arXiv subjects

H. I. Jang

Publications and source records attributed to H. I. Jang.

32 records · Page 2Linked to original sources

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.

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arXiv2020

The JSNS$^{2}$ data acquisition system

The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS$^{2}$ inner detector is filled with 17 tons of gadolinium(Gd)-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate $γ$-catcher and an optically separated outer veto volumes. A total of 120 10-inch photomultiplier tubes observe the scintillating optical photons and each analog waveform is stored with the flash analog-to-digital converters. We present details of the data acquisition, processing, and data quality monitoring system. We also present two different trigger logics which are developed for the beam and self-trigger.

physics.ins-det↗

arXiv2020

Performance of PMTs for the JSNS2 experiment

The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24\,m short baseline at J-PARC. The JSNS$^{2}$ inner detector is filled with 17 tons of gadolinium-loaded liquid scintillator (LS) and both the intermediate $γ$-catcher and the optically separated outer veto are filled with un-loaded LS. Optical photons from scintillation are observed by 120 Photomultiplier Tubes (PMTs). A total of 130 PMTs for the JSNS2 experiment were both donated by other experiments and purchased from Hamamatsu. Donated PMTs were purchased around 10 years ago, therefore JSNS$^{2}$ did pre-calibration of the PMTs including the purchased PMTs. 123 PMTs demonstrated acceptable performance for the JSNS$^{2}$ experiment, and 120 PMTs were installed in the detector.

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arXiv2020

Production and optical properties of liquid scintillator for the JSNS$^{2}$ experiment

The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment will search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS$^{2}$ inner detector will be filled with 17 tons of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate $γ$-catcher and outer veto volumes. JSNS$^{2}$ has chosen Linear Alkyl Benzene (LAB) as an organic solvent because of its chemical properties. The unloaded LS was produced at a refurbished facility, originally used for scintillator production by the RENO experiment. JSNS$^{2}$ plans to use ISO tanks for the storage and transportation of the LS. In this paper, we describe the LS production, and present measurements of its optical properties and long term stability. Our measurements show that storing the LS in ISO tanks does not result in degradation of its optical properties.

physics.ins-det↗

arXiv2019

Observation of Reactor Antineutrino Disappearance Using Delayed Neutron Capture on Hydrogen at RENO

The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors of 44.5 tons since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen. Based on 1500 live days of data taken with 16.8 GW$_{th}$ reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with a delayed neutron capture on hydrogen. This provides an independent measurement of $θ_{13}$ and a consistency check on the validity of the result from n-Gd data. Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin$^{2}$2$θ_{13}$= 0.087 $\pm$ 0.008 (stat.) $\pm$ 0.014 (syst.).

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arXiv2018

Hyper-Kamiokande Design Report

On the strength of a double Nobel prize winning experiment (Super)Kamiokande and an extremely successful long baseline neutrino programme, the third generation Water Cherenkov detector, Hyper-Kamiokande, is being developed by an international collaboration as a leading worldwide experiment based in Japan. The Hyper-Kamiokande detector will be hosted in the Tochibora mine, about 295 km away from the J-PARC proton accelerator research complex in Tokai, Japan. The currently existing accelerator will be steadily upgraded to reach a MW beam by the start of the experiment. A suite of near detectors will be vital to constrain the beam for neutrino oscillation measurements. A new cavern will be excavated at the Tochibora mine to host the detector. The experiment will be the largest underground water Cherenkov detector in the world and will be instrumented with new technology photosensors, faster and with higher quantum efficiency than the ones in Super-Kamiokande. The science that will be developed will be able to shape the future theoretical framework and generations of experiments. Hyper-Kamiokande will be able to measure with the highest precision the leptonic CP violation that could explain the baryon asymmetry in the Universe. The experiment also has a demonstrated excellent capability to search for proton decay, providing a significant improvement in discovery sensitivity over current searches for the proton lifetime. The atmospheric neutrinos will allow to determine the neutrino mass ordering and, together with the beam, able to precisely test the three-flavour neutrino oscillation paradigm and search for new phenomena. A strong astrophysical programme will be carried out at the experiment that will detect supernova neutrinos and will measure precisely solar neutrino oscillation.

physics.ins-det↗

arXiv2018

Measurement of Reactor Antineutrino Oscillation Amplitude and Frequency at RENO

The RENO experiment reports more precisely measured values of $θ_{13}$ and $|Δm_{ee}^2|$ using $\sim$2\,200 live days of data. The amplitude and frequency of reactor electron antineutrino ($\overlineν_e$) oscillation are measured by comparing the prompt signal spectra obtained from two identical near and far detectors. In the period between August 2011 and February 2018, the far (near) detector observed 103\,212 (850\,666) electron antineutrino candidate events with a background fraction of 4.7\% (2.0\%). A clear energy and baseline dependent disappearance of reactor $\overlineν_e$ is observed in the deficit of the measured number of $\overlineν_e$. Based on the measured far-to-near ratio of prompt spectra, we obtain $\sin^2 2 θ_{13} = 0.0896 \pm 0.0048({\rm stat}) \pm 0.0048({\rm syst})$ and $|Δm_{ee}^2| =[2.68 \pm 0.12({\rm stat}) \pm 0.07({\rm syst})]\times 10^{-3}$~eV$^2$.

hep-ex↗

arXiv2018

Spectral Measurement of the Electron Antineutrino Oscillation Amplitude and Frequency using 500 Live Days of RENO Data

