P01 : Yukitoshi Ota
(pdf):Development of Chelating Fibers for Adsorption of Ultra-trace Radioactive Impurities

P02 : Mao Nishigami
(pdf):Neutron Detection Efficiency Evaluation in the Super-Kamiokande Gd Phases

P03 : Kanji Mori
(pdf):Supernova explosions hindered by eV-mass sterile neutrinos

P04 : Ayuki Takeshita
(pdf):Evaluation of the Fluorescence Properties of PMT Quartz Window for the XLZD Liquid Xenon Dark Matter Experiment

P05 : Yuya Inaba
(pdf):Temperature dependence of Rn adsorption performance by silver zeolite in air and noble gases.

P06 : Naoki Kinjo
(pdf):Evaluation of Chelate-Resin Adsorption Efficiency for Collecting 48Sc for 48Ca Beta-Decay Half-life Measurement

P07 : Junying Huang
(pdf):Probing Inelastic Higgsino Dark Matter at High Recoil Energies with XENONnT

P08 : Hiroto Bambara
(pdf):Development of the Radon Removal System Using Silver Zeolite for Hyper-Kamiokande

P09 : Kenta Noda
(pdf):Development of the CaF₂ Scintillating Calorimeter

P10 : Hiyori Nishimura
(pdf):Study of Radon Adsorption Performance of Silver Zeolites

P11 : Shunsuke Adachi
(pdf):DOSUE-RR–Searching for Wavy Dark Matter using Millimeter-Wave Receivers

P12 : Takashi Toma
(pdf):A radiative neutrino mass model with semi-annihilating boosted dark matter

P13 : Shinya Aoyama
(pdf):Evaluation of the stability of the energy scale using decay electrons detected in Super-Kamiokande

P14 : Tomoaki Tada
(pdf):Measurement of the kaon-to-pion ratio for the atmospheric neutrino using the cosmic-ray muon data in Super-Kamiokande

P15 : Nozomu Tominaga
(pdf):Neutrino Process in Supernovae: Insights from Nucleosynthesis and Metal-Poor Stars

P16 : Alejandro Yankelevich
(pdf):Measurement of the solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV

P17 : Tatsuki Washimi
(pdf):Studies on Underground Gravitational Wave Detectors: Direct Heavy Dark Matter Search and Gravity Gradient Noise

P18 : Wakako Toyama
(pdf):Development of pixel readout negative ion gaseous TPC for dark matter searches

P19 : Akihiro Inoue
(pdf):A diagnostic method for Proto-Neutron Star magnetic fields by supernova fallback neutrinos

P20 : Keigo Kadota
(pdf):Measurement of the quenching factor for BGO crystals for the BISCOTTEE experiment

P21 : Satoshi Kato
(pdf):Detector Calibration and Initial Measurement of Double Beta Decay of 96Zr in the ZICOS Experiment

P22 : Atsuya Yoshida
(pdf):Measurement of cosmic-ray muon with the BISCOTTEE setup

P23 : Fuminobu TAKAHASHI
(pdf):Resolving the QCD axion domain wall problem with a light axion

P24 : Kaede Furukawa
(pdf):Estimation of background events induced by solar neutrinos in fluorine-based dark matter detectors

P25 : Ryota Namai
(pdf):Status of C/N-1.0: A Large Gaseous TPC for Direction-Sensitive Dark Matter Search

P26 : Hanwook BAE
(pdf):Status of Front-End Board Development for KamLAND2

P27 : Takumi Omori
(pdf):New Constraint on the Two-Neutrino Double Beta Decay of 160Gd with the PIKACHU Experiment

P28 : Makita Airu
(pdf):Search for the Toponium-like Signal with the ATLAS Experiment at the LHC: Expected Sensitivity Including Systematic Uncertainties in the Single-Lepton

P29 : Hatsume Chujo
(pdf):Disc-Based Estimation of Dark Matter Density and Velocity Distribution Near the Sun

P30 : Wentao Cai
(pdf):Toward Nuclear De-Excitation Measurements with Oxygen-Ion Beams for Improved DSNB Searches at Super-Kamiokande

P31 : Yuno LEE
(pdf):Development and Performance Evaluation of Neutron Tagging for WCTE

P32 : Kaori Hattori
(pdf):Development of Superconducting Transition-Edge Sensors for Light Dark Matter Search

P33 : ANAWAT RITTIRONG
(pdf):The Status of Laser Isotope Separation (LIS) of 48Ca for the Study of Neutrinoless Double Beta Decay

P34 : Tomoki Endo
(pdf):Quark Matter Equations of State in Strong Magnetic Fields and Hybrid Stars

P35 : Kiyoto Ogawa
(pdf):Full three-loop electroweak multiplet contributions to the electron electric dipole moment

P36 : Hiroyuki Fujioka
(pdf):Toward a study of the charge density distribution of 48Ca via X-ray spectroscopy of muonic atoms

P37 : Rei Tanaka
(pdf):Optimization of an Atomic Beam System for Laser Isotope Separation of 48Ca

P38 : Hiroto Iseki
(pdf):Rabi oscillation for isotope enrichment

P39 : Yoshihito Gando
(pdf):Formulation of Copper-Ion-Exchanged Zeolites for Xenon Enrichment

P40 : Tatsuya Gonda
(pdf):Inferring Proto-Neutron Star Parameters from Supernova Neutrino Data with Realistic Detector Background

P41 : Soma Deguchi
(pdf):Indirect Dark Matter Search using MeV Gamma-Ray Observations of the Galactic Center

P42 : Michinori Hirose
(pdf):Performance Characterization of a 38-50 GHz Millimeter-Wave Receiver System for Dark Photon Dark Matter Search in the DOSUE-RR Experiment

P43 : Ryuto Ishida
(pdf):Do neutrinos transmit spin?

P44 : Yuto Kamei
(pdf):Fundamental Evaluation of Hafnium LEKIDs Fabricated by Sputtering with Substrate Heating for Future Dark Matter Searches

P45 : Yukikatsu Terada
(pdf):High-resolution X-ray astrophysical search for r-process nucleosynthesis signatures from Galactic binary neutron-star mergers

P46 : Shuki Nomura
(pdf):Development of Low-Radioactivity Photosensors for Future Large Liquid-Xenon Dark Matter Detectors

P47 : Masamichi Zaizen
(pdf):Toward unified modeling of asymptotic states of collective neutrino oscillation

P48 : Yuko Watanabe
(pdf):AXEL Experiment : High-Precision Correction of MPPC Nonlinearity Using Signal Waveform Deconvolution

P49 : Mai Morizawa
(pdf):Neutron Track Identification with a 3D Convolutional Neural Network

P50 : Hanchun Jiang
(pdf):Matter-Neutrino Resonance in Binary Neutron Star Merger Outflows

P51 : Takuya Sako
(pdf):Performance Evaluation of Ultra-Low-Radioactivity PMTs and Impurity Evaluation of High-Purity GAGG Crystal in the PIKACHU experiment

P52 : Kelin QIAO
(pdf):A New High-Intensity Ultracold Neutron Source for New Physics Probes

P01 : Yukitoshi Ota
(pdf):Development of Chelating Fibers for Adsorption of Ultra-trace Radioactive Impurities
 In experiments such as KamLAND, Super-Kamiokande, and other ultra-low-background experiments, radioactive impurities contained in liquid scintillators, ultrapure water, and Gd-water are significant sources of background radiation. In this study, we are developing filters optimized for U/Th/Ra using chelating resin. In this presentation, we will report on the current status and future prospects of chelating filter development for liquid scintillators, ultrapure water, and Gd-water.

P02 : Mao Nishigami
(pdf):Neutron Detection Efficiency Evaluation in the Super-Kamiokande Gd Phases
 Super-Kamiokande has been operating with gadolinium loading (SK-Gd) to enhance its sensitivity to the diffuse supernova neutrino background (DSNB). The addition of Gd significantly improves the detection efficiency of neutrons produced by inverse beta decay of electron antineutrinos. These neutrons are identified using the neutron tagging (ntag) algorithm. In this study, we evaluated the ntag efficiency using 241Am-Be (Am/Be) neutron source via a delayed coincidence method. Comparing calibration data with Geant4-based Monte Carlo simulation allowed us to estimate the systematic uncertainties of the detector simulation. Furthermore, we investigated the long-term stability of the ntag efficiency to ensure the reliability of the ongoing SK-Gd dataset for DSNB analysis.

P03 : Kanji Mori
(pdf):Supernova explosions hindered by eV-mass sterile neutrinos
 Light sterile neutrinos, 𝜈𝑠, are often introduced to explain an anomalous deficit in the electron antineutrino flux from nuclear reactors. If they exist, sterile neutrinos would also be produced in collapsing massive stars through the active-sterile neutrino oscillation. In order to investigate the impacts of sterile neutrinos on supernova dynamics, we perform two-dimensional neutrino-radiation hydrodynamic simulations of stellar core-collapse coupled with the active-sterile oscillation. We find that, if the mixing angle and the mass difference between 𝜈𝑒 and 𝜈𝑠 are large enough, the star fails to explode. This suggests that these mixing parameters relevant to sterile neutrinos could be constrained by supernova explodability.

P04 : Ayuki Takeshita
(pdf):Evaluation of the Fluorescence Properties of PMT Quartz Window for the XLZD Liquid Xenon Dark Matter Experiment
 The future liquid xenon dark matter experiment XLZD plans to use photomultiplier tubes (PMTs) as its photosensors. Since quartz is used as the PMT window material, understanding its properties is of great importance. In recent years, delayed photon noise following the S1 and S2 scintillation signals has become a significant concern, and fluorescence from the quartz window is considered to be one of its primary sources. In this study, we evaluate several quartz glass samples as candidate window materials for next-generation PMTs by comparing their fluorescence properties.

P05 : Yuya Inaba
(pdf):Temperature dependence of Rn adsorption performance by silver zeolite in air and noble gases.
 In underground experiments, Rn-222 is the primary source of background radiation, and in recent years, silver zeolite has attracted attention as an adsorbent capable of reducing this background radiation. In this study, we investigated the temperature dependence of Rn adsorption performance in air and noble gases for 8Ag-FER-B and Ag-ETS-10, two silver zeolites known for their particularly high adsorption capacity. In this presentation, I will report on the interim results of this research.

P06 : Naoki Kinjo
(pdf):Evaluation of Chelate-Resin Adsorption Efficiency for Collecting 48Sc for 48Ca Beta-Decay Half-life Measurement
 To measure the beta decay half-life of 48Ca, we use a chelating resin that selectively adsorbs and concentrates the daughter scandium ions, followed by gamma-ray measurement. This approach aims to reduce the overall sample volume and compact the experimental system. In this study, we conducted experiments to evaluate the ion adsorption efficiency of the chelating resin.

