A5083747502- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- High-Energy Particle Collisions Research
- Superconducting Materials and Applications
- Advanced NMR Techniques and Applications
- Particle Detector Development and Performance
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Muon and positron interactions and applications
- Atomic and Subatomic Physics Research
- X-ray Spectroscopy and Fluorescence Analysis
- Astrophysics and Cosmic Phenomena
- Nuclear reactor physics and engineering
- Photocathodes and Microchannel Plates
- Medical Imaging Techniques and Applications
- Plasma Diagnostics and Applications
- Black Holes and Theoretical Physics
- Radiation Therapy and Dosimetry
- Magnetic confinement fusion research
- Radiation Effects in Electronics
Osaka University
2006-2025
Hokkaido University
2025
High Energy Accelerator Research Organization
2013-2022
Institute of Particle and Nuclear Studies
2004-2021
Japan Proton Accelerator Research Complex
2015-2019
The Graduate University for Advanced Studies, SOKENDAI
2014
Tohoku University
1998-2009
Seoul National University
2003-2006
Hitachi (Japan)
2002
This paper introduces a new approach to measure the muon magnetic moment anomaly |$a_{\mu} = (g-2)/2$| and electric dipole (EDM) |$d_{\mu}$| at J-PARC facility. The goal of our experiment is |$a_{\mu}$| using an independent method with factor 10 lower momentum, 20 smaller diameter storage-ring solenoid compared previous ongoing |$g-2$| experiments unprecedented quality storage field. Additional significant differences from present experimental include 1000 transverse emittance beam...
We report on the first measurement of a hypernuclear gamma-transition probability. gamma rays emitted in E2(5/2(+)-->1/2(+)) transition (7)(Lambda)Li were detected by large-acceptance germanium detector array (Hyperball), and lifetime parent state ( 5/2(+)) was determined Doppler shift attenuation method. The obtained result, 5.8(+0.9)(-0.7)+/-0.7 ps, then converted into reduced probability [ B(E2)] to be B(E2;5/2(+)-->1/2(+)) = 3.6+/-0.5(+0.5)(-0.4) e(2) fm(4). Compared with B(E2)...
Using a large-acceptance germanium detector array (Hyperball), we have observed spin-flip M1 gamma transition between the ground-state spin doublet of (7)(Lambda)Li (3/2(+)-->1/2(+)). The energy 691.7+/-0.6(stat)+/-1.0(syst) keV provides crucial information on strength spin-spin interaction Lambda and nucleon. This is first observation well-identified hypernuclear transitions using detectors.
We have studied the (pi(-),K+) reaction on a silicon target to investigate sigma-nucleus potential. The inclusive spectrum was measured at beam momentum of 1.2 GeV/c with an energy resolution 3.3 MeV (FWHM) by employing superconducting kaon spectrometer system. compared theoretical calculations within framework distorted-wave impulse approximation, which demonstrates that strongly repulsive potential nonzero size imaginary part reproduces observed spectrum.
A hydrogen-like atom consisting of a positive muon and an electron is known as muonium. It near-ideal two-body system for precision test bound-state theory fundamental symmetries. The MuSEUM collaboration performed new measurement the muonium ground-state hyperfine structure at J-PARC using high-intensity pulsed beam high-rate capable positron counter. resonance transition was successfully observed near-zero magnetic field, interval $ν_{\text{HFS}}$ = 4.463302(4) GHz obtained with relative...
Transport networks spanning the entire body of an organism are key infrastructures for achieving a functional system and facilitating distribution nutrients signals. The large amoeba-like Physarum polycephalum has gained attention as useful model studying biological transport owing to its visible rapidly adapting vein structure. Using particle-tracking velocimetry, we measured flow velocity protoplasmic streaming over plasmodia during development intricate network. Based on these...
