The Facility for Rare Isotope Beams will be completed in late 2021. We report here on the current efforts to commission the first stages of the 200-MeV/u superconducting, continuous wave heavy-ion linac. The statuses of the cryogenic plant and its distribution system, the accelerator cryomodule commissioning and operations, the ion source and front end transport development, the radio-frequency quadrupole commissioning, and thenbeam dynamics development to support high-power operation are reviewed. Plans for commissioning the remainder of the linac systems are presented.

The Facility for Rare Isotope Beams (FRIB) superconducting (SC) driver linac is designed to accelerate all stable ions including uranium to energies above 200 MeV/u primarily with 46 cryomodules containing 324 quarter-wave resonators (QWR) and half-wave (HWR) resonators. With the newly commissioned helium refrigeration system supplying liquid helium to the QWR and solenoids, heavy ion beams including Ne, Ar, Kr and Xe were accelerated to the charge stripper location above 20 MeV/u with the first linac segment consisting of 15 cryomodules containing 10⁴ QWRs of β=0.041 and 0.085 and 39 solenoids. Installation of cryomodules with β=0.29 and 0.53 HWRs is proceeding in parallel. Development of β=0.65 elliptical resonators is on-going supporting the FRIB energy upgrade to 400 MeV/u. This paper summarizes the SC-linac installation and phased commissioning status that is on schedule and on budget to the FRIB project.

The commissioning of the FRIB Front End (FE) with 12 keV/u argon beam started in the summer of 2017. Beam profile monitors were used to evaluate RMS Twiss parameters in various locations along the beam line. Beam dynamics in the LEBT was simulated using full 3D model of beam optics elements in the tracking codes. We found a good consistency between measured and simulated data. A beam image viewer was used to measure the beam density distribution in the real space. A hollow beam structure was observed in the Ar9+ beam with the current of ~20 μA. Extensive beam dynamics studies with 3D tracking code suggest that the hollow density distribution can be generated by space charge effects of the multi-component, multicharge state ion beams just after the ECR ion source. This paper reports studies of a mechanism that can produce a hollow beam structure.

T. Xu†, K. Saito, H. Ao, B. Bird, N.K. Bultman, F. Casagrande, C. Compton, K.D. Davidson, K. Elliott, V. Ganni, A. Ganshyn, W. Hartung, M. Ikegami, P. Knudsen, S.M. Lidia, E.S. Metzgar, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, M.A. Reaume, S. Shanab, M. Shuptar, S. Stark, D.R. Victory, J. Wei, J.D. Wenstrom, M. Xu, T. Xu, Y. Xu, Y. Yamazaki, FRIB, Michigan State University, East Lansing, Michigan, USA A. Facco, INFN/LNL, Legnaro (PD), Italy K. Hosoyama, KEK, Ibaraki, Japan M.P. Kelly, ANL, Argonne, Illinois, USA R.E. Laxdal, TRIUMF, Vancouver, Canada M. Wiseman, JLab, Newport News, Virginia, USA

The Facility for Rare Isotope Beams' heavy ion continuous-wave (CW) linac extends superconducting RF to low beam energy of 500 keV/u. 332 low-beta cavities are housed in 48 cryomodules. Technical development of high performance subsystems including resonator, coupler, tuner, mechanical damper, solenoid and magnetic shielding is necessary. In 2015, the first innovatively designed FRIB bottom-up prototype cryomodule was tested meeting all FRIB specifications. In 2016, the first full production cryomodule is constructed and tested. The preproduction and production cryomodule procurements and in-house assembly are progressing according to the project plan.

With an average beam power two orders of magnitude higher than operating heavy-ion facilities, the Facility for Rare Isotope Beams (FRIB) stands at the power frontier of the accelerator family. This report summarizes the current design and construction status as well as plans for commissioning, operations, and upgrades.

FRIB (Facility for Rare Isotope Beams) is a heavy ion linac facility to accelerate all stable ions to the energy of 200 MeV/u with the beam power of 400 kW, which is under construction at Michigan State University in USA. FRIB driver linac is a beam power frontier accelerator aiming to realize two orders of magnitude higher beam power than existing facilities. It consists of more than 300 low-beta superconducting cavities with unique folded layout to fit into the existing campus with innovative features including multi charge state acceleration. In this talk, we overview accelerator physics challenges in FRIB driver linac with highlight on recent progresses and activities preparing for the coming beam commissioning.