P07 : Junying Huang
(pdf):Probing Inelastic Higgsino Dark Matter at High Recoil Energies with XENONnT
 Inelastic dark matter (iDM) provides an extension to the standard WIMP paradigm, naturally arising in scenarios such as Higgsino-like dark matter. In this framework, scattering proceeds via a transition to a heavier degenerate state, where the associated kinematic threshold shifts the expected nuclear recoil (NR) spectrum toward significantly higher energies. Consequently, standard WIMP searches leave a vast high-recoil window largely unexplored. We report the status of a dedicated iDM search using XENONnT data. Moving beyond conventional WIMP methodologies, this project incorporates liquid xenon (LXe) response modeling and systematic calibration studies at elevated recoil energies for both NR and electronic recoil (ER) signals.

P08 : Hiroto Bambara
(pdf):Development of the Radon Removal System Using Silver Zeolite for Hyper-Kamiokande
 For Hyper-Kamiokande, a next-generation large-scale water Cherenkov detector, it is desirable to reduce the concentration of background radon in both water and air to 1 mBq/m³ or less. In this study, we constructed a device to evaluate the radon adsorption performance using silver zeolite, which exhibits high adsorption properties for radon in air, and assessed its suitability for application in Hyper-Kamiokande. In this presentation, we will report on the progress made in the development of a radon removal system designed for actual operation.

P09 : Kenta Noda
(pdf):Development of the CaF₂ Scintillating Calorimeter
 Neutrinoless double-beta decay (0νββ) is one of the most important processes in the search for new physics. The CANDLES collaboration aims to observe the 0νββ decay of 48Ca.48Ca has the highest Q-value, making it particularly advantageous for suppressing background (BG) events. Although previous CANDLES experiments did not observe 0νββ decay, the limited energy resolution of the detector allowed the two-neutrino double-beta decay (2νββ) of 48Ca to contribute as a background to the expected 0νββ peak. To overcome this limitation, we are developing a CaF₂ scintillating calorimeter, which offers significantly improved energy resolution. In this presentation, we report the results of performance tests of the readout sensor conducted as part of the detector development.

P10 : Hiyori Nishimura
(pdf):Study of Radon Adsorption Performance of Silver Zeolites
  Radon (Rn-222), a natural radioactive noble gas, can be a major background source in underground experiments.Reducing radon levels is crucial for improving experimental sensitivity. Some silver zeolites have been reported to exhibit radon adsorption capacities in air about 700 times higher than those of activated carbon at room temperature, attracting attention as promising radon mitigation materials. The strong adsorption of noble gases such as radon by silver zeolites is believed to involve chemisorption by metallic silver or silver ions, although the mechanism remains unclear. In this study, we compare radon adsorption by various silver zeolites in air and argon to provide data for elucidating their noble-gas adsorption mechanism. The current status of this research is reported.

P11 : Shunsuke Adachi
(pdf):DOSUE-RR–Searching for Wavy Dark Matter using Millimeter-Wave Receivers
 Our project, DOSUE-RR (Dark-photon dark-matter Observing System for Un-Explored Radio-Range), aims to detect ultra-light dark matter using millimeter-wave receivers. Our targets are the dark photon and axion-like particles (ALPs) in the μeV–meV mass range, among the leading dark matter candidates. A dark photon (or ALP) can convert into an ordinary photon at a metallic boundary, with the photon frequency corresponding to the dark matter mass via hν∼mc². We target the full millimeter-wave band (20–300 GHz), corresponding to a mass range of about 80 μeV to 1.2 meV, splitting the measurement into several bands and modifying receivers for each band. I will present an overview of our current activities, mainly the dark photon search, plus an ALP search using a magnet.

P12 : Takashi Toma
(pdf):A radiative neutrino mass model with semi-annihilating boosted dark matter
 In this work, we construct a radiative neutrino mass model that allows for the production of boosted dark matter in the present universe through semi-annihilation. A Dirac fermion serves as the dark matter candidate, which semi-annihilates into an anti-dark matter particle and a neutrino. Taking into account the relevant experimental and theoretical constraints, we find that the boosted dark matter can be probed by DARWIN if its mass lies in the range of 20–50 MeV and the semi-annihilation proceeds through a resonance with a tuning of O(0.1)%. Furthermore, the monochromatic neutrino produced simultaneously with the boosted dark matter can also be detected at Hyper-Kamiokande and DUNE in part of the allowed parameter space.

P13 : Shinya Aoyama
(pdf):Evaluation of the stability of the energy scale using decay electrons detected in Super-Kamiokande
 In the Super-Kamiokande (SK) experiment, understanding the energy scale and its time dependence is essential. In this study, we develop a calibration method using decay electrons from cosmic-ray muons, which are distributed throughout the detector and are continuously available as a calibration sample. However, the evaluation of the energy scale is affected by the anisotropic emission of decay electrons due to muon polarization, as well as by the spatial distribution of stopping muons combined with the position-dependent detector response. In this presentation, we report the current status of a simulation that incorporates these effects and present an evaluation of the time dependence of the energy scale.

P14 : Tomoaki Tada
(pdf):Measurement of the kaon-to-pion ratio for the atmospheric neutrino using the cosmic-ray muon data in Super-Kamiokande
 Atmospheric neutrinos and cosmic-ray muons are produced by interactions of primary cosmic rays with the atmosphere. Pions and kaons decay into atmospheric neutrinos and cosmic-ray muons, carrying information on hadronic interactions. Atmospheric neutrino flux models still have significant uncertainties, mainly due to the poorly known parent meson ratio. Cosmic-ray muons provide an effective probe to constrain this uncertainty. In this poster, we analyze the seasonal variation of TeV cosmic-ray muons observed with the Super-Kamiokande detector and their correlation with atmospheric temperature. From this correlation, we determine the parent meson K/π ratio, providing new constraints on atmospheric neutrino flux models.

P15 : Nozomu Tominaga
(pdf):Neutrino Process in Supernovae: Insights from Nucleosynthesis and Metal-Poor Stars
 Core-collapse supernovae (CCSNe) are key sources of heavy elements and drivers of cosmic chemical evolution. To constrain the neutrino process and explosion mechanisms, we combine supernova nucleosynthesis with abundance patterns of metal-poor stars. Our simulations show that Sc, Ti, and V abundances in very metal-poor stars require explosive nucleosynthesis under a neutrino exposure of ~10^35 erg cm^-2 and temperatures of 2.0-3.2 GK, conditions that may be realized in multidimensional explosions. We also present abundance studies of EMP and CEMP stars, including signatures of the weak r-process, K production, and F production in energetic supernovae, demonstrating that metal-poor stars provide quantitative probes of the neutrino process in CCSNe.

P16 : Alejandro Yankelevich
(pdf):Measurement of the solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV
 Observing boron-8 solar neutrino interactions in Super-Kamiokande at low energies is crucial for probing the transition between MSW-dominated and vacuum-dominated neutrino flavor conversion. We present a new analysis of the solar neutrino interaction rate below the previous 3.49 MeV electron kinetic energy threshold for the full SK-IV period, utilizing wideband intelligent trigger data and a boosted decision tree for background reduction. A signal indication is observed between 2.99 and 3.49 MeV with 2.76σ significance and a data to unoscilated Monte Carlo ratio of 0.307 +0.112 -0.111. These low-energy data have a negligible effect on the 1σ intervals of the fits to the solar neutrino energy spectrum but have a noticeable effect on the best fit when using the exponential parametrization.

P17 : Tatsuki Washimi
(pdf):Studies on Underground Gravitational Wave Detectors: Direct Heavy Dark Matter Search and Gravity Gradient Noise
 This research is a pilot study aimed at the direct detection of heavy dark matter using underground gravitational-wave detectors such as KAGRA and ET. The setup utilizes the gravitational interaction between dark matter and the test-mass mirrors of a laser interferometer—which is suspended by a multi-stage pendulum vibration isolation system—thereby eliminating the need to assume other types of interactions and enabling a background-free search, provided the signal-to-noise ratio is sufficient. The study involves precisely modeling the complex response of the gravitational-wave detector and utilizing this response model to evaluate gravity gradient noise.

P18 : Wakako Toyama
(pdf):Development of pixel readout negative ion gaseous TPC for dark matter searches
 NEWAGE is a direct dark matter search experiment with directional analysis. We use a low-pressure gaseous time projection chamber to detect nuclear recoils and to reconstruct their 3D tracks. Our current detector is 2D strip readout and operates with CF4 gas. In future experiments, we plan to adopt a pixel-readout gaseous TPC filled with SF6, which is a negative-ion gas. Pixel readout can distinguish real tracks from ghost tracks. It allows to improve the angular resolution. In SF6 gas, two types of negative ions are produced, and they drift through the gas. The difference of drift velocity allows to reconstruct 3D absolute track position. It contributes to improve the BG rejection. In this poster, we present the development of a new pixel-readout gaseous TPC using SF6.

P19 : Akihiro Inoue
(pdf):A diagnostic method for Proto-Neutron Star magnetic fields by supernova fallback neutrinos
 We propose a novel diagnostic to probe proto-neutron star (PNS) magnetic fields using neutrinos associated with supernova fallback. Our general-relativistic MHD simulations show that stronger magnetic fields and lower fallback accretion rates produce softer neutrino spectra. This spectral softening arises because neutrinos are mainly emitted near the magnetospheric radius, which is larger for stronger magnetic fields and lower accretion rates. For a normal neutrino mass ordering, fallback neutrinos from a Galactic supernova could constrain PNS magnetic fields if the accretion rate exceeds about 1e-3 Msun/sec and fallback begins more than 10 seconds after core bounce. This method may offer a new way to study neutron-star diversity.

P20 : Keigo Kadota
(pdf):Measurement of the quenching factor for BGO crystals for the BISCOTTEE experiment
 Atmospheric-neutrino–induced neutral-current quasi-elastic (NCQE) interactions on oxygen are a major background in searches for the diffuse supernova neutrino background (DSNB). The predicted NCQE event rate currently has a large systematic uncertainty. To reduce this uncertainty, we propose BISCOTTEE, which aims to measure neutrino–oxygen NCQE interactions in short baseline. It is important to observe recoil nuclei in the BISCOTTEE, and we measured the scintillation quenching factor for oxygen nuclear recoils in BGO using a BGO detector and a liquid-scintillator neutron detector. The measurement was performed with a 61.9 MeV monoenergetic neutron beam at RCNP. We will present the experimental setup and analysis of the beam test.

P21 : Satoshi Kato
(pdf):Detector Calibration and Initial Measurement of Double Beta Decay of 96Zr in the ZICOS Experiment
 The ZICOS (ZIrconium Complex in Organic Scintillator) experiment aims to observe the neutrinoless double beta decay of 96Zr. As an initial proof-of-principle step toward this goal, we installed the detector at the Lab-A experimental area in the Kamioka mine, performed calibration using gamma-ray sources, and conducted an initial measurement with 0.2 g of 96Zr from November 24 to 25, 2025. In this presentation, we report the results of the gain calibration of the Hamamatsu Photonics R10789 photomultiplier tubes (PMTs), the detector energy calibration, and the initial results from the two-neutrino double beta decay measurement using 96Zr.

