New Approaches to Final Cooling

TL;DR

This paper discusses new methods for muon collider final cooling, comparing traditional high-field solenoid techniques with innovative approaches involving emittance exchange and beam shaping to optimize transverse and longitudinal emittance reduction.

Contribution

It introduces alternative final cooling strategies that explicitly incorporate emittance exchange and beam manipulation techniques, expanding beyond the baseline solenoidal cooling method.

Findings

Baseline approach achieves low transverse emittance with high longitudinal heating.

Alternative methods include round-to-flat beam transform and longitudinal bunch coalescence.

Simulation results suggest potential improvements in cooling efficiency.

Abstract

A high-energy muon collider scenario requires a "final cooling" system that reduces transverse emittance by a factor of ~10 while allowing longitudinal emittance increase. The baseline approach has low-energy transverse cooling within high-field solenoids, with strong longitudinal heating. This approach and its recent simulation are discussed. Alternative approaches which more explicitly include emittance exchange are also presented. Round-to-flat beam transform, transverse slicing, and longitudinal bunch coalescence are possible components of the alternative approach. A more explicit understanding of solenoidal cooling beam dynamics is introduced.