With a finite energy bandwidth each reflection is smeared RADIALLY by
sigma_bw = bandwidth_sigma * R_px (R_px = distance from the beam centre, so large
at high resolution): high-resolution spots become radial streaks. The isotropic
per-shell Gaussian both mis-weights them and clips the streak tail on the fixed
profile grid, losing intensity (biased low, noisy).
When a bandwidth is set, fit each reflection with a per-reflection Gaussian
elongated only along its radial direction - sigma^2_radial = sigma^2_intrinsic +
sigma_bw^2, sigma^2_tangential = sigma^2_intrinsic - on a grid grown to hold the
streak. Unlike an isotropic widening this adds no tangential background. It only
engages where the smear exceeds the intrinsic spot (high resolution); low/mid
resolution and monochromatic data (bandwidth 0, e.g. rotation) are untouched.
On the HEWL serial-stills jet (with the background sigma-clip) this lifts the
overall CC-vs-reference 52 -> 55% and the high-resolution I/sig (1.7 A 0.5 -> 1.4),
recovering the 2.0-2.5 A band, with CC1/2 preserved (the per-shot noise the wider
region adds is averaged out by the high serial multiplicity). Rotation ISa 19.1
unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
leonarski_fandClaude Opus 4.8
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