1. Jeffrey Eldred, Sasha Valishev AAC Workshop 2016
Integrable RCS as a proposed replacement for Fermilab Booster
Jeffrey Eldred,
Sasha Valishev
AAC Workshop 2016 1 1 1 1

2. Integrable Optics 2 2 2 2

3. Integrable Optics for High Intensity
Integrable optics provides a way to provide strong nonlinear focusing while avoiding parametric resonances.
Application to high-intensity proton beams:
Laslett betatron tune spread can cross resonances.
Landau damping mitigates collective effects.
Increase beam intensity be a factor of 4-6.
Integrable optics as part of a comprehensive proposal to replace the Fermilab Booster with an RCS. 3 3

4. Integrable Optics safdsf
Integrable optics avoids parametric resonances.
Integrable optics nonlinearity provides Landau damping
safdsf
From S. Nagaitsev 4 4

5. FAST/IOTA Facility FAST: Fermilab Accelerator Science and Technology
150 MeV electron superconducting Linac, serves as R&D for ILC
2.7 MeV proton RFQ
IOTA ring for physics experiments
IOTA: Integrable Optics Test Accelerator 5 5

6. Fermilab High Intensity
Proton Program 6 6 6 6

7. 7 7 7 7 7 7

8. Proton Improvement Plan II (PIP-II)
New 800 MeV SRF Linac
Proton power at 120 GeV to increase from 700kW to 1.2MW in year 2019.
Laslett Tune-shift
from PIP-II 8 8

9. LBNF/DUNE Era at Fermilab
“Long Baseline Neutrino Facility” (LBNF)
beamline to produce neutrinos for the
“Deep Underground Neutrino Experiment” (DUNE).
P5 Report: “Form a new international collaboration to design and execute a highly capable LBNF hosted by the US. […] LBNF is the highest priority project in its lifetime.”
from DUNE CDR 9 9

10. DUNE Neutrino Exposure Req.
P5 Report: “[...] , we set as the goal a mean sensitivity to CP violation of better than 3σ [...] over more than 75% of the range of possible values of the unknown CP-violating phase δCP”
Corresponds to 900 kt MW yr.
Keep PIP-II Proton Power:
1.2MW, 50kt -> 15 years
Upgrade Proton Power:
5MW, 20kt -> 9 years
from DUNE CDR 10 10

11. Limitations of Fermilab Booster
Fermilab Booster is over 45 years old!
Reliability concerns.
RF cavities will not sustain a ramp rate beyond 20 Hz.
Impedance problem at Transition Energy:
No beampipe in magnets, impedance problem.
~200kV deceleration during transition crossing.
Booster beam is slip-stacking in the Fermilab Recycler which may not be possible at higher intensity.
Slip-stacking is an accumulation technique which doubles the number of Booster batches that can be stored in the Main Injector. 11 11

12. Siting for Booster Replacement12
Siting for Booster Replacement
Image credit Steve Dixon 12 12 12 12 12

13. Integrable RCS Design 13 13 13 13

14. RCS Lattice Requirements
Standard Requirements:
Bounded beta functions.
Chromaticity correction.
Modern RCS Design:
No transition crossing.
Long dispersion-free drifts.
Separate function magnets.
Integrable optics
Removes parametric resonances, provides Landau damping
Beam intensity may increase by a factor of 4-6. 14 14

15. Lattice Requirements for IO
Integrable lattices are composed of:
Arcs with pi-integer betatron phase-advance.
Dispersion-free drifts, with horizontal and vertical beta functions matched.
Special nonlinear octupole magnets in those drifts.
The horizontal and vertical chromaticity should match.
From S. Nagaitsev 15 15

16. iRCS Example Lattice 16 16

17. 17 17

18. Other Considerations
Drift space provides ample sufficient space for 1.2 MV and 20Hz ramp rate. Room to upgrade in the future.
Switch from parallel-biased ferrite cavities to perpendicular-biased ferrite cavities
Active R&D effort on perpendicular-biased Yttrium-Iron-Garnet cavities.
Resonant-circuit sinusoidal magnet ramp
Longitudinal emittance after capture of 0.08 eVs
Requires a 1-2ms fill time from a 5mA linac.
Requires adiabatic capture or aggressive chopping.
Harmonic cavity could be used to further control emittance. 18 18

19. Future Work on iRCS Design
General High-Intensity RCS Research
Harmonic cancellation of sextupoles.
H- stripping and chicane design.
Target design for 2-5 MW beams.
High-Intensity Integrable Optics
Synergia simulation with both space-charge forces and integrable optics.
Transverse phase-space painting scheme.
Lattice optimization incorporated with Synergia simulation. 19 19

20. Thank you! 20 20 20 20

21. Traditional Approach: Transverse Focusing
Four degrees of freedom:
x, x’, y, y’
Betatron Oscillations: 21 21

22. The Problem is Parametric Resonances
octupole
If the betatron frequency is a rational multiple of the revolution frequency, there is a parametric resonance.
The orbit errors accumulate over many revolutions and lead to particle loss. 22 22

23. Tune Diagram
The betatron tunes are carefully picked to avoid parametric resonances.
As the beam intensity increases, the betatron tune spread increases and losses become unavoidable. 23 23

24. Nonlinear Magnet 24 24

25. Novel Features of IOTA: Nonlinear Magnets for Integrable Optics
Electron Lens for space-charge compensation
Optical Stochastic Cooling 25