DataDifference in Reflectometry

[Owen Arnold]

Running the old and new algorithms/scripts produce identical results:

config['default.instrument'] = 'INTER'
LoadISISNexus(Filename='13463', OutputWorkspace='13463')
LoadISISNexus(Filename='13464', OutputWorkspace='13464')
run = LoadISISNexus(Filename='13460', OutputWorkspace='13460')
 
incidentAngle = 0.7
 
trans_ws_new = CreateTransmissionWorkspaceAuto(Params= 0.02,
                                           StartOverlap=10.0, 
                                           EndOverlap=12.0, 
                                           FirstTransmissionRun='13463', 
                                           SecondTransmissionRun='13464')



IvsQ_new, IvsLam_new, thetaOut_new= ReflectometryReductionOneAuto(InputWorkspace=run, ThetaIn=incidentAngle, FirstTransmissionRun=trans_ws_new)

from isis_reflectometry.quick import quick
IvsLam, IvsQ, thetaOut=quick(run, trans=trans_ws_new, theta=incidentAngle)


plotSpectrum([IvsQ_new, IvsQ], 0)

Doing the same thing in the reflectometry gui produces plots that are scaled differently. We need to understand what is happening here.

[Owen Arnold]

This screenshot shows that the error is probably induced via the way that the refl_gui script uses quick (green line). All other schenarios are in agreement (RRO via the GUI, RRO via the script, and quick via the script)

[Owen Arnold]

refs #9797. ThetaIn missing.

ThetaIn missing as input to RRO algorithm. The algorithm tries to determine the ThetaIn, but this won't work correctly if the detectors are also out of alignment. Adding the known ThetaIn fixes the issue.

Changeset: 3663d1814af743abb3af2a09b488370604ec27b9

[Owen Arnold]

Tester

• Open MantidPlot
• On the Interfaces menu select Reflectometry->ISIS Reflectometry
• When the interface opens, go to File and Open Table. Load the attached .tbl file
• Set the instrument on the interface to 'INTER'
• On the options menu of the GUI, set the interface (Options -> Refl Gui Options) check the box 'Use ReflectometryReductionOneAutoAlgorithm'.
• Hit the process button
• Rename 13460_IvsQ to 13460_IvsQ_new
• On the options, now unselect the 'Use ReflectometryReductionOneAutoAlgorithm' option
• Hit the process button
• Plot 13460_IvsQ to 13460_IvsQ_new (all spectrum) using Plot Spectrum.
• The curves produced should be almost identical (LogX, LogY works best)

[Owen Arnold]

This is done, pending #9785 to be tested so that I can mark this as complete

[Peter Parker]

Merge remote-tracking branch 'origin/feature/9797_fix_data_difference'

Full changeset: ​bdcf4f843b0229806e9e661766c081c18158f254

[Peter Parker]

The plots were closely overlapped.

[Stuart Campbell]

This ticket has been transferred to github issue ​10639