\(\renewcommand\AA{\unicode{x212B}}\)

AlignAndFocusPowderFromFiles v1¶

Summary ¶

The algorithm used for reduction of powder diffraction data

Properties ¶

Name	Direction	Type	Default	Description
Filename	Input	list of str lists	Mandatory	Files to combine in reduction. Allowed extensions: [‘_event.nxs’, ‘.nxs.h5’]
MaxChunkSize	Input	number	0	Specify maximum Gbytes of file to read in one chunk. Default is whole file.
FilterBadPulses	Input	number	0	Filter out events measured while proton charge is more than 5% below average
AbsorptionWorkspace	Input	MatrixWorkspace		Divide data by this Pixel-by-pixel workspace
CacheDir	Input	string		Directory storing cache files for reuse, in-lieu of repetitive, time-consuming calculations
OutputWorkspace	Output	MatrixWorkspace	Mandatory	Combined output workspace
UnfocussedWorkspace	Output	MatrixWorkspace		Treated data in d-spacing before focussing (optional). This will likely need rebinning.
Characterizations	Input	TableWorkspace		Characterizations table
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)
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
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
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.
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
FrequencyLogNames	Input	str list	SpeedRequest1,Speed1,frequency,skf1.speed	Candidate log names for frequency
WaveLengthLogNames	Input	str list	LambdaRequest,lambda,skf12.lambda,BL1B:Det:TH:BL:Lambda,freq	Candidate log names for wave length

This is a workflow algorithm that wraps AlignAndFocusPowder to perform a double loop over files with chunks, followed by accumulating the results. The additional properties from what is allowed in AlignAndFocusPowder is for how the file is loaded (e.g. MaxChunkSize and FilterBadPulses), an optional Characterizations table, and an optional AbsorptionWorkspace. The AbsorptionWorkspace should be in units of Wavelength for every detector pixel and is divided from the chunk after loaded. For all other information, see AlignAndFocusPowder.

In broad terms, the following pseudo-code describes the general concept of this algorithm:

for filename in filenames:
    cachefile = CreateCacheFilename(filename, ...)
    if cachefile exists:
        wksp_single = LoadNexusProcessed(cachefile)
    else:
        for chunk in DetermineChunking(filename):
            wksp_single_chunk = Load(chunk)
            wksp_single_chunk = AlignAndFocusPowder(wksp_single_chunk, ...)
        # accumulate chunks into wksp_single
        SaveNexusProcess(wksp_single, cachefile)
    # accumulate data from files into OutputWorkspace

Algorithms used by this are:

Categories: AlgorithmIndex | Diffraction\Reduction

Source ¶

Python: AlignAndFocusPowderFromFiles.py

AlignAndFocusPowderFromFiles v1¶

Summary ¶

See Also ¶

Properties ¶

Description ¶

Source ¶

AlignAndFocusPowderFromFiles v1¶

Summary¶

See Also¶

Properties¶

Description¶

Source¶

Summary ¶

See Also ¶

Properties ¶

Description ¶

Source ¶