First observation of 28O [NPS-333]

by Dr Yosuke Kondo

Thursday 17 Oct 2024, 13:30 → 15:00 Asia/Tokyo

Room 201 (RIBF)

Paper = https://www.nature.com/articles/s41586-023-06352-6

Nuclear shell structure characterized by magic numbers is a key to understanding atomic nuclei, consisting of strongly interacting many nucleons. The shell structure and magic numbers are well established for stable nuclei, while the magic numbers can change when the proton and neutron numbers are much different from the stable nuclei. It is thus quite important to identify which unstable nuclei show double magic characters. Based on the conventional magic numbers, there are only seven candidates for doubly magic unstable nuclei accessible with current technology: 10He, 28O, 48Ni, 56Ni, 78Ni, 100Sn, and 132Sn. Among them, 28O (Z=8, N=20) is the only candidate yet to be observed. First observation has been succeeded at RIBF using the SAMURAI spectrometer. The 28O nucleus was produced by one-proton removal reaction from 29F, followed by decay via four neutron emission. A resonant peak of the 28O ground state has been observed in its decay energy spectrum reconstructed by the invariant mass method from measured momentum vectors of decay products, 24O and four neutrons. In the presentation, I will talk about the results on 28O and its neighbor 27O, published in Nature 620, 965 (2023).

Zoom link:
https://riken-jp.zoom.us/j/96577967679?pwd=YmgrOW9pTmNhUkIvODFycEdRSUpuQT09

20241017RIBF semiPoster-333.pdf