Scientists Accelerate Uranium Beam with Record Power

The Science

Scientists and engineers at the Facility for Rare Isotope Beams (FRIB) have reached a new milestone in isotope studies. They accelerated a high-power beam of uranium ions and delivered a record 10.4 kilowatts of continuous beam power to a target. Uranium is the most difficult element to accelerate. However, it is extremely important to scientific research. Of the more than 17 highest-priority scientific programs with rare isotope beams identified by the National Academy of Sciences and the Nuclear Science Advisory Committee, more than half require a uranium primary beam. Researchers value uranium because it can produce a large variety of isotopes after fragmentation or fission.

The Impact

Establishing the acceleration of a uranium beam with unprecedented power is a crucial milestone for FRIB. The achievement opens a new avenue of research with rare isotopes. Within the first 8 hours of operation, the high-power uranium beam enabled FRIB scientists to produce and identify three new isotopes, gallium-88, arsenic-93, and selenium-96. The high-power uranium beam required the stable operation of all accelerator devices at the highest accelerating gradients. This achievement creates a foundation for providing the heaviest ion beams for creating rare isotopes. It extends scientific reach into unexplored regions of the nuclear landscape.

Summary

The accelerator facility at FRIB produced the highest-power accelerated continuous wave uranium beam ever seen, leading to the separation and identification of three previously unknown isotopes. This achievement was possible thanks to the successful operation of FRIB, including a new superconducting linear accelerator composed of 324 resonators in 46 cryomodules, a newly developed liquid-lithium stripper, and novel technologies such as uranium production in the Electron Cyclotron Resonance (ECR) ion source, the unique heavy-ion Radio-Frequency Quadrupole (RFQ), the high-power target and beam dump.

Researchers developed new techniques to set up the simultaneous acceleration of three charge states of uranium after stripping with liquid-lithium film. This approach achieved the record-high power for uranium. The three previously unobserved isotopes — gallium-88, arsenic-83, and selenium-96—were produced in a 1.2 mm graphite target, separated, and identified for the first time in the Advanced Rare Isotope Separator at FRIB. This work was performed in collaboration with scientists from the United States, Japan, and South Korea.

Funding

This material is based on work supported by the Department of Energy Office of Science, Office of Nuclear Physics, the National Science Foundation, and the Institute for Basic Science in South Korea.