# Scientists detect nuclear reactor's ghostly afterglow for first time Antineutrinos from shut-down reactors measured for the first time. - **Source:** [Latest Science News -- ScienceDaily](https://brifing.si/source/0eef8637-6c5b-4e79-8f5b-6c9c6b36cf16) - **Published:** 2026-08-14 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/70e8323b-1a3d-46a2-b69a-6320396328f2 ## Radioactive processes continue even after reactor shutdown Long-lived radioactive fission products in nuclear reactor cores continue decaying for months or years after shutdown, emitting antineutrinos - among the lightest and most elusive particles in the universe. These ghostly particles can pass through reactor shielding with minimal interaction, making them extremely challenging to detect. ## Double Chooz collaboration makes historic discovery Researchers led by Anthony Onillon and Thierry Lasserre from Germany's Max-Planck-Institut für Kernphysik have measured antineutrino emissions from a shut-down nuclear reactor for the first time, as published in Physical Review Letters. This breakthrough opens new possibilities for monitoring nuclear reactors even when they're not operating. ## Experiment conducted at Chooz nuclear plant in France The measurement took place at the Chooz nuclear power plant in northern France. The Double Chooz detector, located about 400 meters from two reactor cores underground, contains over 30 cubic meters of liquid scintillator that produces tiny light flashes when antineutrinos interact within it. ## Special techniques developed to detect elusive particles Antineutrinos rarely interact with matter, but when they do in the Double-Chooz detector, they produce a characteristic double-light signal distinguishable from background events. This unique signature allows scientists to identify antineutrinos originating from nuclear reactors with unprecedented precision. ## 100 antineutrino candidates detected during 17-day observation Scientists analyzed 17.2 days of data collected while both reactor units were completely shut down. During this period, the detector recorded approximately 100 antineutrino candidate events linked to residual radioactivity in reactor cores and nearby spent-fuel cooling pools. ## Results closely match detailed simulations The detected signal closely matched sophisticated simulations accounting for remaining nuclear fuel inventory and decay of long-lived fission products. This provides the first direct experimental confirmation of predictions about antineutrino emissions from shut-down reactors and spent nuclear fuel. ## New era for nuclear safety monitoring begins Years of development by the Double Chooz collaboration resulted in ultra-low background levels and refined analysis techniques capable of detecting the extremely weak antineutrino signal from inactive reactors. This technology could prove valuable for independently verifying reactor status and tracking spent-fuel inventories. ## New chapter opens in neutrino physics Originally built to study neutrino oscillations, Double Chooz played a key role in measuring the neutrino mixing angle θ13 - a fundamental parameter describing how neutrinos change types. Now, it has added another first to its scientific record by detecting the faint neutrino glow persisting after reactor shutdown. ## Sources covering this story - https://www.sciencedaily.com/releases/2026/08/260814011036.htm — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._