Post on 08-Jan-2016
description
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The High-Emittance Muon The High-Emittance Muon ColliderCollider
David Neuffer
June 2009Low Emittance Muon Collider Workshop Preview
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OutlineOutline
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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Motivation- E. EichtenMotivation- E. Eichten
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Other physics 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 !!
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2A
2 TeV
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HEMC Parameters HEMC Parameters
Parameter Symbol Value
Proton Beam Power Pp 2.4 MW
Bunch frequency Fp 60 Hz
Protons per bunch Np 3×1013
Proton beam energy Ep 8 GeV
Number of muon bunches nB 12
+/-/ bunch N 1011
Transverse emittance t,N 0.003m
Collision * * 0.05m
Collision max * 10000m
Beam size at collision x,y 0.013cm
Beam size (arcs) x,y 0.55cm
Beam size IR quad max 5.4cm
Collision Beam Energy E+,E_ 1 TeV (2TeV total)
Storage turns Nt 1000
Luminosity L0 4×1030
Proton Linac 8 GeV
Accumulator,Buncher
Hg target
Linac
RLAs
Collider Ring
Drift, Bunch, Cool
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Proton DriverProton Driver
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
Proton Linac 8 GeV
Accumulator,Buncher
Drift, Bunch, Cool
Hg target
Linac
RLAs
Collider Ring
Detector
p tot
2F N
3r N
2 B
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Solenoid lens captureSolenoid 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
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High-frequency Buncher and High-frequency Buncher and φφ-E -E RotatorRotator
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 beam 201.25MHz
10 m ~50 m
FE
Targ et
Solenoid Drift Buncher Rotator Cooler
~30m 36m ~80 m
p
π→μ
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Adiabatic Buncher; Adiabatic Buncher; φφ-E rotation-E rotation Set rf phase to be zero for
reference energies Spacing is N rf
rf increases
gradually increase rf gradient
Match to rf= ~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
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Bunch train for ColliderBunch 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× 1011
μ/bunch in acceptance
εt,rms, normalized ≈ 0.003m (accepted μ’s)
εL,rms, normalized≈ 0.034m (accepted μ’s)
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Simulations (NSimulations (NBB=10)=10)
-30m 30m
500 MeV/c
0
Drift andBunch
s = 89ms = 1m
Rotate
s = 125m s = 219m
Cool
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HEMC collider bunchesHEMC collider bunches
Scenario is unoptimized ~60% of μ’s in best 12
bunches ~75% in best 16
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Acceleration-RLA’s ? Acceleration-RLA’s ?
1.2 GeV/pass7.2 GeV
1.8 GeV244 MeV
300 m
160 m
5 GeV/pass
528 m32.5GeV
7 pass Ef
E0
= 30Dogbone RLA II example
Linac
140 GeV/pass
32.5 GeV
1000 GeV
Dogbone geometry is long. (140 GeV @20MV/m is 7km.)Racetrack is more compact.
A. Bogacz – Dogbone RLAs
Beam is probably too big for 1300MHz.800 MHz - OK
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Collider RingCollider Ring
12 bunches of μ+ and μ-
1011 μ/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
,4 beam beamN rms
N r
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Upgrade pathUpgrade 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
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ConclusionsConclusions
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
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First First μμ Collider may not be perfect Collider may not be perfect ……