Acceleration Overview J. Scott Berg Brookhaven National Laboratory January 8, 2014

Acceleration Goals Accelerate rapidly to avoid decays –High average RF gradient: ≈5 MV/m for 70% transmission Control costs and power use –Make many passes through RF –To simultaneously maintain high average RF gradient: high average dipole field Handle large emittance beams January 8,

Energies and Emittances Neutrino Factory Higgs Factory Top Factory 1.5 TeV Collider 3 TeV Collider ≈6 TeV Collider Energy (GeV) ≈3000 Transverse Emittance (µm) –40050–20025 Longitudinal Emittance (mm) 241–1.51.5–1070 January 8,

Beam Properties Wide variety of emittances to accelerate Biggest challenge is the large longitudinal emittance for the higher energy colliders Higgs factory beam is more reasonable size –But still need to accelerate large longitudinal emittance through that energy range Neutrino factory beam has very large transverse emittance –Specific solution for neutrino factory discussed earlier January 8,

Acceleration Scenario Low Energy Induction linac Low-frequency RF Cooling RF Acceleration to 63 GeV Dogbone RLAs Acceleration to ≈375 GeV Fast-Ramping synchrotron Dogbone RLAs Hybrid synchrotrons Acceleration to 750, 1500, 3000 GeV Hybrid synchrotrons January 8,

Accelerator Types: Linac Best for low energies, large beams Large longitudinal emittance –325 MHz SCRF not possible for low energies (until about 700 MeV) Use technologies from final cooling for acceleration (expensive) –Induction linacs: low gradient –Low frequency RF: low gradient –Cooling RF: high gradient, longitudinal acceptance No re-use of RF January 8,

Accelerator Types: RLA Recirculating linear accelerator Multiple passes through RF Large longitudinal acceptances possible Can’t put too many beamlines in switchyard –Large emittance beam –Limits number of passes Dogbone geometry –Maximizes separation for given number of passes –Gives very high average accelerating gradient Start these right after cooling RF January 8,

Accelerator Types: FFAG Fixed field alternating gradient accelerator Single beamline with wide energy range –No switchyard limiting number of passes Trade single beamline with large magnets for many beamlines with smaller magnets in RLA Passes limited by tolerable longitudinal emittance distortion –Worse with large longitudinal emittance –Do not appear to be cost-effective with 70 mm longitudinal emittance January 8,

Accelerator Types: Synchrotron Synchrotron with very fast ramping time –1.5 T maximum fields Low average bend field: low RF efficiency –Pulse times: 63–375 GeV, 200 µs for 5 MV/m –Beam moves in aperture to correct time of flight –Pulse times too short at low energies Hybrid synchrotron –Alternate fixed-field high-field dipoles and low-field bipolar pulsed dipoles to get large average dipole field –More passes through RF, but faster ramp times –Ideal solution at high energies January 8,

Acceleration Scenario Low Energy Induction linac Low-frequency RF Cooling RF Acceleration to 63 GeV Dogbone RLAs Acceleration to ≈375 GeV Fast-Ramping synchrotron Dogbone RLAs Hybrid synchrotrons Acceleration to 750, 1500, 3000 GeV Hybrid synchrotrons January 8,

Acceleration Scenario Linac with cooling technologies to ≈700 MeV RLA to 63 GeV –Compatible with 70 mm longitudinal emittance Acceleration to ≈375 GeV –RLA or non-hybrid synchrotron Appear to have comparable costs Synchrotron could share tunnel with next stage Relatively safe technologies –Hybrid synchrotron (two stages) Appears better for cost/efficiency Short pulse times a challenge (70 µs for 5 MV/m) January 8,

Acceleration Scenario Hybrid synchrotron above ≈375 GeV –Gets easier as energies increase –10 T SC dipoles, 1.5 T ramped dipoles, looks like could accelerate to 3 TeV on Fermilab site January 8,

Design Challenges RLA switchyard layout Injection/extraction Time of flight correction Collective effects Showstoppers unlikely, but cost escalation an issue January 8,

Status NuMAX concept in place Concept for 63 GeV acceleration in place –May need modifications for 70 mm longitudinal emittance Hybrid synchrotron design exists –Needs modification for current magnet parameters –Needs time of flight correction –Should look at chromaticity correction –Needs to be scaled to other energies January 8,

Key Technologies RF –High-gradient SCRF: higher helps efficiency & decays –High gradients for cooling RF systems used for early acceleration Superconducting magnets: higher fields help efficiency and decays Kickers for injection/extraction January 8,

Key Technologies: Pulsed Magnets Workable designs for 1.5 T –1.8 T with grain oriented steel, but Field line pinning makes this sensitive to construction tolerances Not possible to model accurately with existing codes –FeCo could achieve 2.2 T But need shielding solution for Co activation, unlikely Quadrupole design Better understand steel behavior with short pulse times, high fields, thin laminates –Pushing limits on existing measurements –Consequences of short pulse times Power supplies: controlled ramp January 8,

Schedule FY14FY15FY16 NuMAX to ≈1 GeV NuMAX to 5 GeV To 63 GeV MC Initial To 750 GeV To 1500 GeV To ≈3000 GeV Higher Energy Interface to Ring January 8, ConceptLatticeSign-OffInterfaceTechnology Sign-offReview OKInitial ReviewReviewSpecification

Effort & Key Personnel NuMAX Lattice DesignA. BogaczJLab0.2 RLA Lattice DesignA. BogaczJLab0.4 Switchyard Magnet Design0.2 Switchyard Layout0.2 Synchrotron DesignJ. S. BergBNL1.0 Pulsed Quadrupole DesignH. WitteBNL0.2 Pulsed Power Supply0.2 Kicker System0.3 Initial AccelerationR. B. Palmer, H. Sayed, J. S. BergBNL0.4 Tracking/Verification0.7 Collective Effects0.5 Report/Review PreparationJ. S. BergBNL0.3 Report/Review PreparationA. BogaczJLab January 8,