The acceptance test counted frames: a frame indexed if at least six of its spots
and a fifth of them fell on the lattice, and a run was refused if fewer than ten of
sixty sampled frames did. That test comes from serial crystallography, where each
image is its own experiment. A rotation sweep is one crystal and one orientation
matrix, and its frames are not independent of each other - so what the count mostly
measured was how many spots happen to land on a frame. A sweep carrying four spots
an image cannot reach six on three frames in four however right the lattice is, and
one such run found the correct cell and threw it away at three frames of sixty.
Count the spots instead: the fraction of all spots in the sampled frames that the
lattice explains, against what the same lattice explains when each frame's spots are
put at another frame's angle. Same lattice, same spots, same detector, same
refinement - only the claim that these spots were seen at these angles is removed.
That difference is the evidence, and it carries no spots-per-frame number anywhere,
so nothing has to be chosen for a crystal that diffracts weakly.
Measured on the sparse sweeps this was found with: ninety-three per cent of spots
explained against nought point nought by chance, and they merge to 0.58 A with the
deposited cell. Over a hundred and three datasets the chance level never exceeds
2.6 per cent and the smallest true margin is seventeen points; ninety-nine of them
are byte-identical, because only the refusal is decided this way - every rescue and
every arbiter still counts frames.
The floor on --min-indexed-spots goes from six to four. Six was the serial gate's
number; four is where a lattice stops being fitted by any three spots.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011GxZqDiFP3KqriBhNdcR56
leonarski_fandClaude Opus 5
926b68c658