The rotation per-image mosaicity was ~3x too small (0.045 vs the true 0.13deg),
which crippled the partiality model and capped per-observation precision: it
predicted reflections on too few frames and over-peaked the rocking partiality,
so the rot3d-combined fulls were ~1.7x noisier than XDS's, the integration
bottleneck behind the jungfraujoch-vs-XDS ISa gap.
Two root causes, both fixed:
- CalcMosaicityXDS (Kabsch-2010 MLE) searched each spot's exact-Bragg phi only
within +-wedge (the 0.2deg oscillation). Reflections recorded at larger rocking
offset - the tail that defines the mosaic width - fell outside and were dropped,
truncating the tau distribution so the MLE underestimated ~2x. Widen the search
window to wedge+0.8deg; the MLE then converges to the true 0.13deg (and is
insensitive to widening further, since it weights by the recorded fraction).
- ScaleOnTheFly then re-refined the mosaicity from the intensity residual, which
is degenerate with the per-image scale G and collapses it toward its floor.
Trust the (now correct) indexing mosaicity and keep it fixed during scaling.
With the correct mosaicity, --capture-uncertainty (which down-weights the
over-extrapolated under-captured fulls) now pays off strongly, so default it ON
(1.0) for the rot3d combine; it stays off for non-rot3d. Together on the HEWL
rotation crystal: ISa 10.7 -> 19.1, and anomalous peak height vs XDS goes from
52% to ~78% (CL_CL 1.92x -> 1.29x). This reaches XDS's own published-correction
ceiling (DECAY+ABSORP+MODPIX ~= 19.6); the remaining gap to its quoted ISa 28 is
the I->inf extrapolation. No effect on the stills path (rotation-only code).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
leonarski_fandClaude Opus 4.8
82b8a9752c