True is Dspace; False is TOF) |
| DMin | Input | dbl list | Minimum for Dspace axis. (Default 0.) | |
| DMax | Input | dbl list | Maximum for Dspace axis. (Default 0.) | |
| DeltaRagged | Input | dbl list | Step parameter for rebin | |
| TMin | Input | number | Optional | Minimum for TOF axis. Defaults to 0. |
| TMax | Input | number | Optional | Maximum for TOF or dspace axis. Defaults to 0. |
| PreserveEvents | Input | boolean | True | If the InputWorkspace is an EventWorkspace, this will preserve the full event list (warning: this will use much more memory!). |
| RemovePromptPulseWidth | Input | number | 0 | Width of events (in microseconds) near the prompt pulse to remove. 0 disables |
| ResonanceFilterUnits | Input | string | Wavelength | Units for resonances to be filtered in. The data will be converted to these units temporarily to filter. Allowed values: [‘Energy’, ‘Wavelength’] |
| ResonanceFilterLowerLimits | Input | dbl list | Minimum values to filter absorption resonance. This must have same number of values as ResonanceFilterUpperLimits. Default behavior is to not filter. | |
| ResonanceFilterUpperLimits | Input | dbl list | Maximum values to filter absorption resonance. This must have same number of values as ResonanceFilterLowerLimits. Default behavior is to not filter. | |
| CompressTolerance | Input | number | 1e-05 | Compress events (in microseconds) within this tolerance. (Default 1e-5) |
| CompressWallClockTolerance | Input | number | Optional | The tolerance (in seconds) on the wall-clock time for comparison. Unset means compressing all wall-clock times together disabling pulsetime resolution. |
| CompressStartTime | Input | string | An ISO formatted date/time string specifying the timestamp for starting filtering. Ignored if WallClockTolerance is not specified. Default is start of run | |
| LorentzCorrection | Input | boolean | False | Multiply each spectrum by sin(theta) where theta is half of the Bragg angle |
| UnwrapRef | Input | number | 0 | Reference total flight path for frame unwrapping. Zero skips the correction |
| LowResRef | Input | number | 0 | Reference DIFC for resolution removal. Zero skips the correction |
| CropWavelengthMin | Input | number | 0 | Crop the data at this minimum wavelength. Overrides LowResRef. |
| CropWavelengthMax | Input | number | Optional | Crop the data at this maximum wavelength. Forces use of CropWavelengthMin. |
| PrimaryFlightPath | Input | number | -1 | If positive, focus positions are changed. (Default -1) |
| SpectrumIDs | Input | int list | Optional: Spectrum Nos (note that it is not detector ID or workspace indices). | |
| L2 | Input | dbl list | Optional: Secondary flight (L2) paths for each detector | |
| Polar | Input | dbl list | Optional: Polar angles (two thetas) for detectors | |
| Azimuthal | Input | dbl list | Azimuthal angles (out-of-plain) for detectors | |
| LowResSpectrumOffset | Input | number | -1 | Offset on spectrum No of low resolution spectra from high resolution one. If negative, then all the low resolution TOF will not be processed. Otherwise, low resolution TOF will be stored in an additional set of spectra. If offset is equal to 0, then the low resolution will have same spectrum Nos as the normal ones. Otherwise, the low resolution spectra will have spectrum IDs offset from normal ones. |
| ReductionProperties | Input | string | __powdereduction |
This is a workflow algorithm that does the bulk of the work for time focusing diffraction data. This is done by executing several sub-algorithms as listed below. The way that algorithms are connected together is better described in the workflow diagram
LowResRef is specifiedCropWavelengthMin and CropWavelengthMax are preferedThe main workflow of the algorithm can be described in following diagram.
In this diagram, the CalibrationWorkspace, MaskWorkspace, and GroupingWorkspace are abstractions of the many ways that this information can be provided (see below).
The way that calibration is supplied can be confusing. This section will attempt to clarify it.
Workspaces provided:
If the GroupingWorkspace, CalibrationWorkspace, or MaskWorkspace are supplied as parameters they are used.
If the OffsetsWorkspace is supplied it is converted to a CalibrationWorkspace using ConvertDiffCal v1.
The values of CalFileName and GroupFilename will be ignored
Filenames provided, Workspaces not:
Assuming the instrument short-name is <INSTR> (replace with the actual instrument short-name), the algorithm will look for the workspaces <INSTR>_group, <INSTR>_cal (falling back to <INSTR>_offsets), and <INSTR>_mask and use them without consulting the files.
This behavior is to reduce the amount of overhead in processing a collection of input data.
When loading information from a file, all 3 workspaces can be read from either type of calibration file (.h5 or .cal) and will get the default names.
If the GroupFilename is provided, that will override the grouping information in the CalFilename.
Note
If the user wishes to force reading the supplied calibration file(s), they must delete the workspaces <INSTR>_group, <INSTR>_cal, <INSTR>_offsets, and <INSTR>_mask.
Example: A simple Powgen example
The files needed for this example are not present in our standard usage data download due to their size. They can however be downloaded using these links: PG3_9830_event.nxs and pg3_mantid_det.cal.
You will have to rename pg3_mantid_det.cal manually, as its name in the link above is a list of random characters.
PG3_9830_event = Load('PG3_9830_event.nxs')
PG3_9830_event = AlignAndFocusPowder(PG3_9830_event,
CalFileName='pg3_mantid_det.cal', Params='100')
Categories: AlgorithmIndex | Workflow\Diffraction