Beam Commissioning Results from the CBETA Fractional Arc Test

This work describes first commissioning results from the Cornell Brookhaven Energy RecoveryTest Accelerator Fractional Arc Test. These include the recommissioning of the Cornell photo-injector, the first full energy operationof the main linac with beam, as well as commissioning of the lowest energy matching beamline( splitter) and a partial section of the Fixed Field Alternating gradient (FFA) return loop featuring first production Halbach style permanent magnets. Achieving these tasks required characterization of the injection beam, calibration and phasing of the main linac cavities, demonstration of the required 36 MeV energy gain, and measurement of the splitterline horizontal dispersion and R56 at the nominal 42 MeV. In addition, a procedure for determining the BPM offsets, as well as the tune per cell in the FFA section via scanning the linac energy and inducing betatronoscillations around the periodic orbit in the fractional arc was developed and tested. A detailed comparison of these measurements to simulation is discussed.