FRIB, East Lansing, Michigan, USA
Facility for Rare Isotope Beams (FRIB) at Michigan State University is based on a high power heavy ion linac and beam commissioning is under way. For evaluation of beam Twiss parameters and rms emittance, we routinely use multiple profile measurements while the strength of an upstream quadrupole is varied. The change of the quadrupole strength results in a beam mismatch downstream of the profile monitor which can cause beam losses. This is not acceptable in a high energy beamline. To avoid this transverse mismatch, we developed a beam matching procedure by optimization of quadrupoles’ setting downstream of the profile monitor. Using this procedure we were able to eliminate beam losses during the quadrupole scan, and evaluate beam Twiss parameters and rms emittance. Examples of using this procedure in the folding segment of the FRIB linac will be reported.
FRIB, East Lansing, Michigan, USA
Beam loss in accelerators is an unavoidable and often unwanted reality, but it is not without its use. Information from beam loss can be leveraged to optimize the tune and improve beam quality, in addition to monitoring for machine fault and failure conditions. The folded geometry at the Facility for Rare Isotope Beams (FRIB) presents a unique challenge in the detection of radiative losses, resulting in the introduction of non-traditional measurement schemes. In addition to neutron detectors and pressurized ionization chambers, FRIB will utilize halo ring monitors, fast thermometry within the cryomodules, and differential beam-current measurements. This paper will present an analysis of beam-loss measurements from commissioning the first segment of the FRIB accelerator, and a discussion of ways to evaluate and monitor the health of the beam loss monitoring system.
