20.9.2019 A dissertation brought new high precision mass measurements for atomic masses of isotopes heavier than iron

A large portion of elements surrounding us are produced in fusion reactions in stars. However, elements heavier than iron require more complex processes taking place in a variety of astrophysical environments to be produced. Modeling these processes requires knowledge on properties of the nuclides taking part in the reactions, such as atomic mass. In his doctoral thesis in the field of nuclear physics at the Ģֱ Markus Vilén has measured the atomic masses of 27 isotopes heavier than iron and three long-lived excited nuclear states. Out of them 16 masses were measured for the first time.
Published
20.9.2019

The measurement were performed using the JYFLTRAP Penning trap at the Accelerator Laboratory of the Ģֱ. The results help improve theoretical models on, for example, nucleosynthesis in neutron star mergers and in a particular type of x-ray bursts.

The exotic radioactive isotopes were produced using the IGISOL facility at the Accelerator Laboratory. The study focused mainly on mass measurements on neutron-rich rare-earth isotopes using the JYFLTRAP Penning trap. Additionally, isotopes with nearly equal proton and neutron numbers were studied.

“The results led to improved accuracy of predicitions by theoretical models on the quantities in which different elements are produced in, for example, neutron star mergers. The measurements also reveled new information on the nuclear structure of neutron-rich and neutron-deficient isotopes”, says the Markus Vilén from the University oh Jyväskylä.

Techniques for high-precision mass measurements and producing radioactive ion beams were developed and tested in the study.

“Masses of even single ions were measured with precisions of a few parts per billion”, says Vilén.

The dissertation has been published in the JYU Dissertations -series, number 123, 2019, Jyväskylä
university. ISBN 978-951-39-7838-9 (PDF) , ISSN 2489-9003; 123.
Link to publication:

M.Sc. Markus Vilén defends his doctoral dissertation "Mass measurements and production of ions at IGISOL for the astrophysical r- and rp-processes" 20th of September 2019 at 12 o'clock at the Department of Physics, lecture hall FYS1 (Ylistönrinne, Survontie 9). The opponent is Professor Dan Melconian from Texas A&M University, USA, and the custos is Associate professor Anu Kankainen from the Ģֱ. The dissertation is held in English.

Markus Vilén graduated at Tampereen Lyseon lukio in 2010. He started studying physics at the Ģֱ in the fall 2011 and graduated as a Master of Science in 2016, majoring in physics. From fall 2016 onwards, he has worked as a part of the IGISOL research group at the Accelerator Laboratory of the Ģֱ.

For further information:
Doctoral student Markus Vilén, markus.k.vilen@student.jyu.fi
Communications officer Tanja Heikkinen, tanja.s.heikkinen@jyu.fi, tel. +358 50 581 8351
The Faculty of Mathematics and Science
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