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ConvertToMDMinMaxGlobal v1

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Summary

Calculate limits for ConvertToMD transformation, achievable on a spheric instrument.

See Also

ConvertToMD

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	An input Matrix Workspace (Workspace2D or Event workspace)
QDimensions	InOut	string	CopyToMD	String, describing MD-analysis modes, this algorithm can process. There are 3 modes currently available and described in details on*MD Transformation factory* page. The modes names are CopyToMD, |Q| and Q3D. Allowed values: [‘CopyToMD’, ‘Q3D’, ‘|Q|’]
dEAnalysisMode	InOut	string	Direct	You can analyze neutron energy transfer in Direct, Indirect or Elastic mode. The analysis mode has to correspond to experimental set up. Selecting inelastic mode increases the number of the target workspace dimensions by one. See MD Transformation factory for further details. Allowed values: [‘Elastic’, ‘Direct’, ‘Indirect’]
Q3DFrames	Input	string	AutoSelect	What will be the Q-dimensions of the output workspace in Q3D case? AutoSelect: Q by default, HKL if sample has a UB matrix. Q - momentum in inverse angstroms. Can be used for both laboratory or sample frame. HKL - reciprocal lattice units. Allowed values: [‘AutoSelect’, ‘Q’, ‘HKL’]
OtherDimensions	Input	str list		List(comma separated) of additional to Q and DeltaE variables which form additional (orthogonal) to Q dimensions in the target workspace (e.g. Temperature or Magnetic field). These variables had to be logged during experiment and the names of these variables have to coincide with the log names for the records of these variables in the source workspace.
MinValues	Output	dbl list
MaxValues	Output	dbl list

Description

The algorithm calculates the MinValues and MaxValues limits produced by the ConvertToMD v1 algorithm for three MD transformation possibilities namely CopyToMD, |Q| and Q3D. To estimate these limits the algorithm uses the following procedure:

• If QDimensions is CopyToMD the first value in MinValues is going to be the workspace minimum X coordinate, and the first value in MaxValues is going to be the maximum X coordinate

• If QDimensions is |Q| or Q3D, first we calculate the maximum momentum transfer, \(Q_{max}\). If dEAnalysisMode is Elastic, we convert to Momentum units, find the maximum value, and multiply by 2, since the maximum momentum transfer occurs when the incident beam and the scattered beam are anti-parallel.

• If dEAnalysisMode is Direct or Indirect, we convert to DeltaE units, find the minimum and maximum (\(dE_{min},dE_{max}\)), calculate to \(k_{i}\) and \(k_{f}\). The maximum momentum transfer is \(k_{i}+k_{f}\).

• If QDimensions is |Q|, the first value of the MinValues is 0, and the first value of MaxValues is \(Q_{max}\)

• If QDimensions is Q3D, and Q3DFrames is Q, the first three values of the MinValues are \(-Q_{max};-Q_{max};-Q_{max}\), and the first three values of MaxValues are \(Q_{max};Q_{max};Q_{max}\)

• If QDimensions is Q3D, and Q3DFrames is HKL the first three values of the MinValues are \(-Q_{max}\frac{a}{2\pi};-Q_{max}\frac{b}{2\pi};-Q_{max}\frac{c}{2\pi}\) and the first three values of MaxValues are \(Q_{max}\frac{a}{2\pi};Q_{max}\frac{b}{2\pi};Q_{max}\frac{c}{2\pi}\) [1]

• If QDimensions is |Q| or Q3D, and dEAnalysisMode is Elastic or Inelastic, the next value in MinValues is dEmin, and the next value in MaxValues is dEmax

• If any OtherDimensions are added, the last values in MinValues (MaxValues) are the minimum (maximum) of each of the sample log values selected

Notes

[1]

for HKL mode one needs to have an OrientedLattice attached to the sample.

Usage

Example - Find min-max values for |Q| transformation :

# Simulates Load of a workspace with all necessary parameters #################
detWS = CreateSimulationWorkspace(Instrument='MAR',BinParams=[-50,2,50],UnitX='DeltaE')
AddSampleLog(detWS,LogName='Ei',LogText='52.',LogType='Number');
# evaluate |Q| transformation limits
minn,maxx = ConvertToMDMinMaxGlobal(InputWorkspace=detWS,QDimensions='|Q|',dEAnalysisMode='Direct')
# Look at sample results:
print('MD workspace limits:')
print('|Q|_min: {0:10f}, dE_min: {1:10f}'.format(minn[0], minn[1]))
print('|Q|_max: {0:10f}, dE_max: {1:10f}'.format(maxx[0],maxx[1]))

Output:

MD workspace limits:
|Q|_min:   0.000000, dE_min: -50.000000
|Q|_max:  12.025534, dE_max:  50.000000

Example – Find min-max values for Q3D transformation, while converting TOF to energy transfer :

# Simulates Load of a workspace with all necessary parameters #################
detWS = CreateSimulationWorkspace(Instrument='MAR',BinParams=[20000,20,400000],UnitX='TOF')
AddSampleLog(detWS,LogName='Ei',LogText='52.',LogType='Number');

# evaluate Q3D transformation limits, which includes converting units
minn,maxx = ConvertToMDMinMaxGlobal(InputWorkspace=detWS,QDimensions='Q3D',dEAnalysisMode='Direct')
print('Min values::  Qx: {0:10f}, Qy: {1:10f}, Qz: {2:10f},  dE:{3:10f}'.format(minn[0],minn[1],minn[2],minn[3]))
print('Max values::  Qx: {0:10f}, Qy: {1:10f}, Qz: {2:10f},  dE:{3:10f}'.format(maxx[0],maxx[1],maxx[2],maxx[3]))

Output:

Min values::  Qx:  -5.401917, Qy:  -5.401917, Qz:  -5.401917,  dE: 51.680898
Max values::  Qx:   5.401917, Qy:   5.401917, Qz:   5.401917,  dE: 51.999462

Example – Finding min-max values for CopyToMD transformation uses the source workspace limits :

# Simulates Load of a workspace with all necessary parameters #################
detWS = CreateSimulationWorkspace(Instrument='MAR',BinParams=[200,2,20000],UnitX='TOF')
AddSampleLog(detWS,LogName='Ei',LogText='52.',LogType='Number');
minn,maxx = ConvertToMDMinMaxGlobal(InputWorkspace=detWS,QDimensions='CopyToMD',dEAnalysisMode='Direct',OtherDimensions='Ei')
# Look at sample results:
print('MD workspace limits:')
print('TOF_min: {0:10f}, Ei_min: {1:10f}'.format(minn[0],minn[1]))
print('TOF_max: {0:10f}, Ei_max: {1:10f}'.format(maxx[0],maxx[1]))

Output:

MD workspace limits:
TOF_min: 200.000000, Ei_min:  52.000000
TOF_max: 20000.000000, Ei_max:  52.000000

Categories: AlgorithmIndex | MDAlgorithms\Creation

Source

C++ header: ConvertToMDMinMaxGlobal.h

C++ source: ConvertToMDMinMaxGlobal.cpp