arXiv subjects

H. Kinoshita

Publications and source records attributed to H. Kinoshita.

At least 19 recordsLinked to original sources

arXiv2026

First results from the search for an excess of $\barν_{e}$ events in JSNS$^2$

The JSNS$^2$ (J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source) experiment at the Material and Life Science Facility (MLF) of J-PARC is designed to directly test an excess on $\barν_{e}$ events which was indicated by LSND (Liquid Scintillator Neutrino Detector). The combination of a short-pulsed proton beam and a gadolinium-loaded liquid scintillator provides an excellent signal-to-noise ratio. In this article, we report the first results of a direct test based on data collected in 2022. After applying all event selection criteria, two events are observed, consistent with the expected background of 2.3$\pm$0.4 events. No excess of $\barν_e$ events are seen in this report, however the expected number of events due to LSND anomaly is 1.1$\pm$0.5, thus this result is not yet conclusive. Data taking has been ongoing since 2021 and will continue in future runs. In addition, a new far detector has recently been constructed for the second phase experiment, JSNS$^2$-II, marking an important milestone toward forthcoming measurements.

hep-ex↗

arXiv2025

Muon tagging with Flash ADC waveform baselines

This manuscript describes an innovative method to tag the muons using the baseline information of the Flash ADC (FADC) waveform of PMTs in the JSNS1 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment. This experiment is designed for the search for sterile neutrinos, and a muon tagging is an essential key component for the background rejection since the detector of the experiment is located over-ground, where is the 3rd floor of the J-PARC Material and Life experimental facility (MLF). Especially, stopping muons inside the detector create the Michel electrons, and they are important background to be rejected. Utilizing this innovative method, more than 99.8% of Michel electrons can be rejected even without a detector veto region. This technique can be employed for any experiments which uses the similar detector configurations.

physics.ins-det↗

arXiv2025

The first JSNS$^2$ measurement of electron neutrino flux using $^{12}C(ν_{e},e^{-}) ^{12}N_{g.s.}$ reaction

JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment searching for sterile neutrinos through the observation of $\barν_μ \rightarrow \barν_e$ appearance oscillations, using neutrinos produced by muon decay-at-rest. A key aspect of the experiment involves accurately understanding the neutrino flux and the quantities of pions and muons, which are progenitors of (anti-)neutrinos, given that their production rates have yet to be measured. We present the first electron-neutrino flux measurement using $^{12}\mathrm{C}(ν_{e},e^{-}) ^{12}\mathrm{N}_{g.s.}$ reaction in JSNS$^2$, yielding a flux of (6.7 $\pm$ 1.6 (stat.) $\pm$ 1.7 (syst.)) $\times$ 10$^{-9}$ cm$^{-2}$ proton$^{-1}$ at the JSNS$^2$ detector location, located at 24 meters distance from the mercury target. This flux measurement is consistent with predictions from simulations based on hadron models.

hep-ex↗

arXiv2025

PMT calibration for the JSNS2-II far detector with an embedded LED system

The JSNS2-II (the second phase of JSNS2, J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment aimed at searching for sterile neutrinos. This experiment has entered its second phase, employing two liquid scintillator detectors located at near and far positions from the neutrino source. Recently, the far detector of the experiment has been completed and is currently in the calibration phase. This paper presents a detailed description of the calibration process utilizing the LED system. The LED system of the far detector uses two Ultra-Violet (UV) LEDs, which are effective in calibrating all of PMTs at once. The UV light is converted into the visible light wavelengths inside liquid scintillator via the wavelength shifters, providing pseudo-isotropic light. The properties of all functioning Photo-Multiplier-Tubes (PMTs) to detect the neutrino events in the far detector, such as gain, its dependence of supplied High Voltage (HV), and Peak-to-Valley (PV) were calibrated. To achieve a good energy resolution for physics events, up to 10% of the relative gain adjustment is required for all functioning PMTs. This will be achieved using the measured HV curves and the LED calibration. The Peak-to-Valley (PV) ratio values are the similar to those from the production company, which distinguish the single photo-electron signal from the pedestal. Additionally, the precision of PMT signal timing is measured to be 2.1 ns, meeting the event reconstruction requirement of 10 ns.

physics.ins-det↗

arXiv2025

First Measurement of Missing Energy Due to Nuclear Effects in Monoenergetic Neutrino Charged Current Interactions