We performed a search for the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>K</a:mi><a:mi>L</a:mi></a:msub><a:mo stretchy="false">→</a:mo><a:msup><a:mi>π</a:mi><a:mn>0</a:mn></a:msup><a:mi>ν</a:mi><a:mover accent="true"><a:mi>ν</a:mi><a:mo stretchy="false">¯</a:mo></a:mover></a:math> decay using data taken in 2021 at J-PARC KOTO experiment. With newly installed counters and new analysis method, expected background was suppressed to <f:math...
We have observed two gamma-ray transitions in (16)(Lambda)O from the 6.6 MeV excited 1(-)(2) state to both ground-state spin-doublet members (1(-)(1),0(-)) by (K-,pi(-)gamma) reaction. obtained doublet spacing be 26.4+/-1.6(stat)+/-0.5(syst) keV and excitation energy of 6561.7+/-1.1(stat)+/-1.7(syst) keV. The provides a small but nonzero strength tensor interaction between Lambda nucleon. This is first experimental result on LambdaN interaction.
High-resolution spectrometers for both incident beams and scattered particles have been constructed at the K1.8 beam line of Hadron Experimental Facility J-PARC. A point-to-point optics is realized between entrance exit QQDQQ magnets spectrometer. Fine-pitch wire chamber trackers hodoscope counters are installed in spectrometer to accept a high rate up 107 Hz. The superconducting kaon was transferred from KEK with modifications cryogenic system detectors. missing-mass resolution 1.9 ± 0.1...
We have simultaneously measured the energy spectra of neutrons and protons emitted in non-mesonic weak decays HeΛ5 CΛ12 hypernuclei produced via (π+,K+) reaction with much higher statistics than those previous experiments. The neutron-to-proton yield ratios for both at a high threshold (60 MeV) were approximately equal to two, which suggests that ratio neutron- proton-induced decay channels, Γn(Λn→nn)/Γp(Λp→np), is about 0.5. In neutron spectra, we found low-energy component unexpectedly...
In a γ-ray spectroscopy experiment with the (K−,π−) reaction on B10 target, we have observed 7/2+→5/2+ spin-flip M1 transition in Λ7Li via γ-γ coincidence 5/2+→1/2+E2 transition. This is first successful γ−γ measurement for hypernuclei. The measured energy 470.8±1.9(stat)±0.6(syst) keV. spacing of 7/2+,5/2+ doublet consistently explained using strengths spin-spin, Λ-spin-orbit, and tensor interactions obtained from previous γ-spectroscopy experiments.Received 3 December...
We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay $_{\ensuremath{\Lambda}}^{5}\mathrm{He}$ formed via $^{6}\mathrm{Li}({\ensuremath{\pi}}^{+},{K}^{+})$ reaction. The energies and pair number distributions in opening angle between them were measured. In both $np$ $nn$ pairs, we observed clean back-to-back correlation coming two-body reactions $\ensuremath{\Lambda}p\ensuremath{\rightarrow}np$ $\ensuremath{\Lambda}n\ensuremath{\rightarrow}nn$,...
We have measured the angular correlation of pair nucleons np and nn emitted from nonmesonic weak decay (NMWD) ^{12}_{Lambda}C produced via (pi^+,K^+) reaction in coincidence measurement. The Lambda p -> n modes were clearly identified by measuring back-to-back nucleon pairs which is characteristic two-body kinematics. From numbers N_{nn} N_{np}, ratio Gamma_n/Gamma_p partial widths Gamma_n(Lambda nn) Gamma_p(Lambda np) was extracted to be 0.51+-0.13(stat) +- 0.05(syst); this result almost...
The bound-state level structures of the Λ16O and Λ15N hypernuclei were studied by γ-ray spectroscopy using a germanium detector array (Hyperball) via O16 (K−,π−γ) reaction. A scheme for was determined from observation three transitions doublet states (2−,1−) at ~6.7 MeV to ground-state (1−,0−). produced proton emission unbound in Λ16O. Three γ rays observed, lifetime 1/2+;1 state measured Doppler shift attenuation method. By comparing experimental results with shell-model calculations, spin...
