FRIB accelerates argon-36 beam in 37 of 46 cryomodules to full beam energy of 200 MeV/nucleon required at project completion

On 19 March 2020, FRIB accelerated an argon-36 beam through 37 of 46 superconducting cryomodules to 204 million electron-volts per nucleon (MeV/nucleon) or 57 percent of the speed of light. FRIB was designed to accelerate heavy ions to more than 200 MeV/nucleon, and with this FRIB has now demonstrated the accelerator Key Performance Parameter (KPPs) required at project completion.

The milestone comes after successful completion of FRIB’s fourth Accelerator Readiness Review on 16-18 March, where external experts assessed FRIB’s readiness to accelerate beam in the second segment of the linear accelerator. In February 2019, FRIB accelerated beams through the first segment of the linear accelerator — 15 total cryomodules — to 10 percent of FRIB’s final beam energy of 200 MeV/nucleon. In that phase of commissioning, FRIB became the world’s highest-energy continuous-wave hadron linear accelerator.

At the heart of FRIB is a high-power superconducting linear accelerator that now has been demonstrated to accelerate ion beams to above half the speed of light to strike a target, creating rare isotopes. The linear accelerator is made of cryomodules, which contain superconducting radio frequency (SRF) cavities that accelerate the beam while operating at temperatures a few degrees above absolute zero. Much like a heavy truck, heavy ion beams speed up slowly starting from rest. The first three cryomodules accelerate the beam to 1 percent of 200 MeV/nucleon, the first 15 cryomodules to 10 percent of FRIB’s final beam energy, and the remaining 43 cryomodules will provide the other 99 percent of beam energy.

FRIB’s cryomodules are assembled in house by FRIB staff, with components acquired from industry. The most essential components — SRF cavities — were mostly fabricated by industrial providers in Indiana and New York. They operate at cryogenic temperature of 2 Kelvin providing high gradient for most efficient acceleration.

As FRIB prepares for user operation in 2022, several stages of commissioning (integrated testing of individual devices and beam commissioning of devices working together) are planned to demonstrate readiness of the different segments of the accelerator. Integrated testing examines the functionality of the system.