P01 : 岸田有美子
(pdf):Development of Ge detector for purification of CaF2 crystals

P02 : Tuan Khai Bui
(pdf):Status of the neutron veto system of XENONnT

P03 : MASAMITSU MORI
(pdf):Long time simulation of neutrinos and gravitational wave from supernovae

P04 : Umemoto Atsuhiro
(pdf):Diamond detector for dark matter search

P05 : Tomoya Hasegawa
(pdf):Development of a hybrid-photodetector for the DARWIN experiment

P06 : Atsushi Yoshioka
(pdf):Improvement of pulse shape discrimination analysis for background reduction in CANDLES

P07 : Maho Kurasawa
(pdf):Research and development of high-sensitive measurement of trace amount of radioactive elements in organic materials for KamLAND2-Zen

P08 : Kazuki Tanaka
(pdf):Neutrinoless double beta decay in the seesaw mechanism

P09 : Ko Nakamura
(pdf):Neutrino signals from 3D core-collapse supernova models

P10 : Wakana Iwakami
(pdf):A Simulation of Core-collapse Supernovae in Three-dimensional Space with Full Boltzmann Neutrino Transport on the Supercomputer FUGAKU

P11 : Yoshihiro Iwata
(pdf):A study on the emission characteristics of gadolinium ions in a water Cherenkov detector

P12 : Yu Watanabe
(pdf):A Global Analysis of Resonance-enhanced Light Scalar Dark Matter

P13 : Taichi Sakai
(pdf):Ocean Bottom Detector : Towards direct measurement of mantle geo-neutrino

P14 : Kei Kanezaki
(pdf):Development of gaseous TPC for the detection of Migdal effect

P15 : Koji Ishidoshiro
(pdf):New dark matter experiment with superconducting sensors at Kamioka

P16 : Kenta Kotera
(pdf):Background analysis of NaI(Tl) crystals for the development of new PICOLON detector.

P17 : Kodai Iwasawa
(pdf):Development of low background liquid scintillation detector for ambient neutron measurement

P18 : Shohei Ogawa
(pdf):Evaluation of stellar core radii and masses aiming for supernova relic neutrinos with the use of a stellar population synthesis code

P19 : Hiromitsu Yasu
(pdf):Evaluation of the front-end electronics with dual-gain amplification

P20 : HAMADA Yuto
(pdf):Performance test of a gaseous TPC with neutron beam for the detection of Migdal effect

P21 : Yusuke Urano
(pdf):Quenching factor measurement in low-energy nuclear recoil of NaI(Tl) scintillator using monochromatic neutrons for dark matter search

P22 : Masataka Shinoki
(pdf):Measurement of cosmogenic neutron in Super-Kamiokande

P23 : Ayaka Nakayama
(pdf):Direction-sensitive dark matter search using lower　pressure gaseous TPC

P24 : Miyohi Go
(pdf):Data analysis for reduction of 208Tl background events in CANDLES system

P25 : Takashi Iida
(pdf):Study of Gd-160 double beta decay by PIKACHU experiment

P26 : Yuuki Nakano
(pdf):Measurements of the charge ratio of cosmic-ray muons with the Super-Kamiokande detector

P27 : Mizuno Ofuji
(pdf):Evaluation of γ-ray background from neutron beams for the detection of the Migdal effect

P28 : Yuga Ommura
(pdf):Measurement of quenching factor for recoil nuclei from neutron scattering in BGO scintillator

P29 : Naoki Aoyama
(pdf):Development of coated electrodes with low quantum efficiency for the DARWIN experiment.

P30 : Takuya Shiraishi
(pdf):Environmental Sub-MeV Neutron Measurement in Gran Sasso with Ultra Fine-grained Nuclear Emulsion

P31 : Tsukasa Yoshida
(pdf):Tau identification using machine learning image classification in Hyper-Kamiokande

P32 : Ryuta Shirai
(pdf):Energy Resolution Improvement for CaF2 Scitillating Bolometer by Machine Learning Analysis

P33 : Takeshi Nakahata
(pdf):Research and development of new Front-end Electronics for KamLAND2

P34 : Ryo Nakamura
(pdf):Constraint on neutrinos from PBHs with the KamLAND upper limit data

P35 : Minori Eizuka
(pdf):A search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data

P36 : Yuta Yamamoto
(pdf):Analogue tachyon condensation in superconducting transmission lines

P37 : Kanji Mori
(pdf):Core-collapse Supernova Models with Heavy Axion-like Particles

P38 : Hirokazu Sasaki
(pdf):Majorana neutrino-antineutrino oscillations in core-collapse supernovae with strong magnetic fields

P39 : 平岩 侑
(pdf):Development of the atomic beam system for the laser isotope separation of 48Ca

P40 : 阪井俊樹
(pdf):CANDLES実験による二重ベータ崩壊の研究における機械学習を用いた波形解析によるバックグラウンド除去の評価

P01 : 岸田有美子
(pdf):Development of Ge detector for purification of CaF2 crystals
 "In double beta decay experiments. It is important to remove radioactive impurities from the scintillator to reduce the intrinsic background. We have started to produce pure and low-background CaF2 crystals. We measure radioactive impurities in raw materials of CaF2 by a Ge detector, We performed anti-coincidence measurement to reduce the background due to cosmic rays. We will show the results of several samples."

P02 : Tuan Khai Bui
(pdf):Status of the neutron veto system of XENONnT
 XENONnT is a dark matter direct detection experiment set up at the underground Gran Sasso laboratory (LNGS). It is a two-phase time projection chamber (TPC) filled with 5.9 tons of liquid xenon (LXe) and expected to collect 20 ton´years of exposure over the next five years. The radiogenic neutrons in detector structural materials of XENONnT can produce a nuclear recoil signal, which mimics a WIMP signal. The neutron Veto, which was developed based on Gd-loaded water Cherenkov technology of Super-Kamioka and EGADS, is under commissioning to tag background events caused by neutrons. We will present the current status of our XENONnT neutron veto system.

P03 : MASAMITSU MORI
(pdf):Long time simulation of neutrinos and gravitational wave from supernovae
 Core-collapse supernovae emit their gravitational energy as neutrino. They also emit gravitational waves due to multi-dimensional effects. So far, some studies calculated the emission in case neutron stars are left behind for more than 20 seconds in 1D simulations. In the case of black holes, neutrino is also emitted from the surrounding matter. However, the Misner-Sharp metric, which is often employed in simulations, diverges when black holes form. To evade the problem, we are developing a new simulation using the Hernandez-Misner metric. In this poster, we will show long signal of neutrinos and gravitational waves from a supernova, which forms a neutron star and development of the Hernandez-Misner code.

P04 : Umemoto Atsuhiro
(pdf):Diamond detector for dark matter search
 "Diamond has a unique physical characteristic, which realizes a special detector applied in the field of particle physics. I will show the recent development for dark matter search using diamond detector."

P05 : Tomoya Hasegawa
(pdf):Development of a hybrid-photodetector for the DARWIN experiment
 Dark matter, such as Weakly-Interacting-Massive Particles (WIMPs), could interact with nuclei in ordinal matter, and direct detection experiments try to search for such interactions between dark matter and detector medium. In particular, experiments using liquid xenon as a detector target are leading the searches for heavy WIMPs. However, neutron originating from radioactive material contaminated in photomultiplier tube(PMT) can be an irreducible background, and it limits the discovery potential of WIMPs. Therefore, it is important to develop a new photodetector with lower radioactivity. In this study, I will present about R&D results for the hybrid photodetector which we are now developing.

P06 : Atsushi Yoshioka
(pdf):Improvement of pulse shape discrimination analysis for background reduction in CANDLES
 To search for the neutrino-less double beta (0$\nu\beta\beta$) decay of ^{48}Ca (Q=4.27 MeV), CANDLES has been used the pulse shape discrimination (PSD) analysis to reduce the background due to ^{208}Tl->^{208}Pb decay (Q=5.0 MeV) in CaF_{2} crystals. We identify the preceding α decay (^{208}Bi->^{208}Tl) to reduce ^{208}Tl decay background using a characteristic signal waveform of the CaF_{2} scintillator. However, the PSD parameter distribution estimated by Monte Carlo simulation (MC) does not reproduce that of the real data. To solve this problem, we further investigated the PSD parameters of events in the CANDLES data and re-evaluate the uncertainty of waveform, parameter definition, and the calculation formula. Then the distribution of PSD parameters in the CANDLES data was well understood. This presentation will report the results of our research on PSD analysis.

