A powder calibration is run because the file's geometry is in doubt, so a fit that
quietly returns part of that file has answered nothing - and it is indistinguishable
from one that worked, down to the residual and the sigmas arranged around it.
On one of four LaB6 exposures of one detector the tilt came out at 2.93x its own
sigma, a hundredth under the significance gate, so it was declined and pinned - at the
master's hardcoded rot1 -0.08, rot2 -0.22 deg. That is eight times the tilt just
refused, on no evidence, and worth 10 px of PONI at 190 mm. rugnux printed it to four
decimal places, wrote the .poni, and exited 0.
Judge the result on provenance instead of on any residual: a geometry is a measurement
only if every parameter in it came from this data. Two ways out of the fits do not
qualify - a covariance that never conditioned, so the fit cannot say what it
determined, and a declined tilt pinned at a non-zero value from the file. A declined
tilt over a file stating no tilt still qualifies, because reporting no tilt is then
exactly what was measured; so does --no-refine-tilt, because a hold that was asked for
is a stated choice and not a silent substitution.
No single number separates the four. rms is 2.465 px against 1.44-1.64; the
significance of all four lies between 2.93 and 4.47, so the gate is nearly a coin flip
at these distances and moving it would only recalibrate on one population; and the
failed fit has the TIGHTEST parameter sigmas of the set, because pinning the tilt
removes the tilt/centre correlation that inflates a good fit's. The spot cross-check
reads 13.5 px against 0.98-2.66, but 10.4 px of that is the pinned tilt moving the
PONI - the same defect one step downstream, not independent evidence.
On a failure rugnux says so, writes no .poni - a PONI file states where the detector is
and has no field in which to say it does not know - writes the JSON with converged
false and the reason beside it, and exits non-zero. The re-binning pass now prefers a
converged refit over a non-converged one whatever its residual, so a tilt an earlier
pass measured is not what a later one gets pinned at.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 5
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