Per isolated strong spot of the spot-width sample, second moments along and across its radius, with
the exact per-spot Jacobians (pixels per radian of 2theta and of the angle across the scattering
plane, from the geometry) and the sensor parallax fixed from physics (conversion depth exponential
with length L cos(psi), truncated at the thickness, smeared z tan(psi) along the ray's in-plane
direction). y = (m_rad - 1/12 - par_u) - (jr/jt)^2 (m_tan - 1/12 - par_v) is linear in
(2 jr tan theta)^2 with slope sigma^2; fitted over eight equal-count 20%-trimmed bins, error from 200
seeded bootstrap re-draws inflated by the reduced chi^2, significant at z > 3. The pre-scan logs the
FWHM, its standard error, z and chi2 next to the bandwidth the run uses; nothing consumes it, so
output is unchanged.
The truncated-exponential depth variance moves into SensorAbsorption.h
(ConversionDepthVariance_um2), shared with the integrator's parallax_var_px2 (same arithmetic).
Catch2: a synthetic spot population painted with 0.45% FWHM bandwidth and 450 um Si parallax
recovers 0.449% (z 82); the same spots without bandwidth give 0.06% at z 0.7.
On the battery sets (67d49f base, estimate as logged): MicroMAX pink lyso 0.41% z 7.3, thau 0.42%
z 6.9, CHESS 7B2 9q41 0.36% z 14.6, ALS 8.2.1 8u0i 0.27% z 5.6; mono controls lyso_micromax_mono,
lyso_x06da_ref, 5mln and near misses 9z44, 7orr, lyso_x06da_5keV all below z 3.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D1G8gJVAy6gp1K5Dz3NE5C
