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ApplyInstrumentToPeaks v1¶

Summary ¶

Update the instrument attached to peaks within a PeaksWorkspace to match the one provided or the one attached to the input workspace while keeping detectorID and TOF unchanged

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	PeaksWorkspace	Mandatory	Input peaks workspace.
InstrumentWorkspace	Input	Workspace		Workspace from which the instrument will be copied from. If none is provided then the instrument on the input workspace is used.
OutputWorkspace	Output	PeaksWorkspace	Mandatory	Output peaks workspace.

ApplyInstrumentToPeaks will update the instrument contained within peaks of a PeaksWorkspace. It will keep the same detector ID and TOF but recalculate the detector positions and therefore the Q-vectors.

The issue this is trying to address is that the instrument in the PeaksWorkspace can be different to the instrument within the peaks and when the instrument of the PeaksWorkspace is modified (by MoveInstrumentComponent, RotateInstrumentComponent, LoadIsawDetCal, etc) then instrument in the peaks is not updated.

If a workspace is provided to the InstrumentWorkspace property then the instrument from that workspace will be used, otherwise the instrument in the InputWorkspace will be used.

Usage ¶

Example

First create a peaks workspace with 3 peaks with L1 == L2 == 1

ws = CreateSampleWorkspace(NumBanks=3, BankPixelWidth=1)
MoveInstrumentComponent(ws, ComponentName='moderator', RelativePosition=False, X=0, Y=0, Z=-1)
MoveInstrumentComponent(ws, ComponentName='bank1', RelativePosition=False, X=1, Y=0, Z=0) # θ=90, ϕ=0
MoveInstrumentComponent(ws, ComponentName='bank2', RelativePosition=False, X=0, Y=1, Z=0) # θ=90, ϕ=90
MoveInstrumentComponent(ws, ComponentName='bank3', RelativePosition=False, X=0.5, Y=0.5, Z=np.sqrt(2)/2) # θ=45, ϕ=45
peaks = CreatePeaksWorkspace(ws, NumberOfPeaks=0)

AddPeak(peaks, ws, TOF=10000, DetectorID=1) # θ=90, ϕ=0
AddPeak(peaks, ws, TOF=5000, DetectorID=2) # θ=90, ϕ=90
AddPeak(peaks, ws, TOF=1234, DetectorID=3) # θ=45, ϕ=45

for n in range(peaks.getNumberPeaks()):
    print("DetID={DetID} TOF={TOF:.1f}μs λ={Wavelength:.4f}Å Qsample={QSample}".format(**peaks.row(n)))

DetID=1 TOF=10000.0μs λ=19.7802Å Qsample=[-0.317651,0,0.317651]
DetID=2 TOF=5000.0μs λ=9.8901Å Qsample=[0,-0.635301,0.635301]
DetID=3 TOF=1234.0μs λ=2.4409Å Qsample=[-1.28708,-1.28708,0.753953]

Now move source and detectors so L1 == L2 == 2. When you look at the peaks nothing has been updated.

MoveInstrumentComponent(peaks, ComponentName='moderator', RelativePosition=False, X=0, Y=0, Z=-2)
MoveInstrumentComponent(peaks, ComponentName='bank1', RelativePosition=False, X=2, Y=0, Z=0)
MoveInstrumentComponent(peaks, ComponentName='bank2', RelativePosition=False, X=0, Y=2, Z=0)
MoveInstrumentComponent(peaks, ComponentName='bank3', RelativePosition=False, X=1, Y=1, Z=np.sqrt(2))

for n in range(peaks.getNumberPeaks()):
    print("DetID={DetID} TOF={TOF:.1f}μs λ={Wavelength:.4f}Å Qsample={QSample}".format(**peaks.row(n)))

DetID=1 TOF=10000.0μs λ=19.7802Å Qsample=[-0.317651,0,0.317651]
DetID=2 TOF=5000.0μs λ=9.8901Å Qsample=[0,-0.635301,0.635301]
DetID=3 TOF=1234.0μs λ=2.4409Å Qsample=[-1.28708,-1.28708,0.753953]

So we apply this algorithm and the peaks are updated, the wavelength is halved and the q-vector doubled as expected while keeping the same detector ID and TOF.

peaks = ApplyInstrumentToPeaks(peaks)

for n in range(peaks.getNumberPeaks()):
    print("DetID={DetID} TOF={TOF:.1f}μs λ={Wavelength:.4f}Å Qsample={QSample}".format(**peaks.row(n)))

DetID=1 TOF=10000.0μs λ=9.8901Å Qsample=[-0.635301,0,0.635301]
DetID=2 TOF=5000.0μs λ=4.9450Å Qsample=[0,-1.2706,1.2706]
DetID=3 TOF=1234.0μs λ=1.2204Å Qsample=[-2.57415,-2.57415,1.50791]

Categories: AlgorithmIndex | Crystal\Peaks