Filing peaked at 94 records in 2018 and fell to 41 by the 2022 midpoint, continuing downward since. Part of that decline is real: the core detector architectures covered by this search string, including solid-state neutron detectors and standard X-ray imaging arrays, were heavily claimed in the years following the helium-3 supply shortage that drove much of the earlier filing surge. Part of it is measurement artefact, since publication typically lags actual filing by around 18 months, so the last one to two years in any such dataset will always look thinner than they eventually turn out to be. Anyone using this trend to judge whether the field is still active should wait for a later data refresh before drawing firm conclusions about the most recent years.

The search terms used to build this dataset explicitly include helium-3 alternative language, reflecting how much of the field's recent innovation has been driven by the well-known helium-3 supply shortage. Solid-state detector designs, like the boron- or lithium-based pillar structures described in patents such as US8558188B2, are one documented route that avoids helium-3 gas entirely while targeting high thermal neutron detection efficiency and strong gamma discrimination. Scintillator-based and semiconductor-material approaches, visible in the dataset's overlap with G01N and H01L classifications, are the other major documented route. Which one is preferable depends on the application: solid-state designs suit compact or portable instruments, while scintillator arrays tend to dominate large-format imaging panels.

This dataset's assignee ranking is concentrated among a mix of specialty detector manufacturers, large diversified electronics firms, security-screening companies and university research groups, with the strongest documented collaboration being a 28-record pairing between a materials manufacturer and a university partner. Rather than naming a single dominant leader, the pattern here is one of several parallel clusters: medical-imaging assignees, security-screening assignees, and academic-industrial material-science pairings each hold meaningful but non-overlapping shares of the claim space. All tracked assignees show zero filings in the most recent year, which is a strong signal to recheck this ranking after publication lag clears rather than treating it as final.

US8558188B2, assigned to Lawrence Livermore National Security, LLC, claims a specific solid-state thermal neutron detector structure: a p+ region and an n+ region on either side of a thinned intrinsic layer, with pillars etched into one doped region and filled with neutron-sensitive material, engineered to hit detection efficiency above 50% and gamma discrimination above 1.0E4 simultaneously. It does not block neutron detection generally, nor does it block gas-filled or scintillator-based alternatives. It specifically constrains anyone building a pillar-etched solid-state detector aiming at those same numeric efficiency and discrimination thresholds using a similar p+/intrinsic/n+ layer arrangement.

The classification data shows the heaviest concentration sits in G01T detector-hardware claims, with meaningfully lighter coverage at the edges where G01T overlaps C09K materials and H04N imaging-communication codes. Readout electronics for gamma discrimination, pulse-shape discrimination circuits, and large-format imaging-array pixel readout all show comparatively thinner claim density relative to core detector-architecture patents. A first claim in one of these branches would typically pair a specific material or circuit choice with a stated, measurable performance threshold — efficiency, resolution or discrimination ratio — following the pattern set by the most-cited patents in this dataset rather than claiming the detector architecture broadly.