Strategies for data acquisition and processing will be discussed in the context of the Facility for Rare Isotope Beams (FRIB). Design decisions include selecting and designing electronics hardware, data acquisition cards, firmware design, and how to integrate with EPICS control system. With over 300 diagnostic devices and 16 unique types of devices, timing for synchronous data acquisition is important. Strategies to accelerate development as well as reduce maintenance requirements will be discussed, including using common hardware and firmware whenever possible, and defining a common data reporting structure for use by most devices. MicroTCA.4 platform is used to integrate data acquisition cards, distribute timing information, and machine protection signals. FRIB MACHINE REQUIREMENTS The Facility for Rare Isotope Beams (FRIB) is a new scientific user facility for low energy nuclear science. Under construction on campus and operated by Michigan State University, FRIB will provide intense beams of rare isotopes [1]. FRIB will deliver the highest intensity beams of rare isotopes available anywhere. The superconducting linear accelerator (linac) will accelerate ion species from 18Ar up to 238U with energies of no less than 200 MeV/u and provide beam power up to 400 kW. Although designed to support full-scale CW operation, low current and pulsed modes will also be utilized, so diagnostics must support a large dynamic range, from 1 nA to 1 mA of beam current. Figure 1 shows a schematic overview of the accelerator. Machine Protection and Availability In order to achieve high reliability and high availability, permanent accelerator component damage should be prevented, beam loss and residual activations should be minimized, and beam downtime minimized. This leads to an array of diagnostic devices which monitor a variety of beam loss mechanisms. A machine protection system (MPS) has been designed to detect and respond quickly (< 35 sec) to beam loss events and terminate the beam [3]. This is achieved by monitoring not-OK (NOK) signals from a multitude of MPS nodes which digitize diagnostic data and make local NOK decision in less than 15 sec. The remaining 20 sec of the time budget is used to communicate the NOK signal to the MPS Master and to terminate beam production and transport. Table 1 is simplified picture of the acute (fast) and chronic (slow) losses which we must detect. Table 2 shows an overview of diagnostic devices utilized not only for machine protection (MPS), but also for tuning, commissioning, and general diagnostic information [2]. Italicized devices * will provide input to MPS. Table 1: Acute and Chronic Beam Loss Detection Beam Loss Diagnostic Response Time

As a multi-charge-state, heavy-ion, superconducting accelerator with a folded geometry, FRIB faces unique beam loss detection and collimation challenges to protect superconducting cavities from beam-induced damage. Collimation is especially important in the Folding Segment 1 where the multiple charge states are created by a charge stripper and selected by a charge selector. The transported ECR contaminants, interaction with the residual gas, and beam halo due to stripping could induced significant beam losses in this region. We have simulated the potential beam losses and planned collimation accordingly. A layered loss detection network is also specifically designed to visualize potential blind zones and to meet the stringent requirements on loss detection. The related sub-systems are designed and procured and are introduced in this paper.

Gaining in-situ access to relaxation dynamics of radiation induced defects will lead to a better understanding of materials and is important for the verification of theoretical models and simulations. We show preliminary results from experiments at the new Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory that will enable in-situ access to defect dynamics through pump-probe experiments. Here, the unique capabilities of the NDCX-II accelerator to generate intense, nanosecond pulsed ion beams are utilized. Preliminary data of channeling experiments using lithium and potassium ions and silicon membranes are shown. We compare these data to simulation results using Crystal Trim. Furthermore, we discuss the improvements to the accelerator to higher performance levels and the new diagnostics tools that are being incorporated.

