13.3.2020 Probing the nuclei beyond the proton drip line below lead (Hilton)

Researchers at the Department of Physics at the Ä¢¹½Ö±²¥ have discovered three new proton (two-proton) unbound isotopes of 169Au, 165Pt, and 170Hg. For these studies, the recently commissioned MARA separator was used to separate and guide the recoils of interest to the focal plane detector setup for the final identification. In his dissertation, M. Phys Joshua Hilton has carefully analyzed the data from these experiments. He has developed analysis tools for searching for fast decays from digital traces. This new data gives input to the mass surface at the very limit of nuclear existence. In addition to the experiments related to his dissertation, Joshua Hilton participated to the commissioning phase of the MARA recoil separator.
Published
13.3.2020

One of the new isotopes, 169Au, is 28 neutrons lighter than the lightest stable gold isotope, making it further from stability than anything measured before. This discovery was possible due to novel new techniques developed at the Ä¢¹½Ö±²¥ where electronic signals lasting only five microseconds are analysed to extract information about individual atoms.

The new isotopes of platinum and mercury are also the new lightest isotopes of their respective elements, with incredibly short sub-millisecond range half-lives. These new isotopes have such low production yields that only a few atoms of each were observed in an experiment run around the clock for two weeks. Researchers were lucky enough to see not just the proton decay of 169Au, but also the alpha decay, which has an even lower chance of occurring. Only a single atom of 170Hg was observed, but thanks to the excellent electronics systems in place at the Ä¢¹½Ö±²¥, a measurement was still possible.

The discovery of these new nuclides allows physicists to probe the deep inner machinations of nuclear matter, helping to solve the highly complex question of what role quantum physics and collective behaviour play in radioactive processes. The work done in this thesis, along with efforts from other physicists around the world will eventually allow us to understand one of nature’s greatest but smallest mysteries, the atomic nucleus.

The dissertation is published in JYU Dissertations serie, number 198, The Ä¢¹½Ö±²¥, 2020. ISBN 978-951-39-8095-5 (PDF), URN:ISBN:978-951-39-8095-5, ISSN 2489-9003
Link:

Due to university's Coronavirus instructions you can follow the dissertation online. Link to in Zoom Meeting starting at 12:00: 

M. Phys Joshua Hilton defends his dissertation in Physics "Decays of new nuclides 169Au, 170Hg, 165Pt and the ground state of 165Ir discovered using MARA" on Friday 13rd of March 2020 at 12:00 at the Department of Physics (Lecture hall FYS1)  The Opponent is Dr. Jadambaa Khuyagbaatar (Helmholtz-Institute Mainz ja GSI Helmholtz Centre for Heavy Ion Research, Germany) and Custos is Senior Researcher Juha Uusitalo from the Ä¢¹½Ö±²¥. The dissertaion is held in English. 

For further information:
Joshua Hilton, joshua.hilton@liverpool.ac.uk
Communications officer Tanja Heikkinen, tanja.s.heikkinen@jyu.fi, tel. +358 50 581 8351