The score exists so beamline automation can engage a recovery protocol - a two-sweep collection,
a goniometer reorientation - with no human in the loop, so its canonical reading is fixed in one
place with nothing for a beamline to tune: engage at 0.5, do not below, and NO VALUE is a third
state that automation must treat as engage. The error costs are asymmetric - a false negative
leaves the data permanently short, a false positive costs minutes of beamtime - and a frame
nobody could measure must not be read as a frame measured safe.
The 0.5 is derived, not tuned: the score is monotone in the folded miss-angle, so any threshold
is a fold-angle gate, and 0.5 gates at fold <= 0.4040 * theta_max (verified root). Engaging on
any overlap at all would gate at fold < theta_max, whose perpendicular band alone spans
sin(theta_max) per row - 26% of orientation space at 15 deg - and unions over a frame's rows to
well over half of all mountings, degenerating the trigger into "always"; at 0.5 the residual
missed loss stays below half the cone.
Also correct the message-field comment that said the whole cone means "1 - cos theta_max of
every shell": an inner shell loses 1 - cos theta(d) at its own, smaller theta(d).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EFEJG6WBQv8th4UJFNe53N
leonarski_fandClaude Opus 5
bc3d693721