leonarski_fandClaude Opus 5
b22e1b6822
The mask drops a hexagonal-ice ring when its merged half-set CC1/2 falls a fixed 0.05 below its resolution shoulders. That margin is not a significance level: at the populations these rings actually have, 0.05 spans 1.1 to 7.3 sigma across firings, and a nominal Fisher-z error understates the real scatter of these heavy-tailed intensities by ~2.7x, so the null has to be measured rather than derived. Measured it with decoy bands - the identical ring/shoulder statistic evaluated at q positions carrying no ice ring - over the 37-crystal rotation battery: the gap's empirical null is p95 +0.032, p99 +0.095. So 0.05 sits near the 96th percentile, about 4% of ice-free bands clear it, and roughly half the 22 observed firings are indistinguishable from bands with no ice in them. The firing gaps are continuous, not bimodal, with 12 of 22 in [0.05, 0.10). Raise it to 0.10, the 99th percentile of that null. Firings 22 -> 10, crystals 12 -> 5, decoy false-positive rate 3.4% -> 0.8%. An independent check against XDS - which integrates through ice rings and so measures exactly what we delete - agrees: of the firings with a usable comparison, 9 true / 9 false becomes 7 true / 2 false. Battery: space groups 34 OK / 3 DIFF, the same three crystals as baseline, and no other discrete decision changes on 37/37. The heavily iced crystal keeps all five of its rings and its CC1/2 of 96.6; eight others recover 3.9-11.9% more unique reflections and up to 10.4 completeness points. Cost is CC1/2 -0.84 on one crystal, -0.35 on another, and agreement with XDS on the common reflections worse by a median 0.0004. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>