Helical Muon Beam Cooling Channel Engineering Design

The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of high-power RF cavities into the low-temperature superconducting magnets of the HCC. veral SBIR-STTR-developed inventions will be combined in an innovative practical engineering solution for a muon-cooling channel suitable for a muon collider. The design will incorporate the HCC, a Helical Solenoid (HS) magnet, hydrogen-pressurized RF cavities, and emittance exchange using a continuous absorber and be optimized using G4beamline muon beam cooling simulations. The goal of the project is to optimize beam cooling for maximum collider luminosity while including all known engineering constraints, from material properties to affordable RF power sources and cryogenic loads, and to generate an engineering design of a segment of a channel as a prototype to build and test.Conceptual designs for the integration of 805 MHz RF cavities into a 10 T Nb3Sn based HS test section have been developed based on recent tests of a doped H2-pressurized RF cavity that operated in a charged particle beam. Calculations show that dielectric inserts can make the cavities smaller for a given frequency to ease physical constraints, where heat loads will be tolerable and RF breakdown of the inserts will be suppressed by the pressurized hydrogen gas.A complete engineering design of a 1m section of 10 T HCC with integrated 805 MHz RF will be made and optimized using beam cooling simulations. Key components of a 10T, 805 MHz HCC will be demonstrated, including the design, construction, and testing of a full-sized dielectric-loaded cavity and a four-coil 10T Nb3Sn Helical Solenoid.The muon-beam cooling-channel developed in this project will enable a muon collider, the next step toward the energy frontier, Higgs/neutrino/Z-factories, and rare muon decay experiments. Commercial uses of the beams made possible by the cooling techniques developed in this project include scanning for nuclear contraband, studies of material properties with spin resonance techniques, and muon catalyzed fusion.