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ApplyDetailedBalance v1

../_images/ApplyDetailedBalance-v1_dlg.png

ApplyDetailedBalance dialog.

Summary

Transform scattering intensity to dynamic susceptibility.

Properties

Name Direction Type Default Description
InputWorkspace Input MatrixWorkspace Mandatory An input workspace.
Temperature Input string   SampleLog variable name that contains the temperature, or a number
OutputWorkspace Output MatrixWorkspace Mandatory An output workspace.
OutputUnits Input string Energy Susceptibility as a function of energy (meV) or frequency (GHz). Allowed values: [‘Energy’, ‘Frequency’]

Description

The fluctuation dissipation theorem [1,2] relates the dynamic susceptibility to the scattering function

\(\left(1-e^{-\frac{E}{k_B T}}\right) S(\mathbf{q}, E) = \frac{1}{\pi} \chi'' (\mathbf{q}, E)\)

where \(E\) is the energy transfer to the system. The algorithm assumes that the y axis of the input workspace contains the scattering function \(S\). The y axis of the output workspace will contain the dynamic susceptibility. The temperature is either extracted as the average of the values stored in the appropriate entry of the log attached to the workspace (user supplies the name of the entry) or user can pass a number for the temperature.

[1] S. W. Lovesey - Theory of Neutron Scattering from Condensed Matter, vol 1

[2] I. A. Zaliznyak and S. H. Lee - Magnetic Neutron Scattering in “Modern techniques for characterizing magnetic materials”

Usage

Example - Run Applied Detailed Balance

ws = CreateWorkspace(DataX='-5,-4,-3,-2,-1,0,1,2,3,4,5',DataY='2,2,2,2,2,2,2,2,2,2',DataE='1,1,1,1,1,1,1,1,1,1',UnitX='DeltaE')
ows = ApplyDetailedBalance(InputWorkspace='ws',OutputWorkspace='ows',Temperature='100', OutputUnits='Frequency')

print("The Y values in the Output Workspace are")
print(ows.readY(0)[0:5])
print(ows.readY(0)[5:10])

Output:

The Y values in the Output Workspace are
[-4.30861792 -3.14812682 -2.11478496 -1.19466121 -0.37535083]
[ 0.35419179  1.00380206  1.58223777  2.09729717  2.55592407]

Categories: AlgorithmIndex | Inelastic\Corrections

Source

C++ header: ApplyDetailedBalance.h (last modified: 2021-03-31)

C++ source: ApplyDetailedBalance.cpp (last modified: 2021-03-31)