During the first three years since May 2022, FRIB has been operating safely meeting expectations of both scientific and industrial users with high machine availability, while ramping up the beam power to 20 kW for heavy ions including uranium. The paper summarizes the operational experience and challenges, accelerator improvement projects, expansions in user stations, accelerator R&D and workforce growth programs, and preparation for facility upgrades.

The Facility for Rare Isotope Beams signifies a major advancement in rare isotope beams for research. Delivering heavy and exotic rare isotope beams is accomplished with the Advanced Rare Isotope Separator (ARIS), which creates, purifies and transports radioactive beams. These secondary beams can range from hydrogen to uranium. Every RIB is carefully planned, produced and characterized by ARIS’s system of diagnostics, detectors and data acquisition (DAQ). ARIS detectors can measure the time of flight, energy loss, charge, gamma-rays and position of the species in the beam, allowing the identity, rate, purity, energy and emittance of each rare isotope to be accurately quantified. The needs of each experiment drive the requirement for tuning, to achieve the desired RIB properties for diverse experiments. In this presentation, the current ARIS system of scintillators, PPACs (parallel plate avalanche counters), silicon and gamma-ray detectors, and associated DAQ will be discussed. Furthermore, the ARIS detector system will undergo upgrades to support the main LINAC upgrades from the current 20 kW, and these upcoming challenges and changes to detectors and DAQ will be included as well.

The Facility for Rare Isotope Beams (FRIB), operating at Michigan State University since 2022, produces a variety of nuclear species via fragmentation or fission. Heavy ions are accelerated by the FRIB LINAC to energies of >170 MeV/u which impinge on mm-thick graphite targets to make the RIs in-flight. The resulting cocktail of ions are separated and purified with the Advanced Rare Isotope Separator (ARIS). Magnetic separation of isotopes with the same A/Z ratio is performed with an achromatic energy degrader or wedge. As the first stage of ARIS involves a momentum compression of k=3, the pre-separator wedge geometric cross section is more complex than a simple isosceles triangle, having a parabolic shape to reduce aberrations. Wedge inhomogeneities from imperfect machining or within the material itself (e.g., bubbles, density variations) can adversely affect the beam's phase space, resulting in a larger beam spot size and lower transmission. Here we report a comparison of different wedge materials using standard beam diagnostics from viewers and position-sensitive detectors. Particular attention is paid to the calibration procedure for parallel plate avalanche counters (PPACs).