FIONA to Take on the Periodic Table’s Heavyweights

Berkeley Lab scientists Jackie Gates, left, and Kenneth Gregorich work on FIONA, a new device at the Lab’s 88-inch Cyclotron. FIONA experimentally measures the mass number of the periodic table’s superheavy elements, and it could be useful for other types of explorations of superheavy elements. Image courtesy of Marilyn Chung/Berkeley Lab

FIONA (For the Identification Of Nuclide A) is a newly installed device designed to measure the mass numbers of individual atoms of heavy and superheavy elements (HE and SHE), which have higher masses than uranium. FIONA will allow researchers to learn about the shape and structure of heavy nuclei. It will also guide the search for new elements. Further, it will provide better measurements for nuclear fission and related processes in nuclear physics and nuclear chemistry.

The Impact

Six new elements were discovered and named within the last two decades. However, despite significant study, no one has managed to prove that the assumed numbers of protons or neutrons in their nuclei are correct. FIONA will provide the first measurement of the mass numbers of the new elements.


FIONA was installed in November 2016 at Berkeley Lab’s 88-inch Cyclotron. FIONA is an enhancement to a long-running machine called the Berkeley Gas-filled Separator (BGS). Heavy elements are produced in nuclear reactions and are then separated from unwanted reaction products in the BGS. After separation, FIONA slows down the heavy elements, traps them, and then transports the heavy elements through a shielding wall and away from background caused by the nuclear reactions. A section of FIONA then uses crossed electric and magnetic fields to select the heavy elements by mass number before they are implanted into a sensitive silicon-based detector array that can measure the energy, position and timing of the decay of radioactive atoms. With FIONA, an entirely new set of experiments is now possible, enabling answers to many fascinating questions in heavy element physics and chemistry.