P22 : Atsuya Yoshida
(pdf):Measurement of cosmic-ray muon with the BISCOTTEE setup
 One of the major backgrounds in the diffuse supernova neutrino background (DSNB) search with the SK-Gd experiment is neutral-current quasi-elastic (NCQE) scattering of atmospheric neutrinos on oxygen nuclei. To understand this reaction experimentally, we are planning BISCOTTEE (BISmuth-germanate Crystal-based neutrinO [neutrOn]–nucleus scattering Experiment), which will use BGO crystals and a short-baseline neutrino beam. We plan to carry out a neutrino beam test with a newly built setup. Prior to this, it is necessary to understand the setup's response to the muons produced by neutrino interactions. We therefore measured cosmic-ray muons using this setup. In this presentation, we report on the setup and the results of the cosmic-ray muon measurement.

P23 : Fuminobu TAKAHASHI
(pdf):Resolving the QCD axion domain wall problem with a light axion
 We propose a solution to the QCD axion domain wall problem by introducing a massless or light axion coupled to gluons. We focus on the case where the new axion forms strings after inflation. Through mixing with the QCD axion, QCD domain walls become bounded by these strings and confined into cosmologically safe string bundles. Some bundles may survive until today and produce observable signatures, including gravitational waves, cosmic birefringence, and CMB anisotropies. Their detection together with the QCD axion would provide a smoking-gun signal of this mechanism. The Peccei–Quinn mechanism remains effective, so the strong CP problem is not reintroduced. We identify the viable parameter region and discuss the cosmological implications.

P24 : Kaede Furukawa
(pdf):Estimation of background events induced by solar neutrinos in fluorine-based dark matter detectors
 Searching for spin-dependent interactions of dark matter is important 
for understanding the nature of dark matter. The scale-up of experiments
 using fluorine targets to search for spin-dependent dark matter–nucleon
 scattering is currently under consideration. On the other hand, fluorine has a relatively large electron-neutrino absorption rate, and this
 process is expected to produce background events that can mimic dark matter scattering. In this study, we theoretically calculate the
expected numbers of dark matter interactions and solar neutrino-induced 
interactions using CF4 target. We also estimate the potential overlap between dark matter signals and solar neutrino signals.

P25 : Ryota Namai
(pdf):Status of C/N-1.0: A Large Gaseous TPC for Direction-Sensitive Dark Matter Search
 The sensitivity of direct dark matter searches has been steadily improved through energy-sensitive experiments such as dual-phase liquid xenon TPCs. In parallel, direction-sensitive searches are pursued to parameterize dark matter particles after their discovery, or to probe physics beyond the neutrino fog. NEWAGE is a direction-sensitive WIMP search using a micro-pattern gaseous TPC with strip readout. To improve its sensitivity, we constructed C/N-1.0, a next-generation detector with an active volume of approximately 1 m^3, for future underground operation at Kamioka Underground Laboratory, and confirmed that three-dimensional track reconstruction is feasible. In this presentation, we report detector performance studies and discuss the readiness of C/N-1.0 for underground operation.

P26 : Hanwook BAE
(pdf):Status of Front-End Board Development for KamLAND2
 KamLAND2 is a next-generation underground neutrino experiment being constructed at the Kamioka mine, with operation expected in 2027. MoGURA2, its new data acquisition system, is designed to operate even under extreme conditions, such as a nearby supernova or intense muon signals. On the front-end board, analog circuitry amplifies PMT signals and converts them to differential signals for the RFSoC ADC. Its noise performance is evaluated by measuring RMS noise with no input. The RFSoC digitizes the signals and performs real-time processing, including Baseline Restoration (BLR), which compensates for baseline fluctuations after large PMT signals and improves detection of subsequent small signals. We report the analog performance, current digital processing development, and future plans.

P27 : Takumi Omori
(pdf):New Constraint on the Two-Neutrino Double Beta Decay of 160Gd with the PIKACHU Experiment
 This poster reports the first result of the PIKACHU Phase 1 experiment searching for double-beta decay of 160Gd with a GAGG scintillator. PIKACHU Phase 1 was designed to improve the sensitivity of the search and employed a 2.436 kg GAGG crystal containing 270 g of 160Gd, operated for 3102 h. Through a detailed and comprehensive background study, no significant excess from 160Gd 2nu2beta decay was observed, yielding a half-life limit of T1/2 > 4.1 × 10^19 yr at 90% confidence level. This result provides the strongest constraint on 160Gd 2nu2beta decay to date.

P28 : Makita Airu
(pdf):Search for the Toponium-like Signal with the ATLAS Experiment at the LHC: Expected Sensitivity Including Systematic Uncertainties in the Single-Lepton
 Measurements of top-quark pair production at the LHC have shown a significant excess over relativistic perturbative-QCD predictions in the invariant-mass region near the production threshold. ATLAS has observed this excess in the dilepton final state, making an independent validation in the single-lepton + jets final state and a quantitative assessment important. A leading interpretation attributes the excess to “toponium” near threshold; here, “toponium” refers to the quasi-bound top-quark pair and the cross-section enhancement from non-relativistic QCD effects. Using simulated samples, we report the expected discovery sensitivity to “toponium” in the single-lepton + jets final state, including major systematic uncertainties.

P29 : Hatsume Chujo
(pdf):Disc-Based Estimation of Dark Matter Density and Velocity Distribution Near the Sun
 To interpret the results of dark matter direct detection　experiments, the local dark matter density and velocity distribution are important inputs. They are estimated from observations or from cosmological simulations. In cosmological simulations, the estimates can depend on how Milky Way-like galaxies are selected and solar-neighborhood-like regions are extracted. In this study, we use the public TNG50 data of the IllustrisTNG project, selecting disc stars from their positions and local stellar density and extracting the dark matter particles around them. We compare the results with those obtained under less stringent criteria for galaxy selection and solar-neighborhood extraction.

P30 : Wentao Cai
(pdf):Toward Nuclear De-Excitation Measurements with Oxygen-Ion Beams for Improved DSNB Searches at Super-Kamiokande
 The Diffuse Supernova Neutrino Background (DSNB) search at Super-Kamiokande is limited by backgrounds from atmospheric-neutrino interactions with oxygen, whose prediction suffers from large uncertainties in nuclear de-excitation modeling. SAMURAI-79 aims to constrain this model by measuring nuclear de-excitations as a function of excitation energy. Excited 15N and 15O nuclei will be mass produced through the 16O(p,2p)15N and 16O(p,pn)15O reactions using oxygen-ion beams, with their excitation energies reconstructed by the missing-mass method. This poster presents the current status of SAMURAI-79, focusing on the development of the 16O(p,pn)15O* measurement, including neutron-detector readout electronics and Monte Carlo optimization of the detector configuration.

P31 : Yuno LEE
(pdf):Development and Performance Evaluation of Neutron Tagging for WCTE
 Neutron tagging in water Cherenkov detectors plays a crucial role in neutrino observation and background reduction. The Water Cherenkov Test Experiment (WCTE) is currently evaluating neutron tagging performance.  In this study, we develop a neutron tagging method for WCTE and evaluate its detection efficiency and associated systematic uncertainties by comparing neutron source calibration data with Monte Carlo (MC) simulations. We also investigate the effects of detector position dependence and accidental backgrounds, such as dark noise, on the tagging efficiency. This poster presents the current status of the neutron tagging analysis in WCTE, together with the latest results on neutron detection efficiency and associated systematic uncertainties.

P32 : Kaori Hattori
(pdf):Development of Superconducting Transition-Edge Sensors for Light Dark Matter Search
 Our group is developing superconducting transition-edge sensors (TES) sensitive to sub-eV signals for direct detection of light dark matter in the mass range of approximately 0.01 MeV to 100 MeV. The experiment is being prepared for deployment at the Kamioka underground lab. Using cryogenically cooled aluminum as the target, we aim to detect sub-eV signals generated by dark matter-electron scattering through TESs. We will report on testing of AlMn TESs and array readout.

P33 : ANAWAT RITTIRONG
(pdf):The Status of Laser Isotope Separation (LIS) of 48Ca for the Study of Neutrinoless Double Beta Decay
 Neutrinoless double beta decay (0νββ) can probe lepton number violation and neutrino mass. The CANDLES experiment uses 48Ca because of its high Q-value (4.23 MeV), but large-scale production remains challenging. We developed Laser Isotope Separation using a 422.792 nm blue laser to selectively deflect 48Ca. Isotope shifts were measured by fluorescence spectroscopy to optimize the laser wavelength. By reducing background pressure and improving beam collimation, the 40Ca halo was suppressed to 0.1%, achieving ~20% 48Ca enrichment at 25 mm off-axis, about 100 times its natural abundance (0.187%). We are now targeting 10 g/year production using a 2 W multi-slave injection laser system with improved collimation and a calcium collection substrate, toward future kilogram-scale production.

P34 : Tomoki Endo
(pdf):Quark Matter Equations of State in Strong Magnetic Fields and Hybrid Stars
 In strong magnetic fields, such as those expected in the cores of neutron stars, quark matter is significantly affected by the magnetic field and exhibits discretized energy states due to Landau levels, resulting in a stiffening of the equation of state. Hybrid stars containing quark matter in their cores are therefore expected to be capable of supporting large stellar masses, with their maximum masses readily exceeding twice the solar mass when this stiffened equation of state is applied.

P35 : Kiyoto Ogawa
(pdf):Full three-loop electroweak multiplet contributions to the electron electric dipole moment
 The electron electric dipole moment (EDM) is a powerful probe of CP violation beyond the Standard Model. Future experiments may reach new physics whose contribution first arises at the three-loop level. We consider additional SU(2)$_L$ multiplets with CP-violating Yukawa interactions, which induce the electron EDM at three loops. Previously, we estimated this contribution through the electroweak-Weinberg operator using SMEFT. However, its one-loop matching onto the electron EDM has no large logarithmic enhancement. Thus, other contributions at the same loop order can be important. We directly calculate the electron EDM at the full three-loop level and find that it is about three times larger than the contribution from the electroweak-Weinberg operator alone.

P36 : Hiroyuki Fujioka
(pdf):Toward a study of the charge density distribution of 48Ca via X-ray spectroscopy of muonic atoms
 The energy levels of a muonic atom, in which a negatively charged muon replaces an electron, are affected by the charge density distribution of the core nucleus. Inversely, by measuring X-ray energies of the muonic atom, information on the charge density distribution can be obtained. We plan to measure X-ray energies of muonic calcium atoms (in particular 48Ca) using transition-edge-sensor (TES) detectors at J-PARC MLF. We have already measured X-rays from a CaF2 target with natural isotropic abundance. In this presentation, we outline the project and report the current status of the analysis.

P37 : Rei Tanaka
(pdf):Optimization of an Atomic Beam System for Laser Isotope Separation of 48Ca
 The CANDLES group searches for neutrinoless double-beta decay (0νββ) to investigate the Majorana nature of neutrinos. To improve the sensitivity of 0νββ detection, we aim to produce a large quantity of isotope-enriched 48Ca. Improving the production efficiency of 48Ca requires highly directional atomic beams generated by optimizing the atomic beam system. In this study, we investigate the atomic beam system using both experiments and Monte Carlo simulations. We analyze the effects of collimator geometry, temperature, and material on atomic beam characteristics and compare the simulation results with experimental data. In this presentation, we report the current status of the study.

