0e23fd3ab9b40143631c31c9a0cb63abfd5d6adc
Two independent pieces in the same code path. The background-estimate variance was never propagated. A reflection's background comes from a finite ring of n_b pixels, so subtracting it adds var(B)/n_b per signal pixel - sqrt(1 + n_d/n_b) = 1.109 with the shipped stencil. Both engines omitted it, which is exactly the 1.11-1.19 gap measured between the off-ring scatter and the reported sigma. Three lines each; it affects every dataset, not only iced ones. The radial correction is new and OFF by default (--background-radial). The signal disk and the background ring are concentric, so for any background LINEAR in position <B>_ann == <B>_disk identically and a plane fit buys nothing; the leading error is the CURVATURE of the radial background, which on a sharp ice ring reaches +26 counts on a single reflection. Since every reflection uses the same stencil, that error is a fixed kernel over radial offset - one short dot product per reflection and no extra pixel reads. Validated on empty apertures before any C++: mean |bias| over 9 bands / 3 crystals 4.33 -> 0.79 counts with the scatter unchanged. Three things it cost a battery each to learn, all now in the code: - the radial curve must be accumulated from CLIPPED annulus pixels, inside the clip pass, or it carries neighbour tails and zingers (so it is inert under --integrator boxsum, which has no clip pass); - the GPU version was a 1.8x slowdown from atomicAdd contention on a small radial array - staged in shared memory per block it now costs nothing measurable; - it is battery-NEUTRAL as a default, because the reflections whose bias it fixes are the ones the ice handling already excludes. Hence off by default. CPU/GPU parity extended with two radial sections: 9002 assertions. Also fixes a latent French-Wilson quadrature collapse: j_max = I + 8 sigma on a fixed 400-point grid degenerates to a single cell once sigma >> 50 <I>, giving F = 0.1 sqrt(sigma) with sigmaF -> 0. Harmless today, but any sigma-inflation scheme detonates it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Jungfraujoch
Application to receive data from the PSI JUNGFRAU and EIGER detectors.
All documentation is now placed in docs/ subdirectory and for the current version hosted on Jungfraujoch Read The Docs page.
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