P07 : Maho Kurasawa
(pdf):Research and development of high-sensitive measurement of trace amount of radioactive elements in organic materials for KamLAND2-Zen
 "This study aims to measure ultra-trace amounts of radioactive elements(uranium/thorium) in organic materials used in the next generation 0νββ experiment, KamLAND2-Zen. To measure such trace amounts (O(10 ppq)), we are now developing a method of the combination of dry ashing and ICP-MS measurement. In this presentation, the current status of the dry ashing method, the current achieved sensitivity for some samples and future prospects will be reported."

P08 : Kazuki Tanaka
(pdf):Neutrinoless double beta decay in the seesaw mechanism
 "We studied the contributions of right-handed neutrinos to the neutrinoless double beta decay in the seesaw mechanism. Especially, we consider the case when right-handed neutrinos are lighter than TeV scale, which potentially give significant effects to it.We also discuss the possibility of verifying these contributions in future experiments and show the impact on the direct search for right-handed neutrinos."

P09 : Ko Nakamura
(pdf):Neutrino signals from 3D core-collapse supernova models
 Systematic studies of core-collapse supernovae have been conducted based on hundreds of one-dimensional artificial models (O'Connor & Ott 2011,2013; Ugliano et al. 2013, Ertl et al. 2015) and two-dimensional self-consistent simulations (Nakamura et al. 2015;2019, Burrows & Vartanyan 2020). We have performed three-dimensional core-collapse simulations for 16 progenitor models. Our models present a wide variety of explosion properties such as shock evolution and explosion energy. We present the dependence of the neutrino emission on the progenitor structure.

P10 : Wakana Iwakami
(pdf):A Simulation of Core-collapse Supernovae in Three-dimensional Space with Full Boltzmann Neutrino Transport on the Supercomputer FUGAKU
 Using a radiation-hydrodynamics code with full Boltzmann neutrino transport, we have conducted the core-collapse supernova simulation for a 11.2M progenitor model in three-dimensional space up to 50 ms after bounce on the supercomputer FUGAKU. We solve the six-dimensional Boltzmann equations for three neutrino species and the three-dimensional compressible Euler equations with Furusawa and Togashiʼs nuclear equation of state. The shock wave reach almost 160km from the center of the PNS, which is the almost same as the radial position of the shock wave in the two-dimensional simulation.

P11 : Yoshihiro Iwata
(pdf):A study on the emission characteristics of gadolinium ions in a water Cherenkov detector
 The SK-Gd experiment is currently ongoing where gadolinium sulfate is dissolved in a water Cherenkov detector to increase the detection sensitivity of supernova relic neutrino events. In this work, the emission characteristics of gadolinium ions are studied to estimate the effect of ion emission caused by cosmic ray muons on the background level of the detector.

P12 : Yu Watanabe
(pdf):A Global Analysis of Resonance-enhanced Light Scalar Dark Matter
 We study a minimal model for a light scalar dark matter, requiring a light scalar mediator to address the core-cusp problem and interact with the standard model particles. We analyze the model comprehensively by focusing on the Breit-Wigner resonance for dark matter annihilation and self-scattering channels, considering the thermal relic abundance condition that includes the early kinetic decoupling effect, as well as the present and future constraints from collider, direct, and indirect dark matter detections. We found that the scalar dark matter with the mass of 0.3 - 2 GeV remains uncharted, which will be efficiently tested by the near future MeV gamma-ray observations.

P13 : Taichi Sakai
(pdf):Ocean Bottom Detector : Towards direct measurement of mantle geo-neutrino
 "Observation of geo-neutrinos originating from radioactive isotopes in the Earth (238U,232Th, etc.) can be converted to the amount of radioactive isotopes and the heat generated by their decays which governs the Earth dynamics. To date, two experiments (KamLAND and Borexino) have measured geo-neutrinos and constrained the range of acceptable models for the Earth’s chemical composition, but distinguishing the mantle flux by land-based detectors is challenging as the crust signal is about 70% of the total anti-neutrino flux. Given the oceanic crust is thinner and has lower concentration of radioactive elements than continental crust, geo-neutrino detector in the ocean, Ocean Bottom Detector (OBD), makes it sensitive to geo-neutrinos originating from the Earth’s mantle. Our working group was jointly constructed from interdisciplinary communities in Japan which include particle physics, geoscience, and ocean engineering. We have started to work on technological developments of OBD. We are now developing a 20 kg prototype liquid scintillator detector. This detector will undergo operation deployment tests at 1 km depth seafloor in 2022. Our first big goal is 1.5 kt size detector, and we aim world first direct observation of mantle geo-neutrinos. In my presentation, I will give our detector concept, current development status and performance evaluation result."

P14 : Kei Kanezaki
(pdf):Development of gaseous TPC for the detection of Migdal effect
 Recently, the search for light dark matter using the Migdal effect has become popular. However, it has not yet been confirmed whether the Migdal effect is caused by nuclear recoil or not. In this study, we aim to observe a characteristic two-cluster signal caused by the Migdal effect using a neutron beam and a gaseous TPC. When neutrons enter the detector, detector material emit γ-rays due to neutron capture reaction. To reduce this γ-ray backgrounds, we have developed a low-mass argon gas TPC. In this presentation, we will report the results of a neutron beam test using the TPC.

P15 : Koji Ishidoshiro
(pdf):New dark matter experiment with superconducting sensors at Kamioka
 We are planning to set up a cryogenic laboratory at the Kamioka in cooperation with RCNS, KEK QUP, and LBNL. The goal of our first physical search is about low-mass dark matter studies. We will present the overall plan and the efforts on the Japanese side.

P16 : Kenta Kotera
(pdf):Background analysis of NaI(Tl) crystals for the development of new PICOLON detector.
 "The PICOLON group uses low background NaI(Tl) detectors to search for dark matter. The highly radiopure NaI(Tl) crystal has the large advantage in searching for dark matter and verifying the annual modulation reported by the DAMA/LIBRA group.We report the results of background analysis of high-purity NaI(Tl) crystals purified with specially optimized method. The low-background data was taken in the Kamioka underground laboratory. Additionally, we prospect plans for dark matter search and new detector design."

P17 : Kodai Iwasawa
(pdf):Development of low background liquid scintillation detector for ambient neutron measurement
 "In a direct dark matter search, the main background events are ambient neutrons from outside the detector and α-rays from inside the detector.Accurate estimation of these two background events are of great importance.The main sources of α-rays are leaks of radioactive Rn-222 from inside the detector components to liquid scintillator and radioactive impurities in the liquid scintillator itself.For the former, the inside of the detector was electropolished to reduce the surface area, and for the latter,the liquid scintillator was purified by liquid-liquid extraction with ultrapure water, and an α-ray background of 0.8 mBq was achieved.In this presentation, the results of these measurements and analyses will be presented."

P18 : Shohei Ogawa
(pdf):Evaluation of stellar core radii and masses aiming for supernova relic neutrinos with the use of a stellar population synthesis code
 In general, most of stellar population synthesis codes don't calculate stellar CO core radii. Hence we have improved a stellar population synthesis code based on the result computed with detailed stellar evolution codes so that the code becomes able to calculate CO core radii and comes in useful for the estimate of supernova relic neutrinos. This poster aims to explain how we have incorporated the treatment of CO core radii into the stellar population synthesis code.

P19 : Hiromitsu Yasu
(pdf):Evaluation of the front-end electronics with dual-gain amplification
 We develop a gaseous TPC in a dark matter search experiment using SF6, which drifts negative ions instead of electrons. Since it produces two types of negative ions with different signal magnitudes, it requires a large dynamic range for readout. In order to achieve it, we have developed an ASIC that dynamically changes two types of amplifiers with different gains. In this study, we evaluated the performance of the ASIC.

P20 : HAMADA Yuto
(pdf):Performance test of a gaseous TPC with neutron beam for the detection of Migdal effect
 Migdal effect is recently attracting attention in the context of light dark matter search. The Migdal effect is a phenomenon in which ionization and excitation occur with low probability as a result of the rapid motion of nuclear. MIRACLUE experiment aims to detect Migdal effect in nuclear recoil which has not been detected yet. In this presantation, we will report the neutron beam test results of a gaseous TPC for MIRACLUE experiment.

P21 : Yusuke Urano
(pdf):Quenching factor measurement in low-energy nuclear recoil of NaI(Tl) scintillator using monochromatic neutrons for dark matter search
 "PICOLON aims to search for cosmic dark matter using an ultra-pure NaI(Tl) scintillator at the Kamioka underground observatory.In this study, to measure the quenching factor (QF), we irradiated NaI(Tl) scintillator with 2.45-MeV monochromatic neutrons produced by the deuteron-deuteron fusion. Scattered neutrons from NaI(Tl) were detected with 6 liquid scintillator modules placed at scattering angle range of 25~60 degrees.By removing the backgrounds with the techniques of pulse shape discrimination (PSD) and time of flight (TOF), we confirmed the angular dependence of the nuclear recoil energy and succeeded in calculating the QF.This poster reports on the details of the experiments conducted in 2021, their results, and future plans."

