K. Yoshida
A5003482513- Nuclear physics research studies
- Nuclear Physics and Applications
- Quantum Chromodynamics and Particle Interactions
- Atomic and Molecular Physics
- Astronomical and nuclear sciences
- Advanced Chemical Physics Studies
- Nuclear reactor physics and engineering
- Advanced NMR Techniques and Applications
- Quantum, superfluid, helium dynamics
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- X-ray Spectroscopy and Fluorescence Analysis
- Particle accelerators and beam dynamics
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Atomic and Subatomic Physics Research
- High-pressure geophysics and materials
- Dark Matter and Cosmic Phenomena
- Radiopharmaceutical Chemistry and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Materials and Properties
- Particle Detector Development and Performance
- Astro and Planetary Science
- ZnO doping and properties
- Ga2O3 and related materials
Japan Atomic Energy Agency
2018-2025
RIKEN Nishina Center
2013-2025
Advanced Science Research Center
2018-2024
Kyoto University
2022
Osaka University
2010-2021
RIKEN
1999-2020
Kyushu University
2019
Ibaraki University
2016
The University of Tokyo
1992-2016
Niigata University
2013
We have surveyed the neutron separation energies (S(n)) and interaction cross sections (sigma(I)) for neutron-rich p-sd sd shell region. Very recently, both measurements reached up to drip line, or close nuclei of Z</=8. A neutron-number dependence S(n) shows clear breaks at N = 16 near line (T(Z)>/=3), which creation a new magic number. sigma(I) large increase 15, supports The origin number is also discussed.
The interaction cross sections $({\ensuremath{\sigma}}_{I})$ of ${}^{A}\mathrm{Na}$ isotopes $(A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}20--23,25--32)$ on a carbon target have been measured at $950A\mathrm{MeV}$. effective root-mean-square matter radii these were deduced from ${\ensuremath{\sigma}}_{I}$ by Glauber-type calculation. By combining the isotope-shift data with present neutrons compared those protons for first time along chain stable and unstable isotopes. A monotonic...
The cross sections for single-neutron removal from the very neutron-rich nucleus $^{31}\mathrm{Ne}$ on Pb and C targets have been measured at $230\text{ }\text{ }\mathrm{MeV}/\mathrm{\text{nucleon}}$ using RIBF facility RIKEN. deduced large Coulomb breakup section of 540(70) mb is indicative a soft $E1$ excitation. Comparison with direct-breakup model calculations suggests that valence neutron occupies low-$\ensuremath{\ell}$ orbital (most probably $2{p}_{3/2}$) small separation energy...
A search for isomeric \ensuremath{\gamma} decays among fission fragments from 345 MeV/nucleon ${}^{238}$U has been performed at the RIKEN Nishina Center RI Beam Factory. Fission were selected and identified using superconducting in-flight separator BigRIPS implanted in an aluminum stopper. Delayed rays detected three clover-type high-purity germanium detectors located focal plane within a time window of 20 \ensuremath{\mu}s following implantation. We total 54 microsecond isomers with...
A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained double-charge-exchange reaction ^{4}He(^{8}He,^{8}Be) at 186 MeV/u. The energy of 0.83±0.65(stat)±1.25(syst) MeV above threshold four-neutron decay with a significance level 4.9σ. Utilizing large positive Q value (^{8}He,^{8}Be) reaction, an almost recoilless condition system was achieved so as to obtain weakly interacting efficiently.
We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at RIKEN Radioactive Isotope Beam Factory by using time-of-flight magnetic-rigidity technique. The atomic excesses ^{55-57}Ca are determined for time to be -18650(160), -13510(250), and -7370(990) keV, respectively. examine emergence magicity N=34 based on new masses. masses provide experimental evidence appearance a sizable energy gap between 2p_{1/2} 1f_{5/2} orbitals in ^{54}Ca,...
The discovery of the important neutron-rich nucleus 6020Ca40 and seven others near limits nuclear stability is reported from fragmentation a 345 MeV/u 70Zn projectile beam on 9Be targets at radioactive ion-beam factory RIKEN Nishina Center. produced fragments were analyzed unambiguously identified using BigRIPS two-stage in-flight separator. eight new nuclei discovered, 47P, 49S, 52Cl, 54Ar, 57K, 59,60Ca, 62Sc, are most isotopes respective elements. In addition, one event consistent with 59K...
α particles in stable nuclei Decay is a common mode of radioactivity heavy elements such as uranium that entails the loss comprising two protons and neutrons. Despite more than century study, when where these form unstable alike remains an open question. Tanaka et al. bombarded series tin isotopes with high-energy detected ejected at abundance inversely correlated mass number (see Perspective by Hen). This observation, relating particle accumulation to neutron skin thickness nuclear surface,...
We report the measurement of reaction cross sections (${\ensuremath{\sigma}}_{R}^{\mathrm{ex}}$) $^{27,29}\mathrm{F}$ with a carbon target at RIKEN. The unexpectedly large ${\ensuremath{\sigma}}_{R}^{\mathrm{ex}}$ and derived matter radius identify $^{29}\mathrm{F}$ as heaviest two-neutron Borromean halo to date. is attributed neutrons occupying $2{p}_{3/2}$ orbital, thereby vanishing shell closure associated neutron number $N=20$. results are explained by state-of-the-art model...
