The monitor fitted each batch's relative-B on SINGLE observations -
ln(I_ref/I_obs) regressed on s^2, weighted by (I_obs/sigma)^2, with the
logarithm requiring I_obs > 0. The observation therefore sits in the
response and in its own weight, and the positivity requirement keeps only
the upward half of the noise, so the estimate is biased downwards wherever
I/sigma approaches 1 and is unbounded in the limit. Simulated: on a batch
with no relative-B at all and <I/sigma> = 0.3 it reads -28 A^2; on a batch
whose true relative-B is +30 A^2 it reads -29. The bias grows with dose,
so it inverts the answer on exactly the data the number exists for.
That is not a corner case. Re-measured on stored integrated intensities,
a 360 deg sweep obstructed over a 60 deg wedge - whose honest curve is flat
for 130 deg, dips over the wedge and comes back - printed a per-batch curve
saturated at -31.4 A^2 for twelve consecutive batches (the +-50 A^2 clamp
less the low-dose anchor, "no data here" reported as a measurement) under a
headline of -19 A^2 of radiation damage. A deliberately dosed dataset
printed -39 A^2 where the honest measurement is about +34: the one crystal
with real damage got the sign wrong. Eight of thirty-eight datasets
reported |dB| > 5 A^2 and their curves oscillate by tens of A^2.
So pool the observations into ten equal-occupancy resolution shells per
batch before taking the logarithm, and fit slope AND intercept over the
shell means, weighting each shell by its own pooled (I/sigma)^2. A shell
mean is well determined where a single observation is not, it admits
negative intensities, and it carries the I/sigma that says whether the
batch can be measured at all. The same simulations then reproduce the
truth to under 1 A^2 at every signal level. The intercept keeps a batch
that is merely dimmer than the run - an attenuated beam, a mis-fitted frame
scale - out of the damage number: a batch mis-scaled by 2x read +12 A^2 of
"damage" without it and +0.05 with it.
A batch whose shells are too weak to fit is now absent from the curve,
printed as "-", instead of pinned to the clamp. And the clamp itself is
now an argument of the solve rather than one shared constant: it guards
against divergence, and the correction keeps the bound it was tuned with,
but with the estimator fixed a heavily dosed crystal's honest relative-B
runs past it - the monitor pinned thirteen consecutive batches at +49 A^2,
which is the same defect in the other direction. The monitor is given room
a real relative-B cannot reach and drops any batch that lands on it anyway.
The shells are laid inside the range the run actually diffracted to,
not across the whole merged range: a resolution limit taken from another
program or left generous spends most of an equal-occupancy grid on noise
and leaves a batch with too few shells to fit at all - on the battery that
silenced three crystals outright and cost two of them nineteen batches of
thirty-six. Where the merged range already sits inside the signal the grid
is unchanged and so is every number.
The first->last headline
is reported only where a straight line explains at least half of the
curve's variance, or where the curve is flat to within a couple of A^2 and
the answer is simply "no damage"; otherwise there is no headline and the
report says the loss was not dose and points at the sweep-quality section.
The three shapes separate cleanly - progressive damage R^2 0.97, the
obstructed sweep 0.24, the clean control flat at +0.35 A^2. And the label
now follows the sign: damage fades the high-resolution intensity, so only a
positive change is dose, where before any |dB| > 5 was called damage.
Report-only throughout - the monitor never touches corr, and the per-batch
curve's only consumer beyond the report is a sweep-quality field no reader
reads; classification runs on the per-frame scale and CC, and is unmoved.
The decay correction's global slope and the opt-in per-batch relative-B
share this estimator and are left alone here: they fold into the scale, so
Full 38-crystal rotation battery, twice (the second confirming the shell
placement), against a clean baseline at the same base:
space groups unchanged at 35/38
merge metrics move on three crystals only - the same three whose two-pass
lattice search takes a different branch on nearly every arm run
this session, one of which moves its own R_meas by 1.5 points on
thread count alone
A report-only change ought to be bit-identical and this is not quite, which is
worth saying plainly: the three crystals that move are the known unstable ones
and no space group moves, but "identical except where nothing is ever identical"
is a weaker statement than "identical", and the residue has not been chased to
ground.
The three validation cases behave as they must:
60 deg beam-obstructed wedge, no decay -23.02, labelled damage, twelve
batches printing the clamp
-> NOT_A_TREND, curve within 3 A^2, the
two unmeasurable batches absent, and a
pointer to the sweep-quality section
genuine progressive damage -39.46, sign inverted
-> +94.50, monotone, corroborated by a
per-image CC that falls 0.608 -> 0.159
and never recovers
clean control +0.18 -> +0.76, flat within 1 A^2
Across the battery the report now names four crystals as radiation-damaged
instead of ten; the other three are the two lowest-energy datasets and the
pink-beam one, each showing a monotone rise of about ten square Angstroms.
Sweep-quality classification is untouched, and the coupling that was assumed to
exist does not: rad_damage_b_batch reaches it through one field that is written
and never read. Ranges and reasons are identical on 35 of 38, the three that
differ by one to seven frames are the same unstable crystals, and the census of
stretches called radiation damage is one before and one after.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 5
7ce47bd4d1
