Rol - July 21, 2009 Rol - July 21, 2009 NuFact09 NuFact09 1 Muon Cooling for a Neutrino Factory Rolland P. Johnson Muons, Inc. (http://www.muonsinc.com/ ) More muon cooling in NF designs would improve synergy between NF and MC R&D. Present designs of MC front-ends would fill NF storage rings very well. 6D muon cooling progress has been encouraging. It may well be ready for prime time when a NF is to be built. Muons, Inc.
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Rol - July 21, 2009Rol - July 21, 2009 NuFact09NuFact09 11
Muon Cooling for a Neutrino Factory
Rolland P. JohnsonMuons, Inc. (http://www.muonsinc.com/)
More muon cooling in NF designs would improve synergy between NF and MC R&D.
Present designs of MC front-ends would fill NF storage rings very well.
6D muon cooling progress has been encouraging. It may well be ready for prime time when a NF is to be built.
Rol - July 21, 2009Rol - July 21, 2009 NuFact09NuFact09 22
Muons, Inc. Scenario for:Muons, Inc. Scenario for:High-Energy High-Luminosity High-Energy High-Luminosity
Muon CollidersMuon Colliders precision lepton machines at the energy frontierprecision lepton machines at the energy frontier achieved in physics-motivated stages that require achieved in physics-motivated stages that require
developing inventions and technology, e.g.developing inventions and technology, e.g.• intense proton driver (CW Linac, H- Source, Laser Stripping) intense proton driver (CW Linac, H- Source, Laser Stripping) • stopping muon beams (HCC, EEX w Homogeneous absorber)stopping muon beams (HCC, EEX w Homogeneous absorber)• neutrino factory (HCC with HPRF, RLA in CW Proj-X)neutrino factory (HCC with HPRF, RLA in CW Proj-X)• Z’ factory (low Luminosity collider, HE RLA)Z’ factory (low Luminosity collider, HE RLA)• Higgs factory (extreme cooling, low beta, super-detectors)Higgs factory (extreme cooling, low beta, super-detectors)• Energy-frontier muon collider (more cooling, lower beta)Energy-frontier muon collider (more cooling, lower beta)
Muons, Inc.
LEMC ScenarioLEMC Scenario
Rol - July 21, 2009Rol - July 21, 2009 NuFact09NuFact09 33
Muons, Inc.
Bogacz DogbonesScheme
NF from MC front endNF from MC front endWhile many aspects of MC and NF R&D are shared, muon beam cooling is While many aspects of MC and NF R&D are shared, muon beam cooling is
an exception. an exception.
In the present ISS NF scheme, relatively little transverse and no In the present ISS NF scheme, relatively little transverse and no longitudinal muon cooling is required, while longitudinal muon cooling is required, while
MC plans require at least 6 orders of magnitude 6-D cooling. MC plans require at least 6 orders of magnitude 6-D cooling.
MC front-ends (p-driver, target, collection, cooling, acceleration to 30 MC front-ends (p-driver, target, collection, cooling, acceleration to 30 GeV) are well-suited to fill a NF storage ring, with good duty factor and GeV) are well-suited to fill a NF storage ring, with good duty factor and high intensity. high intensity.
The smaller emittance due to muon cooling can reduce the cost and The smaller emittance due to muon cooling can reduce the cost and difficulty of the RF and magnet systems of the NF. difficulty of the RF and magnet systems of the NF.
The incorporation of more cooling into NF designs can lead to better The incorporation of more cooling into NF designs can lead to better cooperation and faster progress for both machines. cooperation and faster progress for both machines.
A CW 8-GeV proton driver could provide sufficient beam power to do both A CW 8-GeV proton driver could provide sufficient beam power to do both simultaneously. simultaneously.
Recent muon cooling progress is very encouraging. Yonehara slides from Recent muon cooling progress is very encouraging. Yonehara slides from LEMC09 follow:LEMC09 follow:
Rol - July 21, 2009Rol - July 21, 2009 NuFact09NuFact09 44
Muons, Inc.
Progress of Helical Cooling Channel Design
K. YoneharaAPC, Fermilab
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 1
Work on HCC project• Test high pressure RF cavity• Study RF incorporating into helical magnet• Improve cooling performance
– Cooling factor & Transmission efficiency
• Phase space matching• Design 6D cooling demo experiment
A. Tollestrup, M. Chung
M. Lopez,M. Popovic
R. Abram,S. Kahn
Speakers in this workshop
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 2
Optimization of HCC
• In past, mainly optimized helical magnet– Adjust dispersion function
• Cooling decrements• Momentum slip factor
• In present, take into account RF parameters– Increase longitudinal acceptance
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 3
Clue: How to tune RF parameter• HCC has sufficient size of transverse phase space acceptance• HCC acceptance is limited by longitudinal phase space
Increase longitudinal acceptance by increasing RF bucket
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 4
RF bucket dependence
E = 31.4343 MV/m, ψ=160˚, Lrf = 100 mmE = 16.0 MV/m, ψ=140˚, Lrf = 50 mm
• A 400 MHz HCC may be sufficient to accept the beam phase space after conventional frontend channel• If Luminosity estimation is correct we can reach 1034 even only HCC section (but reverse emittance exchange is still needed)
Average momentum = 0.25 GeV/cGH2 pressure = 200 atm @ room tempDispersion factor = = 1.83Length of each channel = 100 m
RF cellRF length will be double to save RF powerFor instance, 400 MHz HCC, Lrf = 200 mm, Erf = 40 MV/m
HCC field can be produced withcorrection magnets (although itis not a final design)
LEMC’09 @ Fermilab, K. Yonehara 9
Muons, Inc.
High Pressure RF for HCC
HPRF can be operated in strong magnetic fieldsWe do not know how HPRF works under high rad conditionDopant gas will reduce electron density in the cavity
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 10
HPRF simulation
LEMC’09 @ Fermilab, K. Yonehara 11
Muons, Inc.
RF system in HCC
Traveling wave RF systemLrf = 50 mm, 400 MHz helical RFRequired RF power is ~2.5 GW/m!!The reason is that it has a couplinghole only at the center of cell window
By putting a magnetic coupling holes on side of cell, required power is SIGNIFICANTLY reduced down to ~40 MW/mField quality is also good (but it has a thinmetallic window)
First design Second design
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 12
Wedge shape RF system
L. Thorndahl tried further challenge!He designs a wedge shape RF systemAdvantage: Reduce peak E field Probably, reduce number of cellsChallenge: Asymmetric field distribution
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 13
Dielectric loaded RFCu/Steel
ceramics
Vaccum/H/He
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 14
Possible way to put RF power
RF powercoupling port
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 15
Next-to-do
• More tuning up• Design matching section• Study RF power issue• Push high pressurizing RF cavity test harder• Propose dielectric loaded RF test• Mechanical design of HCC
Muons, Inc.
LEMC’09 @ Fermilab, K. Yonehara 16
Conclusion• A 400 MHz HCC can be a first cooling• Achieve luminosity 1034 even without extra
cooling channel – but emittance exchange is still needed
• High pressure RF with dopant gas seems ok• HPRF with beam is crucial• Need to study RF power issue• Dielectric loaded RF test