Muon Cooling
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MOWAUD03 Overview of Muon Cooling 1
 
  • D.M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: DOE
Muon cooling techniques are surveyed, along with a concise overview of relevant recent R&D. 		 
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MOZAUD02
 Overview of Muon Colliders  
 
  • R.B. Palmer
    BNL, Upton, Long Island, New York, USA
  
  Placeholder  
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MOPF01
 Final Cooling for a High Energy High Luminosity Collider  
 
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  • T.L. Hart, D.J. Summers
    UMiss, University, Mississippi, USA
  
  The final cooling system for a high-energy high-luminosity muon collider requires reduction of the transverse emittance by an order of magnitude to ~0.00003 m (rms, N), while allowing longitudinal emittance increase to ~0.1m. In an initial approach, this is obtained by transverse cooling of low-energy muons within a sequence of high field solenoids with low-frequency rf systems. Since the final cooling steps are actually emittance exchange, much of this transformation can be obtained by thick wedge absorbers at matched parameters. Other variations using quad-based cooling channels, transverse beam slicing and round to flat transforms can be used. in x-y, with transverse slicing and longitudinal recombination are discussed. Development of lowest emittance cooling with final exchange is discussed.  
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MOPF07 Final Muon Ionization Cooling Channel using Quadrupole Doublets for Strong Focusing 43
 
  • J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, D.J. Summers
    UMiss, University, Mississippi, USA
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  
  Considerable progress has been made in the design of muon ionization cooling for a collider. A 6D normalized emittance of 0.123 cubic mm has been achieved in simulation, almost a factor of a million in cooling. However, the 6D emittance required by a high luminosity muon collider is 0.044 cubic mm. We explore a final cooling channel composed of quadrupole doublets limited to 14 Tesla. Flat beams formed by a skew quadrupole triplet are used. The low beta regions, as low as 5 mm, produced by the strong focusing quadrupoles are occupied by dense, low Z absorbers that cool the beam. Work is in progress to keep muons with different path lengths in phase with the RF located between cells and to modestly enlarge quadrupole admittance. Calculations and individual cell simulations indicate that the final cooling needed may be possible. Full simulations are in progress. After cooling, emittance exchange in vacuum reduces the transverse emittance to 25 microns and lets the longitudinal emittance grow to 70 mm as needed by a collider. Septa slices a bunch into 17 parts. RF deflector cavities, as used in CLIC tests, form a 3.7 meter long bunch train. Snap bunch coalescence combines the 17 bunches into one in a 21 GeV ring in 55 microseconds.  
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TUWAUD01 Status, Recent Results and Prospect of the International Muon Ionization Cooling Experiment (MICE) 67
 
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  Muon accelerators have been proposed as a means to produce intense, high energy muon beams for particle physics. Designs call for beam cooling to provide suitable beams. Existing cooling schemes cannot operate on time scales that are competitive with the muon lifetime. Ionisation cooling has been proposed as a means to achieve sufficient cooling, but it has never been demonstrated practically. In the Muon Ionisation Cooling Experiment (MICE), based at the Rutherford Appleton Laboratory, ionisation cooling will be demonstrated. MICE Step IV is currently in progress and will be completed in 2016. Muons are brought onto an absorber, resulting in a reduction of momentum and hence reduction of normalised transverse emittance. The full Demonstration of Ionisation Cooling will take place in 2017. An extra magnet module and RF cavities will be installed, as in a cell of a cooling channel. This will enable demonstration of reduction of emittance and subsequent re-acceleration, both critical components for a realistic ionisation cooling channel.  
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TUWAUD02
 Affordable, Scalable, and Convincing 6-d Muon Cooling Demonstrations  
 
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  • S.A. Bogacz, Y.S. Derbenev, V.S. Morozov, A.V. Sy
    JLab, Newport News, Virginia, USA
  • K. Yonehara
    Fermilab, Batavia, Illinois, USA
  
  The number of applications that could benefit from effective, affordable muon cooling include stopping muon beams for rare decay searches and spin resonance, intermediate energy beams for neutrino factories and cargo scanning, and muon colliders for HIggs factories and the energy frontier. The simple ionization cooling equation implies that if you have a low-Z energy absorber in a strong magnetic field, sufficient RF to contain the beam and replace the lost energy, and some mechanism for emittance exchange, you can achieve low 6-d emittance down to the limit implied by multiple scattering. The first cooling simulations that were based on a ring were exciting and encouraging. Unfortunately, injection difficulties, beam loading of RF cavities and energy absorbers, and the need to modify cooling parameters as the beam cools have led us away from a ring towards a cooling channel. An effective demonstration experiment must show that the final muon beam parameters to achieve the required luminosity can be achieved at an acceptable cost. We discuss the possibility that a demonstration experiment is a section of a practical, high performance cooling channel.  
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TUWAUD03 Study of Helical Cooling Channel for Intense Muon Source 72
 
  • K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • Y.S. Derbenev
    JLab, Newport News, Virginia, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Linear beam dynamics of muons in a helical cooling channel is non-trivial. Betatron oscillation in the channel is induced by coupling of motions in xyz-planes. As a result, the analytic eigen values are very complicated. The cooling decrements are controlled by tuning coupling strength. The helical dynamic parameters are translated into the conventional accelerator physics term. Non-linear dynamics in the helical channel is studied by using the conventional accelerator technique. The beam-plasma interaction in a high-pressure hydrogen gas-filled RF cavity is a new physics process and important to design the cooling channel. Machine development of helical beam elements is also shown in this presentation.  
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TUWAUD04 Progress on Parametric-resonance Ionization Cooling 77
 
