T Abrahão, H Almazan, J C Dos Anjos, S Appel, J C Barriere, I Bekman, T J C Bezerra, L Bezrukov, E Blucher, C Bourgeois, C Buck, J Busenitz, A Cabrera, M Cerrada, E Chauveau, P Chimenti, O Corpace, J V Dawson, J F Du, Z Djurcic, A Etenko, H Furuta, I Gil-Botella, A Givaudan, H Gomez, M C Goodman, T Hara, J Haser, D Hellwig, A Hourlier, M Ishitsuka, J Jochum, C Jollet, K Kale, M Kaneda, M Karakac, T Kawasaki, E Kemp, D Kryn, M Kuze, T Lachenmaier, C E Lane, T Lasserre, D Lhuillier, H P Lima, M Lindner, J M LoSecco, B Lubsandorzhiev, J Maeda, C Mariani, J Maricic, J Martino, T Matsubara, G Mention, A Meregaglia, T Miletic, R Milincic, A Minotti, X Mougeot, D Navas-Nicolás, Y Nikitenko, P Novella, L Oberauer, M Obolensky, A Onillon, A Oralbaev, C Palomares, I M Pepe, L Perisse, G Pronost, J Reichenbacher, S Schönert, S Schoppmann, L Scola, R Sharankova, V Sibille, V Sinev, M Skorokhvatov, P Soldin, A Stahl, I Stancu, M R Stock, L F F Stokes, F Suekane, S Sukhotin, T Sumiyoshi, C Veyssiere, B Viaud, M Vivier, S Wagner, C Wiebusch, G Yang, F Yermia, Double Chooz Collaboration
Neutrino emission from nuclear reactors provides real-time insights into reactor power and fuel evolution, with potential applications in monitoring and nuclear safeguards. Following reactor shutdown, a low-intensity flux of "residual neutrinos" persists due to the decay of long-lived fission isotopes in the partially burnt fuel remaining within the reactor cores and in spent nuclear fuel stored in nearby cooling pools. The Double Chooz experiment at the Chooz B nuclear power plant in France achieved the first quantitative measurement of this residual flux based on 17.2 days of reactor-off data. In the energy range where the residual signal is most pronounced, the neutrino detector located 400 m from the cores recorded 106±18 neutrino candidate events (5.9σ significance). This measurement is in excellent agreement with the predicted value of 88±7 events derived from detailed reactor simulations modeling the decay activities of fission products and incorporating the best-available models of neutrino spectra.