Muon Bunching for a Muon Collider David Neuffer

Muon Bunching for a Muon Collider David Neuffer FNAL August 3, 2010 1

0 utline Ø Motivation § μ+-μ- Collider • Multi-Te. V high-energy collider Ø Produce, collect and cool as many muons as possible § Start with ν-Factory IDS design study § Reoptimize for Collider • Shorter bunch train • § Higher energy capture, shorter front-end Larger gradients Ø ν-Factory→μ+-μ- Collider Ø Discussion 2

Muon Collider at Fermilab • Beamstrahlung in any e+e- collider • E/E 2 Need ~4 MW pulsed proton source from Project X Initial Project X is (currently) cw 3 Ge. V linac <1 G$ will need upgrade 3

Muon Collider/NF Beam Preparation Ø Baseline Muon Collider beam preparation system identical to that for Neutrino Factory § downstream portions (6 D cooling, acceleration, collider) are distinct • much more cooling and acceleration needed for collider Neutrino Factory Muon Collider 4

Front End variations Ø Muon Collider front end optimum is somewhat different § Short bunch train preferred • Bunches are recombined later … • • NF will debug gradient limits Cost is less constrained § Maximum μ/bunch wanted § Longitudinal cooling included; may accept larger δp § Larger rf gradient can be used (? ) Ø For variant, we will have shorter BR system, more gradient, and capture at higher momentum § § 230 270 Me. V/c 150 m 120 m 9/12/15 MV/m 15/16/18 or 15/18/20 MV/m 1. 5 T 2 T 5

High-frequency Buncher and φ-E Rotator Ø Drift (π→μ) Ø “Adiabatically” bunch beam first (weak 350 to 232 MHz rf) Ø Φ-E rotate bunches – align bunches to ~equal energies § 232 to 202 MHz, 12 MV/m Ø Cool beam 201. 25 MHz p π→μ FE Tar get Solenoid 18. 9 m Drift ~40 m Buncher ~33 m Rotator 34 m Cooler ~80 m 6

Rotated version Ø End up with fewer, denser bunches § More μ/p § Larger δp 15 bunches 7

Neutrino Factory version Ø NF baseline version p π→μ FE Tar get Solenoid 18. 9 m Drift ~60. 7 m Buncher ~33 m Rotator 42 m Cooler ~80 m 23 bunches 8

Collider version 1. 0 Ge. V/c Ø Has ~30% shorter train Ø More μ/p § ~0. 12 μ/p (from ~0. 09) NEW MC Ø Captures more of the “core” of the initial π/μ § Rather than lower half of the core … 1. 0 0 Ge. V/c All at target 8 Ge. V p Older IDS 0 9

Comments Ø Muon Collider version is an incremental change from IDS μ/p § ~25% shorter § Higher gradients • • 9/12/15 15/16/18/20 ? 0. 25 All μ’s § Capture at ~275 Me. V/c rather 0. 15 than 230 Me. V/c Ø Collider optimum might be a further increment along … ? Ø Optimization should include initial cooling with 6 -D 0. 10 εt<0. 03, εL<0. 3 0. 0 § Used only transverse in present study, Li. H absorbers (~1. 2 cm) 10

Thoughts for IDS/NF Ø Shoud central capture momentum be increased § 210 230 270? Ø Would start cooling at higher momentum § Longer channel for cooling Ø Might want to increase acceptance 11