Helical muon beam cooling channel engineering design

Technical Report · Fri Aug 07 04:00:00 EDT 2015

DOI:https://doi.org/10.2172/1266464· OSTI ID:1266464

Johnson, Rolland ^[1]

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1. Muons, Inc., Batavia, IL (United States); Muons, Inc.

The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet. The first phase of this project saw the development of a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb₃Sn-based HS test section. Two very novel ideas are required to realize the design. The first idea is the use of dielectric inserts in the RF cavities to make them smaller for a given frequency so that the cavities and associated plumbing easily fit inside the magnet cryostat. Calculations indicate that heat loads will be tolerable, while RF breakdown of the dielectric inserts will be suppressed by the pressurized hydrogen gas. The second new idea is the use of a multi-layer Nb₃Sn helical solenoid. The technology demonstrations for the two aforementioned key components of a 10T, 805 MHz HCC were begun in this project. The work load in the Fermilab Technical Division made it difficult to test a multi-layer Nb₃Sn solenoid as originally planned. Instead, a complementary project was approved by the DOE Technical Topic Manager to develop magnets for the Mu2e experiment that fit well into the Fermilab Technical Division availability. The difference between the MCC helical solenoid and the Mu2e bent solenoid described in Appendix I is that the helical solenoid is made of coils that are in parallel planes with offset centers, while the coils in the bent solenoid follow the central particle trajectory and look much like a “slinky” toy. The muon-beam cooling-channel technologies developed in this project will enable a muon collider, the next step toward the energy frontier, Higgs/neutrino/Z-factories, and rare muon decay experiments. Commercial uses of the beams made possible by the cooling techniques developed in this project include scanning for nuclear contraband, studies of material properties with spin resonance techniques, and muon-catalyzed fusion.

• Research Organization: Muons, Inc., Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Contributing Organization: Fermi National Accelerator Laboratory, Batavia, IL (United States)
• DOE Contract Number: SC0006266
• OSTI ID: 1266464
• Report Number(s): DOE-Muons--6266; FRA-2012-0001
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM COOLING
BEAM EMITTANCE
BREAKDOWN
CONSTRUCTION
DESIGN
DIELECTRIC MATERIALS
DIPOLES
HEATING LOAD
HYDROGEN
IMPLEMENTATION
INTERMETALLIC COMPOUNDS
IONIZATION
LAYERS
LENGTH
MAGNETIC FIELDS
MAGNETRONS
MHZ RANGE 100-1000
MUON BEAMS
Muon
NIOBIUM BASE ALLOYS
QUADRUPOLES
SOLENOIDS
SUPERCONDUCTING CAVITY RESONATORS
SUPERCONDUCTING MAGNETS
TIN ALLOYS
beam
dielectric-loaded
helical
ionization cooling
magnet
pressurized
rf cavities
superconducting