P38 : Hiroto Iseki
(pdf):Rabi oscillation for isotope enrichment
 The CANDLES experiment searches for neutrinoless double-beta decay (0νββ) using 48Ca, which has a high Q value of 4.27 MeV and thus enables low-background measurements. However, the natural abundance of 48Ca is only 0.187%, making isotope enrichment essential for increasing the amount of decaying nuclei(for a new CANDLES detector). This study employs a laser deflection method based on isotope shifts among Ca isotopes to selectively impart momentum to 48Ca atoms. Its efficiency is limited by momentum loss from spontaneous emission and by stimulated absorption and emission associated with Rabi oscillations at high laser power. We therefore investigate a method that induces stimulated emission to suppress photon loss and uses Rabi oscillations to improve isotope separation efficiency.

P39 : Yoshihito Gando
(pdf):Formulation of Copper-Ion-Exchanged Zeolites for Xenon Enrichment
 Future experiments searching for neutrinoless double-beta decay and direct dark matter detection will require approximately 100 tons of xenon. To ensure the feasibility of these experiments, we are developing a method to collect xenon from atmospheric air by adsorbing it using copper-ion-exchanged zeolites. We report on the method of formulation of the copper-ion-exchange zeolites and the current status of this project.

P40 : Tatsuya Gonda
(pdf):Inferring Proto-Neutron Star Parameters from Supernova Neutrino Data with Realistic Detector Background
 Supernova (SN) neutrinos are key messengers for exploring the interior of an SN, especially the properties of the Proto-Neutron Star (PNS). SPECIAL BLEND (Harada et al.2023) is a framework developed to estimate PNS parameters from SN neutrino data. It can estimate PNS radius, mass, and total emitted neutrino energy. However, in realistic observations, low-energy background events overlap in energy with SN neutrino events and degrade the estimation accuracy. To address this issue, we updated the estimation method by introducing an energy threshold. By excluding events below the threshold, background contamination can be reduced. We found that, for the SK fiducial volume, the energy threshold of 5.5 MeV allows the 1σ credible intervals to capture the true values for an SN up to 100 kpc away.

P41 : Soma Deguchi
(pdf):Indirect Dark Matter Search using MeV Gamma-Ray Observations of the Galactic Center
 The detailed spatial distributions and energy spectra of MeV gamma-rays from the Galactic Center region provide stringent constraints on the abundance of MeV dark matter and primordial black holes in the mass range of 10^{16-17} g. However, observations in this energy range remain challenging due to focusing difficulties and high background levels. To overcome these issues, we are developing an Electron-Tracking Compton Camera (ETCC) with powerful background rejection capabilities. We are preparing for the next scientific balloon mission, SMILE-3, which is planned for Spring 2028. In this poster, we present the scientific targets and an overview of the SMILE-3 mission.

P42 : Michinori Hirose
(pdf):Performance Characterization of a 38-50 GHz Millimeter-Wave Receiver System for Dark Photon Dark Matter Search in the DOSUE-RR Experiment
 Dark photons are one of the candidates for dark matter and are theoretically predicted to convert into photons at metal surfaces, with a frequency corresponding to their mass. The DOSUE-RR experiment searches for dark photons by detecting this converted photon with a millimeter-wave receiver. We have searched the 10-26.5 GHz band, but no significant signal has been observed. To extend the search to higher frequencies, the receiver's signal transmission system must be redesigned for the target band. In this study, based on the cryostat from our previous work, we changed the transmission line from coaxial cable to waveguide, developing a receiver covering 38–50 GHz (dark photon mass ~157-207 μeV). In this poster, we report the receiver characterization and the resulting search sensitivity.

P43 : Ryuto Ishida
(pdf):Do neutrinos transmit spin?
 We reformulate neutrino oscillation in the complete basis of Lorentz-covariant spinor wave packets. The oscillation kernel then closes exactly in terms of a single modified Bessel function, with no saddle-point approximation. Two results follow. First, in the nonrelativistic regime the covariant kernel reproduces the Gaussian localization and momentum-conservation factors with identical width-squared parameters. Second, spin is transmitted through a Wigner rotation whose angle depends on the mass eigenstate. A transverse momentum mismatch between production and detection therefore opens a spin-flipped oscillation channel whose weights carry the inverse neutrino masses at the level of packet overlaps.

P44 : Yuto Kamei
(pdf):Fundamental Evaluation of Hafnium LEKIDs Fabricated by Sputtering with Substrate Heating for Future Dark Matter Searches
 Kinetic Inductance Detectors (KIDs) are highly sensitive energy detectors that utilize superconductivity. Hafnium has the lowest superconducting transition temperature among metals accessible with modern refrigerator technologies. This characteristic enables a lower energy threshold compared to other superconductors, thereby expanding the potential for light dark matter searches. Therefore, we conducted R&D on the fabrication of hafnium-based KIDs and herein report the verification of their operation and fundamental evaluation.

P45 : Yukikatsu Terada
(pdf):High-resolution X-ray astrophysical search for r-process nucleosynthesis signatures from Galactic binary neutron-star mergers
 Binary neutron star mergers (NSMs) are widely considered r-process nucleosynthesis sites, as suggested by infrared observations of kilonovae and by the gravitational‑wave event. Unstable heavy nuclei produced via the r‑process later decay, emitting nuclear gamma rays along with internal conversion X‑rays. The flux of a single merger is far below the sensitivity of existing observatories. Detectability, however, becomes plausible if we focus on emission from r‑process nuclei with Myr‑scale decay times synthesized in multiple NSMs (like in globular clusters or the nuclear stellar cluster) , tracing the integrated merger history over their decay time. In this presentation, we introduce an astronomical survey strategy using the recent high resolution X-ray observatory XRISM.

P46 : Shuki Nomura
(pdf):Development of Low-Radioactivity Photosensors for Future Large Liquid-Xenon Dark Matter Detectors
 Direct dark matter searches using large liquid-xenon time projection chambers have achieved high sensitivity to weakly interacting massive particles. For future experiments with larger target masses and longer exposures, further reduction of radioactive backgrounds from detector components will become increasingly important. PAD and SiGHT are novel hybrid photosensor concepts that combine a photocathode for converting photons into photoelectrons with a SiPM for detecting the photoelectrons. These concepts aim to achieve low-radioactivity photosensors for future liquid-xenon detectors. We studied and optimized the geometries of PAD and SiGHT using electric-field simulations to efficiently collect photoelectrons onto the SiPM. In this poster, we present results of the geometry optimization.

P47 : Masamichi Zaizen
(pdf):Toward unified modeling of asymptotic states of collective neutrino oscillation
 Neutrinos are emitted from core-collapse supernovae and binary neutron-star mergers, where neutrino transport plays a crucial role in shaping the dynamics and observables. Recent studies have revealed that quantum kinetics of neutrinos can induce dramatic flavor evolution, fundamentally altering the neutrino radiation field in such astrophysical events. However, the physical scale is the order of sub-centimeter and is difficult to be directly resolved with global dynamics in explosive phenomena simultaneously. In this study, we exhibit the numerical simulations of nonlinear neutrino flavor conversion under multi-energy, multi-angle, and inhomogeneous neutrino background. We will then discuss how the asymptotic states are analytically predicted based on the linear stability analysis.

P48 : Yuko Watanabe
(pdf):AXEL Experiment : High-Precision Correction of MPPC Nonlinearity Using Signal Waveform Deconvolution
 In the AXEL (A Xenon ElectroLuminescence detector) experiment, we are developing a high-pressure Xe gas TPC toward a high-sensitivity search for neutrinoless double beta decay. We have developed the ELCC (Electroluminescence Light Collection Cell), which converts ionization electrons into photons with low fluctuations and detects them with MPPCs, achieving high energy resolution. However, the MPPC output signals must be passed through a low-pass filter (LPF), and this LPF degrades the correction accuracy of the MPPC nonlinearity. Therefore, we attempt to improve the energy resolution by deconvolving acquired signals with the LPF’s impulse response to restore the high-frequency components necessary for the correction. In this presentation, I report on this method and its effectiveness.

P49 : Mai Morizawa
(pdf):Neutron Track Identification with a 3D Convolutional Neural Network
 In direct detection of dark matter (DM), distinguishing signals from background events is essential for sensitivity. Since neutron-induced events can be similar to those of DM, measuring the environmental neutron flux is important. Nuclear emulsion is suitable for this measurement, because the energy and direction of each neutron can be reconstructed from a single recoil track. However, the readout produces tens to a hundred TB of image data, and selecting the tracks quickly and accurately is the main difficulty in scaling up the analysis. We investigate the automated selection of neutron events using a 3D convolutional neural network applied to particle tracks in nuclear emulsions, and evaluate the performance using signal probability, noise efficiency, and signal-to-noise curves.

P50 : Hanchun Jiang
(pdf):Matter-Neutrino Resonance in Binary Neutron Star Merger Outflows
 Binary neutron star mergers produce neutron-rich outflows where neutrino flavor conversion can modify the electron fraction and r-process nucleosynthesis. At high neutrino density, matter-neutrino resonance (MNR) can occur when the matter and neutrino self-interaction potentials nearly cancel. We study multi-angle MNR with nonlinear flavor simulations and linear stability analysis. Different angular modes undergo Landau-Zener-like crossings at different radii. Both approaches show that instability develops when the matter potential decreases faster than the self-interaction potential, but not for the opposite ordering. These results identify the mechanism of multi-angle MNR and the radial-profile condition for its instability.

P51 : Takuya Sako
(pdf):Performance Evaluation of Ultra-Low-Radioactivity PMTs and Impurity Evaluation of High-Purity GAGG Crystal in the PIKACHU experiment
 In the search for double beta decay of 160Gd using GAGG crystals in the PIKACHU experiment, reducing background events (BG) originating from 40K is an important challenge. In particular, gamma-ray BG from 40K contained in the current PMT (R6231-04) are expected to be reduced by using an ultra-low-radioactivity PMT (R11065-20). In this presentation, we report the results of evaluations of the ultra-low-radioactivity PMT, including its long-term stability and its impact on pulse-shape discrimination performance, in comparison with the current PMT. In addition to the PMT performance evaluation, we also report the results of the BG measurement and impurity evaluation using Crystal 9, a new high-purity GAGG crystal, with the aim of improving the sensitivity of the search.

P52 : Kelin QIAO
(pdf):A New High-Intensity Ultracold Neutron Source for New Physics Probes
 The neutron electric dipole moment (nEDM) is a sensitive probe of CP violation beyond the Standard Model and is relevant to questions such as baryogenesis and dark matter. To improve nEDM sensitivity, the TUCAN collaboration has commissioned a spallation-driven ultracold neutron (UCN) source at TRIUMF. Neutrons produced by a 483 MeV proton beam are moderated by heavy water and liquid deuterium, converted to UCNs in superfluid helium at about 1 K, and extracted to the experimental area. A continuous UCN rate of 6.75(3) × 10^5 UCN/s was measured, making it the world’s highest-intensity UCN source and enabling nEDM sensitivity toward 10^-27 e·cm. This contribution presents recent source results and prospects for future nEDM and new-physics searches.