We present the first measurement of the missing energy due to nuclear effects in monoenergetic, muon neutrino charged-current interactions on carbon, originating from $K^+ \rightarrow μ^+ ν_μ$ decay at rest ($E_{ν_μ}=235.5$ MeV), performed with the J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source liquid scintillator based experiment. Toward characterizing the neutrino interaction, ostensibly $ν_μn \rightarrow μ^- p$ or $ν_μ$$^{12}\mathrm{C}$ $\rightarrow μ^-$$^{12}\mathrm{N}$, we define the missing energy as the energy transferred to the nucleus ($ω$) minus the kinetic energy of the outgoing proton(s), $E_{m} \equivω-\sum T_p$, and relate this to visible energy in the detector, $E_{m}=E_{ν_μ} (235.5 \mathrm{MeV})-m_μ(105.7 \mathrm{MeV}) + [m_n-m_p (1.3 \mathrm{MeV})] - E_{\mathrm{vis}}$. The missing energy, which is naively expected to be zero in the absence of nuclear effects (e.g. nucleon separation energy, Fermi momenta, and final-state interactions), is uniquely sensitive to many aspects of the interaction, and has previously been inaccessible with neutrinos. The shape-only, differential cross section measurement reported, based on a $(77\pm3)$% pure double-coincidence kaon decay-at-rest signal (621 total events), provides detailed insight into neutrino-nucleus interactions, allowing even the nuclear orbital shell of the struck nucleon to be inferred. The measurement provides an important benchmark for models and event generators at hundreds of MeV neutrino energies, characterized by the difficult-to-model transition region between neutrino-nucleus and neutrino-nucleon scattering, and relevant for applications in nuclear physics, neutrino oscillation measurements,and Type-II supernova studies.

hep-ex↗

arXiv2025

Pulse Shape Discrimination in JSNS$^2$

JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that is searching for sterile neutrinos via the observation of $\barν_μ \rightarrow \barν_e$ appearance oscillations using neutrinos with muon decay-at-rest. For this search, rejecting cosmic-ray-induced neutron events by Pulse Shape Discrimination (PSD) is essential because the JSNS$^2$ detector is located above ground, on the third floor of the building. We have achieved 95$\%$ rejection of neutron events while keeping 90$\%$ of signal, electron-like events using a data driven likelihood method.

physics.ins-det↗

arXiv2025

Evaluation of the performance of the event reconstruction algorithms in the JSNS$^2$ experiment using a $^{252}$Cf calibration source

JSNS$^2$ searches for short baseline neutrino oscillations with a baseline of 24~meters and a target of 17~tonnes of the Gd-loaded liquid scintillator. The correct algorithm on the event reconstruction of events, which determines the position and energy of neutrino interactions in the detector, are essential for the physics analysis of the data from the experiment. Therefore, the performance of the event reconstruction is carefully checked with calibrations using $^{252}$Cf source. This manuscript describes the methodology and the performance of the event reconstruction.

hep-ex↗

arXiv2024

Study on the accidental background of the JSNS$^2$ experiment

JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment which searches for sterile neutrinos via the observation of $\barν_μ \to \barν_{e}$ appearance oscillations using muon decay-at-rest neutrinos. The data taking of JSNS$^2$ have been performed from 2021. In this manuscript, a study of the accidental background is presented. The rate of the accidental background is (9.29$\pm 0.39) \times 10^{-8}$ / spill with 0.75 MW beam power and comparable to the number of searching signals.

hep-ex↗

arXiv2023

The acrylic vessel for JSNS$^{2}$-II neutrino target

The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment designed for the search for sterile neutrinos. The experiment is currently at the stage of the second phase named JSNS$^{2}$-II with two detectors at near and far locations from the neutrino source. One of the key components of the experiment is an acrylic vessel, that is used for the target volume for the detection of the anti-neutrinos. The specifications, design, and measured properties of the acrylic vessel are described.

hep-ex↗

arXiv2022

Characterization of the correlated background for a sterile neutrino search using the first dataset of the JSNS$^2$ experiment

JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that is searching for sterile neutrinos via the observation of $\barν_μ \to \barν_{e}$ appearance oscillations using muon decay-at-rest neutrinos. Before dedicated data taking in the first-half of 2021, we performed a commissioning run for 10 days in June 2020. Using the data obtained in this commissioning run, in this paper, we present an estimate of the correlated background which imitates the $\barν_{e}$ signal in a sterile neutrino search. In addition, in order to demonstrate future prospects of the JSNS$^2$ experiment, possible pulse shape discrimination improvements towards reducing cosmic ray induced fast neutron background are described.

