A5065802750- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Atomic and Subatomic Physics Research
- Galectins and Cancer Biology
- Glycosylation and Glycoproteins Research
- Radiation Detection and Scintillator Technologies
- Gamma-ray bursts and supernovae
- Caveolin-1 and cellular processes
- Scientific Research and Discoveries
- Particle Detector Development and Performance
- Law, logistics, and international trade
- Enzyme Structure and Function
- Urban and spatial planning
- Cholesterol and Lipid Metabolism
- Radioactivity and Radon Measurements
- Cosmology and Gravitation Theories
- Energy and Environmental Systems
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Isotope Analysis in Ecology
- Advanced Semiconductor Detectors and Materials
- Radioactive contamination and transfer
- Semiconductor Quantum Structures and Devices
Tohoku University
1993-2024
Tokushima University
2019-2020
Tohoku Medical and Pharmaceutical University
2012
Komatsu (Japan)
2012
Miyagi Prefectural Hospital Organization
1998-2008
The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νββ) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search upgraded detector with almost double amount of xenon and ultralow radioactivity container, corresponding to exposure 970 kg yr ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation xenon, have required use novel background rejection...
We report on a search for electron antineutrinos ($\bar{\nu}_e$) from astrophysical sources in the neutrino energy range 8.3 to 30.8 MeV with KamLAND detector. In an exposure of 6.72 kton-year liquid scintillator, we observe 18 candidate events via inverse beta decay reaction. Although there is large background uncertainty neutral current atmospheric interactions, find no significant excess over model predictions. Assuming several supernova relic spectra, give upper flux limits 60--110...
Abstract The electron antineutrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range 1.8–200 MeV using Kamioka Liquid Scintillator Antineutrino Detector. Using multiple time windows ranging from minutes to days surrounding event search antineutrinos coincident with GRB, we set an upper limit on under assumption several power-law neutrino source spectra, indices 1.5 3 in steps 0.5. No excess was observed any seconds around trigger T 0 ....
Abstract Highly radiopure NaI(Tl) was developed to search for particle candidates of dark matter. Optimized methods were combined reduce various radioactive impurities. $^{40}$K effectively reduced by the recrystallization method. The progenies decay chains uranium and thorium appropriate resins. concentration natural potassium in crystal 20 ppb. Concentrations alpha-ray emitters successfully resin selection. present concentrations series $^{226}$Ra $1.2\pm1.4$$\mu$Bq/kg $13\pm4$$\mu$Bq/kg,...
Abstract The decay of the primordial isotopes 238 U, 235 232 Th, and 40 K has contributed to terrestrial heat budget throughout Earth's history. Hence, individual abundance those are key parameters in reconstructing contemporary Earth models. geoneutrinos produced by radioactive decays uranium thorium have been observed with Kamioka Liquid‐Scintillator Antineutrino Detector (KamLAND). Those measurements improved more than 18‐year observation time, improvement detector background levels...
We report a measurement of the strange axial coupling constant ${g}_{A}^{s}$ using atmospheric neutrino data at KamLAND. This is component form factor neutral-current quasielastic (NCQE) interaction. The value significantly changes ratio proton and neutron NCQE cross sections. KamLAND suitable for measuring interactions as it can detect nucleon recoils with low-energy thresholds measure multiplicity high efficiency. data, including information on associated interactions, makes possible to...
We present a search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{136}$Xe using the full KamLAND-Zen 800 dataset with 745 kg enriched xenon, corresponding to an exposure $2.097$ ton yr $^{136}$Xe. This updated benefits from more than twofold increase in exposure, recovery photo-sensor gain, and reduced background muon-induced spallation xenon. Combining previous phase, we obtain lower limit $0\nu\beta\beta$ half-life $T_{1/2}^{0\nu} > 3.8 \times 10^{26}$ at 90% C.L., factor 1.7...
The KamLAND-Zen 800 experiment is searching for the neutrinoless double-beta decay of $^{136}$Xe by using $^{136}$Xe-loaded liquid scintillator. scintillator enclosed inside a balloon made thin, transparent, low-radioactivity film that we call Inner Balloon (IB). IB, apart from guaranteeing containment, also allows to minimize background cosmogenic muon-spallation products and $^{8}$B solar neutrinos. Indeed these events could contribute total counts in region interest around Q-value...