P01 : Yukitoshi Ota
(pdf):Development of Chelating Fibers for Adsorption of Ultra-trace Radioactive Impurities

P02 : Mao Nishigami
(pdf):Neutron Detection Efficiency Evaluation in the Super-Kamiokande Gd Phases

P03 : Kanji Mori
(pdf):Supernova explosions hindered by eV-mass sterile neutrinos

P04 : Ayuki Takeshita
(pdf):Evaluation of the Fluorescence Properties of PMT Quartz Window for the XLZD Liquid Xenon Dark Matter Experiment

P05 : Yuya Inaba
(pdf):Temperature dependence of Rn adsorption performance by silver zeolite in air and noble gases.

P06 : Naoki Kinjo
(pdf):Evaluation of Chelate-Resin Adsorption Efficiency for Collecting 48Sc for 48Ca Beta-Decay Half-life Measurement

P07 : Junying Huang
(pdf):Probing Inelastic Higgsino Dark Matter at High Recoil Energies with XENONnT

P08 : Hiroto Bambara
(pdf):Development of the Radon Removal System Using Silver Zeolite for Hyper-Kamiokande

P09 : Kenta Noda
(pdf):Development of the CaF₂ Scintillating Calorimeter

P10 : Hiyori Nishimura
(pdf):Study of Radon Adsorption Performance of Silver Zeolites

P11 : Shunsuke Adachi
(pdf):DOSUE-RR–Searching for Wavy Dark Matter using Millimeter-Wave Receivers

P12 : Takashi Toma
(pdf):A radiative neutrino mass model with semi-annihilating boosted dark matter

P13 : Shinya Aoyama
(pdf):Evaluation of the stability of the energy scale using decay electrons detected in Super-Kamiokande

P14 : Tomoaki Tada
(pdf):Measurement of the kaon-to-pion ratio for the atmospheric neutrino using the cosmic-ray muon data in Super-Kamiokande

P15 : Nozomu Tominaga
(pdf):Neutrino Process in Supernovae: Insights from Nucleosynthesis and Metal-Poor Stars

P16 : Alejandro Yankelevich
(pdf):Measurement of the solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV

P17 : Tatsuki Washimi
(pdf):Studies on Underground Gravitational Wave Detectors: Direct Heavy Dark Matter Search and Gravity Gradient Noise

P18 : Wakako Toyama
(pdf):Development of pixel readout negative ion gaseous TPC for dark matter searches

P19 : Akihiro Inoue
(pdf):A diagnostic method for Proto-Neutron Star magnetic fields by supernova fallback neutrinos

P20 : Keigo Kadota
(pdf):Measurement of the quenching factor for BGO crystals for the BISCOTTEE experiment

P21 : Satoshi Kato
(pdf):Detector Calibration and Initial Measurement of Double Beta Decay of 96Zr in the ZICOS Experiment

P22 : Atsuya Yoshida
(pdf):Measurement of cosmic-ray muon with the BISCOTTEE setup

P23 : Fuminobu TAKAHASHI
(pdf):Resolving the QCD axion domain wall problem with a light axion

P24 : Kaede Furukawa
(pdf):Estimation of background events induced by solar neutrinos in fluorine-based dark matter detectors

P25 : Ryota Namai
(pdf):Status of C/N-1.0: A Large Gaseous TPC for Direction-Sensitive Dark Matter Search

P26 : Hanwook BAE
(pdf):Status of Front-End Board Development for KamLAND2

P27 : Takumi Omori
(pdf):New Constraint on the Two-Neutrino Double Beta Decay of 160Gd with the PIKACHU Experiment

P28 : Makita Airu
(pdf):Search for the Toponium-like Signal with the ATLAS Experiment at the LHC: Expected Sensitivity Including Systematic Uncertainties in the Single-Lepton

P29 : Hatsume Chujo
(pdf):Disc-Based Estimation of Dark Matter Density and Velocity Distribution Near the Sun

P30 : Wentao Cai
(pdf):Toward Nuclear De-Excitation Measurements with Oxygen-Ion Beams for Improved DSNB Searches at Super-Kamiokande

P31 : Yuno LEE
(pdf):Development and Performance Evaluation of Neutron Tagging for WCTE

P32 : Kaori Hattori
(pdf):Development of Superconducting Transition-Edge Sensors for Light Dark Matter Search

P33 : ANAWAT RITTIRONG
(pdf):The Status of Laser Isotope Separation (LIS) of 48Ca for the Study of Neutrinoless Double Beta Decay

P34 : Tomoki Endo
(pdf):Quark Matter Equations of State in Strong Magnetic Fields and Hybrid Stars

P35 : Kiyoto Ogawa
(pdf):Full three-loop electroweak multiplet contributions to the electron electric dipole moment

P36 : Hiroyuki Fujioka
(pdf):Toward a study of the charge density distribution of 48Ca via X-ray spectroscopy of muonic atoms

P37 : Rei Tanaka
(pdf):Optimization of an Atomic Beam System for Laser Isotope Separation of 48Ca

P38 : Hiroto Iseki
(pdf):Rabi oscillation for isotope enrichment

P39 : Yoshihito Gando
(pdf):Formulation of Copper-Ion-Exchanged Zeolites for Xenon Enrichment

P40 : Tatsuya Gonda
(pdf):Inferring Proto-Neutron Star Parameters from Supernova Neutrino Data with Realistic Detector Background

P41 : Soma Deguchi
(pdf):Indirect Dark Matter Search using MeV Gamma-Ray Observations of the Galactic Center

P42 : Michinori Hirose
(pdf):Performance Characterization of a 38-50 GHz Millimeter-Wave Receiver System for Dark Photon Dark Matter Search in the DOSUE-RR Experiment

P43 : Ryuto Ishida
(pdf):Do neutrinos transmit spin?

P44 : Yuto Kamei
(pdf):Fundamental Evaluation of Hafnium LEKIDs Fabricated by Sputtering with Substrate Heating for Future Dark Matter Searches

P45 : Yukikatsu Terada
(pdf):High-resolution X-ray astrophysical search for r-process nucleosynthesis signatures from Galactic binary neutron-star mergers

P46 : Shuki Nomura
(pdf):Development of Low-Radioactivity Photosensors for Future Large Liquid-Xenon Dark Matter Detectors

P47 : Masamichi Zaizen
(pdf):Toward unified modeling of asymptotic states of collective neutrino oscillation

P48 : Yuko Watanabe
(pdf):AXEL Experiment : High-Precision Correction of MPPC Nonlinearity Using Signal Waveform Deconvolution

P49 : Mai Morizawa
(pdf):Neutron Track Identification with a 3D Convolutional Neural Network

P50 : Hanchun Jiang
(pdf):Matter-Neutrino Resonance in Binary Neutron Star Merger Outflows

P51 : Takuya Sako
(pdf):Performance Evaluation of Ultra-Low-Radioactivity PMTs and Impurity Evaluation of High-Purity GAGG Crystal in the PIKACHU experiment

P52 : Kelin QIAO
(pdf):A New High-Intensity Ultracold Neutron Source for New Physics Probes

P01 : Yukitoshi Ota
(pdf):Development of Chelating Fibers for Adsorption of Ultra-trace Radioactive Impurities
 In experiments such as KamLAND, Super-Kamiokande, and other ultra-low-background experiments, radioactive impurities contained in liquid scintillators, ultrapure water, and Gd-water are significant sources of background radiation. In this study, we are developing filters optimized for U/Th/Ra using chelating resin. In this presentation, we will report on the current status and future prospects of chelating filter development for liquid scintillators, ultrapure water, and Gd-water.

P02 : Mao Nishigami
(pdf):Neutron Detection Efficiency Evaluation in the Super-Kamiokande Gd Phases
 Super-Kamiokande has been operating with gadolinium loading (SK-Gd) to enhance its sensitivity to the diffuse supernova neutrino background (DSNB). The addition of Gd significantly improves the detection efficiency of neutrons produced by inverse beta decay of electron antineutrinos. These neutrons are identified using the neutron tagging (ntag) algorithm. In this study, we evaluated the ntag efficiency using 241Am-Be (Am/Be) neutron source via a delayed coincidence method. Comparing calibration data with Geant4-based Monte Carlo simulation allowed us to estimate the systematic uncertainties of the detector simulation. Furthermore, we investigated the long-term stability of the ntag efficiency to ensure the reliability of the ongoing SK-Gd dataset for DSNB analysis.

P03 : Kanji Mori
(pdf):Supernova explosions hindered by eV-mass sterile neutrinos
 Light sterile neutrinos, 𝜈𝑠, are often introduced to explain an anomalous deficit in the electron antineutrino flux from nuclear reactors. If they exist, sterile neutrinos would also be produced in collapsing massive stars through the active-sterile neutrino oscillation. In order to investigate the impacts of sterile neutrinos on supernova dynamics, we perform two-dimensional neutrino-radiation hydrodynamic simulations of stellar core-collapse coupled with the active-sterile oscillation. We find that, if the mixing angle and the mass difference between 𝜈𝑒 and 𝜈𝑠 are large enough, the star fails to explode. This suggests that these mixing parameters relevant to sterile neutrinos could be constrained by supernova explodability.

P04 : Ayuki Takeshita
(pdf):Evaluation of the Fluorescence Properties of PMT Quartz Window for the XLZD Liquid Xenon Dark Matter Experiment
 The future liquid xenon dark matter experiment XLZD plans to use photomultiplier tubes (PMTs) as its photosensors. Since quartz is used as the PMT window material, understanding its properties is of great importance. In recent years, delayed photon noise following the S1 and S2 scintillation signals has become a significant concern, and fluorescence from the quartz window is considered to be one of its primary sources. In this study, we evaluate several quartz glass samples as candidate window materials for next-generation PMTs by comparing their fluorescence properties.

P05 : Yuya Inaba
(pdf):Temperature dependence of Rn adsorption performance by silver zeolite in air and noble gases.
 In underground experiments, Rn-222 is the primary source of background radiation, and in recent years, silver zeolite has attracted attention as an adsorbent capable of reducing this background radiation. In this study, we investigated the temperature dependence of Rn adsorption performance in air and noble gases for 8Ag-FER-B and Ag-ETS-10, two silver zeolites known for their particularly high adsorption capacity. In this presentation, I will report on the interim results of this research.

P06 : Naoki Kinjo
(pdf):Evaluation of Chelate-Resin Adsorption Efficiency for Collecting 48Sc for 48Ca Beta-Decay Half-life Measurement
 To measure the beta decay half-life of 48Ca, we use a chelating resin that selectively adsorbs and concentrates the daughter scandium ions, followed by gamma-ray measurement. This approach aims to reduce the overall sample volume and compact the experimental system. In this study, we conducted experiments to evaluate the ion adsorption efficiency of the chelating resin.

P07 : Junying Huang
(pdf):Probing Inelastic Higgsino Dark Matter at High Recoil Energies with XENONnT
 Inelastic dark matter (iDM) provides an extension to the standard WIMP paradigm, naturally arising in scenarios such as Higgsino-like dark matter. In this framework, scattering proceeds via a transition to a heavier degenerate state, where the associated kinematic threshold shifts the expected nuclear recoil (NR) spectrum toward significantly higher energies. Consequently, standard WIMP searches leave a vast high-recoil window largely unexplored. We report the status of a dedicated iDM search using XENONnT data. Moving beyond conventional WIMP methodologies, this project incorporates liquid xenon (LXe) response modeling and systematic calibration studies at elevated recoil energies for both NR and electronic recoil (ER) signals.