P22 : Masataka Shinoki
(pdf):Measurement of cosmogenic neutron in Super-Kamiokande
 Cosmic-ray muons that enter the Super-Kamiokande detector cause hadronic showers, and the showers can produce radioactive isotopes out of oxygen via spallation. The produced neutrons and isotopes are major background sources for MeV-scale neutrino analysis and searches for rare events. Observations in Super-Kamiokande have been performed using ultra-pure water, and gadolinium was introduced into the water to improve the detection efficiency of neutrons and suppress the background due to radioactivities and PMT dark noises. In this study, we analyzed data for about one year after the gadolinium loading and measured the cosmogenic neutron production yield. The results will be presented in this poster.

P23 : Ayaka Nakayama
(pdf):Direction-sensitive dark matter search using lower　pressure gaseous TPC
 NEWAGE is a directionally sensitive dark matter search experiment. In this study, we aim to achieve a low energy threshold by extending the trajectory by lowering the gas pressure and reducing the external background by installing a copper shield. In this presentation, we will present the status of the analysis.

P24 : Miyohi Go
(pdf):Data analysis for reduction of 208Tl background events in CANDLES system
 "Double beta decay is predicted to include a rare process in which no neutrinos are emitted (0νββ). The CANDLES experiment aims to observe 0νββ decay of 48Ca using 96 CaF2 crystals in the experiment. The Q-value of 208Tl is 5 MeV, which is above Q-value of ββ decay of 48Ca. We have to remove this 208Tl background to realize background-free measurement. In order to further reduce this background, it is necessary to develop the precise Monte Carlo simulation to reproduce the energy spectrum and position distribution of 208Tl decays. This requires accurate position information and photoelectron distributions to be incorporated into the simulation. I report on the analytical method and results for obtaining this information."

P25 : Takashi Iida
(pdf):Study of Gd-160 double beta decay by PIKACHU experiment
 "The discovery of neutrino less double beta decay (0nbb) is important to verify the Majorana nature of neutrinos. Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences (PIKACHU) project was launched, and large, high-purity Ce:Gd3(Ga,Al)5O12 (GAGG) crystals are being developed to study the double beta decay of 160Gd.We have constructed a 6.5cmφ×14.5cmL (3.1kg) GAGG crystal detector combined with a Photomultiplier tube sensitive to long wavelengths and investigated its energy resolution (σ=5.7% @662 keV) and good pulse shape discrimination performance. Furthermore, in July 2020, this detector was installed in a lead shield at 1000 m underground in Kamioka, and high-sensitivity background measurements were performed. As a result, it was found that the crystals contain a large amounts of Th-series radioactive impurities, and we measured the impurity concentration in the crystal materials with a Ge detector. Among the materials, gadolinium oxide is contaminated by Th impurities, and we are developing a method for high purity crystals by material selection and purification. The results will be presented in this poster."

P26 : Yuuki Nakano
(pdf):Measurements of the charge ratio of cosmic-ray muons with the Super-Kamiokande detector
 Cosmic-ray muons arise from the showers of secondary particles produced via the interactions of primary cosmic particles with air nuclei at the top of the atmosphere. The interaction products, pions and kaons composing showers mostly decay to muons reflect the details of the hadronic interactions depending on their energy. Measurements of the charge ratio of cosmic-ray muons can be used to constrain high energy hadronic interaction models in the atmosphere. In this poster presentation, we will report the current status of the measurement of the charge ratio using data collected by the Super-Kamiokande (SK) detector. Using the data taken in the fourth phase of SK (SK-IV), the charge ratio is measured to be 1.42 ± 0.02 (statistical uncertainty only), at the energy of 1.3 TeV. This result for the charge ratio is in good agreement with those previously obtained by deep underground experiments.

P27 : Mizuno Ofuji
(pdf):Evaluation of γ-ray background from neutron beams for the detection of the Migdal effect
 The Migdal effect has been used to directly search for low-mass dark matter. The MIRACLUE experiment plans to use a neutron beam to make the first observation of a certain Migdal effect. In contrast, gamma rays from neutron capture reactions at the laboratory wall will be one of the main background events. To understand the background event, a neutron beam experiment was conducted at the National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba, Japan, in April 2022, and the energy spectrum of gamma rays was measured using a CsI scintillator. In this presentation, we will report the results of this measurement and the contribution of the gamma-ray background event to the MIRALUE experiment.

P28 : Yuga Ommura
(pdf):Measurement of quenching factor for recoil nuclei from neutron scattering in BGO scintillator
  BGO scintillator is widely used in underground particle physics experiments. As an example, it is used with Am/Be neutron source in Super-Kamiokande(SK) to evaluate the detection efficiency of neutron. In SK, a relative 10% discrepancy between the measured and simulated efficiency of neutron detection was reported with the Am/Be source and the scattering of neutron in BGO is considered as one of the sources of the discrepancy. Therefore, a precise measurement of responses of the BGO scintillator to neutrons is important to suppress the systematic uncertainty. For this purpose, we carried out a neutron beam test at AIST, Japan to measure neutron scattering in BGO detectors. The data of elastic scattering with neutron and nuclei in BGO crystal are recorded when signals are simultaneously observed by both BGO and liquid scintillator detectors. Background events of gamma rays are suppressed by the pulse shape discrimination method in liquid scintillation detector. We found a light yield of nuclear recoil tends to be smaller than the expectation, which is assumed for electrons with the same kinetic energy as the recoil nuclei. The recoil energy of nuclei is calculated from the initial energy of neutron and its scattering angle. The ratio of electron equivalent energy to recoil energy is defined as quenching factor. Varying the scattering angle, the quenching factor as a function of the recoil energy has been measured. In this presentation, we will report the details of the data analysis and the results of the measurements.

P29 : Naoki Aoyama
(pdf):Development of coated electrodes with low quantum efficiency for the DARWIN experiment.
 In direct dark matter search experiments using liquid xenon (Xe), scintillation and ionization signals are produced by the interaction between Xe and dark matter. Scintillation photons can produce photoionization electrons through photoelectric effect on electrodes, which is one of the major backgrounds for low-mass dark matter searches. For DARWIN, a future direct dark matter search experiment using 50 tons of liquid Xe, we are developing coated electrodes with low quantum efficiency to reduce ionization signas originating from photoionization of electrodes. In this poster presenation, I will present about the results of quantum efficiency measurements for some electrodes (Au, Pt, Al, SUS304, etc) in vacuum, liquid Xe and gas Xe.

P30 : Takuya Shiraishi
(pdf):Environmental Sub-MeV Neutron Measurement in Gran Sasso with Ultra Fine-grained Nuclear Emulsion
 We have developed a new detection method for neutrons above sub-MeV using ultra fine-grained nuclear emulsion. Because of three-dimensional tracking of neutron-recoil protons with sub-micrometric accuracy, this method has extremely high γ-ray rejection power, and furthermore, it has energy resolution and directionality even in the sub-MeV energy region. Currently, environmental neutron measurements are ongoing at the surface laboratory of Gran Sasso, and results of flux, energy spectra, and angular anisotropy will be reported.

P31 : Tsukasa Yoshida
(pdf):Tau identification using machine learning image classification in Hyper-Kamiokande
 Hyper-Kamiokande is a next-generation neutrino experiment that is under construction in Japan. The Hyper-Kamiokande far detector will be instrumented by thousands of photomultipliers (PMT) which detect the Cherenkov light emitted by charged particles produced by neutrino interactions in the water. The neutrino flavor can be specified by identifying the type of charged particles produced in neutrino interactions. In addition to the electron neutrinos and muon neutrinos produced in the atmosphere, the Hyper-Kamiokande also observes tau neutrinos which are mainly produced by oscillations of muon neutrinos. Tau particles decay into charged leptons or hadrons with a short lifetime. When tau decay into hadrons, many Cherenkov rings are produced. We attempt to distinguish such events from deep inelastic scattering interactions of electron and muon neutrinos using machine learning based on the PMT signals. The performance of the selection is presented in the poster.

