SetBeam to prevent invalid bounding box error when running AddAbsorptionWeightedPathLengths in ISIS SX reduction classes

[RichardWaiteSTFC]

Description of work

Bounding box error comes from AddAbsorptionWeightedPathLengths algorithm - this sets the beam size to something sensible for each instrument such that the bounding box calculation is correct.

The error is thrown here

mantid/Framework/Geometry/inc/MantidGeometry/Objects/BoundingBox.h

Line 67 in 005e651

error << "Error creating bounding box, inconsistent values given:\n"

I think the max > min comparison is invalid (sometimes - not all the time!) due to to floating point precision? But this doesn't happen when a sensible beam size is used.

There is no associated issue.

Report to: SXD (found during beta testing with SXD scientists)

To test:

(1) Run this script

from mantid.simpleapi import *
from Diffraction.single_crystal.sxd import SXD
from Diffraction.single_crystal.base_sx import PEAK_TYPE

runno = 34768
ws = Load(Filename=f'SXD{runno}.raw', OutputWorkspace=f'SXD{runno}')

SetSample(
    ws,
    Geometry={'Shape': 'Cylinder', 'Height': 0.4, 'Radius': 0.065, 'Center': [0.,0.,0.]},
    Material={"ChemicalFormula": "C2 H4", "SampleNumberDensity": 0.02, "NumberDensityUnit": "Formula Units"},
)
# make peaks workspace and set intensity to 1
peaks = FindSXPeaksConvolve(InputWorkspace=ws, PeaksWorkspace=ws.name() + '_peaks', 
                            ThresholdIoverSigma=50, NRows=3, NCols=3, GetNBinsFromBackToBackParams=True, 
                            NFWHM=3, PeakFindingStrategy="IOverSigma")

sxd = SXD()
sxd.set_ws(runno, ws)
sxd.set_peaks(runno, peaks, PEAK_TYPE.FOUND)
sxd.calc_absorption_weighted_path_lengths(PEAK_TYPE.FOUND)

(2) Check that tbar column is populated in peak table

This does not require release notes because bug in feature added in this release

---

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[SilkeSchomann]

Code looks good and the script output is as expected 👍🏻