Zahlavi

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. 

Příští semináře:

15. 5. 2025, 10:00, zasedací místnost ÚJF

  • prof. RNDr. Jan Kvasil, DrSc. (Ústav částicové a jaderné fyziky, MFF UK): Toroidal, compressional, scissor, breathing  and other collective excitations in nuclei

22. 5. 2025, 10:00, zasedací místnost ÚJF

  • prof. Alan Cooper (Gulbali Institute, Charles Sturt University, Australia): Cosmic Radiation and the Earth’s Magnetic Field: A History of Environmental and Archaeological Transitions

Abstrakty:
 
Toroidal, compressional, scissor, breathing  and other collective excitations in nuclei

prof. RNDr. Jan Kvasil, DrSc.
Ústav částicové a jaderné fyziky, MFF UK

In the last decade we can observe an increased interest in internal excitations with special behavior of nucleon densities and currents – e.g. the toroidal dipole resonance (TDR), compressional dipole resonance (CDR), scissor and spin-flip M1 resonances, breathing E0 resonance, etc. For example, (a) the toroidal TDR resonance is located in the spectrum in the energy region typical for well-known pygmy E1 resonance (PDR) and it can give a new interpretation of PDR; (b) in light nuclei with large prolong deformation TDR exists as a vortex ring or vortex-antivortex pair; (c) the shape of the electric monopole E0 resonance is influenced by its coupling with the quadrupole resonance; (d) scissor M1 resonance can only be present in the spectrum in deformed nuclei; etc. In the present talk, a recent progress in the theoretical description of such excitations is discussed.

Cosmic Radiation and the Earth’s Magnetic Field: A History of Environmental and Archaeological Transitions

prof. Alan Cooper
Gulbali Institute, Charles Sturt University, Australia

The inability of humans to sense magnetic fields potentially explains the relatively limited amount of mainstream scientific interest in the history of earth’s geomagnetic field, and the central role it played in allowing life on earth. The importance of this protection becomes obvious during periodic collapses in geomagnetic field strength (excursions) that occur regularly throughout the past, when the ionising impacts of cosmic radiation (solar and galactic) on the upper atmosphere are recorded as increased rates of cosmic nuclide production (eg. 14C, 10Be). Modelling studies of this radiation predict considerable impacts on climate, ozone distribution and UV radiation levels among myriad other effects.  The best known recent large geomagnetic excursion (Laschamps, 42-41ka) saw a vast increase in 14C production correlated with Grand Solar Minima, alongside many global environmental and archaeological transitions (eg. Neandertal extinction/arrival of Aurignacian populations) - although precise modes of action remain unclear. However, there are many other major geomagnetic excursions throughout the Late Pleistocene, raising questions about their potential role in paleoclimatic and paleoanthropological records. Preliminary analysis of global ice, sediment 10Be and geomagnetic records over the past 130ka reveals a wide variety of unexpected patterns and associations, confirming the need for finescale analysis of the impacts and events during an excursion. This information is also required to allow planning for major solar weather events that will inevitably occur this century, and have the potential for destructive impacts on modern life.

Archiv ústavních seminářů:

2024

 

2023

 

Pro odbornou veřejnost
O Ústavu jaderné fyziky
Oddělení
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Naše služby
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