K. I. Hahn
A5014247682- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Nuclear physics research studies
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Astronomical and nuclear sciences
- Nuclear reactor physics and engineering
- X-ray Spectroscopy and Fluorescence Analysis
- Medical Imaging Techniques and Applications
- Neutrino Physics Research
- Advanced Chemical Physics Studies
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Advanced NMR Techniques and Applications
- Stochastic processes and statistical mechanics
- Gamma-ray bursts and supernovae
- Atomic and Subatomic Physics Research
- Boron Compounds in Chemistry
- Atmospheric Ozone and Climate
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Markov Chains and Monte Carlo Methods
Ewha Womans University
2015-2024
Columbia University Irving Medical Center
2024
ScienceMedia (United States)
2024
Institute for Basic Science
2019-2024
Royal College of Physicians
2024
Instituto de Estructura de la Materia
2023
HUN-REN Institute for Nuclear Research
2022
Université de Strasbourg
2019-2020
Centre National de la Recherche Scientifique
2019-2020
Baewha Women's University
2005-2020
A long-standing question in nuclear physics is whether chargeless systems can exist. To our knowledge, only neutron stars represent near-pure systems, where neutrons are squeezed together by the gravitational force to very high densities. The experimental search for isolated multi-neutron has been an ongoing quest several decades1, with a particular focus on four-neutron system called tetraneutron, resulting few indications of its existence so far2-4, leaving tetraneutron elusive six...
The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding tightly bound core, are found in the light, neutron-rich region, where neutrons experience only weak binding and weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes structure nuclei. Despite more than four decades these studies on benchmark one-neutron nucleus 11Be, spectroscopic factors for two states remain poorly constrained. In present work,...
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...
Angular distributions of the Coulomb dissociation 8B in field 208Pb at Ein = 51.9 MeV/u were measured 0° ⩽ θ8 10° and 0.5 Erel 2.25 MeV. The data analyzed using a quantum mechanical method where E1, E2 ℓ 2 nuclear amplitudes are included. Although systematic effects could be large, extracted components appear to considerably smaller than any theoretical predictions reported so far.
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...
The extraction of detailed nuclear structure information from transfer reactions requires reliable, well-normalized data as well optical potentials and a theoretical framework demonstrated to work in the relevant mass beam energy ranges. It is rare that ingredients can be tested for exotic nuclei owing paucity data. halo nucleus Be-11 has been examined through 10Be(d,p) reaction inverse kinematics at equivalent deuteron energies 12,15,18, 21.4 MeV. Elastic scattering Be-10 on protons was...
The PHENIX Collaboration has measured the ratio of yields $\ensuremath{\psi}(2S)$ to $\ensuremath{\psi}(1S)$ mesons produced in $p+p$, $p+\mathrm{Al}$, $p+\mathrm{Au}$, and $^{3}\mathrm{He}+\mathrm{Au}$ collisions at $\sqrt{{s}_{{}_{\mathit{NN}}}}=200$ GeV over forward backward rapidity intervals $1.2<|y|<2.2$. We find that $p+p$ is consistent with measurements other collision energies. In nuclei, we ($p$-going or $^{3}\mathrm{He}$-going) direction, relative yield value collisions. However,...
This paper describes preparing radiopure molybdenum trioxide powder enriched with Mo-100 isotope for the AMoRE-II experiment. AMoRE-II, second phase of AMoRE experiments, will search neutrinoless double-beta decay (0νDBD) 100 Mo using over kg embedded in 200 ultra-pure Li 2 MoO 4 bolometric crystals. Efficient purification technology was developed and adapted to purify 3 a 5 per month production capacity. Based on ICP-MS analysis purified powder, 232 Th 238 U were reduced &lt;9.4 μBq/kg...
Gamma decays were observed in $^{56}$Ca and $^{58}$Ca following quasi-free one-proton knockout reactions from $^{57,59}$Sc beams at $\approx 200$ MeV/nucleon. For $^{56}$Ca, a $\gamma$ ray transition was measured to be 1456(12) keV, while for an indication 1115(34) keV. Both transitions tentatively assigned as the $2^+_1 \rightarrow 0^+_{gs}$ decays, compared results ab initio conventional shell-model approaches. A calculation wide model space with marginally modified effective...
