Search

The NEON experiment, situated at the Hanbit Nuclear Power Plant, is designed to observe coherent neutrinonucleus scattering (CE{\nu}NS) and search for dark sector particle such as axion-like particles (ALPs). Using six NaI(Tl) detector modules, data were collected during both reactor-on and reactor-off periods between April 2022 and June 2023, providing a total exposure of 1596 kg{\cdot}days and 1467 kg{\cdot}days, respectively. The search for ALPs leverages the difference between reactor-on and reactor-off datasets. A thorough understanding of time-dependent backgrounds, including cosmogenic activation and seasonal variations of radon contamination, is essential to the analysis. This paper presents detailed modeling of these backgrounds, identifying their contributions across different energy ranges and detector modules. Systematic uncertainties arising from energy resolution, background shape, and rate variations are considered in the final analysis. The results provide insights into the future potential of ALP searches in short-baseline reactor experiments and demonstrate the efficacy of background reduction techniques in the NEON experiment., Comment: We have included information on the time-dependent background model for the NEON experiment in this manuscript. The manuscript will be updated later with the corrected results from the ALP search

A new experiment, which is called as NEOS (NEutrino Oscillation at Short baseline), is proposed on the site of Hanbit reactors at Yonggwang, South Korea, to investigate a reactor antineutrino anomaly. A homogeneous NEOS detector having a 1000-L target volume has been constructed and deployed at the tendon gallery ~25 m away from the reactor core. A linear alkylbenzene (LAB) is used as a main base solvent of the NEOS detector. Furthermore, a di-isopropylnaphthalene (DIN) is added to improve the light output and pulse shape discrimination (PSD) ability. The ratio of LAB to DIN is 90:10. PPO (3 g/L) and bis-MSB (30 mg/L) are dissolved to formulate the mixture of LAB- and DIN-based liquid scintillator (LS). Then, ~0.5% gadolinium (Gd) is loaded into the LS by using the solvent-solvent extraction technique. In this paper, we report the characteristics of Gd-loaded LS (GdLS) for the NEOS detector and the handling during mass production.

A precision measurment of inclusive electron scattering cross sections was carried out at Jefferson Lab in the quasi-elastic region for ${^4}$He, ${^{12}}$C, ${^{56}}$Fe and ${^{208}}$Pb targets. Longitudinal ($R_{L}$) and transverse ($R_{T}$) response functions of nucleon were extracted in the momentum transfer range 0.55 GeV/c$\le$$|q|$$\le$1.0 GeV/c. To achieve the above goal, a NaI (Tl) calorimeter was used to distinguish good electrons from background including pions and low energy electrons rescattered from walls of the spectrometer magnets. Due to a large set of kinematics and changes in HV settings, a number of calibrations were performed for the NaI (Tl) detector. Corrections for a few blocks of NaI (Tl) with bad or no signal were applied. The resolution of NaI (Tl) detector after calibration reached $\frac{\delta E}{\sqrt{E}} \approx 3\%$ at E=1 GeV. The performance of NaI (Tl) detector was compared with a simulation.