In May 2022, the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) launched its precision measurement program. This program, led by the Low Energy Beam and Ion Trap (LEBIT) facility at FRIB, focuses on cooling high-energy rare-isotope beams to a lower energy state and conducting high-precision mass measurements on specific particles. The team, co-led by Ryan Ringle and Georg Bollen, recently published a research paper showcasing their work on verifying the mass of aluminum-22, an exotic isotope that exhibits a unique “halo” structure of protons loosely orbiting the nucleus.
While most atoms have electrons tightly orbiting the nucleus, halo structures in atoms are rare phenomena that occur when protons or neutrons are not contained within the nucleus itself. The team at FRIB aimed to investigate the proton halo structure of aluminum-22, a challenging task that required advanced beam preparation techniques. By creating a high-energy isotope beam of aluminum-22 using “projectile fragmentation” at FRIB, the researchers were able to measure the particle’s mass accurately, providing crucial insights into its physical properties.
The measurement of aluminum-22’s mass was a significant milestone in verifying its proton halo structure, but further experiments are needed to confirm its existence conclusively. The collaboration between FRIB’s LEBIT facility and the Beam Cooler and Laser Spectroscopy (BECOLA) facility will play a crucial role in measuring the charge radius and the deformation of the nucleus to shed more light on the proton halo phenomenon. This multi-faceted approach combines theoretical physics with experimental techniques to unravel the mysteries of rare isotopes like aluminum-22.
A notable aspect of the research on aluminum-22’s proton halo structure is the involvement of graduate students in leading and executing experiments. Scott Campbell, a graduate student at LEBIT, played a significant role in running the experiment as part of his dissertation work. This hands-on experience not only contributes to scientific discovery but also provides students with invaluable training and expertise that can shape their future careers in physics and research. The unique environment of FRIB, situated on a university campus, allows students to engage in research activities alongside their academic coursework.
The recent research by FRIB’s LEBIT facility on aluminum-22’s proton halo structure marks a significant advancement in the field of rare isotope studies. The precision measurement program at FRIB opens up new avenues for exploring exotic nuclear structures and phenomena that were previously inaccessible. The collaboration between researchers, experimentalists, and students underscores the importance of interdisciplinary teamwork in pushing the boundaries of scientific knowledge. As FRIB continues to pioneer groundbreaking research in nuclear physics, the quest to unravel the mysteries of the universe’s building blocks remains a compelling and rewarding endeavor.