P. Koseoglou
A5000223880- 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
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Advanced Chemical Physics Studies
- Radiation Detection and Scintillator Technologies
- Laser-Plasma Interactions and Diagnostics
- Radioactivity and Radon Measurements
- X-ray Spectroscopy and Fluorescence Analysis
- Boron Compounds in Chemistry
- Laser Design and Applications
- Crystallography and Radiation Phenomena
- Nuclear Materials and Properties
- Particle physics theoretical and experimental studies
- Laser-induced spectroscopy and plasma
- Rare-earth and actinide compounds
- Radiopharmaceutical Chemistry and Applications
- Mass Spectrometry Techniques and Applications
- Laser-Matter Interactions and Applications
- Radioactive contamination and transfer
- Quantum, superfluid, helium dynamics
Technical University of Darmstadt
2016-2025
GSI Helmholtz Centre for Heavy Ion Research
2018-2024
RIKEN Nishina Center
2021-2023
Institut für Hochschulforschung
2023
TRIUMF
2020-2022
National Physical Laboratory
2022
University of Surrey
2022
Institute of Nuclear Physics, Polish Academy of Sciences
2019
Florida State University
2019
Universidad Autónoma de Madrid
2019
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 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...
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...
<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi mathvariant="italic">γ</a:mi></a:math> decays of the isovector giant dipole resonance (IVGDR) deformed nucleus <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:mmultiscripts><d:mrow><d:mi>Sm</d:mi></d:mrow><d:mprescripts/><d:none/><d:mrow><d:mn>154</d:mn></d:mrow></d:mmultiscripts></d:mrow></d:math> were measured using <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"...
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 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...
The nuclear two-photon or double-gamma (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>2</a:mn><a:mi>γ</a:mi></a:math>) decay is a second-order electromagnetic process whereby nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>2</c:mn><c:mi>γ</c:mi></c:math> rate low-energy regime below electron-positron pair-creation threshold, we combined...
We report on spectroscopic information and lifetime measurements of even-even neutron-rich Te isotopes. Excited states were populated in fast-neutron induced fission $^{238}\mathrm{U}$ at the ALTO facility IJCLab with LICORNE neutron source detected using hybrid $\ensuremath{\nu}$-ball spectrometer. provide first results lifetimes ${6}_{1}^{+}$ state $^{136}\mathrm{Te}$ (${6}_{1}^{+}$), (${4}_{1}^{+}$), (${2}_{1}^{+}$) $^{138}\mathrm{Te}$ discuss context large-scale shell-model calculations....
We report on the first measurement of half-lives Kπ=11− and 12+ four-quasiparticle states in even-even nucleus 178W. The sub-nanosecond were measured by applying centroid shift method to data taken with LaBr3(Ce) scintillator detectors NuBall array at ALTO facility Orsay, France. these only became experimentally accessible combination several experimental techniques - fast timing, isomer spectroscopy a pulsed beam, event-by-event calorimetry information provided array. are 476(44)ps...
Background: Shape coexistence in the $Z\ensuremath{\approx}82$ region has been established mercury, lead, and polonium isotopes. For even-even mercury isotopes with $100\ensuremath{\le}N\ensuremath{\le}106$ multiple fingerprints of this phenomenon are observed, which seems to be no longer present for $N\ensuremath{\ge}110$. According a number theoretical calculations, shape is predicted $^{188}\mathrm{Hg}$ isotope.Purpose: The aim work was measure lifetimes excited states infer their...
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 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...
In the present work, a dedicated experimental study of lifetimes in Te and Sb isotopes was undertaken at 9 MV Tandem accelerator IFIN-HH. Beams 11B 35 MeV impinged on natAg target to populate nuclei interest their decay using activation method. The emitted gamma rays charged particles were detected by ROSPHERE SORCERER arrays. Lifetimes decaying isomeric ground states 117Te 115,117Sb measured. results update existing literature data from half century ago employing new reaction mechanism...
Delineating the evolution, with proton and neutron numbers, of nuclear phase transitions from spherical to deformed shapes is one most challenging tests models. This paper presents new data---taken by an international collaboration centered at Institut Laue-Langevin in Grenoble, France, analyzed team researchers led scientists TU Darmstadt, Germany---on transition rates ${}^{148}$Ce, a neutron-rich nucleus located near iconic $N=88$--90 shape-phase-transition region. In standard geometric...
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 population of isomeric states in the prompt decay fission fragments---so-called yield ratios (IYRs)---is known to be sensitive angular momentum $J$ that fragment emerged with, and may therefore contain valuable information on mechanism behind process. In this work, we investigate how changes fissioning system impact measured IYRs fragments learn more about what parameters affect generation. To enable this, a new technique for measuring is first demonstrated. It based time arrival...