ReflectometryReductionOne should correct positions

[Owen Arnold]

This is a simple principle: If you have known incident theta angle, and a reflection condition, i.e. theta_in == theta_out, then you can correct the detector positions accordingly.

I've avoided this problem so far, because for the multi-detector case you may have a number of 'masked' pixels, in which case there is no easily identifiable vertical centre position.

Having had a chat with Tim about this, we've agreed that if you have a range of pixels in the processing instructions, you should find the centre location and use that, along with the theta position to correct location. Corrections should still be optional.

Changes should apply to ReflectometryReductionOne, ReflectometryReductionOneAuto, CreateTransmissionWorkspace and CreateTransmissionWorkspaceAuto.

As part of this. We should also update ReflectometryReductionOne (following #9401) to calculate The OuptutTheta value if Multiple Spectrum numbers are given instead of component names.

[Owen Arnold]

This can be fixed around lines 308 of ReflectometryReductionOne.cpp. Instead of knowing the exact components to use in the multidetector case, we must determine them from the ProcessingCommands. Should be relatively easy given that we know the Reference frame and the detector positions corresponding to these workspace indexes.

[Owen Arnold]

This is complex enough that the functionality to do it is deserving of it's own algorithm. I'm going to create a new blocking ticket to do this first.

[Owen Arnold]

refs #9184. Test point detector position correction.

Changeset: d0d12dd1ffc5e0c102d319b21acfde55f23527b2

[Owen Arnold]

refs #9184. Employ and test position correction multidetector

Changeset: 759476e7b68a2c30968ca8a03ffb2ebc4dc2bec7

[Owen Arnold]

Tester:

Unit tests demonstrate this new functionality behaving properly. To manually test...

1) Run the following. It prints out the x,y,z of the linear detector of the corrected component. This is taken from an existing system test. The z-offset is correct.

from mantid.simpleapi import *


class ReflectometryISIS():
    

    def get_workspace_name(self):
        return "POLREF4699"
    
    def runTest(self):
        
        workspace_name = self.get_workspace_name()
        workspace_nexus_file = workspace_name + ".nxs"
        
        PIX=1.1E-3 #m
        SC=75
        avgDB=29
        Load(Filename=workspace_nexus_file,OutputWorkspace=workspace_name)
        X=mtd[workspace_name]
        X = ConvertUnits(InputWorkspace=X,Target="Wavelength",AlignBins="1")
        # Reference intensity to normalise by
        CropWorkspace(InputWorkspace=X,OutputWorkspace='Io',XMin=0.8,XMax=14.5,StartWorkspaceIndex=2,EndWorkspaceIndex=2)
        # Crop out transmission and noisy data 
        CropWorkspace(InputWorkspace=X,OutputWorkspace='D',XMin=0.8,XMax=14.5,StartWorkspaceIndex=3)
        Io=mtd['Io']
        D=mtd['D']
    
        # Peform the normaisation step
        Divide(LHSWorkspace=D,RHSWorkspace=Io,OutputWorkspace='I',
               AllowDifferentNumberSpectra='1',ClearRHSWorkspace='1')
        I=mtd['I'][0]
        
        # Automatically determine the SC and averageDB 
        FindReflectometryLines(InputWorkspace=I, StartWavelength=10, OutputWorkspace='spectrum_numbers')
        spectrum_table = mtd['spectrum_numbers']
        
        x = CloneWorkspace(I)
        y = CloneWorkspace(I)
        
        # Move the detector so that the detector channel matching the reflected beam is at 0,0
        MoveInstrumentComponent(Workspace=y,ComponentName="lineardetector",X=0,Y=0,Z=-PIX*( (SC-avgDB)/2.0 +avgDB) )
        
        
        return x, y
        
   
# Specialisation for testing POLREF
z = ReflectometryISIS()
x, y = z.runTest()

print y.getInstrument().getComponentByName('lineardetector').getPos()

2) Now run ReflectometryReductionOneAuto below. This handles the same problem but the correction is made in the algorithm. The Z-offset should be similar to (1)

from mantid.simpleapi import *


class ReflectometryISIS():
    
    def get_workspace_name(self):
        return "POLREF4699"
    
    def runTest(self):
        
        workspace_name = self.get_workspace_name()
        workspace_nexus_file = workspace_name + ".nxs"
        ws = Load(workspace_nexus_file)
        
        out_lam, out_q, s = ReflectometryReductionOneAuto(ws, CorrectDetectorPositions=True, AnalysisMode='MultiDetectorAnalysis', ProcessingInstructions='73', ThetaIn=0.49/2)
        return out_lam, out_q

z = ReflectometryISIS()
x, y = z.runTest()

print y[0].getInstrument().getComponentByName('lineardetector').getPos()

[Owen Arnold]

refs #9184. Merge branch 'master'

Merge branch 'master' into feature/9184_correct_positions_rro

Conflicts:

Code/Mantid/Framework/Algorithms/src/ReflectometryReductionOne.cpp

Changeset: 396ba4e249e42331b914f8e34b19b9e77de98988

[Martyn Gigg]

There is a cppcheck error in ReflectometryReductionOne: ​http://builds.mantidproject.org/job/cppcheck_develop/430/cppcheckResult/

[Owen Arnold]

refs #9184. Unused var removed.

Changeset: 10ad21ac02469ab949e266094c4e6d5339477324

[Keith Brown]

Scripts return the same values to 2 decimal places

[Keith Brown]

Merge remote-tracking branch 'origin/feature/9184_correct_positions_rro'

Full changeset: ​59a5abba7f9326fde8702242fc61387ad7b52b86

[Stuart Campbell]

This ticket has been transferred to github issue ​10027