Transcript DOE 9/07/05

Muons, Inc.
Advances in Beam Cooling
for Muon Colliders*
Rolland Johnson, Muons, Inc.
Yaroslav Derbenev, JLab
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Several new ideas are being developed which have the
potential to form intense muon beams with normalized
transverse emittances of a few mm-mrad
This has created new enthusiasm for a low-emittance
energy-frontier muon collider
A 6D muon beam cooling experiment is being designed to
demonstrate in a Helical Cooling Channel segment
Papers and presentations can be found on
http://muonsinc.com
*Supported by DOE SBIR/STTR grants DE-FG02-02ER86145, 03ER83722, 04ER84015,
04ER86191, and 04ER84016
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Muons, Inc.
Recent Inventions and Developments
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New Ionization Cooling Techniques
• Emittance exchange with continuous absorber for longitudinal cooling
• Helical Cooling Channel
 Effective 6D cooling (simulations: cooling factor 50,000 in 150 m)
• Momentum-dependent Helical Cooling Channel
 6D Precooling device
 6D cooling demonstration experiment (400% 6 D cooling in 4 m)
 6D cooling segments between RF sections
• Ionization cooling using a parametric resonance
Methods to manipulate phase space partitions
• Reverse emittance exchange using absorbers
• Muon bunch coalescing
Technology for better cooling
• Pressurized RF cavities
 simultaneous energy absorption and acceleration and
 phase rotation, bunching, cooling to increase initial muon capture
 Higher Gradient in magnetic fields than in vacuum cavities
• High Temperature Superconductor for up to 50 T magnets
 Faster cooling, smaller equilibrium emittance
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PARTICIPANTS:
• NFMCC Members:
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Fermilab
Thomas Jefferson Lab
Brookhaven National Lab
Argonne National Lab
Lawrence Berkeley National Lab
Illinois Institute of Technology
Michigan State University
University of California at Los Angeles
University of California at Riverside
University of Mississippi
KEK
Muons, Inc.
• Non-NFMCC Members:
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Fermilab
Thomas Jefferson Lab
Illinois Institute of Technology
University of Michigan
University of Tsukuba / Waseda University
Osaka University
KEK
Hbar Technologies, LLC
Muons, Inc.
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Please come to the next LEMC
Workshop February 12-16 2007!
Check out the muonsinc.com
web site for plans to use the
new cooling ideas to make a 5
TeV COM or 1.5 TeV COM
collider with 1035 Luminosity
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Muons, Inc.
Benefits of low emittance approach
Lower emittance allows lower muon current for a given luminosity.
This diminishes several problems:
• radiation levels due to the high energy neutrinos from muon beams
circulating and decaying in the collider that interact in the earth near
the site boundary;
• electrons from the same decays that cause background in the
experimental detectors and heating of the cryogenic magnets;
• difficulty in creating a proton driver that can produce enough protons
to create the muons;
• proton target heat deposition and radiation levels;
• heating of the ionization cooling energy absorber; and
• beam loading and wake field effects in the accelerating RF cavities.
Smaller emittance also:
• allows smaller, higher-frequency RF cavities with higher gradient for
acceleration;
• makes beam transport easier; and
• allows stronger focusing at the interaction point since that is limited by
the beam extension in the quadrupole magnets of the low beta
insertion.
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Muons, Inc.
Ionization Cooling (reduction in angular
divergence of a muon beam)
Fast enough for muons
Only works for muons
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Muons, Inc.
Transverse Emittance IC
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The equation describing the rate of cooling is a balance
between cooling (first term) and heating (second term):
d n
1 dE  n 1  (0.014)2
 2
 3
ds
 ds E  2E m X 0
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Here n is the normalized emittance, Eµ is the muon energy in
GeV, dEµ/ds and X0 are the energy loss and radiation length of
the absorber medium,  is the transverse beta-function of the
magnetic channel, and  is the particle velocity.
n
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( equ .)

  (0.014)2
2 m
dE
ds
X0
pZ
, where   
BZ
Small emittance means large X, dE/ds, and B, and small p.
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Muons, Inc.
Pressurized High Gradient RF Cavities
(IIT, Dan Kaplan)
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Copper plated, stainless-steel, 800 MHz test cell with GH2 to 1600 psi and 77 K
in Lab G, MTA
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Paschen curve verified
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Maximum gradient limited by breakdown of metal
• fast conditioning seen, no limitation by external magnetic field!
Cu and Be have same breakdown limits (~50 MV/m), Mo ~28% better
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Muons, Inc.
MuCool Test Area (MTA)
5T Solenoid
Pressure
barrier
Wave guide to
coax adapter
800 MHz
Mark II
Test Cell
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Muons, Inc.
Maximum Gradient Measurements at Fermilab
Paschen region of gas breakdown
Region of electrode breakdown
Results show no B dependence, much different metallic breakdown than
for vacuum cavities. Need beam tests to prove HPRF works.
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800 MHz Vacuum cavity Max Gradient vs Bexternal
From Al Moretti, MICE meeting IIT, 3/12/06
Safe Operating Gradient Limit vs Magnetic
Field Level at Window for the three different
Coil modes
(Opposing)
Red
Electric Gradient in MV/m
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(Single Coil)
4040
37.66
Black Diamond
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35.2
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32.4
31.7
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28.8
28.5
27.327
26.4
25.9
25.7526.74
23.25
22.5
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21.5
20.9
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30
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16.5
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(Solenoid)
Yellow
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13.5
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MTA Result
5
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0
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Peak Magnectic Field in T at the Window
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Muons, Inc.