The Facility for Rare Isotope Beams (FRIB) will use a superconducting linear accelerator to extend the heavy ion intensity frontier for ion species from protons to uranium. The unique design of the twice-folded linac, coupled with the 5 orders of range of beam intensities present new challenges for instrumentation, and machine protection systems. Multi-charge state beams in the low energy linac and dispersive arc regions add complexity to instrumentation systems used for longitudinal tuning and transverse orbit optimization. Beam loss monitoring systems must distinguish losses from the three parallel linac segments sharing the same enclosure. Finally, quick response to abnormal conditions is required to prevent catastrophic damage to beam line components from the high power, heavy ion beams. We present an overview of beam diagnostic systems and detection networks required for the safe tuning, operation, and maintenance of FRIB. FRIB FACILITY OVERVIEW Facility for Rare Isotope Beams (FRIB) is a high-power, high-brightness, heavy ion facility under construction at Michigan State University under cooperative agreement with the US DOE [1]. The linac will accelerate ions to energies above 200 MeV/u, with up to 400 kW of beam power on target. The linac facility, shown in Fig. 1, consists of a Front End, three Linac Segments (LSs) connected by two Folding Segments (FSs), and a Beam Delivery System (BDS) leading to the production target [2]. The front-end consists of two ECR (Electron Cyclotron Resonance) ion sources, a normal conducting CW (continuous wave) RFQ (Radio Frequency Quadrupole) linac, and beam transport lattices. Ion sources are located on the ground level and beam from one of two ion sources is delivered to the linac tunnel through a vertical beam drop. An electrostatic chopper upstream of the vertical beam drop is the primary control of the time structure and duty cycle of the ion beam. A multi-harmonic buncher (MHB) precedes the RFQ and impresses the initial 80.5 MHz RF time structure on the beam. The front end is shown schematically in Fig. 2. Figure 2: Front end schematic layout. This paper will first discuss the requirements and specifications of the beam instrumentation systems necessary for FRIB commissioning and operation. Then specific challenges and issues will be presented, along with proposed solutions, which arise from the unique design and operation of this facility. Figure 1: FRIB drive linac schematic layout. OVERVIEW OF BEAM DIAGNOSTIC INSTRUMENTATION The suite of beam instrumentation systems is designed to facilitate initial commissioning and tuning activities ___________________________________________ *This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661, the State of Michigan and Michigan State University. #lidia@frib.msu.edu Proceedings of HB2014, East-Lansing, MI, USA WEO2AB01 Instrumentations and Beam Material Interactions ISBN 978-3-95450-173-1 267 C op yr ig ht © 20 14 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s preceding user operations, and then to monitor beam transport and acceleration function, and to provide sensors for machine protection during operations. Diagnostic systems will be provided to continuously measure beam position and orbit deviations, beam current and transmission at several points, and beam loss induced radiation fields. On-demand diagnostics will produce measurements of beam phase space densities, bunch duration, 1-D beam profiles and 2-D transverse (x-y) or hybrid (x-z) distributions. Time of flight measurements using a dense network of beam position monitors will enable phase and amplitude tuning of the linac sections [3].

The heavy ion linac under construction at Michigan State University as part of the Facility for Rare Isotope Beams requires a Beam Position Monitoring System with dual-plane pick-ups at 147 locations. Four different pickup designs will be used with apertures of 40, 50, 100, and 150 mm. The 40 mm BPMs are designed to operate at cryogenic temperatures, as 39 are bolted to superconducting RF cavities and reside in the insulating vacuum of the cryomodule. The other designs serve only room temperature locations. Requirements, designs, analyses, tests, and status is reported

We employ intense and short pulses of energetic lithium (Li+) ions to investigate the relaxation dynamics of radiation induced defects in single crystal silicon samples. Ions both create damage and track damage evolution simultaneously at short time scales when we use the channeling effect as a diagnostic tool. Ion pulses, ~20 to 600 ns long and with peak currents of up to ~1 A are formed in an induction type linear accelerator, the Neutralized Drift Compression experiment at Lawrence Berkeley National Laboratory. By rotating silicon (<100>) membranes of different thicknesses and changing the incident ion energy, the fraction of channeled ions in the transmitted beam could be varied. In preliminary experiments we find that the Li ion intensity is not high enough to generate overlapping cascades (in time and space) that would be necessary to measure a change in the shape of the current waveform of the transmitted ion beam. We discuss the concept of pump-probe type experiments with short ion beam pulses to access defect dynamics in materials and outline a path to increasing damage rates with heavier ions and by the application of longitudinal and lateral pulse compression techniques.