The PHENIX experiment has studied nuclear effects in $p$$+$Al and $p$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV on charged hadron production forward rapidity ($1.4<\eta<2.4$, $p$-going direction) backward ($-2.2<\eta<-1.2$, $A$-going direction). Such are quantified by measuring modification factors as a function of transverse momentum pseudorapidity various collision multiplicity selections. In central collisions, suppression (enhancement) is observed (backward) compared to the binary...
The $^{14}\mathrm{O}(\ensuremath{\alpha},p)^{17}\mathrm{F}$ reaction is one of the key reactions involved in breakout from hot-CNO cycle to rp-process type-I x-ray bursts (XRBs). resonant properties compound nucleus $^{18}\mathrm{Ne}$ have been investigated through elastic scattering $^{17}\mathrm{F}+p$. radioactive $^{17}\mathrm{F}$ beam was separated by Center for Nuclear Study ion separator (CRIB) and bombarded a thick ${\mathrm{H}}_{2}$ gas target at 3.6 MeV/nucleon. recoiling light...
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured longitudinal double spin asymmetries, $A_{LL}$, for charged pions midrapidity ($|η|<0.35$) in longitudinally polarized $p$$+$$p$ collisions $\sqrt{s}=510$ GeV. These measurements are sensitive to gluon contribution total of proton parton momentum fraction $x$ range between 0.04 and 0.09. One can infer sign polarization from ordering pion asymmetries with charge alone. found be consistent global...
The nuclear structure of 66Se, nucleus beyond the N=Z line on proton-rich side valley stability, was investigated by neutron knock-out reaction 67Se(12C,X)66Se using a 12C target. analysis singles spectrum γ-rays emitted during de-excitation populated low-lying excited states revealed two previously detected (927(4) keV, 1460(32) keV) and three new (744(6) 1210(17) 1661(23) transitions. 744-keV, 1210-keV, 1460-keV transitions were found to be in coincidence with one at 927 keV. coincident...
Background: The $^{14}\mathrm{O}(\ensuremath{\alpha},p)^{17}\mathrm{F}$ reaction plays an important role as the trigger for x-ray burst.Purpose: direct measurement of was made studying resonant states in $^{18}\mathrm{Ne}$ and determining rate at astrophysical temperatures.Methods: differential cross section measured using a 2.5-MeV/u $^{14}\mathrm{O}$ radioactive beam thick target method inverse kinematics. Three sets $\mathrm{\ensuremath{\Delta}}E\ensuremath{-}E$ Si telescopes were...
Small nuclear collisions are mainly sensitive to cold-nuclear-matter effects; however, the collective behavior observed in these shows a hint of hot-nuclear-matter effects. The identified-particle spectra, especially $\ensuremath{\phi}$ mesons which contain strange and antistrange quarks have relatively small hadronic-interaction cross section, good tool study PHENIX experiment has measured specific set collision systems $p+\mathrm{Al}$, $p+\mathrm{Au}$, $^{3}\mathrm{He}+\mathrm{Au}$, as...
The Coulomb-dissociation cross section for the process 8 B → 7 Be + p in field of 208 Pb was measured at E ( B) = 46.5 A MeV. Be(p,γ) relevant to high-energy solar-neutrino production extracted C.M. 0.6 - 1.7 Two theoretical models on structure were used evaluate possible corrections due M1 and E2 admixtures dominant E1 sections. Their overall effect is shown be small regardless choice models. present result consistent with results direct measurements Filippone et al. Vaughn within errors....
Low-lying excited states in the $N=32$ isotope $^{50}\mathrm{Ar}$ were investigated by in-beam $\ensuremath{\gamma}$-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, proton inelastic scattering at RIKEN Radioactive Isotope Beam Factory. The energies of two previously reported transitions have been confirmed, five additional are presented for first time, including a candidate ${3}^{\ensuremath{-}}$ state. level scheme built using...