Seminarium fizyki jądra atomowego
Dnia 22 stycznia 2015 odbyło się seminarium pt.
„Experimental investigations of Pygmy Dipole Resonances”
prelegent: prof. Adam Maj (IFJ PAN Kraków)
Streszczenie: Giant Resonances are collective modes of excitation of atomic nuclei, which provide useful information on nuclear structure and on the effective nucleon-nucleon interaction. Such resonances can be excited with different probes as for example: photons, neutrons, charged particles or heavy ions, followed by subsequent decays by emission of particles and gamma-rays. Around and below particle threshold, a large fraction of highly excited states has been found to be of a dipole nature and it has been understood as the Pygmy Dipole Resonance (PDR), which is considered as the oscillation of the neutron skin against the inert proton-neutron core. However, the recent theoretical investigations showed that this simplistic picture of this mode of excitation might not be fully correct. Therefore several experimental groups started to investigate in more details the excitation and decay of pygmy dipole resonances. In my talk I will present the experimental investigations on Pygmy Dipole Resonances carried out by the Milano-Krakow collaboration. In particular I will describe 2 series of experiments performed and results achieved. One of the series, carried out in GSI Darmstadt, used relativistic radioactive beams to Coulomb excite the PDR. Other one, carried out in LNL Legnaro, used inelastic scattering of heavy ions. In addition I will discuss the perspectives of study the gamma decay of PDR in stable nuclei excited in reactions induced by high-energy protons from the Cyclotron Centre Bronowice at IFJ PAN in Krakow.