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The High-Emittance Muon Collider. David Neuffer June 2009 Low Emittance Muon Collider Workshop Preview. Outline. Introduction Motivation Scenario Outline and Features Parameters Proton Driver Front End Accelerator Collider Upgrade Path(s) to Low-Emittance Muon Collider.
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The High-Emittance Muon Collider David Neuffer June 2009 Low Emittance Muon Collider Workshop Preview
Outline • Introduction • Motivation • Scenario Outline and Features • Parameters • Proton Driver • Front End • Accelerator • Collider • Upgrade Path(s) • to Low-Emittance Muon Collider
Other physics • Higgs at high energy • σ≈ 0.6pb • 0.01 fb-1 is 1030 for 107s • need more to sweep nearby energy • First SuperDimensional DarkMatterEnergy HyperSymmetric Particle?? • σ > pb !!
2A 2 TeV
HEMC Parameters Proton Linac 8 GeV Accumulator, Buncher Hg target Drift, Bunch, Cool Linac RLAs Collider Ring
Proton Driver Proton Linac 8 GeV • Proton Driver is variant of Project X • Other variations possible • 8 GeV at Fermilab • 8 GeV SRF linac , 15 Hz • 1.2×1014/cycle • Accumulate, Bunch to form 4 bunches • 3×1013/bunch • εN6π=120π mm-mrad, BF = 0.005 • δν = 0.4 • extract at 60Hz Accumulator, Buncher Hg target Drift, Bunch, Cool Linac RLAs Detector Collider Ring
Solenoid lens capture • Target is immersed in high field solenoid • Particles are trapped in Larmor orbits • B= 20T -> ~2T • Particles with p < 0.3 BsolRsol/2=0.225GeV/c are trapped • π→μ • Focuses both + and – particles • Drift, Bunch and phase-energy rotation pm
High-frequency Buncher and φ-E Rotator p π→μ FE Target Solenoid Drift Buncher Rotator Cooler 10 m ~50 m ~30m 36m ~80 m • Drift (π→μ) • “Adiabatically” bunch beam first (weak 320 to 240 MHz rf) • Φ-E rotate bunches – align bunches to ~equal energies • 240to 202 MHz, 15MV/m • Cool beam201.25MHz
Adiabatic Buncher; φ-E rotation • Set rf phase to be zero for reference energies • Spacing is N rf • rf increases • gradually increase rf gradient • Match torf= ~1.5m at end: • After bunching rephase rf so that higher energy bunches accelerate, low energy bunches • Finish when bunch energies are aligned in E • Transfer to cooling • Captures both μ+ and μ- • born from same proton bunch Example: rf : 0.901.5m
Bunch train for Collider • Drift, buncher, rotator to get “short” bunch train (nB = 10): • 217m ⇒ 125m • 57m drift, 31m buncher, 36m rotator • Rf voltages up to 15MV/m (×2/3) • Obtains ~0.1 μ/p8 in ref. acceptance • At < 0.03, AL <0.2 • Choose best 12 bunches • ~0.008 μ/p8 per bunch • ~0.005 μ/p8 in acceptance • 3 × 1013 protons • 1.5× 1011μ/bunch in acceptance • εt,rms, normalized ≈ 0.003m (accepted μ’s) • εL,rms, normalized≈ 0.034m (accepted μ’s)
Simulations (NB=10) s = 1m s = 89m Drift and Bunch Rotate 500 MeV/c s = 219m s = 125m Cool 0 30m -30m
HEMC collider bunches • Scenario is unoptimized • ~60% of μ’s in best 12 bunches • ~75% in best 16
Acceleration-RLA’s ? Ef = 30 E0 1.8 GeV 244 MeV Dogbone RLA II example 300 m 7 pass 160 m 32.5 GeV 1.2 GeV/pass 7.2 GeV 528 m 1000 GeV 32.5GeV Linac 140 GeV/pass 5 GeV/pass A. Bogacz – Dogbone RLAs Beam is probably too big for 1300MHz. 800 MHz - OK Dogbone geometry is long. (140 GeV @20MV/m is 7km.) Racetrack is more compact.
Collider Ring • 12 bunches of μ+ and μ- • 1011μ/bunch • β*= 3 to 10 cm • σ= 0.01 to 0.016cm • βmax = 10000m • σ=5.5cm (1TeV) • IR quads are large aperture (20cm radius) • εL =0.012 eV-s • δE ~0.12 GeV if σz = 3cm • δE/E = 10-4 • Collider is not beam-beam limited • Δν=0.000036
Upgrade path • More cooling • εt,N→ 0.0005, β*→1cm • L→1032 • Bunch recombination • 12→1 • L→1033 • More cooling • low emittance • εt,N→ 0.00003, β*→0.3cm • L→1034 • More Protons • 2.4→5MW or more • L→1035
Conclusions • An Initial Muon Collider (0.5 to 4 TeV) with low luminosity could be constructed, particularly if motivated by a clear physics goal. Uses trains of μ+ and μ- bunches for acceleration and storage (~ 20m trains) • L= ~4×1030 cm-2s-1 • needs little cooling • does need front end (captures both μ+ and μ-) • Could be upgraded to high-luminosity • more cooling • smaller β* • bunch recombination