Study of a Final Cooling Scheme for a Muon Collider Utilizing High-Field Solenoids

A muon collider with center of mass energy of 1.5-4 TeV would probe fundamental physics phenomena at energies well above the CERN Large Hadron Collider or the proposed International Linear Collider. Unlike electrons, muons have sufficient mass to suffer negligible synchrotron radiation and can be circulated, thus decreasing the machine footprint and cost. This project will develop high-field solenoids for the final cooling of muons in a collider. In the Phase I design, the resistive coils were replaced by superconducting coils: first a Nb3Sn coil operating below 2 K, and then a high temperature superconducting coil (either YBCO or Bi 2212). Simulations conducted in Phase I demonstrated that the required ~25 pi mm-mrad emittance could be achieved with final-stage cooling in 50 T solenoids. Phase II will build and test two insert coils: (1) a 4 T coil using Bi-2212, and (2) a ~12 T coil using YBCO. One or both of the new coils would be tested inside a background field of 19 T. In addition, the needed quench protection for these tests will be designed and constructed. Finally, magnet and quench protection designs for 40-50 T systems will be studied. Commercial Applications and other Benefits as described by the awardee: Beyond the application to high energy physics research, commercial applications include muon radiography for condensed matter studies, nanotechnology, medical applications (particularly for MRI magnets), and homeland-security applications