P32 : Ryuta Shirai
(pdf):Energy Resolution Improvement for CaF2 Scitillating Bolometer by Machine Learning Analysis
 "The CANDLES experiment aims to observe neutrinoless double β-decay of 48Ca, and the development of a detector with good energy resolution is essential to achieve this goal.The CaF2 scintillating bolometer under development consists of a light detector and a thermal detector on the top and bottom. When charged particles are generated and their energy is absorbed by the scintillation crystal, photons and phonons are produced.This raises the temperature of the Ge wafer and phonon collector and decreases the magnetization of the MMC (Metallic Magnetic Calorimeter). The change is read by a SQUID (superconducting quantum interferometer).By measuring both heat and fluorescence in this way, background is eliminated by utilizing quenching in the α event and by discriminating α, γ, and μ- particles.The measured thermal signal consists of three components: photon absorption, phonons, and their thermalization, of which the photon absorption and phonon signals are not used for energy determination.The reason for this is that the phonon signal has a dependence on the location of the event, with a higher wave height when the event occurs in the CaF2 crystal close to the thermal detector and a lower wave height when the event occurs further away, and the photon signal also has a position dependence.This effect deteriorates the energy resolution, and the target resolution (Q value of double β-decay, 0.5% or less at 4.27 MeV) is not achieved. The position identification and energy correction are performed based on the time constant of the decay with position, the change in the rise time of the signal, and the integrated analysis with the optical signal. Since the effect is multidimensional, machine learning was introduced to analyze the waveform of the signal, and the results will be presented."

P33 : Takeshi Nakahata
(pdf):Research and development of new Front-end Electronics for KamLAND2
 KamLAND (Kamioka Liquid-Scintillator Anti-Neutrino Detector) has produced results of the measurements of neutrino oscillations and searched for Majorana nature of neutrinos. Searching for the neutrino-less double beta (0νββ) decay is the only realistic way to verify whether neutrinos are Majorana particles or Dirac particles. Since 2019, we have started the KamLAND-Zen800 Phase with 745 kg enriched xenon to search for neutrino-less double beta decay. Currently, many researches and developments are ongoing for higher sensitive search in the new phase (KamLAND2-Zen). From the dedicated analysis with KamLAND-Zen800 data, we found new serious backgrounds which are long-lived spallation products of 136Xe caused by cosmic-ray muons. The spallation of 136Xe creates a lot of neutrons, and the number of neutrons is correlated with that of the spallation products. Neutron multiplicity is a key to tag the spallation backgrounds. However, neutron detection efficiency is not enough because of PMT’s afterpulses and overshoots. We also suffer from becoming old of current front-end electronics for KamLAND and the end of production of the components to repair it. To improve these situations, we are accelerating our developments of Radio Frequency System-on-Chip-based (RFSoC-based) front-end electronics (FEE). RFSoC is the latest FPGA family from Xilinx, which involves programmable logic (PL) with a large number of digital signal processor (DSP) block, processing system (PS) based on Arm applications and real-time processors, radio-frequency ADCs (RF-ADCs), and radio-frequency digital-to-analog convertors (RF-DACs). We consider that RFSoC-based FEE can correct the PMT’s overshoot by on-board signal processing and record all the waveforms including afterpulses and neutrons signals by the large buffer. We tested the first prototype board of RFSoC based FEE for KamLAND2-Zen.

P34 : Ryo Nakamura
(pdf):Constraint on neutrinos from PBHs with the KamLAND upper limit data
 "Primordial black hole (PBH) is a hypothetical object formed after the inflation. The existence of PBH might be a key to solving several problems related to cosmology.In this poster presentation, we present the details of neutrino emitted from PBH and the upper limit on the fraction of PBH to dark matter from the KamLAND published data. This result is complementary with other constraints from other observational limits. "

P35 : Minori Eizuka
(pdf):A search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data
 On 1987 February 23rd, neutrinos from SN1987A were observed. This observation confirms that neutrinos have an important role in supernova explosions. In order to establish the detailed mechanisms of supernovae, further supernova neutrino signals have been searched for with a variety of detectors. The KamLAND, an anti-neutrino detector using a 1kt liquid scintillator, has significant sensitivity to supernova neutrinos owing to a low radioactivity environment, a large target volume, and a low energy threshold. We searched for supernova neutrino events using the KamLAND data taken from 2002 March 9th to 2020 April 25th. In this talk, we present the result of a search for supernova neutrinos via inverse beta decay reaction (IBD). Multiple IBDs within 10-s window are required as a supernova neutrino event. Assuming theoretical models, we discuss the supernova detectable range at the KamLAND. Constrains on the galactic star formation rate from the point of view of a neutrino observation is also discussed. We present the status of a search for supernova neutrinos via 12C neutral current, too.

P36 : Yuta Yamamoto
(pdf):Analogue tachyon condensation in superconducting transmission lines
 Tachyon condensation is a process in particle physics whereby a system can lower its energy by spontaneously producing particles, leading to "condensation" of particles that fill the volume of the system. Thus, tachyon condensation may explain the formation of matter during the evolution of the early universe. To verify this hypothesis, it would be useful to mimic the cosmogenesis of the universe in a laboratory system. Here we propose a simple method to create analogue tachyon condensation using superconducting transmission lines with superconducting nonlinear asymmetric inductive elements (SNAIL). This system can mimic the tachyonic vacuum by controlling the junction parameters that determine the SNAIL interference. Thus, the condensation process, which is a transition from that state, can be investigated.

P37 : Kanji Mori
(pdf):Core-collapse Supernova Models with Heavy Axion-like Particles
 Axion-like particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma of stars and core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced in a supernova, some of the ALPs can be absorbed by the supernova matter and affect energy transfer. We recently calculated the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics consistently. It is found that the stalled bounce shock can be revived if the coupling between ALPs and photons is as high as $g_{a\gamma}\sim 10^{-9}$ GeV$^{-1}$ and the ALP mass is 40-400 MeV.

P38 : Hirokazu Sasaki
(pdf):Majorana neutrino-antineutrino oscillations in core-collapse supernovae with strong magnetic fields
 We calculate Majorana neutrino-antineutrino oscillations in dense astrophysical sites with strong magnetic fields. With the coupling of the magnetic field potential and the MSW matter potential, Majorana neutrinos can reach a flavor equilibrium sensitive to the baryon density and the electron fractions inside the matter. From the calculation result, we propose a necessary condition for the equilibration of the neutrino-antineutrino oscillations and study whether such a condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibrium would be possible with the typical magnetic fields of magnetars (10^14 G).

P39 : 平岩 侑
(pdf):Development of the atomic beam system for the laser isotope separation of 48Ca
 " We are searching for neutrino-less double beta decay (0νββ) of 48Ca to verify the Majorana nature of neutrinos. 48Ca has the highest Q value (4.27 MeV), which is advantageous for background reduction. On the other hand, its natural abundance is very low (0.187%), and it is necessary to enrich it to increase the number of target nuclei, although an inexpensive and effective enrichment method has not been found. We are developing a laser deflection method for Ca isotope enrichment. Isotope separation is achieved through momentum transfer by irradiating the laser tuned only to the target isotope (48Ca) perpendicular to the Ca atomic beam. After the proof-of-principle, R&D for the mass production of 48Ca is underway, and UF collaborators are in charge of the development of the atomic beam system. For the mass production of 48Ca, it is necessary to improve the concentration and recovery rates by efficiently converting the raw calcium into atomic beams and by improving the separation of 48Ca from the deflected 48Ca. To achieve this, an atomic beam is created in the form of a sheet that is thin with respect to the direction of laser incidence for deflection and long in that perpendicular direction. At present, it is assumed that multiple thin cylindrical tubes will be used for collimation. In addition, various Ca atomic beam monitoring systems are needed to verify the collimating effect of the atomic beam and to check the concentration and recovery efficiency of the deflected 48Ca. Until now, time-of-flight (TOF) ionization measurements have been used, which are accurate but time-consuming. We have developed a system with coating thickness gauge that can measure positional distribution more quickly and simply, and a spatial/momentum distribution measurement system based on fluorescence observation from an atomic beam at the deflection laser irradiated position. As for the latter, we are considering applying it to control the wavelength of the deflection laser in near future. The collimating effect of a single thin tube on atomic beams from a small crucible has been measured using three different monitoring systems. The results of the TOF measurement method confirm that the expected collimation effect is almost achieved. We also evaluated the performance of two newly developed monitoring systems by comparison. Based on these results, we are planning to conduct tests using a larger crucible and multiple tubes. In this poster presentation, we will report on the current status of these tests."

