3.7

VesuvioTOFFit v1

../_images/VesuvioTOFFit-v1_dlg.png

VesuvioTOFFit dialog.

Summary

Processes runs for Vesuvio at ISIS

Properties

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]
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.

Description

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.

Usage

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 = 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