T. Lokotko
A5035433531- Nuclear physics research studies
- Nuclear Physics and Applications
- Astronomical and nuclear sciences
- Atomic and Molecular Physics
- Quantum Chromodynamics and Particle Interactions
- Nuclear reactor physics and engineering
- Advanced Chemical Physics Studies
- Radiation Detection and Scintillator Technologies
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum, superfluid, helium dynamics
- Boron Compounds in Chemistry
- Astro and Planetary Science
- Particle physics theoretical and experimental studies
- Superconducting Materials and Applications
- Rare-earth and actinide compounds
- Radiation Therapy and Dosimetry
- Particle Detector Development and Performance
- Muon and positron interactions and applications
- Radioactive Decay and Measurement Techniques
- High-Energy Particle Collisions Research
- Electron and X-Ray Spectroscopy Techniques
- Cold Atom Physics and Bose-Einstein Condensates
University of Hong Kong
2017-2024
Laboratoire de Physique Corpusculaire de Caen
2024
École Nationale Supérieure d'Ingénieurs de Caen
2024
Michigan State University
2024
Rudjer Boskovic Institute
2024
Université Paris-Saclay
2019-2023
Institut de Recherche sur les Lois Fondamentales de l'Univers
2019-2023
CEA Paris-Saclay
2019-2023
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2019-2023
Eötvös Loránd University
2022
The β-decay half-lives of 94 neutron-rich nuclei ^{144-151}Cs, ^{146-154}Ba, ^{148-156}La, ^{150-158}Ce, ^{153-160}Pr, ^{156-162}Nd, ^{159-163}Pm, ^{160-166}Sm, ^{161-168}Eu, ^{165-170}Gd, ^{166-172}Tb, ^{169-173}Dy, ^{172-175}Ho, and two isomeric states ^{174m}Er, ^{172m}Dy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops are observed neutron-number N=97 for _{58}Ce, _{59}Pr, _{60}Nd, _{62}Sm, N=105...
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 first $\ensuremath{\gamma}$-ray spectroscopy of $^{52}\mathrm{Ar}$, with the neutron number $N=34$, was measured using $^{53}\mathrm{K}(p,2p)$ one-proton removal reaction at $\ensuremath{\sim}210\text{ }\text{ }\mathrm{MeV}/\mathrm{u}$ RIBF facility. ${2}_{1}^{+}$ excitation energy is found 1656(18) keV, highest among Ar isotopes $N>20$. This result experimental signature persistence $N=34$ subshell closure beyond $^{54}\mathrm{Ca}$, i.e., below magic proton $Z=20$. Shell-model...
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...
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...
We report on the first proton-induced single proton- and neutron-removal reactions from neutron-deficient ^{14}O nucleus with large Fermi-surface asymmetry S_{n}-S_{p}=18.6 MeV at ∼100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections parallel momentum distributions of ^{13}N ^{13}O residues are compared to state-of-the-art reaction models, nuclear structure inputs many-body shell-model calculations. Our results provide quantitative...
Data on the structure of sulphur isotopes close to neutron drip-line are rather scarce. The excited states very neutron-rich \(^{46}\)S and \(^{47}\)S nuclei have been investigated by in-beam gamma-ray spectroscopy at Radioactive Isotope Beam Factory RIKEN Nishina Center. After multi-nucleon knockout reactions liquid-hydrogen MINOS target, \(2^{+}_{1}\rightarrow 0^{+}_{1}\) gamma transition \(^{46}\)S, already reported in literature, has confirmed. Additionally, two new rays assigned this...
The one-neutron knockout from ^{52}Ca in inverse kinematics onto a proton target was performed at ∼230 MeV/nucleon combined with prompt γ spectroscopy. Exclusive quasifree scattering cross sections to bound states ^{51}Ca and the momentum distributions corresponding removal of 1f_{7/2} 2p_{3/2} neutrons were measured. sections, interpreted within distorted-wave impulse approximation reaction framework, are consistent shell closure neutron number N=32, found as strong N=28 N=34 Ca isotopes...
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...
Excited states in the nucleus $^{133}\mathrm{Sn}$, with one neutron outside double magic $^{132}\mathrm{Sn}$ core, were populated following one-neutron knockout from a $^{134}\mathrm{Sn}$ beam on carbon target at relativistic energies Radioactive Isotope Beam Factory RIKEN. Besides $\ensuremath{\gamma}$ rays emitted decay of known single-particle $^{133}\mathrm{Sn}$ additional strength energy range 3.5--5.5 MeV was observed for first time. Since neutron-separation is low,...
A new neutron SIMulation program based on the versatile GEANT4 toolkit, neuSIM4, has been developed to describe interactions of neutrons in NE213 liquid scintillator from 0.1 3000 MeV. neuSIM4 is designed accommodate complicated modern detector geometry setups with multiple detectors, each which can be outfitted more than one photo-multiplier. To address a broad spectrum energies, two interaction physics models, KSCIN and NxQMD, have implemented GEANT4. For energy below 110 MeV, we...