P40 : 阪井俊樹
(pdf):CANDLES実験による二重ベータ崩壊の研究における機械学習を用いた波形解析によるバックグラウンド除去の評価
 CANDLES実験では、48Caのββ崩壊の研究を行なっている。48Caの2νββ崩壊の半減期はより精度の高い測定が求められているが、結晶内に含まれる放射性不純物の232Th崩壊系列の娘核(212Bi,212Po)の連続崩壊事象が主要なバックグラウンドとなっている。本研究ではこの連続崩壊事象の波形をCANDLES検出器で得られた実データから擬似的に作成し、機械学習を用いることで、連続崩壊事象を識別する。本講演では識別の精度を定量的に議論する。

P01 : 岸田有美子
(pdf):Development of Ge detector for purification of CaF2 crystals

P02 : Tuan Khai Bui
(pdf):Status of the neutron veto system of XENONnT

P03 : MASAMITSU MORI
(pdf):Long time simulation of neutrinos and gravitational wave from supernovae

P04 : Umemoto Atsuhiro
(pdf):Diamond detector for dark matter search

P05 : Tomoya Hasegawa
(pdf):Development of a hybrid-photodetector for the DARWIN experiment

P06 : Atsushi Yoshioka
(pdf):Improvement of pulse shape discrimination analysis for background reduction in CANDLES

P07 : Maho Kurasawa
(pdf):Research and development of high-sensitive measurement of trace amount of radioactive elements in organic materials for KamLAND2-Zen

P08 : Kazuki Tanaka
(pdf):Neutrinoless double beta decay in the seesaw mechanism

P09 : Ko Nakamura
(pdf):Neutrino signals from 3D core-collapse supernova models

P10 : Wakana Iwakami
(pdf):A Simulation of Core-collapse Supernovae in Three-dimensional Space with Full Boltzmann Neutrino Transport on the Supercomputer FUGAKU

P11 : Yoshihiro Iwata
(pdf):A study on the emission characteristics of gadolinium ions in a water Cherenkov detector

P12 : Yu Watanabe
(pdf):A Global Analysis of Resonance-enhanced Light Scalar Dark Matter

P13 : Taichi Sakai
(pdf):Ocean Bottom Detector : Towards direct measurement of mantle geo-neutrino

P14 : Kei Kanezaki
(pdf):Development of gaseous TPC for the detection of Migdal effect

P15 : Koji Ishidoshiro
(pdf):New dark matter experiment with superconducting sensors at Kamioka

P16 : Kenta Kotera
(pdf):Background analysis of NaI(Tl) crystals for the development of new PICOLON detector.

P17 : Kodai Iwasawa
(pdf):Development of low background liquid scintillation detector for ambient neutron measurement

P18 : Shohei Ogawa
(pdf):Evaluation of stellar core radii and masses aiming for supernova relic neutrinos with the use of a stellar population synthesis code

P19 : Hiromitsu Yasu
(pdf):Evaluation of the front-end electronics with dual-gain amplification

P20 : HAMADA Yuto
(pdf):Performance test of a gaseous TPC with neutron beam for the detection of Migdal effect

P21 : Yusuke Urano
(pdf):Quenching factor measurement in low-energy nuclear recoil of NaI(Tl) scintillator using monochromatic neutrons for dark matter search

P22 : Masataka Shinoki
(pdf):Measurement of cosmogenic neutron in Super-Kamiokande

P23 : Ayaka Nakayama
(pdf):Direction-sensitive dark matter search using lower　pressure gaseous TPC

P24 : Miyohi Go
(pdf):Data analysis for reduction of 208Tl background events in CANDLES system

P25 : Takashi Iida
(pdf):Study of Gd-160 double beta decay by PIKACHU experiment

P26 : Yuuki Nakano
(pdf):Measurements of the charge ratio of cosmic-ray muons with the Super-Kamiokande detector

P27 : Mizuno Ofuji
(pdf):Evaluation of γ-ray background from neutron beams for the detection of the Migdal effect

P28 : Yuga Ommura
(pdf):Measurement of quenching factor for recoil nuclei from neutron scattering in BGO scintillator

P29 : Naoki Aoyama
(pdf):Development of coated electrodes with low quantum efficiency for the DARWIN experiment.

P30 : Takuya Shiraishi
(pdf):Environmental Sub-MeV Neutron Measurement in Gran Sasso with Ultra Fine-grained Nuclear Emulsion

P31 : Tsukasa Yoshida
(pdf):Tau identification using machine learning image classification in Hyper-Kamiokande

P32 : Ryuta Shirai
(pdf):Energy Resolution Improvement for CaF2 Scitillating Bolometer by Machine Learning Analysis

P33 : Takeshi Nakahata
(pdf):Research and development of new Front-end Electronics for KamLAND2

P34 : Ryo Nakamura
(pdf):Constraint on neutrinos from PBHs with the KamLAND upper limit data

P35 : Minori Eizuka
(pdf):A search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data

P36 : Yuta Yamamoto
(pdf):Analogue tachyon condensation in superconducting transmission lines

P37 : Kanji Mori
(pdf):Core-collapse Supernova Models with Heavy Axion-like Particles

P38 : Hirokazu Sasaki
(pdf):Majorana neutrino-antineutrino oscillations in core-collapse supernovae with strong magnetic fields

P39 : 平岩 侑
(pdf):Development of the atomic beam system for the laser isotope separation of 48Ca

P40 : 阪井俊樹
(pdf):CANDLES実験による二重ベータ崩壊の研究における機械学習を用いた波形解析によるバックグラウンド除去の評価

P01 : 岸田有美子
(pdf):Development of Ge detector for purification of CaF2 crystals
 "In double beta decay experiments. It is important to remove radioactive impurities from the scintillator to reduce the intrinsic background. We have started to produce pure and low-background CaF2 crystals. We measure radioactive impurities in raw materials of CaF2 by a Ge detector, We performed anti-coincidence measurement to reduce the background due to cosmic rays. We will show the results of several samples."

P02 : Tuan Khai Bui
(pdf):Status of the neutron veto system of XENONnT
 XENONnT is a dark matter direct detection experiment set up at the underground Gran Sasso laboratory (LNGS). It is a two-phase time projection chamber (TPC) filled with 5.9 tons of liquid xenon (LXe) and expected to collect 20 ton´years of exposure over the next five years. The radiogenic neutrons in detector structural materials of XENONnT can produce a nuclear recoil signal, which mimics a WIMP signal. The neutron Veto, which was developed based on Gd-loaded water Cherenkov technology of Super-Kamioka and EGADS, is under commissioning to tag background events caused by neutrons. We will present the current status of our XENONnT neutron veto system.

P03 : MASAMITSU MORI
(pdf):Long time simulation of neutrinos and gravitational wave from supernovae
 Core-collapse supernovae emit their gravitational energy as neutrino. They also emit gravitational waves due to multi-dimensional effects. So far, some studies calculated the emission in case neutron stars are left behind for more than 20 seconds in 1D simulations. In the case of black holes, neutrino is also emitted from the surrounding matter. However, the Misner-Sharp metric, which is often employed in simulations, diverges when black holes form. To evade the problem, we are developing a new simulation using the Hernandez-Misner metric. In this poster, we will show long signal of neutrinos and gravitational waves from a supernova, which forms a neutron star and development of the Hernandez-Misner code.

P04 : Umemoto Atsuhiro
(pdf):Diamond detector for dark matter search
 "Diamond has a unique physical characteristic, which realizes a special detector applied in the field of particle physics. I will show the recent development for dark matter search using diamond detector."

P05 : Tomoya Hasegawa
(pdf):Development of a hybrid-photodetector for the DARWIN experiment
 Dark matter, such as Weakly-Interacting-Massive Particles (WIMPs), could interact with nuclei in ordinal matter, and direct detection experiments try to search for such interactions between dark matter and detector medium. In particular, experiments using liquid xenon as a detector target are leading the searches for heavy WIMPs. However, neutron originating from radioactive material contaminated in photomultiplier tube(PMT) can be an irreducible background, and it limits the discovery potential of WIMPs. Therefore, it is important to develop a new photodetector with lower radioactivity. In this study, I will present about R&D results for the hybrid photodetector which we are now developing.

P06 : Atsushi Yoshioka
(pdf):Improvement of pulse shape discrimination analysis for background reduction in CANDLES
 To search for the neutrino-less double beta (0$\nu\beta\beta$) decay of ^{48}Ca (Q=4.27 MeV), CANDLES has been used the pulse shape discrimination (PSD) analysis to reduce the background due to ^{208}Tl->^{208}Pb decay (Q=5.0 MeV) in CaF_{2} crystals. We identify the preceding α decay (^{208}Bi->^{208}Tl) to reduce ^{208}Tl decay background using a characteristic signal waveform of the CaF_{2} scintillator. However, the PSD parameter distribution estimated by Monte Carlo simulation (MC) does not reproduce that of the real data. To solve this problem, we further investigated the PSD parameters of events in the CANDLES data and re-evaluate the uncertainty of waveform, parameter definition, and the calculation formula. Then the distribution of PSD parameters in the CANDLES data was well understood. This presentation will report the results of our research on PSD analysis.

