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) enables groundbreaking research in nuclear physics, astrophysics, and fundamental interactions, as well as the societal applications of this work. Critical to the science program at FRIB is the Advanced Rare Isotope Separator (ARIS), which separates, identifies, and purifies fragments produced via projectile fragmentation and fission using a variety of beamline elements, including eight superconducting dipole magnets. An accurate magnetic rigidity calibration of these dipole magnets is crucial for obtaining peak fragment yields with optimal transport conditions in minimal time and comparing to simulations. This work reports on the use of the FRIB linear accelerator to provide charge states of a U-238 beam of known energies, with accuracy of 0.1%, to calibrate the ARIS dipole field versus effective bend radius over a range of magnetic rigidities. Due to saturation of the iron in the dipoles, the effective radius varies significantly, especially above about 1.2 T. Details of the procedure and results will be presented.

The FRIB accelerator, constructed and commissioned in 2022, serves as a leading facility for producing rare isotope beams and exploring elements beyond the limits of stability. These beams are produced by reactions between stable primary beams and a graphite production target. Meanwhile, approximately 20–40% of the primary beam power is deposited in the target, necessitating efficient heat dissipation. Currently, FRIB operates at a primary beam power of 15 kW. To enhance thermal dissipation efficiency, a single-slice rotating graphite target with a diameter of approximately 30 cm is employed. This paper presents an overview of the current status of the production target system and ongoing R&D efforts to enhance its performance and durability under high-power beam conditions.

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).

The Facility for Rare Isotope Beams (FRIB) provides rare-isotope beams for user experiments in nuclear physics, nuclear astrophysics, fundamental symmetries, etc. A superconducting driver-linac accelerates heavy-ion beams onto the production target, and the Advanced Rare Isotope Separator (ARIS) collects and purifies the rare isotope fragments of interest. Subsequently, the transfer hall beamlines deliver isotopes to user setups at experiment stations. The isotope beam condition from ARIS strongly depends on the fragment of interest. Therefore, the beamline settings are optimized for each experiment based on various users’ requirements on the fly. Two new beamlines in the transfer hall were commissioned in 2025, bringing the total number of available end stations to five. Since the first user experiments in 2022, ongoing beam tests and operations have continued to improve operational efficiency and user satisfaction. Results and findings of beam tuning obtained from the commissioning and recent operations will be reported.

The Advance Rare Isotope Separator (ARIS) at FRIB provides in-flight purification of rare-isotope beams (RIB) generated by projectile fragmentation or fission on a target. Beams of stable ions from a driver linac impinge on a graphite target thin enough such that products main-tain velocities close to that of the incident beam. The incident primary beam impinges on-target at about 200 MeV/u (for uranium and higher for lighter species). The energy may be lower than the maximum allowed, de-pending on the requirements of the experiment. Using multi-charge state acceleration, the linac has most recently provided up to 20 kW on-target with a long-term goal of reaching 400 kW. Specialized magnets, collimators and other components have been integrated into the separator to withstand harsh conditions and facil-itate maintenance. The optics properties at the beam dump are important since the power density must be kept low enough to avoid failure of the material. We describe the various optics modes that have been developed for safe operations and maximizing the beam power allowed for RIB production.

The production of radioactive beams is crucial to understand structure of atomic nuclei away from stability. The operation of FRIB will ultimately provide access to previously unreachable unstable nuclei. Radioactive beams produced at FRIB can be selected and purified using the Advanced Rare Isotope Separator (ARIS) for further study by users. Ions are identified based on the energy loss, magnetic rigidity, gamma rays, time of flight, total energy in a suite of detectors. The transport of cocktail beams to the end of ARIS can impact the path length and the measured flight time. This can lead to uncertainty in the particle identification and worse timing resolution can occur if not corrected for. Characterizing the ion optics with position-sensitive detectors allows for corrections to the flight path of the ions. This in conjunction with the use of transfer matrices allows for the particle’s trajectory to be reconstructed and thus correct for the variation in the measured time of flight. These corrections are crucial for enhancing charge-state identification, especially in a high-resolution optics mode. The impact of applying a trajectory reconstruction method will be presented.