The $\ensuremath{\beta}$ decay of the odd-odd nucleus $^{70}\mathrm{Br}$ has been investigated with BigRIPS and EURICA setups at Radioactive Ion Beam Factory (RIBF) RIKEN Nishina Center. $T=0({J}^{\ensuremath{\pi}}={9}^{+})$ $T=1({J}^{\ensuremath{\pi}}={0}^{+})$ isomers have both produced in in-flight fragmentation $^{78}\mathrm{Kr}$ ratios 41.6(8)% 58.4(8)%, respectively. A half-life ${t}_{1/2}={2157}_{\ensuremath{-}49}^{+53}$ ms measured for ${J}^{\ensuremath{\pi}}={9}^{+}$ isomer from...
Direct proton-knockout reactions of $^{55}\mathrm{Sc}$ at $\ensuremath{\sim}220\text{ }\text{ }\mathrm{MeV}/\mathrm{nucleon}$ were studied the RIKEN Radioactive Isotope Beam Factory. Populated states $^{54}\mathrm{Ca}$ investigated through $\ensuremath{\gamma}$-ray and invariant-mass spectroscopy. Level energies calculated from nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to distorted-wave impulse approximation estimates multiplied by...
The structures of the neutron-rich $^{69,71,73}\mathrm{Co}$ isotopes were investigated via $(p,2p)$ knockout reactions at Radioactive Isotope Beam Factory, RIKEN. Isotopes interest studied using DALI2 $\ensuremath{\gamma}$-ray detector array combined with MINOS target and tracker system. Level schemes reconstructed $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence technique, tentative spin-parity assignments based on measured inclusive exclusive cross sections....
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...
The shell closure at $N=32$ has been investigated by a first spectroscopy of the $N=31$ nucleus $^{49}\mathrm{Ar}$ Radioactive Isotope Beam Factory. Using $^{50}\mathrm{Ar}(p,pn)$ reaction channel in inverse kinematics, $^{50}\mathrm{Ar}$ projectiles 217 MeV/nucleon impinged on 150 mm long liquid hydrogen target, part MINOS device. Prompt deexcitation $\ensuremath{\gamma}$ rays were measured with NaI(Tl) array ${\mathrm{DALI}2}^{+}$. Reaction products analyzed SAMURAI spectrometer, which...
The calcium isotopes are an ideal system to investigate the evolution of shell structure and magic numbers. Although properties surface nucleons in have been well studied, probing deeply bound remains a challenge. Here, we report on first measurement unbound states $^{53}$Ca $^{55}$Ca, populated from \ts{54,56}Ca($p,pn$) reactions at beam energy around 216 MeV/nucleon RIKEN Radioactive Isotopes Beam Factory. resonance properties, partial cross sections, momentum distributions these were...
A first gamma-ray study of 47,49Cl spectroscopy was performed at the Radioactive Isotope Beam Factory with 50Ar projectiles 217 MeV/nucleon, impinging on liquid hydrogen target MINOS device. Prompt de-excitation gamma-rays were measured NaI(Tl) array DALI2+. Through one-proton knockout reaction 50Ar(p,2p), a spin assignment could be determined for low-lying states 49Cl from momentum distribution obtained SAMURAI spectrometer. spin-parity J = 3/2+ is deduced ground state 49Cl, similar to...
Differential cross sections of |$p$|–|$\mathrm{^6He}$| elastic scattering were measured in inverse kinematics at an incident energy 200 |$A \mathrm{MeV}$|, covering the high momentum transfer region 1.7–2.7 |$\mathrm{fm^{-1}}$|. The sensitivity low and transfers to density distribution was investigated quantitatively using relativistic impulse approximation calculations. In region, where present data taken, differential section has order magnitude higher inner part |$\mathrm{^6He}$|...
The β-decay of the even-even nucleus 70Kr with Z=N+2, has been investigated at Radioactive Ion Beam Factory (RIBF) RIKEN Nishina Center using BigRIPS fragment separator, ZeroDegree Spectrometer, WAS3ABI implantation station and EURICA HPGe cluster array. Fifteen γ-rays associated into 70Br have identified for first time, defining ten populated states below Eexc=3300 keV. half-life was derived increased precision found to be t1/2=45.19±0.14 ms. β-delayed proton emission probability also...
States in the $N=35$ and 37 isotopes $^{55,57}$Ca have been populated by direct proton-induced nucleon removal reactions from $^{56,58}$Sc $^{56}$Ca beams at RIBF. In addition, $(p,2p)$ quasi-free single-proton reaction was studied. Excited states $^{55}$K, $^{55}$Ca, $^{57}$Ca were established for first time via in-beam $\gamma$-ray spectroscopy. Results proton neutron to $^{55}$K $^{55}$Ca level energies, excited state lifetimes, exclusive cross sections agree well with state-of-the-art...
The reduced transition probability $\mathrm{B}(E2;\phantom{\rule{4pt}{0ex}}{0}_{1}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})$ to the first excited ${2}^{+}$ state of neutron-rich nucleus $^{136}\mathrm{Te}$, with two protons and neutrons outside doubly magic $^{132}\mathrm{Sn}$ core, was measured via Coulomb excitation at relativistic energies RIKEN Radioactive Isotope Beam Factory. A value $\mathrm{B}(E2)=0.191(26)$ ${\mathrm{e}}^{2}{\mathrm{b}}^{2}$ extracted from inelastic scattering cross...