A membrane-associated ganglioside-hydrolyzing sialidase was purified to apparent homogeneity from bovine brain. The enzyme solubilized with Triton X-100 plus sodium cholate the particulate fraction and over 100,000-fold by sequential chromatography on DEAE-cellulose, octyl-Sepharose, heparin-Sepharose, Sephacryl S200, MonoQ, RCA-agarose, thiol-activated Sepharose, ganglioside-affinity Sepharose. final preparation exhibited a specific activity of 4, 851.3 μmol/h/mg protein an molecular mass...
Cosmic-ray muons produce various radioisotopes when passing through material. These spallation products can be backgrounds for rare event searches such as in solar neutrino, double-$\ensuremath{\beta}$ decay, and dark matter search experiments. The KamLAND-Zen experiment neutrinoless decay 745 kg of xenon dissolved liquid scintillator. includes dead-time-free electronics with a high efficiency detecting muon-induced neutrons. production yields different are measured combination delayed...
Abstract Preceding a core-collapse supernova (CCSN), various processes produce an increasing amount of neutrinos all flavors characterized by mounting energies from the interior massive stars. Among them, electron antineutrinos are potentially detectable terrestrial neutrino experiments such as KamLAND and Super-Kamiokande (SK) via inverse beta decay interactions. Once these pre-supernova (pre-SN) observed, early warning upcoming CCSN can be provided. In light this, SK, both located in...
We report the result of a search for neutrinos in coincidence with solar flares from GOES flare database. The was performed on 10.8 kton-year exposure KamLAND collected 2002 to 2019. This large allows us explore previously unconstrained parameter space neutrinos. found no statistical excess and established 90% confidence level upper limits $8.4 \times 10^7$ cm$^{-2}$ ($3.0 10^{9}$ cm$^{-2}$) electron anti-neutrino (electron neutrino) fluence at 20 MeV normalized X12 flare, assuming that...
We present the results of a search for MeV-scale electron antineutrino events in KamLAND coincident with 60 gravitational wave events/candidates reported by LIGO/Virgo collaboration during their second and third observing runs. find no significant signals within $\pm$ 500 s timing window from each 90% C.L. upper limits on fluence between $10^{8}$-$10^{13}\,{\mathrm cm^2}$ neutrino energies energy range 1.8-111 MeV.
We present the results of a search for core-collapse supernova neutrinos, using long-term KamLAND data from 2002 March 9 to 2020 April 25. focus on electron antineutrinos emitted supernovae in energy range 1.8--111 MeV. Supernovae will make neutrino event cluster with duration $\sim$10 s data. find no clusters and give upper limit rate as be 0.15 yr$^{-1}$ 90% confidence level. The detectable range, which corresponds >95% detection probability, is 40--59 kpc 65--81 failed supernovae,...
We present the results of a time-coincident event search for low-energy electron antineutrinos in KamLAND detector with gamma-ray bursts from Gamma-ray Coordinates Network and Fermi Burst Monitor. Using variable coincidence time window $\pm$500s plus duration each burst, no statistically significant excess above background is observed. place world's most stringent 90% confidence level upper limit on antineutrino fluence below 17.5 MeV. Assuming Fermi-Dirac neutrino energy spectrum burst...
The Weakly Interacting Massive Particles (WIMPs) are considered to be the hypothetical particles that have been leading candidate for dark matter decades. PICOLON project is directly searching WIMPs using ultra-pure NaI(Tl) crystals at Kamioka underground laboratory. To determine WIMP sensitivity, it necessary know quenching factor (QF) of NaI(Tl), which scintillation light yield ratio nuclear recoil and electron same energy deposit. Several groups reported QF absolute values its dependence...
Preceding a core-collapse supernova, various processes produce an increasing amount of neutrinos all flavors characterized by mounting energies from the interior massive stars. Among them, electron antineutrinos are potentially detectable terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova observed, early warning upcoming supernova can be provided. In light this, have been monitoring since 2015 2021,...
Particle dark matter could belong to a multiplet that includes an electrically charged state. WIMP (χ0) accompanied by negatively excited state (χ−) with small mass difference (e.g. < 20 MeV) can form bound-state nucleus such as xenon. This formation is rare and the released energy O(1−10) MeV depending on nucleus, making large liquid scintillator detectors suitable for detection. We searched events xenon in two experimental phases of KamLAND-Zen experiment, xenon-doped detector. No...
The electron antinuetrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range 1.8\,-\,200\,MeV using Kamioka Liquid Scintillator Anti Neutrino Detector (KamLAND). Using variety time windows to search antineutrinos coincident with GRB, we set an upper limit on under assumption various neutrino source spectra. No excess was observed in any ranging from seconds days around event trigger time. compared results by IceCube.