Epicyclic Helical Channels for Parametric Resonance Ionization Cooling

Muon beam ionization cooling is a key element in the design of next-generation low-emittance and high-luminosity muon colliders. New approaches in that cooling could greatly improve the performance and capabilities of these colliders. To obtain low-emittance muon beams, a new concept is being developed that combines ionization cooling in a Helical Cooling Channel (HCC) with parametric resonances. The novelty consists of creating alternating orbit dispersion in the HCC by imposing an additional helical field of opposite helicity. In this project we will first develop a theoretical description of an alternating-dispersion muon cooling channel that includes a solenoid with two superimposed transverse helical fields with different characteristic periods. We will then conduct an extensive numerical analysis of the orbital motion in such a channel by identifying the periodic orbit, its stability region, its characteristic parameters and their control. On the basis of this numerical analysis, we will perform simulations of the Epicyclic Parametric-resonance Ionization Cooling (EPIC) channel including parametric resonance excitation, ionization cooling and the analysis of non-linear effects, such as chromatic and spherical aberrations and their compensation. This analysis will provide the basis for the full-scale engineering-design simulations to be performed in Phase II. Commercial Applications and Other Benefits: This new approach will allow more aggressive designs of cooling channels for muon colliders that will result in significant increase of luminosity with lower detector backgrounds. The resulting greater feasibility and discovery potential of muon colliders such as Higgs factories and energy-frontier machines will make their construction more likely. Formation of highly focused neutrino beams can also benefit from the technology that will be developed in this project.