  • V.S. Morozov, Y.S. Derbenev, A.V. Sy
    JLab, Newport News, Virginia, USA
  • A. Afanasev
    GWU, Washington, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  • J.A. Maloney
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: Work supported in part by U.S. DOE STTR Grants DE-SC0005589 and DE-SC0007634. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Proposed next-generation muon collider will require major technical advances to achieve the rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam's angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented. 		 
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TUPF04 The MICE Demonstration of Ionization Cooling 104
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  
  Muon beams of low emittance can provide the intense, well known beams for physics of flavour at the Neutrino Factory and multiTev collisions at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate the technique proposed to reduce the phase­space volume of the muons. In an ionization ­cooling channel, the combination of energy loss by muons traversing an absorbing material with reacceleration by RF cavities reduces the transverse emittance of the beam (transverse cooling). The rebaselined MICE project will deliver a demonstration of ionization cooling by Sep 2017: a central Li­-H absorber, two superconducting focus-coil modules and two 201 MHz single­cavity RF modules. The phase space of the muons entering and leaving the cooling cell will be measured by two solenoidal spectrometers. All the magnets for the ionization-cooling demonstration are available at RAL and the first single­cavity prototype was tested successfully in the MTA Area at Fermilab. The design of the cooling demonstration experiment, a summary of the performance of each of its components and the cooling performance of the configuration will be presented.  
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TUPF06
 The Status of MICE Step IV  
 
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  • V.C. Palladino
    INFN-Napoli, Napoli, Italy
  
  Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams of the Neutrino Factory and for lepton-antilepton collisions at energies of up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling ' the technique by which it is proposed to reduce the μ-beam phase-space volume. MICE is being constructed in a series of steps. At Step IV, MICE will study the properties of liquid hydrogen and lithium hydride that affect cooling. A solenoidal spectrometer will measure emittance up and downstream of the absorber vessel, where a focusing coil will focus muons. The construction of Step IV at RAL is nearing completion. The status of the project will be described together with a summary of the performance of the principal components. Plans for the commissioning and operation and the Step IV measurement programme will be described.  
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THWCR04 RF Technologies for Ionization Cooling Channels 145
 
  • B.T. Freemire, Y. Torun
    IIT, Chicago, Illinois, USA
  • D.L. Bowring, A. Moretti, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • A.V. Kochemirovskiy
    University of Chicago, Chicago, Illinois, USA
  • D. Stratakis
    BNL, Upton, Long Island, New York, USA
  
  Funding: Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359
Ionization cooling is the preferred method of cooling a muon beam for the purposes of a bright muon source. This process works by sending a muon beam through an absorbing material and replacing the lost longitudinal momentum with radio frequency (RF) cavities. To maximize the effect of cooling, a small optical beta function is required at the locations of the absorbers. Strong focusing is therefore required, and as a result normal conducting RF cavities must operate in external magnetic fields on the order of 10 Tesla. Vacuum and high pressure gas filled RF test cells have been studied at the MuCool Test Area at Fermilab. Methods for mitigating breakdown in both test cells, as well as the effect of plasma loading in the gas filled test cell have been investigated. The results of these tests, as well as the current status of the two leading muon cooling channel designs, will be presented. 		 
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THYAUD01
 muCool: Towards a Much Improved Phase Space Slow Positive Muon Beam  
 
  • A. Knecht
    PSI, Villigen PSI, Switzerland
  
  Over the past decades meson production facilities have been providing powerful surface muon beams to experiments with intensities of up to several 108 mu+/s. Due to the production process in dedicated targets and the limited time, the phase space of these beams is generally poor. We are developing a tertiary beamline to decrease the phase space of a mu+ beam by a factor of 1010 with an efficiency of 10−3 . The idea is to stop the MeV muon beam in helium gas at cryogenic temperatures and compress the muon swarm by means of a gas density gradient and electric and magnetic fields in longitudinal and transversal dimensions. This talk will give an outline of the general principles behind the compression mechanism and give an update on the current experimental status.
Talk given on behalf of the muCool collaboration. 		 
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THYAUD02 Front End and HFOFO Snake for a Muon Facility 150
 
  • D.V. Neuffer, Y.I. Alexahin
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Contract No. De-AC02-07CH11359 with the U. S. Department of Energy
A neutrino factory or muon collider requires the capture and cooling of a large number of muons. Scenarios for capture, bunching, phase-energy rotation and initial cooling of muonss produced from a proton source target have been developed for neutrino factory and Muon Collider designs. The baseline scenarios requires a drift section from the target, a bunching section and a phase-energy rotation section leading into the cooling channel. The currently preferred cooling channel design is an 'HFOFO Snake' configuration that cools both μ+ and μ- transversely and longitudinally. The status of the design is presented and variations are discussed. 		 
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THYAUD03
 Rectilinear Channel for Muon Cooling Towards Micron Scale Emittances  
 
  • D. Stratakis
    BNL, Upton, Long Island, New York, USA
  
  Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Generation of bright muon sources requires a reduction of the six-dimensional emittance of the captured muon beam by several orders of magnitude. In this study, we present a new cooling scheme that should meet this requirement. First, we present the conceptual design of our proposed scheme wherein we detail its basic features. Then, we present the first end-to-end simulation of 6D cooling for a Muon Collider and show a notable reduction of the 6D emittance by five orders of magnitude. Finally, we examine the influence of space-charge fields on the cooling process and present a space-charge compensation solution by means of increasing the rf gradient. We establish a quantitative relationship between the required compensation gradient and bunch charge. 		 
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