CalculateMuonAsymmetry v1¶

CalculateMuonAsymmetry dialog.

Table of Contents

Summary
Properties
Description
Usage
Source

Summary ¶

This algorithm calculates the asymmetry for a transverse field.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	The name of the input 2D workspace.
OutputWorkspace	Output	MatrixWorkspace	Mandatory	The name of the output 2D workspace.
Spectra	Input	int list		The workspace indices to remove the exponential decay from.
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).
FittingFunction	Input	string	name = GausOsc, A = 10.0, Sigma = 0.2, Frequency = 1.0, Phi = 0.0	The additional fitting functions to be used.
InputDataType	Input	string	counts	If the data is raw counts or asymmetry. Allowed values: [‘counts’, ‘asymmetry’]
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’, ‘More-Sorensen’, ‘Simplex’, ‘SteepestDescent’, ‘Trust Region’]
MaxIterations	Input	number	500	Stop after this number of iterations if a good fit is not found
NormalizationConstant	Output	dbl list
PreviousNormalizationConstant	Input	dbl list		Normalization constant used to estimate asymmetry

Description ¶

This algorithm calculates the asymmetry from the specified muon spectra. By default, all of the spectra 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), :math:’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

$N_0[1+f(t)]$

where $f(t)$ is a user defined function.

It is also possible to calculate the asymmetry from an estimated asymmetry.

Usage ¶

Example - Calculating Asymmetry From Counts: This example is for calculating the Asymmetry from counts.

import math
import numpy as np
xData=np.linspace(start=0,stop=10,num=22)
yData=[]
tau =  2.1969811
for x in xData:
     yData.append(50.*(1+10.*math.cos(3.*x))*math.exp(-x/tau))
input = CreateWorkspace(xData,yData)
run = input.getRun()
run.addProperty("goodfrm","10","None",True)
output,norm=CalculateMuonAsymmetry   (InputWorkspace=input,spectra=0,StartX=1,EndX=5,FittingFunction= "name = GausOsc, A = 10.0, Sigma = 0.2, Frequency = 1.0, Phi = 0.0",InputDataType="counts",Minimizer="Levenberg-MarquardtMD",MaxIterations=500 )
print  "Asymmetry: ",['{0:.2f}'.format(value)  for value in output.readY(0)]
print "Normalization constant: {0:.2f}".format(norm[0])

Output:

Asymmetry:  ['10.00', '1.42', '-9.60', '-4.14', '8.42', '6.53', '-6.57', '-8.39', '4.20', '9.58', '-1.48', '-10.00', '-1.35', '9.62', '4.08', '-8.46', '-6.48', '6.62', '8.36', '-4.25', '-9.56', '1.54']
Normalization constant: 5.00

Example - Calculating Asymmetry From Estimated Asymmetry: This example is for calculating the Asymmetry from an estimate of the asymmetry.

import math
import numpy as np
xData=np.linspace(start=0,stop=10,num=22)
yData=[]
tau =  2.1969811
for x in xData:
    yData.append(50.*(1+10.*math.cos(3.*x))*math.exp(-x/tau))
input = CreateWorkspace(xData,yData)
run = input.getRun()
run.addProperty("goodfrm","10","None",True)
estAsymm,estNorm=CalculateMuonAsymmetry(InputWorkspace=input,spectra=0,StartX=1,EndX=5)
output,norm=CalculateMuonAsymmetry(InputWorkspace=estAsymm,spectra=0,StartX=1,EndX=5,FittingFunction= "name = GausOsc, A = 10.0, Sigma = 0.2, Frequency = 1.0, Phi = 0.0",InputDataType="asymmetry",Minimizer="Levenberg-MarquardtMD",MaxIterations=500,PreviousNormalizationConstant=estNorm )
print  "Asymmetry: ",['{0:.2f}'.format(value)  for value in output.readY(0)]
print "Normalization constant: {0:.2f}".format(norm[0])

Output:

Asymmetry:  ['10.00', '1.42', '-9.60', '-4.14', '8.42', '6.53', '-6.57', '-8.39', '4.20', '9.58', '-1.48', '-10.00', '-1.35', '9.62', '4.08', '-8.46', '-6.48', '6.62', '8.36', '-4.25', '-9.56', '1.54']
Normalization constant: 5.00

Categories: Algorithms | Muon