P07 : Maho Kurasawa
(pdf):Research and development of high-sensitive measurement of trace amount of radioactive elements in organic materials for KamLAND2-Zen
 "This study aims to measure ultra-trace amounts of radioactive elements(uranium/thorium) in organic materials used in the next generation 0νββ experiment, KamLAND2-Zen. To measure such trace amounts (O(10 ppq)), we are now developing a method of the combination of dry ashing and ICP-MS measurement. In this presentation, the current status of the dry ashing method, the current achieved sensitivity for some samples and future prospects will be reported."

P08 : Kazuki Tanaka
(pdf):Neutrinoless double beta decay in the seesaw mechanism
 "We studied the contributions of right-handed neutrinos to the neutrinoless double beta decay in the seesaw mechanism. Especially, we consider the case when right-handed neutrinos are lighter than TeV scale, which potentially give significant effects to it.We also discuss the possibility of verifying these contributions in future experiments and show the impact on the direct search for right-handed neutrinos."

P09 : Ko Nakamura
(pdf):Neutrino signals from 3D core-collapse supernova models
 Systematic studies of core-collapse supernovae have been conducted based on hundreds of one-dimensional artificial models (O'Connor & Ott 2011,2013; Ugliano et al. 2013, Ertl et al. 2015) and two-dimensional self-consistent simulations (Nakamura et al. 2015;2019, Burrows & Vartanyan 2020). We have performed three-dimensional core-collapse simulations for 16 progenitor models. Our models present a wide variety of explosion properties such as shock evolution and explosion energy. We present the dependence of the neutrino emission on the progenitor structure.

P10 : Wakana Iwakami
(pdf):A Simulation of Core-collapse Supernovae in Three-dimensional Space with Full Boltzmann Neutrino Transport on the Supercomputer FUGAKU
 Using a radiation-hydrodynamics code with full Boltzmann neutrino transport, we have conducted the core-collapse supernova simulation for a 11.2M progenitor model in three-dimensional space up to 50 ms after bounce on the supercomputer FUGAKU. We solve the six-dimensional Boltzmann equations for three neutrino species and the three-dimensional compressible Euler equations with Furusawa and Togashiʼs nuclear equation of state. The shock wave reach almost 160km from the center of the PNS, which is the almost same as the radial position of the shock wave in the two-dimensional simulation.

P11 : Yoshihiro Iwata
(pdf):A study on the emission characteristics of gadolinium ions in a water Cherenkov detector
 The SK-Gd experiment is currently ongoing where gadolinium sulfate is dissolved in a water Cherenkov detector to increase the detection sensitivity of supernova relic neutrino events. In this work, the emission characteristics of gadolinium ions are studied to estimate the effect of ion emission caused by cosmic ray muons on the background level of the detector.

P12 : Yu Watanabe
(pdf):A Global Analysis of Resonance-enhanced Light Scalar Dark Matter
 We study a minimal model for a light scalar dark matter, requiring a light scalar mediator to address the core-cusp problem and interact with the standard model particles. We analyze the model comprehensively by focusing on the Breit-Wigner resonance for dark matter annihilation and self-scattering channels, considering the thermal relic abundance condition that includes the early kinetic decoupling effect, as well as the present and future constraints from collider, direct, and indirect dark matter detections. We found that the scalar dark matter with the mass of 0.3 - 2 GeV remains uncharted, which will be efficiently tested by the near future MeV gamma-ray observations.

P13 : Taichi Sakai
(pdf):Ocean Bottom Detector : Towards direct measurement of mantle geo-neutrino
 "Observation of geo-neutrinos originating from radioactive isotopes in the Earth (238U,232Th, etc.) can be converted to the amount of radioactive isotopes and the heat generated by their decays which governs the Earth dynamics. To date, two experiments (KamLAND and Borexino) have measured geo-neutrinos and constrained the range of acceptable models for the Earth’s chemical composition, but distinguishing the mantle flux by land-based detectors is challenging as the crust signal is about 70% of the total anti-neutrino flux. Given the oceanic crust is thinner and has lower concentration of radioactive elements than continental crust, geo-neutrino detector in the ocean, Ocean Bottom Detector (OBD), makes it sensitive to geo-neutrinos originating from the Earth’s mantle. Our working group was jointly constructed from interdisciplinary communities in Japan which include particle physics, geoscience, and ocean engineering. We have started to work on technological developments of OBD. We are now developing a 20 kg prototype liquid scintillator detector. This detector will undergo operation deployment tests at 1 km depth seafloor in 2022. Our first big goal is 1.5 kt size detector, and we aim world first direct observation of mantle geo-neutrinos. In my presentation, I will give our detector concept, current development status and performance evaluation result."

P14 : Kei Kanezaki
(pdf):Development of gaseous TPC for the detection of Migdal effect
 Recently, the search for light dark matter using the Migdal effect has become popular. However, it has not yet been confirmed whether the Migdal effect is caused by nuclear recoil or not. In this study, we aim to observe a characteristic two-cluster signal caused by the Migdal effect using a neutron beam and a gaseous TPC. When neutrons enter the detector, detector material emit γ-rays due to neutron capture reaction. To reduce this γ-ray backgrounds, we have developed a low-mass argon gas TPC. In this presentation, we will report the results of a neutron beam test using the TPC.

P15 : Koji Ishidoshiro
(pdf):New dark matter experiment with superconducting sensors at Kamioka
 We are planning to set up a cryogenic laboratory at the Kamioka in cooperation with RCNS, KEK QUP, and LBNL. The goal of our first physical search is about low-mass dark matter studies. We will present the overall plan and the efforts on the Japanese side.

P16 : Kenta Kotera
(pdf):Background analysis of NaI(Tl) crystals for the development of new PICOLON detector.
 "The PICOLON group uses low background NaI(Tl) detectors to search for dark matter. The highly radiopure NaI(Tl) crystal has the large advantage in searching for dark matter and verifying the annual modulation reported by the DAMA/LIBRA group.We report the results of background analysis of high-purity NaI(Tl) crystals purified with specially optimized method. The low-background data was taken in the Kamioka underground laboratory. Additionally, we prospect plans for dark matter search and new detector design."

P17 : Kodai Iwasawa
(pdf):Development of low background liquid scintillation detector for ambient neutron measurement
 "In a direct dark matter search, the main background events are ambient neutrons from outside the detector and α-rays from inside the detector.Accurate estimation of these two background events are of great importance.The main sources of α-rays are leaks of radioactive Rn-222 from inside the detector components to liquid scintillator and radioactive impurities in the liquid scintillator itself.For the former, the inside of the detector was electropolished to reduce the surface area, and for the latter,the liquid scintillator was purified by liquid-liquid extraction with ultrapure water, and an α-ray background of 0.8 mBq was achieved.In this presentation, the results of these measurements and analyses will be presented."

P18 : Shohei Ogawa
(pdf):Evaluation of stellar core radii and masses aiming for supernova relic neutrinos with the use of a stellar population synthesis code
 In general, most of stellar population synthesis codes don't calculate stellar CO core radii. Hence we have improved a stellar population synthesis code based on the result computed with detailed stellar evolution codes so that the code becomes able to calculate CO core radii and comes in useful for the estimate of supernova relic neutrinos. This poster aims to explain how we have incorporated the treatment of CO core radii into the stellar population synthesis code.

P19 : Hiromitsu Yasu
(pdf):Evaluation of the front-end electronics with dual-gain amplification
 We develop a gaseous TPC in a dark matter search experiment using SF6, which drifts negative ions instead of electrons. Since it produces two types of negative ions with different signal magnitudes, it requires a large dynamic range for readout. In order to achieve it, we have developed an ASIC that dynamically changes two types of amplifiers with different gains. In this study, we evaluated the performance of the ASIC.

P20 : HAMADA Yuto
(pdf):Performance test of a gaseous TPC with neutron beam for the detection of Migdal effect
 Migdal effect is recently attracting attention in the context of light dark matter search. The Migdal effect is a phenomenon in which ionization and excitation occur with low probability as a result of the rapid motion of nuclear. MIRACLUE experiment aims to detect Migdal effect in nuclear recoil which has not been detected yet. In this presantation, we will report the neutron beam test results of a gaseous TPC for MIRACLUE experiment.

P21 : Yusuke Urano
(pdf):Quenching factor measurement in low-energy nuclear recoil of NaI(Tl) scintillator using monochromatic neutrons for dark matter search
 "PICOLON aims to search for cosmic dark matter using an ultra-pure NaI(Tl) scintillator at the Kamioka underground observatory.In this study, to measure the quenching factor (QF), we irradiated NaI(Tl) scintillator with 2.45-MeV monochromatic neutrons produced by the deuteron-deuteron fusion. Scattered neutrons from NaI(Tl) were detected with 6 liquid scintillator modules placed at scattering angle range of 25~60 degrees.By removing the backgrounds with the techniques of pulse shape discrimination (PSD) and time of flight (TOF), we confirmed the angular dependence of the nuclear recoil energy and succeeded in calculating the QF.This poster reports on the details of the experiments conducted in 2021, their results, and future plans."

