arXiv subjects

S. G. Yoon

Publications and source records attributed to S. G. Yoon.

8 recordsLinked to original sources

arXiv2026

Scintillation response of cryogenic CsI to few-keV and sub-keV nuclear recoils

Monochromatic neutron emissions from photonuclear sources $^{88}$Y/Be and $^{124}$Sb/Be are employed to obtain the response of pure (undoped) cesium iodide at 80 K. The use of a low-noise, high-quantum-efficiency avalanche photodiode in combination with a novel waveshifter results in a 70 eV analysis threshold. This reach allows to observe signals from sub-keV nuclear recoils originating in neutron scattering. The extracted quenching factor drops much faster towards low energy than the extrapolation of a model developed for room-temperature CsI[Na]. We comment on the impact of our measurement on planned use of cryogenic CsI in neutrino physics and dark matter experiments.

physics.ins-det↗

arXiv2026

Coherent Elastic Neutrino-Nucleus Scattering at the Japan Proton Accelerator Research Complex

The Japan Proton Accelerator Research Complex (J-PARC) currently delivers a 1 MW, 3 GeV proton beam to the Materials and Life Science Experimental Facility (MLF). Power is expected to increase to 1.3 MW, driven by the needs of Hyper-Kamiokande. As a result, the MLF presently provides the highest neutron yield of any spallation source, while potentially holding the best current and foreseeable conditions for Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS) experimentation. We explore this potential, using as examples detector technologies presently funded for construction and under development. We quantify their sensitivity to a rich variety of particle physics scenarios, finding that very-high-statistics CE$ν$NS measurements with significant sensitivity to relevant scenarios are feasible at this facility within the next few years.

hep-ph↗

arXiv2024

Measurement of reactor antineutrino oscillation amplitude and frequency using 3800 days of complete data sample of the RENO experiment

We report an updated neutrino mixing angle of $θ_{13}$ obtained from a complete data sample of the RENO experiment. The experiment has measured the amplitude and frequency of reactor anti-electron-neutrinos ($\barν_{e}$) oscillations at the Hanbit nuclear power plant, Younggwang, Korea, since August 2011. As of March 2023, the data acquisition was completed after a total of 3800 live days of detector operation. The observed candidates via inverse beta decay (IBD) are 1,211,995 (144,667) in the near (far) detector. Based on an observed energy-dependent reactor neutrino disappearance, neutrino oscillation parameters of $θ_{13}$ and $\lvertΔm_{ee}^2\rvert$ are precisely determined as $\sin^{2}2θ_{13}=0.0920_{-0.0042}^{+0.0044}(\text{stat.})_{-0.0041}^{+0.0041}(\text{syst.})$ and $\lvertΔm_{ee}^2\rvert=\left[2.57_{-0.11}^{+0.10}(\text{stat.})_{-0.05}^{+0.05}(\text{syst.})\right]\times10^{-3}~\text{eV}^{2}$. Compared to the previous RENO results published in Ref.~\cite{PhysRevLett.121.201801}, the precision is improved from 7.5\% to 6.4\% for $\sin^{2}2θ_{13}$ and from 5.2\% to 4.5\% for $\lvertΔm_{ee}^2\rvert$. The statistical error of the measurement has reached our goal and is hardly improved with additional data-taking.

hep-ex↗

arXiv2023

New Measurements of $^{71}$Ge Decay: Impact on the Gallium Anomaly

A dedicated high-statistics measurement of the $^{71}$Ge half-life is found to be in accurate agreement with an accepted value of 11.43$\pm$0.03 d, eliminating a recently proposed route to bypass the "gallium anomaly" affecting several neutrino experiments. Our data also severely constrain the possibility of $^{71}$Ge decay to low-energy excited levels of the $^{71}$Ga daughter nucleus as a solution to this puzzle. Additional unpublished measurements of this decay are discussed. Following the incorporation of this new information, the gallium anomaly survives with high statistical significance.

