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VesuvioCorrections v1¶

../_images/ImageNotFound.png — Enable screenshots using DOCS_SCREENSHOTS in CMake¶

Summary ¶

Apply post fitting steps to vesuvio data

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	Input TOF workspace
WorkspaceIndex	Input	long	0	Index of spectrum to calculate corrections for
FitParameters	Input	TableWorkspace		Table containing the calculated fit parametersfor the data in the workspace
Masses	Input	dbl list	Mandatory	Mass values for fitting
MassIndexToSymbolMap	Input	Dictionary	null	A map from the index of the mass in the Masses property to a chemical symbol.
MassProfiles	Input	string	Mandatory	Functions used to approximate mass profile. The format is function=Function1Name,param1=val1,param2=val2;function=Function2Name,param3=val3,param4=val4
IntensityConstraints	Input	string		A semi-colon separated list of intensity constraints defined as lists e.g [0,1,0,-4];[1,0,-2,0]
HydrogenConstraints	Input	Dictionary	null	Constraints used to approximate the intensity of the hydrogen peak in back-scattering spectra for multiple scattering corrections.
ContainerWorkspace	Input	MatrixWorkspace		Container workspace in TOF
ContainerScale	Input	number	0	Scale factor to apply to container, set to 0 for automatic scale based on linear fit
GammaBackground	Input	boolean	True	If true, correct for the gamma background
GammaBackgroundScale	Input	number	0	Scale factor to apply to gamma background, set to 0 for automatic scale based on linear fit
MultipleScattering	Input	boolean	True	If true, correct for the effects of multiple scattering
BeamRadius	Input	number	2.5	Radius of beam in cm
SampleHeight	Input	number	5	Height of sample in cm
SampleWidth	Input	number	5	Width of sample in cm
SampleDepth	Input	number	5	Depth of sample in cm
SampleDensity	Input	number	1	Sample density in g/cm^3
Seed	Input	long	123456789
NumScatters	Input	long	3
NumRuns	Input	long	10
NumEvents	Input	long	50000	Number of neutron events
SmoothNeighbours	Input	long	3
CorrectionWorkspaces	Output	WorkspaceGroup		Workspace group containing correction intensities for each correction
CorrectedWorkspaces	Output	WorkspaceGroup		Workspace group containing individual corrections applied to raw data
LinearFitResult	Output	TableWorkspace		Table workspace containing the fit parameters used tolinearly fit the corrections to the data
OutputWorkspace	Output	MatrixWorkspace	Mandatory	The name of the output workspace

Description ¶

Performs the post fitting corrections steps for Vesuvio data. These steps in include corrections for multiple scattering and gamma.

Usage ¶

Example - VesuvioCorrections

###### Simulates LoadVesuvio with spectrum number 135-136 #################
tof_ws = CreateSimulationWorkspace(Instrument='Vesuvio',BinParams=[50,0.5,562],UnitX='TOF')
tof_ws = CropWorkspace(tof_ws,StartWorkspaceIndex=134,EndWorkspaceIndex=135) # index one less than spectrum number
tof_ws = ConvertToPointData(tof_ws)
SetInstrumentParameter(tof_ws, ParameterName='t0',ParameterType='Number',Value='0.5')
SetInstrumentParameter(tof_ws, ParameterName='sigma_l1', ParameterType='Number', Value='0.021')
SetInstrumentParameter(tof_ws, ParameterName='sigma_l2', ParameterType='Number', Value='0.023')
SetInstrumentParameter(tof_ws, ParameterName='sigma_tof', ParameterType='Number', Value='0.3')
SetInstrumentParameter(tof_ws, ParameterName='sigma_theta', ParameterType='Number', Value='0.028')
SetInstrumentParameter(tof_ws, ParameterName='hwhm_lorentz', ParameterType='Number', Value='24.0')
SetInstrumentParameter(tof_ws, ParameterName='sigma_gauss', ParameterType='Number', Value='73.0')
# Algorithm allows separate parameters for the foils
SetInstrumentParameter(tof_ws, ComponentName='foil-pos0', ParameterName='hwhm_lorentz',
                       ParameterType='Number', Value='144.0')
SetInstrumentParameter(tof_ws, ComponentName='foil-pos0', ParameterName='sigma_gauss',
                       ParameterType='Number', Value='20.0')
SetInstrumentParameter(tof_ws, ComponentName='foil-pos1', ParameterName='hwhm_lorentz',
                       ParameterType='Number', Value='144.0')
SetInstrumentParameter(tof_ws, ComponentName='foil-pos1', ParameterName='sigma_gauss',
                       ParameterType='Number', Value='20.0')

#######################Create dummy fit parameters#############################
params = CreateEmptyTableWorkspace(OutputWorkspace='__VesuvioCorrections_test_fit_params')

params.addColumn('str', 'Name')
params.addColumn('float', 'Value')
params.addColumn('float', 'Error')

params.addRow(['f0.Width', 4.72912, 0.41472])
params.addRow(['f0.FSECoeff', 0.557332, 0])
params.addRow(['f0.C_0', 11.8336, 1.11468])
params.addRow(['f1.Width', 10, 0])
params.addRow(['f1.Intensity', 2.21085, 0.481347])
params.addRow(['f2.Width', 13, 0])
params.addRow(['f2.Intensity', 1.42443, 0.583283])
params.addRow(['f3.Width', 30, 0])
params.addRow(['f3.Intensity', 0.499497, 0.28436])
params.addRow(['f4.A0', -0.00278903, 0.00266163])
params.addRow(['f4.A1', 14.5313, 22.2307])
params.addRow(['f4.A2', -5475.01, 35984.4])
params.addRow(['Cost function value', 2.34392, 0])


masses = [1.0079, 16.0, 27.0, 133.0]
profiles = "function=GramCharlier,hermite_coeffs=[1, 0, 0],k_free=0,sears_flag=1,width=[2, 5, 7];function=Gaussian,width=10;function=Gaussian,width=13;function=Gaussian,width=30"



corrections, corrected, linear_fit, out_ws = VesuvioCorrections(InputWorkspace=tof_ws,
                                                                GammaBackground=True,
                                                                FitParameters=params,
                                                                Masses=masses,
                                                                MassProfiles=profiles,
                                                                ContainerScale=0.1,
                                                                GammaBackgroundScale=0.2)