hep-ex↗

arXiv2021

The JSNS^2 Detector

The JSNS^2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for oscillations involving a sterile neutrino in the eV^2 mass-splitting range. The experiment will search for the appearance of electron antineutrinos oscillated from muon antineutrinos. The electron antineutrinos are detected via the inverse beta decay process using a liquid scintillator detector. A 1MW beam of 3 GeV protons incident on a spallation neutron target produces an intense and pulsed neutrino source from pion, muon, and kaon decay at rest. The JSNS^2 detector is located 24 m away from the neutrino source and began operation from June 2020. The detector contains 17 tonnes of gadolinium (Gd) loaded liquid scintillator (LS) in an acrylic vessel, as a neutrino target. It is surrounded by 31 tonnes of unloaded LS in a stainless steel tank. Optical photons produced in LS are viewed by 120 R7081 Hamamatsu 10-inch Photomultiplier Tubes (PMTs). In this paper, we describe the JSNS^2 detector design, construction, and operation.

physics.ins-det↗

arXiv2020

Proposal: JSNS$^2$-II

This article describes the goal and expected sensitivity of the JSNS$^2$-II experiment at J-PARC Materials and Life Science Experimental Facility (MLF). The JSNS$^2$-II experiment is the second phase of the JSNS$^2$ experiment (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) with two detectors which are located in 24 m (an existing detector) and 48 m (new one) baselines to improve the sensitivity of the search for sterile neutrinos, especially in the low $Δm^2$ region, which has been indicated by the global fit of the appearance mode. The new second detector has a similar structure as the existing JSNS$^2$ detector, which is already working. To compensate for the reduction of the neutrino flux due to the distance from the mercury target, the target mass of the Gd-loaded liquid scintillator which is the Linear AlkylBenzene (LAB) based liquid scintillator inside the acrylic vessel is 35 tons. To keep the same photo-coverage of the detector as the first detector, we will surround the acrylic vessel with 240 PMTs. With this experimental setup and 5 years (times 1 MW beam power) exposure, the sensitivity of the JSNS$^2$-II is significantly improved compared to the current JSNS$^2$, especially in the low $Δm^2$ oscillation parameter region. The JSNS$^2$-II can also confirm or refute the most of the oscillation parameters' space preferred by the previous experiments with 3 sigma C.L.. Considering these situations and world wide status of the sterile neutrino searches, we are eager to start the data taking with the two detector configuration from 2023. The fund to build the second detector was already secured.

hep-ex↗

arXiv2009

Habitable Zones for Earth-mass Planets in Multiple Planetary Systems

We perform numerical simulations to study the Habitable zones (HZs) and dynamical structure for Earth-mass planets in multiple planetary systems. For example, in the HD 69830 system, we extensively explore the planetary configuration of three Neptune-mass companions with one massive terrestrial planet residing in 0.07 AU $\leq a \leq$ 1.20 AU, to examine the asteroid structure in this system. We underline that there are stable zones of at least $10^5$ yr for low-mass terrestrial planets locating between 0.3 and 0.5 AU, and 0.8 and 1.2 AU with final eccentricities of $e < 0.20$. Moreover, we also find that the accumulation or depletion of the asteroid belt are also shaped by orbital resonances of the outer planets, for example, the asteroidal gaps at 2:1 and 3:2 mean motion resonances (MMRs) with Planet C, and 5:2 and 1:2 MMRs with Planet D. In a dynamical sense, the proper candidate regions for the existence of the potential terrestrial planets or HZs are 0.35 AU $< a < $ 0.50 AU, and 0.80 AU $< a < $ 1.00 AU for relatively low eccentricities, which makes sense to have the possible asteroidal structure in this system.

astro-ph.EP↗

arXiv2009

The Dynamical Architecture and Habitable Zones of the Quintuplet Planetary System 55 Cancri

We perform numerical simulations to study the secular orbital evolution and dynamical structure in the quintuplet planetary system 55 Cancri with the self-consistent orbital solutions by Fischer and coworkers (2008). In the simulations, we show that this system can be stable at least for $10^{8}$ yr. In addition, we extensively investigate the planetary configuration of four outer companions with one terrestrial planet in the wide region of 0.790 AU $\leq a \leq $ 5.900 AU to examine the existence of potential asteroid structure and Habitable Zones (HZs). We show that there are unstable regions for the orbits about 4:1, 3:1 and 5:2 mean motion resonances (MMRs) with the outermost planet in the system, and several stable orbits can remain at 3:2 and 1:1 MMRs, which is resemblance to the asteroidal belt in solar system. In a dynamical point, the proper candidate HZs for the existence of more potential terrestrial planets reside in the wide area between 1.0 AU and 2.3 AU for relatively low eccentricities.

