5.1

CalculateMuonAsymmetry v1

../_images/CalculateMuonAsymmetry-v1_dlg.png

CalculateMuonAsymmetry dialog.

Summary

This algorithm calculates the asymmetry for a transverse field.

Properties

Name Direction Type Default Description
NormalizationTable Input TableWorkspace   Name of the table containing the normalizations for the asymmetries.
UnNormalizedWorkspaceList Input str list Mandatory An ordered list of workspaces (to get the initial values for the normalizations).
ReNormalizedWorkspaceList Input str list Mandatory An ordered list of workspaces (to get the initial values for the normalizations).
OutputFitWorkspace Input string fit The name of the output fit workspace.
StartX Input number 0.1 The lower limit for calculating the asymmetry (an X value).
EndX Input number 15 The upper limit for calculating the asymmetry (an X value).
InputFunction Input Function Mandatory The fitting function to be converted.
Minimizer Input string Levenberg-MarquardtMD Minimizer to use for fitting. Allowed values: [‘BFGS’, ‘Conjugate gradient (Fletcher-Reeves imp.)’, ‘Conjugate gradient (Polak-Ribiere imp.)’, ‘Damped GaussNewton’, ‘FABADA’, ‘Levenberg-Marquardt’, ‘Levenberg-MarquardtMD’, ‘Simplex’, ‘SteepestDescent’, ‘Trust Region’]
MaxIterations Input number 500 Stop after this number of iterations if a good fit is not found
OutputStatus Output string    
ChiSquared Output number    
OutputFunction Output Function   The fitting function after fit.
EnableDoublePulse Input boolean False Controls whether to perform a double pulse or single pulse fit.
PulseOffset Input number 0 The time offset between the two pulses
FirstPulseWeight Input number 0.5 Weighting of first pulse (w_1).The second pulse weighting (w_1) is set as w_2 = 1 - w_1.

Description

This algorithm calculates the asymmetry from the first muon spectra in a workspace. in a workspace will be corrected.

The formula for calculating the asymmetry (from counts) is given by:

\textrm{NewData} = (\textrm{OldData}\times e^\frac{t}{\tau})/(F N_0) - 1.0,

where \tau is the muon lifetime (2.1969811e-6 seconds), F is the number of good frames and N_0 is a fitted normalisation constant. The normalisation is calculated by fitting to the normalised counts which is given by

\textrm{normalisedCounts}=(\textrm{OldData}\times e^\frac{t}{\tau})/F

and the fitting function is given by

N_0[1+f(t)]

and the renormalized data is transformed via the equation:

\textrm{NewData} = (\textrm{NormalisedCounts}/(N_0) - 1.0.

Usage

Example - Calculating Asymmetry: This example is for calculating the Asymmetry for a single data set.

import math
import numpy as np

def makeData(name,norm):
    xData=np.linspace(start=0,stop=10,num=200)
    yData=np.sin(5.2*xData)
    result = (1-yData )*norm
    ws= CreateWorkspace(DataX=xData, DataY=result,OutputWorkspace=name)
    return ws

#create a normalisation table
tab = CreateEmptyTableWorkspace()
tab.addColumn('double', 'norm')
tab.addColumn('str', 'name')
tab.addColumn('str', 'method')

tab.addRow([11.,"a","Estimate"])
tab.addRow([22.,"b","Estimate"])

ws= makeData("a",2.30)
ws2= makeData("b",1.10)

myFunc='name=GausOsc,$domains=i,Frequency=5.;'

TFFunc = ConvertFitFunctionForMuonTFAsymmetry(InputFunction=myFunc,NormalizationTable=tab,WorkspaceList=["a"],Mode="Construct")
CalculateMuonAsymmetry(NormalizationTable=tab, unNormalizedWorkspaceList=["a"],
                       ReNormalizedWorkspaceList=["b"], InputFunction= str(TFFunc),
                       OutputFitWorkspace="fit_result",StartX=0.1,EndX=9.9)

print("Normalization constant for b: {0:.2f}".format(tab.column(0)[1]))

Output:

