FRIB's heavy ion accelerator shoots a powerful beam of stable isotopes, usually ionized uranium atoms, at half the speed of light through a 450-meter accelerator tunnel before it smashes into its target, a spinning graphite wheel. It spins to avoid overheating at a particular point. Most ions pass through the graphite, but some collide with carbon nuclei, causing the ionized uranium atoms to break down into smaller combinations of protons and neutrons, or rare isotopes.
The rare isotopes are the primary target in this process.
Of the approximately 10,000 isotope variants theoretically expected in such a decay, only about 3,000 could be studied so far, since many exist only in very small numbers and only for fractions of a second. FRIB aims to change this.
Rare isotopes have become an increasingly important tool for scientific investigation. These range from applications in nuclear physics to biology and medicine.
"The superconducting linear accelerator at the heart of FRIB was designed to produce these rare particles in greater numbers, allowing scientists to study more of these isotopes," says Chris McCarthy, VAT Account Manager at FRIB. "With FRIB, scientists can better understand the nature of these isotopes, as well as their interactions with other elements. In addition to providing additional insights into the fundamental structure of matter, it is expected to improve existing applications of isotopes, for example, in radiation medicine, nuclear safety, or environmental science."
The FRIB accelerator operates in an ultra-high vacuum (UHV) environment to minimize the interaction of the ion beam with residual molecules. The main accelerator tunnel and the individual experiment corridors are equipped with VAT sector valves as well as VAT fast-closing valves. While the sector valves are used for hermetic separation of individual sections of the facility, e.g. the ventilation of experiment chambers for the setup of experiments, the quick-closing valves are used for safety.
"Since the start of the FRIB project 14 years ago, VAT has worked with the FRIB team to design and provide valve solutions for all major parts of the accelerator," explains Chris McCarthy. "In addition to the sector valves used, it is the quick-acting valves used that have received particular attention here. The installed VAT 75.0 series fast-closing valves serve as safety valves that are only activated in the event of a malfunction, e.g. a leakage. Due to their extremely fast closing speed, they are well able to contain the spread of a leakage or vacuum loss. VAT Series 75.0 fast-closing valves are used in research facilities around the world because they operate reliably over extended maintenance-free periods and, like the sector valves, can withstand the high levels of radiation and high temperatures within the accelerator's UHV environment."