P08 : Hiroto Bambara
(pdf):Development of the Radon Removal System Using Silver Zeolite for Hyper-Kamiokande
 For Hyper-Kamiokande, a next-generation large-scale water Cherenkov detector, it is desirable to reduce the concentration of background radon in both water and air to 1 mBq/m³ or less. In this study, we constructed a device to evaluate the radon adsorption performance using silver zeolite, which exhibits high adsorption properties for radon in air, and assessed its suitability for application in Hyper-Kamiokande. In this presentation, we will report on the progress made in the development of a radon removal system designed for actual operation.

P09 : Kenta Noda
(pdf):Development of the CaF₂ Scintillating Calorimeter
 Neutrinoless double-beta decay (0νββ) is one of the most important processes in the search for new physics. The CANDLES collaboration aims to observe the 0νββ decay of 48Ca.48Ca has the highest Q-value, making it particularly advantageous for suppressing background (BG) events. Although previous CANDLES experiments did not observe 0νββ decay, the limited energy resolution of the detector allowed the two-neutrino double-beta decay (2νββ) of 48Ca to contribute as a background to the expected 0νββ peak. To overcome this limitation, we are developing a CaF₂ scintillating calorimeter, which offers significantly improved energy resolution. In this presentation, we report the results of performance tests of the readout sensor conducted as part of the detector development.

P10 : Hiyori Nishimura
(pdf):Study of Radon Adsorption Performance of Silver Zeolites
  Radon (Rn-222), a natural radioactive noble gas, can be a major background source in underground experiments.Reducing radon levels is crucial for improving experimental sensitivity. Some silver zeolites have been reported to exhibit radon adsorption capacities in air about 700 times higher than those of activated carbon at room temperature, attracting attention as promising radon mitigation materials. The strong adsorption of noble gases such as radon by silver zeolites is believed to involve chemisorption by metallic silver or silver ions, although the mechanism remains unclear. In this study, we compare radon adsorption by various silver zeolites in air and argon to provide data for elucidating their noble-gas adsorption mechanism. The current status of this research is reported.

P11 : Shunsuke Adachi
(pdf):DOSUE-RR–Searching for Wavy Dark Matter using Millimeter-Wave Receivers
 Our project, DOSUE-RR (Dark-photon dark-matter Observing System for Un-Explored Radio-Range), aims to detect ultra-light dark matter using millimeter-wave receivers. Our targets are the dark photon and axion-like particles (ALPs) in the μeV–meV mass range, among the leading dark matter candidates. A dark photon (or ALP) can convert into an ordinary photon at a metallic boundary, with the photon frequency corresponding to the dark matter mass via hν∼mc². We target the full millimeter-wave band (20–300 GHz), corresponding to a mass range of about 80 μeV to 1.2 meV, splitting the measurement into several bands and modifying receivers for each band. I will present an overview of our current activities, mainly the dark photon search, plus an ALP search using a magnet.

P12 : Takashi Toma
(pdf):A radiative neutrino mass model with semi-annihilating boosted dark matter
 In this work, we construct a radiative neutrino mass model that allows for the production of boosted dark matter in the present universe through semi-annihilation. A Dirac fermion serves as the dark matter candidate, which semi-annihilates into an anti-dark matter particle and a neutrino. Taking into account the relevant experimental and theoretical constraints, we find that the boosted dark matter can be probed by DARWIN if its mass lies in the range of 20–50 MeV and the semi-annihilation proceeds through a resonance with a tuning of O(0.1)%. Furthermore, the monochromatic neutrino produced simultaneously with the boosted dark matter can also be detected at Hyper-Kamiokande and DUNE in part of the allowed parameter space.

P13 : Shinya Aoyama
(pdf):Evaluation of the stability of the energy scale using decay electrons detected in Super-Kamiokande
 In the Super-Kamiokande (SK) experiment, understanding the energy scale and its time dependence is essential. In this study, we develop a calibration method using decay electrons from cosmic-ray muons, which are distributed throughout the detector and are continuously available as a calibration sample. However, the evaluation of the energy scale is affected by the anisotropic emission of decay electrons due to muon polarization, as well as by the spatial distribution of stopping muons combined with the position-dependent detector response. In this presentation, we report the current status of a simulation that incorporates these effects and present an evaluation of the time dependence of the energy scale.

P14 : Tomoaki Tada
(pdf):Measurement of the kaon-to-pion ratio for the atmospheric neutrino using the cosmic-ray muon data in Super-Kamiokande
 Atmospheric neutrinos and cosmic-ray muons are produced by interactions of primary cosmic rays with the atmosphere. Pions and kaons decay into atmospheric neutrinos and cosmic-ray muons, carrying information on hadronic interactions. Atmospheric neutrino flux models still have significant uncertainties, mainly due to the poorly known parent meson ratio. Cosmic-ray muons provide an effective probe to constrain this uncertainty. In this poster, we analyze the seasonal variation of TeV cosmic-ray muons observed with the Super-Kamiokande detector and their correlation with atmospheric temperature. From this correlation, we determine the parent meson K/π ratio, providing new constraints on atmospheric neutrino flux models.

P15 : Nozomu Tominaga
(pdf):Neutrino Process in Supernovae: Insights from Nucleosynthesis and Metal-Poor Stars
 Core-collapse supernovae (CCSNe) are key sources of heavy elements and drivers of cosmic chemical evolution. To constrain the neutrino process and explosion mechanisms, we combine supernova nucleosynthesis with abundance patterns of metal-poor stars. Our simulations show that Sc, Ti, and V abundances in very metal-poor stars require explosive nucleosynthesis under a neutrino exposure of ~10^35 erg cm^-2 and temperatures of 2.0-3.2 GK, conditions that may be realized in multidimensional explosions. We also present abundance studies of EMP and CEMP stars, including signatures of the weak r-process, K production, and F production in energetic supernovae, demonstrating that metal-poor stars provide quantitative probes of the neutrino process in CCSNe.

P16 : Alejandro Yankelevich
(pdf):Measurement of the solar neutrino interaction rate below 3.49 MeV in Super-Kamiokande-IV
 Observing boron-8 solar neutrino interactions in Super-Kamiokande at low energies is crucial for probing the transition between MSW-dominated and vacuum-dominated neutrino flavor conversion. We present a new analysis of the solar neutrino interaction rate below the previous 3.49 MeV electron kinetic energy threshold for the full SK-IV period, utilizing wideband intelligent trigger data and a boosted decision tree for background reduction. A signal indication is observed between 2.99 and 3.49 MeV with 2.76σ significance and a data to unoscilated Monte Carlo ratio of 0.307 +0.112 -0.111. These low-energy data have a negligible effect on the 1σ intervals of the fits to the solar neutrino energy spectrum but have a noticeable effect on the best fit when using the exponential parametrization.

P17 : Tatsuki Washimi
(pdf):Studies on Underground Gravitational Wave Detectors: Direct Heavy Dark Matter Search and Gravity Gradient Noise
 This research is a pilot study aimed at the direct detection of heavy dark matter using underground gravitational-wave detectors such as KAGRA and ET. The setup utilizes the gravitational interaction between dark matter and the test-mass mirrors of a laser interferometer—which is suspended by a multi-stage pendulum vibration isolation system—thereby eliminating the need to assume other types of interactions and enabling a background-free search, provided the signal-to-noise ratio is sufficient. The study involves precisely modeling the complex response of the gravitational-wave detector and utilizing this response model to evaluate gravity gradient noise.

P18 : Wakako Toyama
(pdf):Development of pixel readout negative ion gaseous TPC for dark matter searches
 NEWAGE is a direct dark matter search experiment with directional analysis. We use a low-pressure gaseous time projection chamber to detect nuclear recoils and to reconstruct their 3D tracks. Our current detector is 2D strip readout and operates with CF4 gas. In future experiments, we plan to adopt a pixel-readout gaseous TPC filled with SF6, which is a negative-ion gas. Pixel readout can distinguish real tracks from ghost tracks. It allows to improve the angular resolution. In SF6 gas, two types of negative ions are produced, and they drift through the gas. The difference of drift velocity allows to reconstruct 3D absolute track position. It contributes to improve the BG rejection. In this poster, we present the development of a new pixel-readout gaseous TPC using SF6.

P19 : Akihiro Inoue
(pdf):A diagnostic method for Proto-Neutron Star magnetic fields by supernova fallback neutrinos
 We propose a novel diagnostic to probe proto-neutron star (PNS) magnetic fields using neutrinos associated with supernova fallback. Our general-relativistic MHD simulations show that stronger magnetic fields and lower fallback accretion rates produce softer neutrino spectra. This spectral softening arises because neutrinos are mainly emitted near the magnetospheric radius, which is larger for stronger magnetic fields and lower accretion rates. For a normal neutrino mass ordering, fallback neutrinos from a Galactic supernova could constrain PNS magnetic fields if the accretion rate exceeds about 1e-3 Msun/sec and fallback begins more than 10 seconds after core bounce. This method may offer a new way to study neutron-star diversity.

P20 : Keigo Kadota
(pdf):Measurement of the quenching factor for BGO crystals for the BISCOTTEE experiment
 Atmospheric-neutrino–induced neutral-current quasi-elastic (NCQE) interactions on oxygen are a major background in searches for the diffuse supernova neutrino background (DSNB). The predicted NCQE event rate currently has a large systematic uncertainty. To reduce this uncertainty, we propose BISCOTTEE, which aims to measure neutrino–oxygen NCQE interactions in short baseline. It is important to observe recoil nuclei in the BISCOTTEE, and we measured the scintillation quenching factor for oxygen nuclear recoils in BGO using a BGO detector and a liquid-scintillator neutron detector. The measurement was performed with a 61.9 MeV monoenergetic neutron beam at RCNP. We will present the experimental setup and analysis of the beam test.

P21 : Satoshi Kato
(pdf):Detector Calibration and Initial Measurement of Double Beta Decay of 96Zr in the ZICOS Experiment
 The ZICOS (ZIrconium Complex in Organic Scintillator) experiment aims to observe the neutrinoless double beta decay of 96Zr. As an initial proof-of-principle step toward this goal, we installed the detector at the Lab-A experimental area in the Kamioka mine, performed calibration using gamma-ray sources, and conducted an initial measurement with 0.2 g of 96Zr from November 24 to 25, 2025. In this presentation, we report the results of the gain calibration of the Hamamatsu Photonics R10789 photomultiplier tubes (PMTs), the detector energy calibration, and the initial results from the two-neutrino double beta decay measurement using 96Zr.

