ELFT HÍRADÓ

[Kormányos Andor <andor.kormanyos AT ttk.elte.hu>]

ELTE TTK Fizikai Intézet / ELTE Institute of Physics


ORTVAY KOLLOKVIUM / ORTVAY COLLOQUIUM
(https://physics.elte.hu/ortvayseminar)


Thursday, 16th November  2023, 15:00h.

Pócza Jenő Classroom,  Physics Building 1.71

Pázmány Péter sétány 1/A, 1117 Budapest.


Ákos  Horváth

ELTE, Department of Atomic Physics

Nuclear resonances beyond the neutron dripline of oxigen isotopes

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.


Andor Kormányos
coordinator