nucl-ex↗

arXiv2022

Search for sterile neutrino oscillation using RENO and NEOS data

We present a reactor model independent search for sterile neutrino oscillation using 2\,509\,days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino\,($\overlineν_e$) disappearance between six reactors and two detectors with baselines of 294\,m\,(RENO) and 24\,m\,(NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor $\overlineν_e$ oscillations to sterile neutrino. Based on the comparison, we obtain a 95\% C.L. excluded region of $0.1<|Δm_{41}^2|<7$\,eV$^2$. We also obtain a 68\% C.L. allowed region with the best fit of $|Δm_{41}^2|=2.41\,\pm\,0.03\,$\,eV$^2$ and $\sin^2 2θ_{14}$=0.08$\,\pm\,$0.03 with a p-value of 8.2\%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.

hep-ex↗

arXiv2022

Measurement of cosmogenic $^9$Li and $^8$He production rates at RENO

We report the measured production rates of unstable isotopes $^9$Li and $^8$He produced by cosmic muon spallation on $^{12}$C using two identical detectors of the RENO experiment. Their beta-decays accompanied by a neutron make a significant contribution to backgrounds of reactor antineutrino events in precise determination of the smallest neutrino mixing angle. The mean muon energy of its near (far) detector with an overburden of 120 (450) m.w.e. is estimated as 33.1 +- 2.3 (73.6 +- 4.4) GeV. Based on roughly 3100 days of data, the cosmogenic production rate of $^9$Li ($^8$He) isotope is measured to be 44.2 +- 3.1 (10.6 +- 7.4) per day at near detector and 10.0 +- 1.1 (2.1 +- 1.5) per day at far detector. This corresponds to yields of $^9$Li ($^8$He), 4.80 +- 0.36 (1.15 +- 0.81) and 9.9 +- 1.1 (2.1 +- 1.5) at near and far detectors, respectively, in a unit of 10$^{-8}$ $μ^{-1}$ g${^-1}$ cm${^2}$. Combining the measured $^9$Li yields with other available underground measurements, an excellent power-law relationship of the yield with respect to the mean muon energy is found to have an exponent of $α$ = 0.75 +- 0.05.

nucl-ex↗

arXiv2021

Measurement of Reactor Antineutrino Flux and Spectrum at RENO

The RENO experiment reports measured flux and energy spectrum of reactor electron antineutrinos\,($\overlineν_e$) from the six reactors at Hanbit Nuclear Power Plant. The measurements use 966\,094\,(116\,111)\,$\overlineν_e$ candidate events with a background fraction of 2.39\%\,(5.13\%), acquired in the near\,(far) detector, from August 2011 to March 2020. The inverse beta decay (IBD) yield is measured as (5.852$\,\pm\,$0.124$) \times 10^{-43}$\,cm$^2$/fission, corresponding to 0.941\,$\pm$ 0.019 of the prediction by the Huber and Mueller (HM) model. A reactor $\overlineν_e$ spectrum is obtained by unfolding a measured IBD prompt spectrum. The obtained neutrino spectrum shows a clear excess around 6\,MeV relative to the HM prediction. The obtained reactor $\overlineν_e$ spectrum will be useful for understanding unknown neutrino properties and reactor models. The observed discrepancies suggest the next round of precision measurements and modification of the current reactor $\overlineν_e$ models.

hep-ex↗

arXiv2020

Search for Sub-eV Sterile Neutrino at RENO

We report a search result for a light sterile neutrino oscillation with roughly 2200 live days of data in the RENO experiment. The search is performed by electron antineutrino ($\overlineν_e$) disappearance taking place between six 2.8 GW$_{\text{th}}$ reactors and two identical detectors located at 294 m (near) and 1383 m (far) from the center of reactor array. A spectral comparison between near and far detectors can explore reactor $\overlineν_e$ oscillations to a light sterile neutrino. An observed spectral difference is found to be consistent with that of the three-flavor oscillation model. This yields limits on $\sin^{2} 2θ_{14}$ in the $10^{-4} \lesssim |Δm_{41}^2| \lesssim 0.5$ eV$^2$ region, free from reactor $\overlineν_e$ flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at $|Δm^2_{41}| \lesssim 0.002$ eV$^2$ using the $\overlineν_e$ disappearance channel.

hep-ex↗