We have measured the branching ratio of three-body process in nonmesonic weak decay Lambda12C to be 0.29+/-0.13. This result was obtained by reproducing nucleon and pair yields introducing a final state interaction. At same time, we determined absolute widths, Gamma(n) Gamma(p), along with Gamma2N, whose relative has been long-standing puzzle. Including process, successfully reproduced energy distribution, coincidence two-nucleon angular correlation, momentum sum distribution simultaneously.
The $\Theta^+$ pentaquark baryon was searched for via the $\pi^-p\to K^-X$ reaction in a missing-mass resolution of 1.4 MeV/$c^2$(FWHM) at J-PARC. $\pi^-$ meson beams were incident on liquid hydrogen target with beam momentum 1.92 GeV/$c$. No peak structure corresponding to mass observed. upper limit production cross section averaged over scattering angle 2$^{\circ}$ 15$^{\circ}$ laboratory frame obtained be 0.26 $\mu$b/sr region 1.51$-$1.55 GeV/$c^2$.The decay width using effective...
We have measured the energy spectra of pions and protons emitted in weak decay $^{\ensuremath{\Lambda}}_{12}\mathrm{C}$, $^{\ensuremath{\Lambda}}_{28}\mathrm{Si}$, $^{\ensuremath{\Lambda}}\mathrm{Fe}$ hypernuclei produced via $({\ensuremath{\pi}}^{+},{K}^{+})$ reaction. The widths ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesonic $(\ensuremath{\Lambda}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}})$ nonmesonic $(\ensuremath{\Lambda}N\ensuremath{\rightarrow}NN)$ were extracted....
We have measured the neutron spectra emitted in weak decay of $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ and $_{\ensuremath{\Lambda}}^{89}\mathrm{Y}$ over energy region above $10\phantom{\rule{0.3em}{0ex}}\text{MeV}$ $({\ensuremath{\pi}}^{+},{K}^{+})$ reaction with better statistics an improved signal-to-background ratio. The yields nonmesonic decays were obtained from spectra. By using proton yield $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$, ${\ensuremath{\Gamma}}_{n}∕{\ensuremath{\Gamma}}_{p}$...
Numbers of protons per Gamma hypernuclear weak decay were measured as a function proton energy above 40 MeV, explicitly identifying production hypernuclei by the (pi+,K+) reaction. The ratios between neutron-stimulated to proton-stimulated nonmesonic widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) extracted fitting spectra. present result claims that yields are suppressed and Gamma(n)/Gamma(p) close 1 both for 12LambdaC 28LambdaSi in contradiction theoretical...
Three beam lines for secondary charged particles are constructed in the hadron experimental hall of J-PARC. The K1.8 line, which incorporates two separators, delivers clean beams kaons up to 2 GeV/c. K1.8BR line is a branch K1.8, low-momentum 1.2 K1.1BR shorter designed kaons. Details these designs, as well commissioning results, described.
The pentaquark $\Theta^+$ has been searched for via the $\pi^-p \to K^-X$ reaction with beam momenta of 1.92 and 2.01 GeV/$c$ at J-PARC. A missing mass resolution 2 MeV (FWHM) was achieved but no sharp peak structure observed. upper limits on production cross section averaged over scattering angle from 2$^{\circ}$ to 15$^{\circ}$ in laboratory frame were found be less than 0.28 $\mu$b/sr 90\% confidence level both 1.92- 2.01-GeV/$c$ data. systematic uncertainty controlled within 10\%....
We have measured the lifetimes of weak decay ${}_{\ensuremath{\Lambda}}^{12}\mathrm{C},$ ${}_{\ensuremath{\Lambda}}^{28}\mathrm{Si},$ and ${}_{\ensuremath{\Lambda}}^{56}\mathrm{Fe}$ hypernuclei which were produced via a $({\ensuremath{\pi}}^{+}{,K}^{+})$ reaction at KEK 12-GeV PS. The obtained by direct measurement production time hypernucleus using fast timing counter system whose resolution was about 83 ps. Our results for ${}_{\ensuremath{\Lambda}}\mathrm{Fe}$ are...