astro-ph.EP↗

arXiv2008

Microtribological Property of Vertically Aligned Carbon Nanotube Film

Microtribological properties of vertically-aligned carbon-nanotube (VACNT) films have been studied. Adhesion forces were obtained by measuring force-displacement curves. Friction experiments were conducted in reciprocating sliding configurations. Effects of tip radius, applied force, scan speed, and relative humidity were investigated. A model of the friction of VACNT film is discussed on the basis of in-situ tribological experiments inside a scanning electron microscope (SEM).

cond-mat.mtrl-sci↗

arXiv2007

Influence of Humidity on Microtribology of Vertically Aligned Carbon Nanotube Film

The aim of this study is to probe the influence of water vapor environment on the microtribological properties of a forestlike vertically aligned carbon nanotube (VACNT) film, deposited on a silicon (001) substrate by chemical vapor deposition. Tribological experiments were performed using a gold tip under relative humidity varying from 0 to 100%. Very low adhesion forces and high friction coefficients of 0.6 to 1.3 resulted. The adhesion and friction forces were independent of humidity, due probably to the high hydrophobicity of VACNT. These tribological characteristics were compared to those of a diamond like carbon (DLC) sample.

cond-mat.mtrl-sci↗

arXiv2006

The Secular Evolution and Dynamical Architecture of the Neptunian Triplet Planetary System HD 69830

We perform numerical simulations to study the secular orbital evolution and dynamical structure in the HD 69830 system with the best-fit orbital solutions by Lovis and coworkers (2006). In the simulations, we show that the triplet Neptunian system can be stable at least for 2 Gyr and the stability would not be greatly influenced even if we vary the planetary masses. In addition, we employ the Laplace-Lagrange secular theory to investigate the long-term behaviors of the system, and the outcomes demonstrate that this theory can well describe the secular orbital evolution for all planets, where the secular periods and amplitudes in the eccentricities well agrees with those of the direct numerical integrations. We first reveal that the secular periods of the eccentricity $e_{1}$ and $e_{2}$ are identical about 8,300 yr. Moreover, we explore the planetary configuration of three Neptune-mass companions with one massive terrestrial planet in 0.07 AU $\leq a \leq 1.20$ AU, to examine the asteroid structure in this system. We underline that there are stable zones at least $10^{5}$ yr for low-mass terrestrial planets locating between 0.3 and 0.5 AU, and 0.8 and 1.2 AU with final low eccentricities. Still, we also find that the secular resonance $ν_{1}$ and $ν_{2}$ of two inner planets can excite the eccentricities of the terrestrial bodies, and the accumulation or depletion of the asteroid belt are also shaped by orbital resonances of the outer planets, i.e., 5:2 and 1:2 MMRs with Planet D... (abridged)

astro-ph↗

arXiv2005

Could the 47 UMa Planetary System be a Second Solar System: predicting the Earth-like planets

(Abridged)We numerically investigated the dynamical architecture of 47 UMa with the planetary configuration of the best-fit orbital solutions by Fischer et al. We systematically studied the existence of Earth-like planets in the region 0.05 AU $\leq a \leq 2.0$ AU for 47 UMa with numerical simulations, and we also explored the packed planetary geometry and Trojan planets in the system. In the simulations, we found that "hot Earths" at 0.05 AU $\leq a < $ 0.4 AU can dynamically survive at least for 1 Myr. The Earth-like planets can eventually remain in the system for 10 Myr in areas involved in the mean motion resonances (MMR) (e.g., 3:2 MMR) with the inner companion. Moreover, we showed that the 2:1 and 3:1 resonances are on the fringe of stability, while the 5:2 MMR is unstable. Additionally, the 2:1 MMR marks out a remarkable boundary between chaotic and regular motions, inside, most of the orbits can survive, outside, they are mostly lost in the orbital evolution. In a dynamical sense, the most likely candidate for habitable environment is Earth-like planets with orbits in the ranges 0.8 AU $\leq a < 1.0$ AU and 1.0 AU $ < a < 1.30$ AU (except several unstable cases) with relatively low eccentricities. The Trojan planets with low eccentricities and inclinations can secularly last at the triangular equilibrium points of two massive planets. Hence, the 47 UMa planetary system may be a close analog to our solar system.

astro-ph↗