P22 : Atsuya Yoshida
(pdf):Measurement of cosmic-ray muon with the BISCOTTEE setup
 One of the major backgrounds in the diffuse supernova neutrino background (DSNB) search with the SK-Gd experiment is neutral-current quasi-elastic (NCQE) scattering of atmospheric neutrinos on oxygen nuclei. To understand this reaction experimentally, we are planning BISCOTTEE (BISmuth-germanate Crystal-based neutrinO [neutrOn]–nucleus scattering Experiment), which will use BGO crystals and a short-baseline neutrino beam. We plan to carry out a neutrino beam test with a newly built setup. Prior to this, it is necessary to understand the setup's response to the muons produced by neutrino interactions. We therefore measured cosmic-ray muons using this setup. In this presentation, we report on the setup and the results of the cosmic-ray muon measurement.

P23 : Fuminobu TAKAHASHI
(pdf):Resolving the QCD axion domain wall problem with a light axion
 We propose a solution to the QCD axion domain wall problem by introducing a massless or light axion coupled to gluons. We focus on the case where the new axion forms strings after inflation. Through mixing with the QCD axion, QCD domain walls become bounded by these strings and confined into cosmologically safe string bundles. Some bundles may survive until today and produce observable signatures, including gravitational waves, cosmic birefringence, and CMB anisotropies. Their detection together with the QCD axion would provide a smoking-gun signal of this mechanism. The Peccei–Quinn mechanism remains effective, so the strong CP problem is not reintroduced. We identify the viable parameter region and discuss the cosmological implications.

P24 : Kaede Furukawa
(pdf):Estimation of background events induced by solar neutrinos in fluorine-based dark matter detectors
 Searching for spin-dependent interactions of dark matter is important 
for understanding the nature of dark matter. The scale-up of experiments
 using fluorine targets to search for spin-dependent dark matter–nucleon
 scattering is currently under consideration. On the other hand, fluorine has a relatively large electron-neutrino absorption rate, and this
 process is expected to produce background events that can mimic dark matter scattering. In this study, we theoretically calculate the
expected numbers of dark matter interactions and solar neutrino-induced 
interactions using CF4 target. We also estimate the potential overlap between dark matter signals and solar neutrino signals.

P25 : Ryota Namai
(pdf):Status of C/N-1.0: A Large Gaseous TPC for Direction-Sensitive Dark Matter Search
 The sensitivity of direct dark matter searches has been steadily improved through energy-sensitive experiments such as dual-phase liquid xenon TPCs. In parallel, direction-sensitive searches are pursued to parameterize dark matter particles after their discovery, or to probe physics beyond the neutrino fog. NEWAGE is a direction-sensitive WIMP search using a micro-pattern gaseous TPC with strip readout. To improve its sensitivity, we constructed C/N-1.0, a next-generation detector with an active volume of approximately 1 m^3, for future underground operation at Kamioka Underground Laboratory, and confirmed that three-dimensional track reconstruction is feasible. In this presentation, we report detector performance studies and discuss the readiness of C/N-1.0 for underground operation.

P26 : Hanwook BAE
(pdf):Status of Front-End Board Development for KamLAND2
 KamLAND2 is a next-generation underground neutrino experiment being constructed at the Kamioka mine, with operation expected in 2027. MoGURA2, its new data acquisition system, is designed to operate even under extreme conditions, such as a nearby supernova or intense muon signals. On the front-end board, analog circuitry amplifies PMT signals and converts them to differential signals for the RFSoC ADC. Its noise performance is evaluated by measuring RMS noise with no input. The RFSoC digitizes the signals and performs real-time processing, including Baseline Restoration (BLR), which compensates for baseline fluctuations after large PMT signals and improves detection of subsequent small signals. We report the analog performance, current digital processing development, and future plans.

P27 : Takumi Omori
(pdf):New Constraint on the Two-Neutrino Double Beta Decay of 160Gd with the PIKACHU Experiment
 This poster reports the first result of the PIKACHU Phase 1 experiment searching for double-beta decay of 160Gd with a GAGG scintillator. PIKACHU Phase 1 was designed to improve the sensitivity of the search and employed a 2.436 kg GAGG crystal containing 270 g of 160Gd, operated for 3102 h. Through a detailed and comprehensive background study, no significant excess from 160Gd 2nu2beta decay was observed, yielding a half-life limit of T1/2 > 4.1 × 10^19 yr at 90% confidence level. This result provides the strongest constraint on 160Gd 2nu2beta decay to date.

P28 : Makita Airu
(pdf):Search for the Toponium-like Signal with the ATLAS Experiment at the LHC: Expected Sensitivity Including Systematic Uncertainties in the Single-Lepton
 Measurements of top-quark pair production at the LHC have shown a significant excess over relativistic perturbative-QCD predictions in the invariant-mass region near the production threshold. ATLAS has observed this excess in the dilepton final state, making an independent validation in the single-lepton + jets final state and a quantitative assessment important. A leading interpretation attributes the excess to “toponium” near threshold; here, “toponium” refers to the quasi-bound top-quark pair and the cross-section enhancement from non-relativistic QCD effects. Using simulated samples, we report the expected discovery sensitivity to “toponium” in the single-lepton + jets final state, including major systematic uncertainties.

P29 : Hatsume Chujo
(pdf):Disc-Based Estimation of Dark Matter Density and Velocity Distribution Near the Sun
 To interpret the results of dark matter direct detection　experiments, the local dark matter density and velocity distribution are important inputs. They are estimated from observations or from cosmological simulations. In cosmological simulations, the estimates can depend on how Milky Way-like galaxies are selected and solar-neighborhood-like regions are extracted. In this study, we use the public TNG50 data of the IllustrisTNG project, selecting disc stars from their positions and local stellar density and extracting the dark matter particles around them. We compare the results with those obtained under less stringent criteria for galaxy selection and solar-neighborhood extraction.

P30 : Wentao Cai
(pdf):Toward Nuclear De-Excitation Measurements with Oxygen-Ion Beams for Improved DSNB Searches at Super-Kamiokande
 The Diffuse Supernova Neutrino Background (DSNB) search at Super-Kamiokande is limited by backgrounds from atmospheric-neutrino interactions with oxygen, whose prediction suffers from large uncertainties in nuclear de-excitation modeling. SAMURAI-79 aims to constrain this model by measuring nuclear de-excitations as a function of excitation energy. Excited 15N and 15O nuclei will be mass produced through the 16O(p,2p)15N and 16O(p,pn)15O reactions using oxygen-ion beams, with their excitation energies reconstructed by the missing-mass method. This poster presents the current status of SAMURAI-79, focusing on the development of the 16O(p,pn)15O* measurement, including neutron-detector readout electronics and Monte Carlo optimization of the detector configuration.

P31 : Yuno LEE
(pdf):Development and Performance Evaluation of Neutron Tagging for WCTE
 Neutron tagging in water Cherenkov detectors plays a crucial role in neutrino observation and background reduction. The Water Cherenkov Test Experiment (WCTE) is currently evaluating neutron tagging performance.  In this study, we develop a neutron tagging method for WCTE and evaluate its detection efficiency and associated systematic uncertainties by comparing neutron source calibration data with Monte Carlo (MC) simulations. We also investigate the effects of detector position dependence and accidental backgrounds, such as dark noise, on the tagging efficiency. This poster presents the current status of the neutron tagging analysis in WCTE, together with the latest results on neutron detection efficiency and associated systematic uncertainties.

P32 : Kaori Hattori
(pdf):Development of Superconducting Transition-Edge Sensors for Light Dark Matter Search
 Our group is developing superconducting transition-edge sensors (TES) sensitive to sub-eV signals for direct detection of light dark matter in the mass range of approximately 0.01 MeV to 100 MeV. The experiment is being prepared for deployment at the Kamioka underground lab. Using cryogenically cooled aluminum as the target, we aim to detect sub-eV signals generated by dark matter-electron scattering through TESs. We will report on testing of AlMn TESs and array readout.

P33 : ANAWAT RITTIRONG
(pdf):The Status of Laser Isotope Separation (LIS) of 48Ca for the Study of Neutrinoless Double Beta Decay
 Neutrinoless double beta decay (0νββ) can probe lepton number violation and neutrino mass. The CANDLES experiment uses 48Ca because of its high Q-value (4.23 MeV), but large-scale production remains challenging. We developed Laser Isotope Separation using a 422.792 nm blue laser to selectively deflect 48Ca. Isotope shifts were measured by fluorescence spectroscopy to optimize the laser wavelength. By reducing background pressure and improving beam collimation, the 40Ca halo was suppressed to 0.1%, achieving ~20% 48Ca enrichment at 25 mm off-axis, about 100 times its natural abundance (0.187%). We are now targeting 10 g/year production using a 2 W multi-slave injection laser system with improved collimation and a calcium collection substrate, toward future kilogram-scale production.

P34 : Tomoki Endo
(pdf):Quark Matter Equations of State in Strong Magnetic Fields and Hybrid Stars
 In strong magnetic fields, such as those expected in the cores of neutron stars, quark matter is significantly affected by the magnetic field and exhibits discretized energy states due to Landau levels, resulting in a stiffening of the equation of state. Hybrid stars containing quark matter in their cores are therefore expected to be capable of supporting large stellar masses, with their maximum masses readily exceeding twice the solar mass when this stiffened equation of state is applied.

P35 : Kiyoto Ogawa
(pdf):Full three-loop electroweak multiplet contributions to the electron electric dipole moment
 The electron electric dipole moment (EDM) is a powerful probe of CP violation beyond the Standard Model. Future experiments may reach new physics whose contribution first arises at the three-loop level. We consider additional SU(2)$_L$ multiplets with CP-violating Yukawa interactions, which induce the electron EDM at three loops. Previously, we estimated this contribution through the electroweak-Weinberg operator using SMEFT. However, its one-loop matching onto the electron EDM has no large logarithmic enhancement. Thus, other contributions at the same loop order can be important. We directly calculate the electron EDM at the full three-loop level and find that it is about three times larger than the contribution from the electroweak-Weinberg operator alone.

P36 : Hiroyuki Fujioka
(pdf):Toward a study of the charge density distribution of 48Ca via X-ray spectroscopy of muonic atoms
 The energy levels of a muonic atom, in which a negatively charged muon replaces an electron, are affected by the charge density distribution of the core nucleus. Inversely, by measuring X-ray energies of the muonic atom, information on the charge density distribution can be obtained. We plan to measure X-ray energies of muonic calcium atoms (in particular 48Ca) using transition-edge-sensor (TES) detectors at J-PARC MLF. We have already measured X-rays from a CaF2 target with natural isotropic abundance. In this presentation, we outline the project and report the current status of the analysis.

P37 : Rei Tanaka
(pdf):Optimization of an Atomic Beam System for Laser Isotope Separation of 48Ca
 The CANDLES group searches for neutrinoless double-beta decay (0νββ) to investigate the Majorana nature of neutrinos. To improve the sensitivity of 0νββ detection, we aim to produce a large quantity of isotope-enriched 48Ca. Improving the production efficiency of 48Ca requires highly directional atomic beams generated by optimizing the atomic beam system. In this study, we investigate the atomic beam system using both experiments and Monte Carlo simulations. We analyze the effects of collimator geometry, temperature, and material on atomic beam characteristics and compare the simulation results with experimental data. In this presentation, we report the current status of the study.

