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Ústavní semináře

Ústavní semináře, obvykle vedené v anglickém jazyce, jsou vyhrazeny tématům, rozšiřujícím znalosti v oblastech zájmu jednotlivých oddělení: zejména jde o semináře významných hostů ÚJF AV ČR, referáty odborných skupin ÚJF a prezentace vynikajících výsledků. Semináře se konají v seminární místnosti ÚJF od 10 hodin.

Příští semináře:

Čvrtek 5. listopadu, 10.00 

Mgr. Eva Čápová Štěpanovská
Beyond Chemical Modification: Physical Engineering of Graphene Anodes and Interphases for Lithium-Ion Batteries
 
Ing. Jekatěrina Grecká
Strange Hadron Production in Jets in Heavy-Ion Collisions with ALICE
 
Abstrakty (v angličtině)
 
Beyond Chemical Modification: Physical Engineering of Graphene Anodes and Interphases for Lithium-Ion Batteries
 
Most strategies for improving lithium-ion batteries focus on chemical modification. Here, we instead ask how electrochemical behaviour can be controlled through physically induced defects, tailored depth profiles, and engineered interphases. Graphene offers high surface area, electrical conductivity, and theoretical capacity, yet its practical use is limited by layer restacking, which reduces accessible surface area and restricts Li⁺ transport, and by its reactive surface, which promotes a heterogeneous solid electrolyte interphase (SEI). The studies addressed both limitations. Multi-energy Cu⁺ and Ag⁺ ion implantation created overlapping depth profiles and a continuous modified region from the surface into the subsurface. In graphene, implanted atoms and generated defects were examined as a means of stabilizing interlayer spacing, creating active sites, and controlling lithiation. The same approach was applied to polyimide, poly(methyl methacrylate), and cyclic olefin copolymer as candidate artificial SEI materials. Energetic ions induced material-specific reorganization of chemical bonding, producing substantial changes in electrical and electrochemical response rather than merely shallow surface damage. A complementary strategy deposited C₆₀ fullerenes onto graphene by thermal evaporation and pulsed laser deposition. Despite identical substrate and modifying species, the methods produced different electrochemical responses, affecting Li⁺ transport, interfacial kinetics, and interphase evolution. Thus, fabrication route itself is an active material-design parameter. Together, the results connect atomic-scale energy deposition with macroscopic electrochemical function and show that advanced battery materials can be developed through precise physical control of defects, depth profiles, and interphase architectures, without relying solely on new chemical compositions.
 
Strange Hadron Production in Jets in Heavy-Ion Collisions with ALICE
 
The ALICE experiment at the Large Hadron Collider (LHC) at CERN studies strongly interacting matter under extreme conditions. In high-energy heavy-ion collisions, a state of matter known as the quark–gluon plasma (QGP) is created, in which quarks and gluons are no longer confined inside hadrons. Jets, produced by energetic quarks and gluons, provide a powerful tool for studying the properties of this medium and the mechanisms of particle production. The production of strange hadrons and the relative abundance of baryons and mesons offer additional insight into the mechanisms of hadron formation and their possible modification in the presence of the QGP. In this seminar, I will introduce the ALICE experiment and discuss how measurements of strange hadrons inside and outside jets can help us understand hadron production in heavy-ion collisions. The main focus will be on strange-hadron production in jets in Pb–Pb collisions, with particular emphasis on the baryon-to-meson ratio and its implications for understanding hadronization in the presence of the quark–gluon plasma.

Středa 11. listopadu

Ing. David John
Two Clocks, One Timeline: Synergy of Radiocarbon and EPR Dating
 
Abstrakt (v angličtině)
 
Accurate dating is essential in both archaeology and wildlife crime investigations, where establishing a reliable timeline is key to interpreting past human activity or identifying the origin of illegally traded biological materials. Radiocarbon (¹⁴C) dating is one of the most reliable used methods, however it has own limitations. In certain periods, plateaus in the ¹⁴C calibration curve reduce chronological resolution, as similar radiocarbon ages can correspond to wide calendar ranges. In addition, modern anthropogenic effects, especially the burning of fossil fuels, is altering the atmospheric ¹⁴C content (the Suess effect), leading to dilution of the isotopic signal and further complicating age determination. These issues highlight the need to combine radiocarbon dating with independent methods in some cases. Electron paramagnetic resonance (EPR) spectroscopy offers such an possibility. As a retrospective dosimetric technique, EPR estimates age by measuring radiation-induced paramagnetic centers in materials. However, its practical application is not straightforward. The EPR signal of hard organic-tissue is complex to interpret, and accurate age determination also depends critically on reliable dose rate estimation. This seminar focuses on the potential of combining ¹⁴C and EPR dating. By integrating these approaches, it is possible to reduce the impact of their individual limitations, improve chronological precision, and build more robust age models for both archaeological and forensic applications.
 