P22 : Masataka Shinoki
(pdf):Measurement of cosmogenic neutron in Super-Kamiokande
 Cosmic-ray muons that enter the Super-Kamiokande detector cause hadronic showers, and the showers can produce radioactive isotopes out of oxygen via spallation. The produced neutrons and isotopes are major background sources for MeV-scale neutrino analysis and searches for rare events. Observations in Super-Kamiokande have been performed using ultra-pure water, and gadolinium was introduced into the water to improve the detection efficiency of neutrons and suppress the background due to radioactivities and PMT dark noises. In this study, we analyzed data for about one year after the gadolinium loading and measured the cosmogenic neutron production yield. The results will be presented in this poster.

P23 : Ayaka Nakayama
(pdf):Direction-sensitive dark matter search using lower　pressure gaseous TPC
 NEWAGE is a directionally sensitive dark matter search experiment. In this study, we aim to achieve a low energy threshold by extending the trajectory by lowering the gas pressure and reducing the external background by installing a copper shield. In this presentation, we will present the status of the analysis.

P24 : Miyohi Go
(pdf):Data analysis for reduction of 208Tl background events in CANDLES system
 "Double beta decay is predicted to include a rare process in which no neutrinos are emitted (0νββ). The CANDLES experiment aims to observe 0νββ decay of 48Ca using 96 CaF2 crystals in the experiment. The Q-value of 208Tl is 5 MeV, which is above Q-value of ββ decay of 48Ca. We have to remove this 208Tl background to realize background-free measurement. In order to further reduce this background, it is necessary to develop the precise Monte Carlo simulation to reproduce the energy spectrum and position distribution of 208Tl decays. This requires accurate position information and photoelectron distributions to be incorporated into the simulation. I report on the analytical method and results for obtaining this information."

P25 : Takashi Iida
(pdf):Study of Gd-160 double beta decay by PIKACHU experiment
 "The discovery of neutrino less double beta decay (0nbb) is important to verify the Majorana nature of neutrinos. Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences (PIKACHU) project was launched, and large, high-purity Ce:Gd3(Ga,Al)5O12 (GAGG) crystals are being developed to study the double beta decay of 160Gd.We have constructed a 6.5cmφ×14.5cmL (3.1kg) GAGG crystal detector combined with a Photomultiplier tube sensitive to long wavelengths and investigated its energy resolution (σ=5.7% @662 keV) and good pulse shape discrimination performance. Furthermore, in July 2020, this detector was installed in a lead shield at 1000 m underground in Kamioka, and high-sensitivity background measurements were performed. As a result, it was found that the crystals contain a large amounts of Th-series radioactive impurities, and we measured the impurity concentration in the crystal materials with a Ge detector. Among the materials, gadolinium oxide is contaminated by Th impurities, and we are developing a method for high purity crystals by material selection and purification. The results will be presented in this poster."

P26 : Yuuki Nakano
(pdf):Measurements of the charge ratio of cosmic-ray muons with the Super-Kamiokande detector
 Cosmic-ray muons arise from the showers of secondary particles produced via the interactions of primary cosmic particles with air nuclei at the top of the atmosphere. The interaction products, pions and kaons composing showers mostly decay to muons reflect the details of the hadronic interactions depending on their energy. Measurements of the charge ratio of cosmic-ray muons can be used to constrain high energy hadronic interaction models in the atmosphere. In this poster presentation, we will report the current status of the measurement of the charge ratio using data collected by the Super-Kamiokande (SK) detector. Using the data taken in the fourth phase of SK (SK-IV), the charge ratio is measured to be 1.42 ± 0.02 (statistical uncertainty only), at the energy of 1.3 TeV. This result for the charge ratio is in good agreement with those previously obtained by deep underground experiments.

P27 : Mizuno Ofuji
(pdf):Evaluation of γ-ray background from neutron beams for the detection of the Migdal effect
 The Migdal effect has been used to directly search for low-mass dark matter. The MIRACLUE experiment plans to use a neutron beam to make the first observation of a certain Migdal effect. In contrast, gamma rays from neutron capture reactions at the laboratory wall will be one of the main background events. To understand the background event, a neutron beam experiment was conducted at the National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba, Japan, in April 2022, and the energy spectrum of gamma rays was measured using a CsI scintillator. In this presentation, we will report the results of this measurement and the contribution of the gamma-ray background event to the MIRALUE experiment.

P28 : Yuga Ommura
(pdf):Measurement of quenching factor for recoil nuclei from neutron scattering in BGO scintillator
  BGO scintillator is widely used in underground particle physics experiments. As an example, it is used with Am/Be neutron source in Super-Kamiokande(SK) to evaluate the detection efficiency of neutron. In SK, a relative 10% discrepancy between the measured and simulated efficiency of neutron detection was reported with the Am/Be source and the scattering of neutron in BGO is considered as one of the sources of the discrepancy. Therefore, a precise measurement of responses of the BGO scintillator to neutrons is important to suppress the systematic uncertainty. For this purpose, we carried out a neutron beam test at AIST, Japan to measure neutron scattering in BGO detectors. The data of elastic scattering with neutron and nuclei in BGO crystal are recorded when signals are simultaneously observed by both BGO and liquid scintillator detectors. Background events of gamma rays are suppressed by the pulse shape discrimination method in liquid scintillation detector. We found a light yield of nuclear recoil tends to be smaller than the expectation, which is assumed for electrons with the same kinetic energy as the recoil nuclei. The recoil energy of nuclei is calculated from the initial energy of neutron and its scattering angle. The ratio of electron equivalent energy to recoil energy is defined as quenching factor. Varying the scattering angle, the quenching factor as a function of the recoil energy has been measured. In this presentation, we will report the details of the data analysis and the results of the measurements.

P29 : Naoki Aoyama
(pdf):Development of coated electrodes with low quantum efficiency for the DARWIN experiment.
 In direct dark matter search experiments using liquid xenon (Xe), scintillation and ionization signals are produced by the interaction between Xe and dark matter. Scintillation photons can produce photoionization electrons through photoelectric effect on electrodes, which is one of the major backgrounds for low-mass dark matter searches. For DARWIN, a future direct dark matter search experiment using 50 tons of liquid Xe, we are developing coated electrodes with low quantum efficiency to reduce ionization signas originating from photoionization of electrodes. In this poster presenation, I will present about the results of quantum efficiency measurements for some electrodes (Au, Pt, Al, SUS304, etc) in vacuum, liquid Xe and gas Xe.

P30 : Takuya Shiraishi
(pdf):Environmental Sub-MeV Neutron Measurement in Gran Sasso with Ultra Fine-grained Nuclear Emulsion
 We have developed a new detection method for neutrons above sub-MeV using ultra fine-grained nuclear emulsion. Because of three-dimensional tracking of neutron-recoil protons with sub-micrometric accuracy, this method has extremely high γ-ray rejection power, and furthermore, it has energy resolution and directionality even in the sub-MeV energy region. Currently, environmental neutron measurements are ongoing at the surface laboratory of Gran Sasso, and results of flux, energy spectra, and angular anisotropy will be reported.

P31 : Tsukasa Yoshida
(pdf):Tau identification using machine learning image classification in Hyper-Kamiokande
 Hyper-Kamiokande is a next-generation neutrino experiment that is under construction in Japan. The Hyper-Kamiokande far detector will be instrumented by thousands of photomultipliers (PMT) which detect the Cherenkov light emitted by charged particles produced by neutrino interactions in the water. The neutrino flavor can be specified by identifying the type of charged particles produced in neutrino interactions. In addition to the electron neutrinos and muon neutrinos produced in the atmosphere, the Hyper-Kamiokande also observes tau neutrinos which are mainly produced by oscillations of muon neutrinos. Tau particles decay into charged leptons or hadrons with a short lifetime. When tau decay into hadrons, many Cherenkov rings are produced. We attempt to distinguish such events from deep inelastic scattering interactions of electron and muon neutrinos using machine learning based on the PMT signals. The performance of the selection is presented in the poster.