Technology Development in Fermilab Technical Division
HTS at LH2 shown, in LHe much better
1600
14 K
1400
RRP Nb3Sn round wire
BSCCO-2223 tape
JE, (A/mm2)
1200
Present efforts are to characterize HTS and to
design a 50 T solenoid for better muon cooling.
1000
800
High Temperature Superconductor (HTS)
can work in extremely high fields
600
400
200
0
0
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Transverse Field (T)
Fig. 9. Comparison of the engineering critical current density, JE, at 14 K as a function
of magnetic field between BSCCO-2223 tape and RRP Nb3Sn round wire.
Emanuela Barzi et al., Novel Muon Cooling Channels Using Hydrogen Refrigeration
and HT Superconductor, PAC05
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Muons, Inc.
6-Dimensional Cooling in a Continuous Absorber
Derbenev & Johnson, Theory of HCC, April/05 PRST-AB
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Helical cooling channel (HCC)
• Continuous absorber for emittance exchange
• Solenoidal, transverse helical dipole and quadrupole fields
• Helical dipoles known from Siberian Snakes
• z-independent Hamiltonian
Simulated example of 10 m long HCC
RF cavities
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End View
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Particle motion in HCC
Red: Reference orbit
Blue: Beam envelope
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f   b  p z Repulsive force
f   bz  p Attractive force
f central
2 a
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p
pz
e
 (b  pz  bz  p )
m
The forces are of opposite sign.
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G4BL (Geant4) results
6D Cooling factor ~ 50,000
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Muons, Inc.
Parametric-resonance Ionization Cooling
Excite ½ integer parametric resonance (in Linac or ring)
 Like vertical rigid pendulum or ½-integer extraction
 Elliptical phase space motion becomes hyperbolic
 Use xx’=const to reduce x, increase x’
 Use IC to reduce x’
Detuning issues being addressed (chromatic and spherical
aberrations, space-charge tune spread). Simulations
underway. New progress by Derbenev.
X’
X’
X
x
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Reverse Emittance Exchange, Coalescing
see Derbenev, Ankenbrandt
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p(cooling)=100MeV/c, p(colliding)=2.5 TeV/c => room in Δp/p space
Shrink the transverse dimensions of a muon beam to increase the
luminosity of a muon collider using wedge absorbers
~30 GeV Bunch coalescing in a ring a new idea for ph II
Neutrino factory and muon collider now have a common path
p
Drift
Incident Muon
Beam
RF
t
Wedge Abs
Cooled at 100 MeV/c
Evacuated
Dipole
RF at 20 GeV
Coalesced in 20
GeV ring
Concept of Reverse Emittance Exch.
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1.3 GHz Bunch Coalescing at 20 GeV
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Muons, Inc.
An example of a momentum-dependent HCC
6DMANX demonstration experiment
Muon Collider And Neutrino Factory eXperiment
• To Demonstrate
– Longitudinal cooling
– 6D cooling in cont. absorber
– Prototype precooler
– Helical Cooling Channel
– Alternate to continuous RF
• 5.5^8 ~ 10^6 6D emittance
reduction with 8 HCC sections
of absorber alternating with
(SC?)RF sections.
– New technology
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Muons, Inc.
Turning the Precooler into MANX
Features:
Z-dependent HCC (fields diminish as muons slow in LHe)
Normalized emittance to characterize cooling
No RF for simplicity (at least in first stage)
LHe instead of LH2 for safety concerns
Use ~300 MeV/c muon beam wherever it can be found
with MICE collaboration at RAL or at Fermilab
Present Efforts:
Creating realistic z-dependent fields
Designing the matching sections
Simulating the experiment with scifi detectors
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Emittance evolution in LHe HCC
Transverse (m-rad)
Longitudinal (m)
6-Dimensional (m3)
Z (m)
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Z (m)
Muons, Inc.
Possible MANX magnet designs
V. Kashikhin et al. MCTFM 7/31/06
•Snake type MANX
•Consists of 4 layers of helix dipole
•Maximum field is ~7 T (coil diameter: 1.0 m)
•Field decays very smoothly
•Hard to adjust the field configuration
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•New MANX
•Consists of 73 single coils (no tilt).
•Maximum field is ~5 T (coil diameter: 0.5 m)
•Field decays roughly
•Flexible field configuration
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Muons, Inc.
That was a very fast survey of some new ideas
H2-Pressurized RF Cavities
Continuous Absorber for Emittance Exchange
Helical Cooling Channel
Parametric-resonance Ionization Cooling
Reverse Emittance Exchange
RF capture, phase rotation, cooling in HP RF Cavities
Bunch coalescing
Z-dependent HCC
MANX 6d Cooling Demo
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Muons, Inc.
Overview
• Several new ideas for high brightness muon beams have rejuvenated the idea of
an energy-frontier muon collider in the nearer future
– several new methods for effective 6D cooling, emittance repartition
• Technology Development
– A High Pressure RF Experiment is underway
• Already shown better high-field behavior, fast conditioning, no dark currents
• beam line tests at Fermilab for final proof of principle in ~1 year
– HTS high-field magnets
• 50 T solenoid?
• The MANX experiment will demonstrate 6D cooling in a HCC
• Magnet designs exist, performance checked with simulations
• Spectrometer design, experimental resolution, significance being studied
• Fermilab is starting to investigate a 1.5 TeV com collider
• Low Emittance Muon Collider workshop for next iterations
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