A5020049783- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Particle accelerators and beam dynamics
- Nuclear physics research studies
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- High-Energy Particle Collisions Research
- Muon and positron interactions and applications
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Advanced NMR Techniques and Applications
- Dark Matter and Cosmic Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Photocathodes and Microchannel Plates
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Scientific Research and Discoveries
High Energy Accelerator Research Organization
2015-2024
Tokyo Institute of Technology
2019-2022
Institute of Particle and Nuclear Studies
2004-2021
Japan Proton Accelerator Research Complex
2011-2021
The Graduate University for Advanced Studies, SOKENDAI
2021
Nippon Soken (Japan)
2019
RIKEN
2001-2019
Japan Atomic Energy Agency
2019
Kyoto University
2019
Lund University
2019
We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at e+e− collider DAΦNE. Almost monochromatic K−’s produced through decay of ϕ(1020) mesons are used to observe K− absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we succeeded detect kaon-bound K−pp its two-body into Λ hyperon and proton. The binding energy width determined from invariant-mass distribution as 115+6−5(stat)+3−4(syst) MeV 67+14−11(stat)+2−3(syst)...
We observed a distinct peak in the Λp invariant mass spectrum of He3(K−,Λp)n, well below mK+2mp, i.e., threshold K− to be bound two protons. By selecting relatively large momentum-transfer region q=350∼650 MeV/c, one can kinematically separate from quasi-free process, K‾N→K‾N followed by non-resonant absorption spectator-nucleons K‾NN→ΛN. found that simplest fit gives us Breit–Wigner pole position at BKpp=47±3(stat.)−6+3(sys.) MeV having width ΓKpp=115±7(stat.)−20+10(sys.) MeV, and S-wave...
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...
As a new method to determine the resonance frequency, Rabi-oscillation spectroscopy has been developed. In contrast conventional which draws curve, fits time evolution of Rabi oscillation. By selecting optimized it is shown that precision twice as good with frequency sweep. Furthermore, data under different conditions can be treated in unified manner, allowing more efficient measurements for systems consisting limited number short-lived particles produced by accelerators such muons. We have...
In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing (pi-,K+) double charge-exchange reaction on 10B target. We observed production of 10LambdaLi hypernucleus. The cross section bound region was found be 11.3+/-1.9 nb/sr with 1.2 GeV/c incident momentum, which is compared 10LambdaB section, 7.8+/-0.3 microb/sr, in (pi+,K+) 1.05 momentum beam.
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...
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 FINUDA experiment performed a systematic study of the charged mesonic weak decay channel $p$-shell $Λ$-hypernuclei. Negatively pion spectra from were measured with magnetic analysis for first time ${^{7}_ΛLi}$, ${^{9}_ΛBe}$, ${^{11}_ΛB}$ and ${^{15}_ΛN}$. shape $π^{-}$ was interpreted through comparison distorted wave calculations that take into account structure both hypernucleus daughter nucleus. Branching ratios $Γ_{π^{-}}/Γ_{tot}$ derived converted to rates $Γ_{π^{-}}$ by means known...
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.
To search for an |${\rm S} = -1$| di-baryonic state which decays to |$\Lambda p$|, the |${}^3{\rm He}(K^-,\Lambda p)n_{\rm missing}$| reaction was studied at 1.0 GeV}/c$|. Unobserved neutrons were kinematically identified from missing mass |$M_{X}$| of p)X$| in order have a large acceptance pn$| final state. The observed events, distributed widely over allowed region Dalitz plot, establish that major component comes three-nucleon absorption process. A concentration events specific neutron...
We have performed an exclusive measurement of the K−+He3→Λpn reaction at incident kaon momentum 1GeV/c. In Λp invariant mass spectrum, a clear peak was observed below threshold K¯+N+N, as signal kaonic nuclear bound state, K¯NN. The binding energy, decay width, and S-wave Gaussian form factor this state were to be BK=42±3(stat.)−4+3(syst.)MeV, ΓK=100±7(stat.)−9+19(syst.)MeV, QK=383±11(stat.)−1+4(syst.)MeV/c, respectively. total production cross section K¯NN, determined by its mode,...
An experiment to search for the $K^-pp$ bound state was performed via in-flight $^3$He($K^-,n)$ reaction using 5.3 $\times$ $10^9$ kaons at 1 GeV/$c$ J-PARC hadron experimental facility. In semi-inclusive neutron missing-mass spectrum $\theta_{n}^{lab}=0^\circ$, no significant peak observed in region corresponding binding energy larger than 80 MeV, where a bump structure has been reported $\Lambda p$ final different reactions. Assuming be isotropically decaying into p$, mass-dependent upper...
Power upgrades of accelerators and the development new beamlines have prompted high-precision measurements to be updated reveal phenomena. Several operate in mega-watt regime, a number experiments are planned for future, search evidence physics beyond standard model by investigating events relevant secondary particles. will constructed based on concepts high-power proton drivers, i.e., meson factories. These transport particles, namely muons, with higher efficiency than conventional...
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.