Horváth Ákos (Atomfizikai Tanszék)

Nuclear resonances beyond the neutron dripline of oxigen isotopes

Az előadás kivonata: The technological development of the intermediate energy heavy ion accelerators has given possibilities to explore the physical properties of atomic nuclei far from the stability line, nowadays, further more upto the neutron dripline. The low atomic number nuclei can have surprisingly high number of neutrons. Like in the 11Li nucleus 3 protons and 8 neutrons are bound and has 11 ms half-life, or 6 protons and 18 neutrons are bound in the 22C with 6 ms half-life. In this lecture the latest experimental results will be shown on the lifetime and strucure of the presumably doubly magic 28O isotope, in which the standard nuclear shell modell predict a closed shell both for the 8 protons and for the 20 neutrons. However, the new results show that 28O exist only as a resonance decaying by emission of 4 neutrons on the nuclear timescale (fm/c). The 27O and the 28O isotopes were produced at the first time in experiment in the RIKEN accelerator center in Tokyo from the radioactive beam of the beta decaying 29F nuclei.

The triple and fourfold coincidences of neutrons were detected by the combination of the NEBULA and the NeuLAND detector systems in a common effort of the SAMURAI and the R3B Collaborations of RIKEN and GSI, repsectively. The comparision of the cross section values with the theoretical calculations based on effective field theories of the QCD ruled out the case in which the 28O has a closed neutron shell structure. The standard nuclear shell modell needs something new to describe this phenomenon.

Az előadóról:

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