About half of the elements heavier than iron have been produced via the rapid neutron capture process, the r process. Its astrophysical site has been one of the biggest outstanding questions in physics. Neutrino-driven winds from proto-neutron stars created in core-collapse supernovae were long considered as the most favourable site for the r process. Recently, neutron-star mergers have become the most promising candidates, and new exciting observations from these compact objects, such as gravitational waves, are expected in the coming years. In order to constrain the astrophysical site for the r process, nuclear binding energies (i.e. masses) of exotic neutron-rich nuclei are needed because they determine the path for the process and therefore have a direct effect on the final elemental abundances. In this project, high precision mass measurements will be performed in three regions relevant for the r process, employing novel production and measurement techniques at the IGISOL facility in JYFL-ACCLAB. Long-living isomeric states, which also play a role in the r process, will be resolved from the ground states to obtain accurate mass values. Post-trap decay spectroscopy will be performed to confirm which state has been measured in order to avoid systematic uncertainties in the mass values. The new data will be compared with theoretical mass models and included in r-process calculations performed for various astrophysical sites. MAIDEN will advance our knowledge of nuclear structure far from stability and reduce nuclear data uncertainties in the r-process calculations, which can potentially constrain the astrophysical site for the r process and lead to a scientific breakthrough in our understanding of the origin of elements heavier than iron in the universe. More about nuclear astrophysics research of the group can be found .
People
Principal Investigator, project leader: Professor Anu Kankainen
Maxime Mougeot, Postdoctoral researcher
Marek Stryjczyk, Postdoctoral researcher
Arthur Jaries, PhD student
Jouni Ruotsalainen, PhD student
Ville Virtanen, PhD student
Marjut Hukkanen, PhD student (cotutelle with the University of Bordeaux , -7/2023)
Lama Al Ayoubi, PhD student (cotutelle with the IJC Lab, Orsay, -6/2023)
Stylianos Nikas, Postdoctoral researcher (-5/2023)
Olga Beliuskina, Postdoctoral researcher (-6/2022)
Zhuang Ge, Postdoctoral researcher (10-11/2021)
Clément Delafosse, Postdoctoral researcher (9/2018-8/2020)
Dmitrii Nesterenko, Postdoctoral researcher (9/2019 -12/2021)
Alexandra Zadvornaya, Postdoctoral researcher (11/2018-12/2021)
Laetitia Canete, PhD student (-4/2019), Postdoctoral researcher (5/2019-8/2019)
Markus Vilén, PhD student (-9/2019)
The project received funding (1 999 575 EUR) from the European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant 2017) under grant agreement No. 771036. Due to the COVID-19 pandemic, the project was extended by 6 months.
The masses and decay properties of neutron-rich nuclei are essential for understanding the rapid neutron capture process producing around half of the heavy-element abudances beyond iron. In this project, we have measured more than 100 atomic masses for exotic, radioactive isotopes using the JYFLTRAP Penning trap masss spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility in the JYFL Accelerator Laboratory at the Ģֱ. Around 30 of the measured masses belong to long-living excited states, isomers. In addition, the JYFLTRAP Penning trap has been utilised as a very high resolution mass separator in trap-assisted decay spectroscopy.