The Reactor Experiment for Neutrino Oscillation (RENO) has been taking electron antineutrino ($\overlineν_{e}$) data from the reactors in Yonggwang, Korea, using two identical detectors since August 2011. Using roughly 500 live days of data through January 2013 we observe 290,775 (31,514) reactor $\overlineν_{e}$ candidate events with 2.8 (4.9)% background in the near (far) detector. The observed visible positron spectra from the reactor $\overlineν_{e}$ events in both detectors show discrepancy around 5 MeV with regard to the prediction from the current reactor $\overlineν_{e}$ model. Based on a far-to-near ratio measurement using the spectral and rate information we have obtained $\sin^2 2 θ_{13} = 0.082 \pm 0.009({\rm stat.}) \pm 0.006({\rm syst.})$ and $|Δm_{ee}^2| =[2.62_{-0.23}^{+0.21}({\rm stat.})_{-0.13}^{+0.12}({\rm syst.})]\times 10^{-3}$eV$^2$.

hep-ex↗

arXiv2017

Technical Design Report (TDR): Searching for a Sterile Neutrino at J-PARC MLF (E56, JSNS2)

In this document, the technical details of the JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment are described. The search for sterile neutrinos is currently one of the hottest topics in neutrino physics. The JSNS$^2$ experiment aims to search for the existence of neutrino oscillations with $Δm^2$ near 1 eV$^2$ at the J-PARC Materials and Life Science Experimental Facility (MLF). A 1 MW beam of 3 GeV protons incident on a spallation neutron target produces an intense neutrino beam from muon decay at rest. Neutrinos come predominantly from $μ^+$ decay: $μ^{+} \to e^{+} + \barν_μ + ν_{e}$. The experiment will search for $\barν_μ$ to $\barν_{e}$ oscillations which are detected by the inverse beta decay interaction $\barν_{e} + p \to e^{+} + n$, followed by gammas from neutron capture on Gd. The detector has a fiducial volume of 17 tons and is located 24 meters away from the mercury target. JSNS$^2$ offers the ultimate direct test of the LSND anomaly. In addition to the sterile neutrino search, the physics program includes cross section measurements with neutrinos with a few 10's of MeV from muon decay at rest and with monochromatic 236 MeV neutrinos from kaon decay at rest. These cross sections are relevant for our understanding of supernova explosions and nuclear physics.

physics.ins-det↗

arXiv2015

Slow Control Systems of the Reactor Experiment for Neutrino Oscillation

The RENO experiment has been in operation since August 2011 to measure reactor antineutrino disappearance using identical near and far detectors. For accurate measurements of neutrino mixing parameters and efficient data taking, it is crucial to monitor and control the detector in real time. Environmental conditions also need to be monitored for stable operation of detectors as well as for safety reasons. In this article, we report the design, hardware, operation, and performance of the slow control system.

physics.ins-det↗

arXiv2015

Physics Potential of a Long Baseline Neutrino Oscillation Experiment Using J-PARC Neutrino Beam and Hyper-Kamiokande

Hyper-Kamiokande will be a next generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of $CP$ asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this paper, the physics potential of a long baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis uses the framework and systematic uncertainties derived from the ongoing T2K experiment. With a total exposure of 7.5 MW $\times$ 10$^7$ sec integrated proton beam power (corresponding to $1.56\times10^{22}$ protons on target with a 30 GeV proton beam) to a $2.5$-degree off-axis neutrino beam, it is expected that the leptonic $CP$ phase $δ_{CP}$ can be determined to better than 19 degrees for all possible values of $δ_{CP}$, and $CP$ violation can be established with a statistical significance of more than $3\,σ$ ($5\,σ$) for $76\%$ ($58\%$) of the $δ_{CP}$ parameter space. Using both $ν_e$ appearance and $ν_μ$ disappearance data, the expected 1$σ$ uncertainty of $\sin^2θ_{23}$ is 0.015(0.006) for $\sin^2θ_{23}=0.5(0.45)$.

hep-ex↗

arXiv2015

A Long Baseline Neutrino Oscillation Experiment Using J-PARC Neutrino Beam and Hyper-Kamiokande

Hyper-Kamiokande will be a next generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of $CP$ asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this document, the physics potential of a long baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis has been updated from the previous Letter of Intent [K. Abe et al., arXiv:1109.3262 [hep-ex]], based on the experience gained from the ongoing T2K experiment. With a total exposure of 7.5 MW $\times$ 10$^7$ sec integrated proton beam power (corresponding to $1.56\times10^{22}$ protons on target with a 30 GeV proton beam) to a $2.5$-degree off-axis neutrino beam produced by the J-PARC proton synchrotron, it is expected that the $CP$ phase $δ_{CP}$ can be determined to better than 19 degrees for all possible values of $δ_{CP}$, and $CP$ violation can be established with a statistical significance of more than $3\,σ$ ($5\,σ$) for $76%$ ($58%$) of the $δ_{CP}$ parameter space.

physics.ins-det↗

arXiv2001

Near Muon Range Detector for the K2K Experiment -Construction and Performance-

A muon range detector (MRD) has been constructed as a near detector for the KEK-to-Kamioka long-baseline neutrino experiment (K2K). It monitors the neutrino beam properties at the near site by measuring the energy, angle and production point of muons produced by charged-current neutrino interaction. The detector has been working stably since the start of the K2K experiment.

hep-ex↗

arXiv1996

Measurement of B(D_s+ -> mu+ nu_mu)/B(D_s+ -> phi mu+ nu_mu) and Determination of the Decay Constant f_{D_s}

We have observed $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> μ^+ ν_μ$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> ϕμ^+ ν_μ$ yield measured previously in this experiment, we obtain $B(D_s^+ --> μ^+ ν_μ) / B(D_s^+ --> ϕμ^+ ν_μ) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constant $f_{D_s}=194 \pm 35 \pm 20 \pm 14 MeV$.

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