A kinematically complete quasi-free $(p,pn)$ experiment in inverse kinematics was performed to study the structure of Borromean nucleus $^{17}$B, which had long been considered have neutron halo. By analyzing momentum distributions and exclusive cross sections, we obtained spectroscopic factors for $1s_{1/2}$ $0d_{5/2}$ orbitals, a surprisingly small percentage 9(2)$\%$ determined $1s_{1/2}$. Our finding such component halo features reported prior experiments can be explained by deformed...
We report on the first spectroscopic study of N=22 nucleus 32Ne at newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy 722(9) keV was observed in both inelastic scattering a 226 MeV/u beam carbon target and proton removal from 33Na 245 MeV/u. This transition is assigned to deexcitation Jpi=2+ state 0+ ground state. Interpreted through comparison state-of-the-art shell-model calculations, low excitation demonstrates that "island inversion" extends least...
Exclusive cross sections and momentum distributions have been measured for quasifree one-neutron knockout reactions from a $^{54}\mathrm{Ca}$ beam striking on liquid hydrogen target at $\ensuremath{\sim}200\text{ }\text{ }\mathrm{MeV}/u$. A significantly larger section to the ${p}_{3/2}$ state compared ${f}_{5/2}$ observed in excitation of $^{53}\mathrm{Ca}$ provides direct evidence nature $N=34$ shell closure. This finding corroborates arising new closure neutron-rich calcium isotopes. The...
The cluster structure of the neutron-rich isotope ^{10}Be has been probed via (p,pα) reaction at 150 MeV/nucleon in inverse kinematics and quasifree conditions. populated states ^{6}He residues were investigated through missing mass spectroscopy. triple differential cross section for ground-state transition was extracted angle pairs (θ_{p},θ_{α}) compared to distorted-wave impulse approximation calculations performed a microscopic framework using successively Tohsaki-Horiuchi-Schuck-Röpke...
Interaction cross sections for ^{42-51}Ca on a carbon target at 280 MeV/nucleon have been measured the first time. The neutron number dependence of derived root-mean-square matter radii shows significant increase beyond magic N=28. Furthermore, this enhancement is much larger than that previously charge radii, indicating novel growth in skin thickness. A simple examination based Fermi-type distribution, and mean field calculations point out anomalous nuclear size N=28 results from an...
Collisions of ${}^{11}\mathrm{Li}+p$ at $68A\mathrm{MeV}$ have been studied by correlational measurements. An excited state ${}^{11}\mathrm{Li}$ ${E}^{*}\ensuremath{\simeq}1.3\mathrm{MeV}$ was observed. The measured angular distributions show the dipole nature excitation 1.3-MeV peak. structure states and ground is discussed.
We have studied spallation reactions for the fission products 137Cs and 90Sr purpose of nuclear waste transmutation. The cross sections on proton deuteron were obtained in inverse kinematics first time using secondary beams at 185 MeV/nucleon RIKEN Radioactive Isotope Beam Factory. target dependence has been investigated systematically, cross-section differences between are found to be larger lighter products. experimental data compared with PHITS calculation, which includes cascade...
The dependence of the single-particle strength on difference between proton and neutron separation energies is studied for oxygen isotopes in a wide range isospins. cross sections quasi-free (|$p,2p$|) reaction |$^{14,16,18,22,24}$|O were measured at intermediate energies. are compared to predictions based distorted wave impulse approximation shell-model |$psd$| valence-space spectroscopic factors. reduction factors, which ratio experimental theoretical predictions, show no apparent...
The parallel momentum distribution (PMD) of the residual nuclei $^{14}\mathrm{O}$($p,pn$)$^{13}\mathrm{O}$ and $^{14}\mathrm{O}$($p,2p$)$^{13}\mathrm{N}$ reactions at 100 200 MeV/nucleon in inverse kinematics is investigated with framework distorted-wave impulse approximation. PMD shows an asymmetric shape characterized by a steep falloff on high side long-ranged tail low side. former found to be due phase volume effect reflecting energy conservation, latter shift outgoing two nucleons...
The $^{120}\mathrm{Sn}(p,p\ensuremath{\alpha})^{116}\mathrm{Cd}$ reaction at 392 MeV is investigated with the distorted wave impulse approximation (DWIA) framework. We show that this very peripheral, mainly because of strong absorption $\ensuremath{\alpha}$ by residue $^{116}\mathrm{Cd}$, and clustering on nuclear surface can be probed clearly. investigate also validity so-called factorization has frequently been used so far. It shown kinematics in interior region significantly affected...
Excited states in the $N=40$ isotone $^{62}$Ti were populated via $^{63}$V$(p,2p)$$^{62}$Ti reaction at $\sim$200~MeV/u Radioactive Isotope Beam Factory and studied using $γ$-ray spectroscopy. The energies of $2^+_1 \rightarrow 0^{+}_{\mathrm{gs}}$ $4^+_1 2^+_1$ transitions, observed here for first time, indicate a deformed ground state. These are increased compared to neighboring $^{64}$Cr $^{66}$Fe isotones, suggesting small decrease quadrupole collectivity. present measurement is well...
We report on the first γ-ray spectroscopy of 51,53K produced via 52,54Ca(p,2p) reactions at ∼250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam intensities down to few particles per second by using a new technique based reaction vertex tracking combined with thick liquid-hydrogen target. Through and exclusive parallel momentum distribution analysis, 3/2+ ground states 1/2+ excited in established quantifying natural ordering 1d3/2 2s1/2 proton-hole...