leonarski_fandClaude Opus 5
ecb0571d8d
The centroid was a first moment of the RAW counts over the signal disk, so it weighted signal plus background. The background is flat over a disk centred on the PREDICTION, which makes its own centroid the prediction exactly: it adds nothing to the displacement and everything to the denominator, and the measured offset comes out shrunk by I/(I + n*bkg). That factor is worst where the background dominates the signal, which is at high resolution - so the one consumer of this quantity, the geometry post-refinement, fits the beam centre and the detector distance on displacements that are systematically too small, by a factor that varies with resolution. An estimator whose bias depends on the very coordinate it is correcting. Subtracting a flat pedestal from a first moment is exact, and the background is not known until the ring has been read, so the positions of the pixels behind the intensity sum are accumulated alongside it and the correction is applied afterwards: sum(x*(px-bkg)) = sum(x*px) - bkg*sum(x). Both engines, identically. Where nothing rises above background there is no signal centroid to compute and the raw one is kept. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EFEJG6WBQv8th4UJFNe53N
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.