VesuvioTOFFit dialog.
Table of Contents
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| InputWorkspace | Input | MatrixWorkspace | Mandatory | Input TOF workspace |
| Masses | Input | dbl list | Mandatory | Mass values for fitting |
| 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 |
| WorkspaceIndex | Input | number | 0 | Workspace index for fit. [Default=0] |
| Background | Input | string | Function used to fit the background. The format is function=FunctionName,param1=val1,param2=val2 | |
| IntensityConstraints | Input | string | A semi-colon separated list of intensity constraints defined as lists e.g [0,1,0,-4];[1,0,-2,0] | |
| Ties | Input | string | A string representing the ties to be applied to the fit | |
| FitMode | Input | string | bank | Fit either bank-by-bank or detector-by-detector. Allowed values: [‘bank’, ‘spectrum’] |
| MaxIterations | Input | number | 5000 | Maximum number of fitting iterations |
| Minimizer | Input | string | Levenberg-Marquardt,AbsError=1e-08,RelError=1e-08 | String defining the minimizer |
| OutputWorkspace | Output | MatrixWorkspace | Mandatory | The name of the fitted workspaces. |
| FitParameters | Output | TableWorkspace | Mandatory | The name of the fitted parameter workspaces. |
| Chi2 | Output | number | The value of the Chi-Squared. |
Runs a Time of Flight (TOF) fit for preprocessed Vesuvio data. This algorithm also constructs the constraints, ties, function strings for the fit based on the inputs.
Example - VesuvioTOFFit
###### 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')
###########################################################################
profiles = "function=GramCharlier,width=[2, 5, 7],hermite_coeffs=[1, 0, 0],k_free=0,sears_flag=1;"\
"function=Gaussian,width=10;function=Gaussian,width=13;function=Gaussian,width=30;"
background = "function=Polynomial,order=3"
out_ws, fit_params, chi_sq = VesuvioTOFFit(InputWorkspace=tof_ws, Masses=[1.0079, 16.0, 27.0, 133.0],
MassProfiles=profiles, Background=background,
IntensityConstraints='[0,1,0,-4]')
Categories: Algorithms | Inelastic\Indirect\Vesuvio
Python: VesuvioTOFFit.py