P32 : Ryuta Shirai
(pdf):Energy Resolution Improvement for CaF2 Scitillating Bolometer by Machine Learning Analysis
 "The CANDLES experiment aims to observe neutrinoless double β-decay of 48Ca, and the development of a detector with good energy resolution is essential to achieve this goal.The CaF2 scintillating bolometer under development consists of a light detector and a thermal detector on the top and bottom. When charged particles are generated and their energy is absorbed by the scintillation crystal, photons and phonons are produced.This raises the temperature of the Ge wafer and phonon collector and decreases the magnetization of the MMC (Metallic Magnetic Calorimeter). The change is read by a SQUID (superconducting quantum interferometer).By measuring both heat and fluorescence in this way, background is eliminated by utilizing quenching in the α event and by discriminating α, γ, and μ- particles.The measured thermal signal consists of three components: photon absorption, phonons, and their thermalization, of which the photon absorption and phonon signals are not used for energy determination.The reason for this is that the phonon signal has a dependence on the location of the event, with a higher wave height when the event occurs in the CaF2 crystal close to the thermal detector and a lower wave height when the event occurs further away, and the photon signal also has a position dependence.This effect deteriorates the energy resolution, and the target resolution (Q value of double β-decay, 0.5% or less at 4.27 MeV) is not achieved. The position identification and energy correction are performed based on the time constant of the decay with position, the change in the rise time of the signal, and the integrated analysis with the optical signal. Since the effect is multidimensional, machine learning was introduced to analyze the waveform of the signal, and the results will be presented."

P33 : Takeshi Nakahata
(pdf):Research and development of new Front-end Electronics for KamLAND2
 KamLAND (Kamioka Liquid-Scintillator Anti-Neutrino Detector) has produced results of the measurements of neutrino oscillations and searched for Majorana nature of neutrinos. Searching for the neutrino-less double beta (0νββ) decay is the only realistic way to verify whether neutrinos are Majorana particles or Dirac particles. Since 2019, we have started the KamLAND-Zen800 Phase with 745 kg enriched xenon to search for neutrino-less double beta decay. Currently, many researches and developments are ongoing for higher sensitive search in the new phase (KamLAND2-Zen). From the dedicated analysis with KamLAND-Zen800 data, we found new serious backgrounds which are long-lived spallation products of 136Xe caused by cosmic-ray muons. The spallation of 136Xe creates a lot of neutrons, and the number of neutrons is correlated with that of the spallation products. Neutron multiplicity is a key to tag the spallation backgrounds. However, neutron detection efficiency is not enough because of PMT’s afterpulses and overshoots. We also suffer from becoming old of current front-end electronics for KamLAND and the end of production of the components to repair it. To improve these situations, we are accelerating our developments of Radio Frequency System-on-Chip-based (RFSoC-based) front-end electronics (FEE). RFSoC is the latest FPGA family from Xilinx, which involves programmable logic (PL) with a large number of digital signal processor (DSP) block, processing system (PS) based on Arm applications and real-time processors, radio-frequency ADCs (RF-ADCs), and radio-frequency digital-to-analog convertors (RF-DACs). We consider that RFSoC-based FEE can correct the PMT’s overshoot by on-board signal processing and record all the waveforms including afterpulses and neutrons signals by the large buffer. We tested the first prototype board of RFSoC based FEE for KamLAND2-Zen.

P34 : Ryo Nakamura
(pdf):Constraint on neutrinos from PBHs with the KamLAND upper limit data
 "Primordial black hole (PBH) is a hypothetical object formed after the inflation. The existence of PBH might be a key to solving several problems related to cosmology.In this poster presentation, we present the details of neutrino emitted from PBH and the upper limit on the fraction of PBH to dark matter from the KamLAND published data. This result is complementary with other constraints from other observational limits. "

P35 : Minori Eizuka
(pdf):A search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data
 On 1987 February 23rd, neutrinos from SN1987A were observed. This observation confirms that neutrinos have an important role in supernova explosions. In order to establish the detailed mechanisms of supernovae, further supernova neutrino signals have been searched for with a variety of detectors. The KamLAND, an anti-neutrino detector using a 1kt liquid scintillator, has significant sensitivity to supernova neutrinos owing to a low radioactivity environment, a large target volume, and a low energy threshold. We searched for supernova neutrino events using the KamLAND data taken from 2002 March 9th to 2020 April 25th. In this talk, we present the result of a search for supernova neutrinos via inverse beta decay reaction (IBD). Multiple IBDs within 10-s window are required as a supernova neutrino event. Assuming theoretical models, we discuss the supernova detectable range at the KamLAND. Constrains on the galactic star formation rate from the point of view of a neutrino observation is also discussed. We present the status of a search for supernova neutrinos via 12C neutral current, too.

P36 : Yuta Yamamoto
(pdf):Analogue tachyon condensation in superconducting transmission lines
 Tachyon condensation is a process in particle physics whereby a system can lower its energy by spontaneously producing particles, leading to "condensation" of particles that fill the volume of the system. Thus, tachyon condensation may explain the formation of matter during the evolution of the early universe. To verify this hypothesis, it would be useful to mimic the cosmogenesis of the universe in a laboratory system. Here we propose a simple method to create analogue tachyon condensation using superconducting transmission lines with superconducting nonlinear asymmetric inductive elements (SNAIL). This system can mimic the tachyonic vacuum by controlling the junction parameters that determine the SNAIL interference. Thus, the condensation process, which is a transition from that state, can be investigated.

P37 : Kanji Mori
(pdf):Core-collapse Supernova Models with Heavy Axion-like Particles
 Axion-like particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma of stars and core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced in a supernova, some of the ALPs can be absorbed by the supernova matter and affect energy transfer. We recently calculated the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics consistently. It is found that the stalled bounce shock can be revived if the coupling between ALPs and photons is as high as $g_{a\gamma}\sim 10^{-9}$ GeV$^{-1}$ and the ALP mass is 40-400 MeV.

P38 : Hirokazu Sasaki
(pdf):Majorana neutrino-antineutrino oscillations in core-collapse supernovae with strong magnetic fields
 We calculate Majorana neutrino-antineutrino oscillations in dense astrophysical sites with strong magnetic fields. With the coupling of the magnetic field potential and the MSW matter potential, Majorana neutrinos can reach a flavor equilibrium sensitive to the baryon density and the electron fractions inside the matter. From the calculation result, we propose a necessary condition for the equilibration of the neutrino-antineutrino oscillations and study whether such a condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibrium would be possible with the typical magnetic fields of magnetars (10^14 G).

P39 : 平岩 侑
(pdf):Development of the atomic beam system for the laser isotope separation of 48Ca
 " We are searching for neutrino-less double beta decay (0νββ) of 48Ca to verify the Majorana nature of neutrinos. 48Ca has the highest Q value (4.27 MeV), which is advantageous for background reduction. On the other hand, its natural abundance is very low (0.187%), and it is necessary to enrich it to increase the number of target nuclei, although an inexpensive and effective enrichment method has not been found. We are developing a laser deflection method for Ca isotope enrichment. Isotope separation is achieved through momentum transfer by irradiating the laser tuned only to the target isotope (48Ca) perpendicular to the Ca atomic beam. After the proof-of-principle, R&D for the mass production of 48Ca is underway, and UF collaborators are in charge of the development of the atomic beam system. For the mass production of 48Ca, it is necessary to improve the concentration and recovery rates by efficiently converting the raw calcium into atomic beams and by improving the separation of 48Ca from the deflected 48Ca. To achieve this, an atomic beam is created in the form of a sheet that is thin with respect to the direction of laser incidence for deflection and long in that perpendicular direction. At present, it is assumed that multiple thin cylindrical tubes will be used for collimation. In addition, various Ca atomic beam monitoring systems are needed to verify the collimating effect of the atomic beam and to check the concentration and recovery efficiency of the deflected 48Ca. Until now, time-of-flight (TOF) ionization measurements have been used, which are accurate but time-consuming. We have developed a system with coating thickness gauge that can measure positional distribution more quickly and simply, and a spatial/momentum distribution measurement system based on fluorescence observation from an atomic beam at the deflection laser irradiated position. As for the latter, we are considering applying it to control the wavelength of the deflection laser in near future. The collimating effect of a single thin tube on atomic beams from a small crucible has been measured using three different monitoring systems. The results of the TOF measurement method confirm that the expected collimation effect is almost achieved. We also evaluated the performance of two newly developed monitoring systems by comparison. Based on these results, we are planning to conduct tests using a larger crucible and multiple tubes. In this poster presentation, we will report on the current status of these tests."

P40 : 阪井俊樹
(pdf):CANDLES実験による二重ベータ崩壊の研究における機械学習を用いた波形解析によるバックグラウンド除去の評価
 CANDLES実験では、48Caのββ崩壊の研究を行なっている。48Caの2νββ崩壊の半減期はより精度の高い測定が求められているが、結晶内に含まれる放射性不純物の232Th崩壊系列の娘核(212Bi,212Po)の連続崩壊事象が主要なバックグラウンドとなっている。本研究ではこの連続崩壊事象の波形をCANDLES検出器で得られた実データから擬似的に作成し、機械学習を用いることで、連続崩壊事象を識別する。本講演では識別の精度を定量的に議論する。