S. Ajimura
A5085219251- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Atomic and Subatomic Physics Research
- Astrophysics and Cosmic Phenomena
- Nuclear Physics and Applications
- Advanced NMR Techniques and Applications
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Quantum, superfluid, helium dynamics
- Atomic and Molecular Physics
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- X-ray Spectroscopy and Fluorescence Analysis
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Pulsars and Gravitational Waves Research
- Robotics and Automated Systems
- High-pressure geophysics and materials
- Gamma-ray bursts and supernovae
- Radiopharmaceutical Chemistry and Applications
Osaka University
2015-2025
High Energy Accelerator Research Organization
2023
Seoul National University of Science and Technology
2023
HUN-REN Institute for Nuclear Research
2019
Toneyama National Hospital
2000-2014
Tohoku University
2008
Seoul National University
2003-2006
North Carolina Agricultural and Technical State University
2000
University of Houston
1998
The University of Tokyo
1996
Hypernuclear mass spectra of ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{10}$B, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{12}$C, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{28}$Si, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{89}$Y, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{139}$La, and ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{208}$Pb were measured by the (${\mathrm{\ensuremath{\pi}}}^{+}$,${\mathit{K}}^{+}$) reaction with an energy resolution 2 MeV (FWHM). The experiment...
Excitation energy spectra of 89ΛY, 51ΛV, and 12ΛC have been measured via the (π+,K+) reaction by using SKS spectrometer at K6 beam line in KEK 12-GeV Proton Synchrotron. In 89ΛY spectrum, obtained with an resolution 1.65 MeV (FWHM) highest statistics so far, we succeeded clearly observing a characteristic fine structure heavy Λ hypernuclear systems precisely obtaining series single-particle energies very wide excitation range more than 20 MeV, for first time. Also 51ΛV similar to that was...
With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in (9)(Lambda)Be hypernucleus which was produced by 9Be(K-,pi(-)) reaction. The energies of gamma rays are 3029 +/- 2 1 keV 3060 keV. energy difference measured be 31.4(+2.5)(-3.6) keV, indicates very small Lambda-spin-dependent spin-orbit force between Lambda nucleon. This is smallest level splitting far ever hypernucleus.
Differential cross sections for γp→K+Λ(1405) and γp→K+Σ0(1385) reactions have been measured in the photon energy range from 1.5 to 2.4 GeV angular of 0.8<cos(Θ)<1.0 K+ scattering angle center-of-mass system. This data is first measurement Λ(1405) photoproduction section. The line shapes Σ+π− Σ−π+ decay modes were different with each other, indicating a strong interference isospin 0 1 terms Σπ amplitudes. ratios production Σ0(1385) two ranges: near threshold (1.5<Eγ<2.0 GeV) far it...
The experimental data obtained from the reaction of ${}^{6}$Li projectiles at 2$A$ GeV on a fixed graphite target were analyzed to study invariant mass distributions $d+{\ensuremath{\pi}}^{\ensuremath{-}}$ and $t+{\ensuremath{\pi}}^{\ensuremath{-}}$. Indications signal in $t+{\ensuremath{\pi}}^{\ensuremath{-}}$ observed with significances 5.3 $\ensuremath{\sigma}$ 5.0 $\ensuremath{\sigma}$, respectively, when including production target, 3.7 5.2 excluding target. estimated mean values for...
A search for $K^-pp$ bound state (the lightest kaonic nucleus) has been performed using the $\gamma d \rightarrow K^+ \pi^- \rm{X}$ reaction at E$_\gamma$=1.5-2.4 GeV LEPS/SPring-8. The differential cross section of $K^+ \pi^-$ photo-production off deuterium measured first time in this energy region, and a bump structure was searched inclusive missing mass spectrum. statistically significant not observed region from 2.22 to 2.36 GeV/$c^2$, upper limits production were determined be 0.1$-$0.7...
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...
The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. 13C(K-,pi(-))(13)(Lambda)C reaction used to excite both the 1/2(-) and 3/2(-) simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from ground state were measured coincidence with pi(-)'s, by ls found be 152+/-54(stat)+/-36(syst) keV. value is 20-30 times smaller than exhibited nuclear shell model. This gives us new insight into YN interaction.
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.
An experiment demonstrating the production of double-Lambda hypernuclei in (K(-),K(+)) reactions on (9)Be was carried out at D6 line BNL alternating-gradient synchrotron. The technique observation pions produced sequential mesonic weak decay, each pion associated with one unit strangeness change. results indicate a significant number double hypernucleus (4)(double Lambda)H and twin (4)(Lambda)H (3)(Lambda)H. relevant decay chains are discussed simple model mechanism is presented. implication...
In order to study the Sigma-nucleus optical potential, we measured inclusive (pi^-,K^+) spectra on medium-to-heavy nuclear targets: CH_2, Si, Ni, and Bi. The CH_2 target was used calibrate excitation energy scale by using elementary process p + pi^- -> K^+ Sigma^-, where C spectrum also extracted. calibration done with +-0.1 MeV precision. angular distribution of cross section measured, agreed well previous bubble chamber data, but better statistics, magnitudes sections were calibrated. All...
We have carried out an experiment to search for a neutron-rich hypernucleus, $^6_{\Lambda}$H, by the $^6$Li($\pi^-,K^+$) reaction at $p_{\pi^-}$ =1.2 GeV/$c$. The obtained missing mass spectrum with estimated energy resolution of 3.2 MeV (FWHM) showed no peak structure corresponding $^6_{\Lambda}$H hypernucleus neither below nor above $^4_{\Lambda}$H$+2n$ particle decay threshold. An upper limit production cross section bound was be 1.2 nb/sr 90% confidence level.
In this document, the technical details of JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment are described. The search for sterile neutrinos is currently one hottest topics in neutrino physics. aims to existence oscillations with $\Delta m^2$ near 1 eV$^2$ Materials and Life Science Experimental Facility (MLF). A MW beam 3 GeV protons incident on a spallation neutron target produces an intense from muon decay rest. Neutrinos come predominantly $\mu^+$...
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.
The branching ratios of negative pions and protons due to the weak decays $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ $_{\ensuremath{\Lambda}}^{11}\mathrm{B}$ hypernuclei were measured. pionic decay rates (${\ensuremath{\Gamma}}_{{\ensuremath{\pi}}^{\ensuremath{-}}}$), proton-induced nonmesonic (${\ensuremath{\Gamma}}_{p}$), total (${\ensuremath{\Gamma}}_{\mathrm{nm}}$), $\ensuremath{\Lambda}n\ensuremath{\rightarrow}\mathrm{nn}$ process $\ensuremath{\Lambda}p\ensuremath{\rightarrow}\mathrm{pn}$...
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.
Hypernuclear production cross sections have been deduced for the first time with induced reaction of heavy ion beam on fixed target and by means invariant mass method HypHI Collaboration exploiting 6Li + 12C at 2A GeV or sNN=2.70 GeV. A section 3.9±1.4 μb 3ΛH 3.1±1.0 4ΛH respectively in projectile rapidity region was inferred as well total Λ hyperon measured found to be equal 1.7±0.8 mb. global fit based a Bayesian approach performed order include propagate statistical systematic...