leonarski_fandClaude Opus 5
7bbf072ad2
The error model's systematic term b is identified only by the spread of I^2/sigma^2 across the intensity bins the fit uses, and those bins hold equal COUNTS. So when fewer reflections are strong than one bin holds - a sixteenth of the pool - the top bin's median sits at an intensity where b cannot be measured at all, and the fit hands it the bins' own noise-selection slope instead: sorting noise by its group mean squared makes dev2 rise with I2 even when the true b is zero, and with no strong bin to out-vote it that slope becomes b. The result is not a small error. On the battery's weakest crystal, 2.2% of whose fulls reach I/sigma 2, the fit returns b = 5.6 - sigma -> 2*I at the strong end - and since corrected_sigma applies b at the GROUP MEAN, sigma^2 = a*sigma^2 + (b*mean)^2 is a per-group constant that caps merged |I/sigma| at sqrt(n)/b. The cap lands at 2.3, so 98.8% of merged reflections come out below 3 and the reported ISa is 0.50, on data whose CC1/2 is 99.3% at multiplicity 18.7. XDS fits 6.13 from the same images. Feeding XDS's own scaled observations through this estimator returns 0.84, so it is the estimator and not the data; synthetic data built with b = 0 and 1.8% strong reproduces a = 0.51 and ISa 0.50 to two digits, and recovers the truth as soon as the strong fraction passes one bin. So refuse to report what was not measured: when the strongest bin's own (I/sigma)^2 is below 4, fit a alone, hold b at zero and warn that ISa is unmeasured. The threshold is not delicate - the two crystals it fires on sit at 0.22 and 0.84 while the next crystal in the battery is at 31.7 and a healthy one at 342, so anything from 4 to 25 selects the same two. Full 38-crystal rotation battery: it fires on those two crystals and no others, and space groups are unchanged at 35/38. Dropping the spurious term also fixes the merge weights it had been distorting - on the worse of the two, R_meas 19.2 -> 13.6%, low-resolution R_meas 13.8 -> 6.9% against XDS's 14.1%, CC1/2 98.7 -> 100.0%, with chi2 1.11 on the one-parameter model. Two further crystals move slightly; the guard never fires on either, and they are marginal crystals of the kind whose two-pass branch any recompilation can shift. This reports the parameter as unmeasured rather than clamping it to something plausible, because the honest statement is that the data do not reach far enough for a systematic error to be seen - not that there is none. 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.