P38 : Hiroto Iseki
(pdf):Rabi oscillation for isotope enrichment
 The CANDLES experiment searches for neutrinoless double-beta decay (0νββ) using 48Ca, which has a high Q value of 4.27 MeV and thus enables low-background measurements. However, the natural abundance of 48Ca is only 0.187%, making isotope enrichment essential for increasing the amount of decaying nuclei(for a new CANDLES detector). This study employs a laser deflection method based on isotope shifts among Ca isotopes to selectively impart momentum to 48Ca atoms. Its efficiency is limited by momentum loss from spontaneous emission and by stimulated absorption and emission associated with Rabi oscillations at high laser power. We therefore investigate a method that induces stimulated emission to suppress photon loss and uses Rabi oscillations to improve isotope separation efficiency.

P39 : Yoshihito Gando
(pdf):Formulation of Copper-Ion-Exchanged Zeolites for Xenon Enrichment
 Future experiments searching for neutrinoless double-beta decay and direct dark matter detection will require approximately 100 tons of xenon. To ensure the feasibility of these experiments, we are developing a method to collect xenon from atmospheric air by adsorbing it using copper-ion-exchanged zeolites. We report on the method of formulation of the copper-ion-exchange zeolites and the current status of this project.

P40 : Tatsuya Gonda
(pdf):Inferring Proto-Neutron Star Parameters from Supernova Neutrino Data with Realistic Detector Background
 Supernova (SN) neutrinos are key messengers for exploring the interior of an SN, especially the properties of the Proto-Neutron Star (PNS). SPECIAL BLEND (Harada et al.2023) is a framework developed to estimate PNS parameters from SN neutrino data. It can estimate PNS radius, mass, and total emitted neutrino energy. However, in realistic observations, low-energy background events overlap in energy with SN neutrino events and degrade the estimation accuracy. To address this issue, we updated the estimation method by introducing an energy threshold. By excluding events below the threshold, background contamination can be reduced. We found that, for the SK fiducial volume, the energy threshold of 5.5 MeV allows the 1σ credible intervals to capture the true values for an SN up to 100 kpc away.

P41 : Soma Deguchi
(pdf):Indirect Dark Matter Search using MeV Gamma-Ray Observations of the Galactic Center
 The detailed spatial distributions and energy spectra of MeV gamma-rays from the Galactic Center region provide stringent constraints on the abundance of MeV dark matter and primordial black holes in the mass range of 10^{16-17} g. However, observations in this energy range remain challenging due to focusing difficulties and high background levels. To overcome these issues, we are developing an Electron-Tracking Compton Camera (ETCC) with powerful background rejection capabilities. We are preparing for the next scientific balloon mission, SMILE-3, which is planned for Spring 2028. In this poster, we present the scientific targets and an overview of the SMILE-3 mission.

P42 : Michinori Hirose
(pdf):Performance Characterization of a 38-50 GHz Millimeter-Wave Receiver System for Dark Photon Dark Matter Search in the DOSUE-RR Experiment
 Dark photons are one of the candidates for dark matter and are theoretically predicted to convert into photons at metal surfaces, with a frequency corresponding to their mass. The DOSUE-RR experiment searches for dark photons by detecting this converted photon with a millimeter-wave receiver. We have searched the 10-26.5 GHz band, but no significant signal has been observed. To extend the search to higher frequencies, the receiver's signal transmission system must be redesigned for the target band. In this study, based on the cryostat from our previous work, we changed the transmission line from coaxial cable to waveguide, developing a receiver covering 38–50 GHz (dark photon mass ~157-207 μeV). In this poster, we report the receiver characterization and the resulting search sensitivity.

P43 : Ryuto Ishida
(pdf):Do neutrinos transmit spin?
 We reformulate neutrino oscillation in the complete basis of Lorentz-covariant spinor wave packets. The oscillation kernel then closes exactly in terms of a single modified Bessel function, with no saddle-point approximation. Two results follow. First, in the nonrelativistic regime the covariant kernel reproduces the Gaussian localization and momentum-conservation factors with identical width-squared parameters. Second, spin is transmitted through a Wigner rotation whose angle depends on the mass eigenstate. A transverse momentum mismatch between production and detection therefore opens a spin-flipped oscillation channel whose weights carry the inverse neutrino masses at the level of packet overlaps.

P44 : Yuto Kamei
(pdf):Fundamental Evaluation of Hafnium LEKIDs Fabricated by Sputtering with Substrate Heating for Future Dark Matter Searches
 Kinetic Inductance Detectors (KIDs) are highly sensitive energy detectors that utilize superconductivity. Hafnium has the lowest superconducting transition temperature among metals accessible with modern refrigerator technologies. This characteristic enables a lower energy threshold compared to other superconductors, thereby expanding the potential for light dark matter searches. Therefore, we conducted R&D on the fabrication of hafnium-based KIDs and herein report the verification of their operation and fundamental evaluation.

P45 : Yukikatsu Terada
(pdf):High-resolution X-ray astrophysical search for r-process nucleosynthesis signatures from Galactic binary neutron-star mergers
 Binary neutron star mergers (NSMs) are widely considered r-process nucleosynthesis sites, as suggested by infrared observations of kilonovae and by the gravitational‑wave event. Unstable heavy nuclei produced via the r‑process later decay, emitting nuclear gamma rays along with internal conversion X‑rays. The flux of a single merger is far below the sensitivity of existing observatories. Detectability, however, becomes plausible if we focus on emission from r‑process nuclei with Myr‑scale decay times synthesized in multiple NSMs (like in globular clusters or the nuclear stellar cluster) , tracing the integrated merger history over their decay time. In this presentation, we introduce an astronomical survey strategy using the recent high resolution X-ray observatory XRISM.

P46 : Shuki Nomura
(pdf):Development of Low-Radioactivity Photosensors for Future Large Liquid-Xenon Dark Matter Detectors
 Direct dark matter searches using large liquid-xenon time projection chambers have achieved high sensitivity to weakly interacting massive particles. For future experiments with larger target masses and longer exposures, further reduction of radioactive backgrounds from detector components will become increasingly important. PAD and SiGHT are novel hybrid photosensor concepts that combine a photocathode for converting photons into photoelectrons with a SiPM for detecting the photoelectrons. These concepts aim to achieve low-radioactivity photosensors for future liquid-xenon detectors. We studied and optimized the geometries of PAD and SiGHT using electric-field simulations to efficiently collect photoelectrons onto the SiPM. In this poster, we present results of the geometry optimization.

P47 : Masamichi Zaizen
(pdf):Toward unified modeling of asymptotic states of collective neutrino oscillation
 Neutrinos are emitted from core-collapse supernovae and binary neutron-star mergers, where neutrino transport plays a crucial role in shaping the dynamics and observables. Recent studies have revealed that quantum kinetics of neutrinos can induce dramatic flavor evolution, fundamentally altering the neutrino radiation field in such astrophysical events. However, the physical scale is the order of sub-centimeter and is difficult to be directly resolved with global dynamics in explosive phenomena simultaneously. In this study, we exhibit the numerical simulations of nonlinear neutrino flavor conversion under multi-energy, multi-angle, and inhomogeneous neutrino background. We will then discuss how the asymptotic states are analytically predicted based on the linear stability analysis.

P48 : Yuko Watanabe
(pdf):AXEL Experiment : High-Precision Correction of MPPC Nonlinearity Using Signal Waveform Deconvolution
 In the AXEL (A Xenon ElectroLuminescence detector) experiment, we are developing a high-pressure Xe gas TPC toward a high-sensitivity search for neutrinoless double beta decay. We have developed the ELCC (Electroluminescence Light Collection Cell), which converts ionization electrons into photons with low fluctuations and detects them with MPPCs, achieving high energy resolution. However, the MPPC output signals must be passed through a low-pass filter (LPF), and this LPF degrades the correction accuracy of the MPPC nonlinearity. Therefore, we attempt to improve the energy resolution by deconvolving acquired signals with the LPF’s impulse response to restore the high-frequency components necessary for the correction. In this presentation, I report on this method and its effectiveness.

P49 : Mai Morizawa
(pdf):Neutron Track Identification with a 3D Convolutional Neural Network
 In direct detection of dark matter (DM), distinguishing signals from background events is essential for sensitivity. Since neutron-induced events can be similar to those of DM, measuring the environmental neutron flux is important. Nuclear emulsion is suitable for this measurement, because the energy and direction of each neutron can be reconstructed from a single recoil track. However, the readout produces tens to a hundred TB of image data, and selecting the tracks quickly and accurately is the main difficulty in scaling up the analysis. We investigate the automated selection of neutron events using a 3D convolutional neural network applied to particle tracks in nuclear emulsions, and evaluate the performance using signal probability, noise efficiency, and signal-to-noise curves.

P50 : Hanchun Jiang
(pdf):Matter-Neutrino Resonance in Binary Neutron Star Merger Outflows
 Binary neutron star mergers produce neutron-rich outflows where neutrino flavor conversion can modify the electron fraction and r-process nucleosynthesis. At high neutrino density, matter-neutrino resonance (MNR) can occur when the matter and neutrino self-interaction potentials nearly cancel. We study multi-angle MNR with nonlinear flavor simulations and linear stability analysis. Different angular modes undergo Landau-Zener-like crossings at different radii. Both approaches show that instability develops when the matter potential decreases faster than the self-interaction potential, but not for the opposite ordering. These results identify the mechanism of multi-angle MNR and the radial-profile condition for its instability.

P51 : Takuya Sako
(pdf):Performance Evaluation of Ultra-Low-Radioactivity PMTs and Impurity Evaluation of High-Purity GAGG Crystal in the PIKACHU experiment
 In the search for double beta decay of 160Gd using GAGG crystals in the PIKACHU experiment, reducing background events (BG) originating from 40K is an important challenge. In particular, gamma-ray BG from 40K contained in the current PMT (R6231-04) are expected to be reduced by using an ultra-low-radioactivity PMT (R11065-20). In this presentation, we report the results of evaluations of the ultra-low-radioactivity PMT, including its long-term stability and its impact on pulse-shape discrimination performance, in comparison with the current PMT. In addition to the PMT performance evaluation, we also report the results of the BG measurement and impurity evaluation using Crystal 9, a new high-purity GAGG crystal, with the aim of improving the sensitivity of the search.

P52 : Kelin QIAO
(pdf):A New High-Intensity Ultracold Neutron Source for New Physics Probes
 The neutron electric dipole moment (nEDM) is a sensitive probe of CP violation beyond the Standard Model and is relevant to questions such as baryogenesis and dark matter. To improve nEDM sensitivity, the TUCAN collaboration has commissioned a spallation-driven ultracold neutron (UCN) source at TRIUMF. Neutrons produced by a 483 MeV proton beam are moderated by heavy water and liquid deuterium, converted to UCNs in superfluid helium at about 1 K, and extracted to the experimental area. A continuous UCN rate of 6.75(3) × 10^5 UCN/s was measured, making it the world’s highest-intensity UCN source and enabling nEDM sensitivity toward 10^-27 e·cm. This contribution presents recent source results and prospects for future nEDM and new-physics searches.