Abstract

We report new results from the neutrino elastic scattering observation with NaI (NEON) experiment in the search for light dark matter (LDM) using 2636 kg·days of NaI(Tl) exposure. The experiment employs an array of NaI(Tl) crystals with a total mass of 16.7 kg, located 23.7 m away from a 2.8 GW thermal power nuclear reactor. We investigated LDM produced by the of dark photons, a well-motivated mechanism generated by high-flux photons during reactor operation. The energy spectra collected during reactor-on and reactor-off periods were compared within the LDM signal region of 1–10 keV. No signal consistent with LDM interaction with electrons was observed, allowing us to set 90% confidence level exclusion limits on the dark matter-electron scattering cross section (σe) across dark matter masses ranging from 1 to 1000 keV/c2. Our results set a 90% confidence level upper limit of σe=3.17×10−35 cm2 for a dark matter mass of 100 keV/c2, marking the best laboratory result in this mass range. Additionally, our search extends the coverage of LDM below 100 keV/c2 for the first time, assuming the specific of dark photons. Published by the American Physical Society 2025