Normalization constant for b: 2.30

Example - Calculating Asymmetry For multiple data sets: This example is for calculating the Asymmetry for multuiple data sets.

import math
import numpy as np

def makeData(name,norm):
   xData=np.linspace(start=0,stop=10,num=200)
   yData=np.sin(5.2*xData)
   result = (1-yData )*norm
   ws= CreateWorkspace(DataX=xData, DataY=result,OutputWorkspace=name)
   return ws

#create a normalisation table
tab = CreateEmptyTableWorkspace()
tab.addColumn('double', 'norm')
tab.addColumn('str', 'name')
tab.addColumn('str', 'method')

tab.addRow([11.,"a","Estimate"])
tab.addRow([22.,"b","Estimate"])
tab.addRow([22.,"c","Estimate"])
tab.addRow([22.,"d","Estimate"])

#create original function and workspace
myFunc='name=GausOsc,$domains=i,Frequency=5.;'
myFunc2='name=GausOsc,$domains=i,Frequency=5.;'
multiFunc='composite=MultiDomainFunction,NumDeriv=1;'+myFunc+myFunc2+'ties=(f0.Frequency=f1.Frequency)'

ws= makeData("a",2.30)
ws2= makeData("b",1.10)
ws3= makeData("c",4.1)
ws4= makeData("d",2.0)

TFFunc = ConvertFitFunctionForMuonTFAsymmetry(InputFunction=multiFunc, NormalizationTable=tab,
                                              WorkspaceList=["a","c"], Mode="Construct")

CalculateMuonAsymmetry(NormalizationTable=tab, unNormalizedWorkspaceList=["a","c"],
                       ReNormalizedWorkspaceList=["b","d"], InputFunction= str(TFFunc),
                       OutputFitWorkspace="fit_result",StartX=0.1,EndX=9.9)

print("Normalization constant for b: {0:.2f}".format(tab.column(0)[1]))
print("Normalization constant for d: {0:.2f}".format(tab.column(0)[3]))

Output:

Normalization constant for b: 2.30
Normalization constant for d: 4.10

Example - Calculating Asymmetry for double pulse data:

import math
import numpy as np

delta = 0.33
x = np.linspace(0.,15.,100)
x_offset = np.linspace(delta/2, 15. + delta/2, 100)
x_offset_neg = np.linspace(-delta/2, 15. - delta/2, 100)

testFunction = GausOsc(Frequency = 1.5, A=0.22)
y1 = testFunction(x_offset_neg)
y2 = testFunction(x_offset)
N0 = 6.38
y = N0 * (1 + y1/2+y2/2)
y_norm = y1/2+y2/2
unnormalised_workspace = CreateWorkspace(x,y)
ws_to_normalise = CreateWorkspace(x,y)
ws_correctly_normalised = CreateWorkspace(x,y_norm)
AddSampleLog(Workspace='ws_to_normalise', LogName="analysis_asymmetry_norm", LogText="1")

innerFunction = FunctionFactory.createInitialized('name=GausOsc,A=0.20,Sigma=0.2,Frequency=1.0,Phi=0')
tf_function = ConvertFitFunctionForMuonTFAsymmetry(InputFunction=innerFunction, WorkspaceList=['ws_to_normalise'])

CalculateMuonAsymmetry(MaxIterations=100, EnableDoublePulse=True, PulseOffset=delta, UnNormalizedWorkspaceList='unnormalised_workspace', ReNormalizedWorkspaceList='ws_to_normalise',
                        OutputFitWorkspace='DoublePulseFit', StartX=0, InputFunction=str(tf_function), Minimizer='Levenberg-Marquardt')

double_parameter_workspace = AnalysisDataService.retrieve('DoublePulseFit_Parameters')
values_column = double_parameter_workspace.column(1)

print("Normalization constant is: {0:.2f}".format(values_column[0]))

Output:

Normalization constant is: 6.38

Categories: AlgorithmIndex | Muon

Source

C++ header: CalculateMuonAsymmetry.h (last modified: 2020-03-25)

C++ source: CalculateMuonAsymmetry.cpp (last modified: 2020-07-23)