CONCEPT FOR MUON ACCELERATION
Pulsed srf
Enhanced gradient
Reduced cryogenic load
Injector/preaccelerator (0.18-2 GeV)
Graded-
b
(0.87-1.0) cavities @ 100 MHz
Maybe 3
rd
-harmonic (300 MHz) cavities for bunching
Two pulsed srf recirculating linacs
Linac pairs for high real-estate gradient
2 to 10 GeV at 100 MHz
sparse/simple recirculator (Bates style?)
bunching built into lattice
10 to 50 GeV, maybe 200 MHz with larger footprint
ISSUES UNDER CONSIDERATION
Performance vs. energy of injection/reinjection
Estimates of collective effects
Preacceleration of large injected momentum spread
Longitudinal phase-space transport
Transverse phase-space transport (rf focussing)
Recirculation of large phase space; Bunch compression in 1
st
RLA?
External focussing: Is it superconducting and/or in the cryostat?
Big aperture means lots of stray fields – shielding is hard
But srf/room-T transitions use lots of real estate
Exacerbated by 40% full momentum spread
High-Q, high-gradient, low-frequency srf cavities
Technology: Pb sputtered on surface-cooled Cu?
Operating temperature (2K vs. 4K?)
Refrigeration efficiency, cost
Quench protection – how to extract large stored rf energy?
Cost optimization