Archiv ústavních seminářů:

2026

20. 10.  2026
doc. RNDr. Ján Nemčík, CSc.:
Heavy quarkonia as a probe of nuclear effects in photonuclear reactions
 
Abstrakt (v angličtině)
 
Heavy quarkonia produced in photonuclear reactions represent a very effective tool for studying various QCD effects. Within the QCD color dipole formalism we analyze the following phenomena:
i)   The correlation between the impact parameter of a collision and dipole orientation;
ii)  The higher-twist nuclear shadowing related to the QQ Fock state of the photon;
iii) The leading-twist gluon shadowing corresponding to higher Fock components of the photon containing gluons;
iv)  Effects of quantum coherence and QCD energy evolution: the Green's function formalism vs. the popular Balitsky-Kovchegov evolution equation.
Our calculations of differential cross sections are in good agreement with recent ALICE data on charmonium production in ultraperipheral nuclear collisions. We also present predictions for the coherent photoproduction of other quarkonium states (ψ′(2S), ϒ(1S) and ϒ ′(2S)), which can be verified by future measurements at the LHC and the planned LHeC. 
 
1. 10. 2026
doc. Mgr. Vojtěch Patkóš, Ph.D.
Testing Fundamental Physics with Precision Spectroscopy of Ordinary and Exotic Atoms
 
Abstrakt (v angličtině)
 
When searching for new physical phenomena, the best-known approach is to look for them in particle collider experiments or through searches for exotic phenomena such as dark matter. It is less widely known that searches for new physics can also be performed by comparing precise theoretical predictions with experimental results in atomic and molecular physics. The most precise experimental measurement to date, that of the 1S–2S transition in the hydrogen atom, has reached a precision of about 15 significant digits. To achieve a comparable precision in theoretical calculations, one has to account for a variety of quantum electrodynamic and nuclear-structure effects, such as the finite nuclear charge radius. Possible new physics may then manifest itself as discrepancies between theory and experiment that cannot be attributed to experimental systematic uncertainties or uncalculated higher-order contributions in theoretical calculations. A prominent example of such a discrepancy is the so-called proton radius puzzle, i.e., the discrepancy between the values of the proton charge radius deduced from spectroscopy of ordinary and muonic hydrogen. In my talk, I will give an overview of the current status of precision atomic spectroscopy and the proton radius puzzle.
 
29. 9. 2026

Kyrylo Merkotan, Ph.D., DHIP NPI CAS
Neutral Pion Production in Au+Au Collisions Studied Using the HADES Electromagnetic Calorimeter ECAL

Abstract: 

The High-Acceptance Dielectron Spectrometer (HADES) at the SIS18 synchrotron of FAIR/GSI Darmstadt investigates strongly interacting matter created in heavy-ion collisions at beam energies of a few GeV per nucleon. In this energy regime, collisions of heavy nuclei provide access to high baryon densities and allow the study of particle production and collective phenomena in dense nuclear matter. The HADES physics program covers a broad range of topics, including dielectron spectroscopy, strangeness production, and collective flow.
The Electromagnetic Calorimeter (ECAL), developed and installed by Czech group from the Nuclear Physics Institute of the CAS together with colleagues from Poland and Germany, extends HADES towards photon measurements and neutral-meson reconstruction through their two-photon decay channels. Neutral pions are particularly relevant for the interpretation of dielectron measurements and provide an additional observable for studying particle production in heavy-ion collisions.
This seminar will focus on the analysis of Au+Au collisions at a beam kinetic energy of 800 AMeV, with neutral pions reconstructed through their π⁰ → γγ decay using ECAL. The performance of the calorimeter relevant for the analysis will be discussed together with the current status of the analysis. The results obtained so far on neutral pion production and pion flow will be presented and discussed in the context of previous HADES measurements. The seminar will also address the prospects for further studies of neutral pion production and collective phenomena in the Au+Au system. 

3. 9. 2026

Prof. RNDr. Jiří Chýla, CSc., Fyzikální ústav AV ČR
The Centenary of Wave–Particle Duality and the Birth of Quantum Mechanics

Abstrakt (v angličtině)

On 25th November 1924 Louis de Broglie defended his Thesis Recherches sur la Théorie des Quanta, in which he extended the concept of wave-particle duality developed by Einstein for the description of the behaviour of the photon to massive particles, like the electron. His Thesis started rapid development of the Wave Mechanics, one approach to emerging Quantum Mechanics, by Erwin Schrȍdinger in 1926. Independently and unrelated to de Broglie hypothesis, Heisenberg with Born and Jordan developed in 1925 the Matrix Mechanics, which Schrȍdinger showed in March 1926 to be equivalent to his Wave Mechanics. 
I will sketch the difficult life of Einstein’s idea, the last attempt of Bohr, Kramers and Slater to save classical physics for the description of atomic phenomena and key role played by Compton experiments with scattering of X-rays on electrons for the final acceptance of the Einstein conception of the photon. I will emphasize the influence of de Broglie idea of matter waves on Schrȍdinger and will show that Schrȍdinger adopted it, but chose its completely different realization based on Hamilton-Jacobi equation of classical physics. I will recall that the final confirmation of the physical relevance of de Broglie’s idea of matter waves came from diffraction experiments of Davisson and Germer with electrons. And I will close with the subtle question of interpretation of matter waves by Max Born. 

 

 

2025

2024

 

2023

 

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Statutární zástupce: Ing. Ondřej Svoboda, Ph.D.  •  IČ: 61389005  •  DIČ: CZ61389005  •  Číslo účtu: 671958383/0300  •  Elektronická podatelna: ujf@ujf.cas.cz  •  ID datové schránky: t8xmzqw
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