The integrator's r1 disk and r2..r3 background ring are fixed in pixels and chosen from spots near
the beam. On small-molecule data at 20-25 keV a spot's standard deviation grows from ~1 px near the
beam to ~5 px at the edge (radially from parallax/obliquity, tangentially from the crystal's
azimuthal spread), so the r1 = 4 disk holds a quarter of the flux there, the background ring a third
of it, and the in-disk second moments the Gaussian is built from saturate near r1^2/4. On top of
that, the profile/summation runaway guard sent 20-30% of these reflections - the strong, wide ones -
back to the truncated r1 box sum.
- SpotFootprint: every pre-scan spot (width frames) is measured with a window that follows it
(3 sigma, iterated, re-centred), radially and tangentially; the medians per distance-from-beam bin
become BraggIntegrationSettings::Footprint. Installed only where some bin outgrows r1, and on the
adaptive side like the radius (pre-pass without; the starvation guard falls back to the settings
without it).
- BraggStencil: where 3 sigma > r1 the background ring starts at 3 sigma along and across the radius,
the summation region is the r1 disk plus the 3-sigma footprint ellipse (so the guard's fallback is a
complete intensity), and the per-reflection Gaussian takes the footprint widths. Compact spots keep
the stencil bit for bit. Both engines build it from the same header.
SHELXL against COD (R1 / fixed-XDS-model R1(F)): citric acid .101/.230 -> .077/.055, HEPES
.070/.179 -> .048/.050, aspirin 20 keV .059/.070 -> .052/.061, aspirin 25 keV unchanged, L-cystine
25 keV unchanged (.145 -> .144).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
leonarski_fandClaude Opus 5.5
8394b5988d