1
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- Neutrino factory (2018)
- 4MW proton driver
- p+ ŕ p+
ŕ m+ ŕ e+nenm
- Linear e+e− collider (2014/5)
- Muon collider (2023)
- p+ ŕ p+,p−
ŕ m+,m−
ŕ
- Multi-TeV lepton collision
- and others…
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2
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3
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- Nonlinear 3-dimensional simulation
- PARMILA was being used before
- Uses realistic initial p+ distribution
- Monté-Carlo simulation by Paul Drumm
- Particle decays with momentum kicks
- Solenoid end-fields included
- OPERA-3d field maps used for FFAG-like magnets in chicane (Mike Harold)
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4
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- 12 parameters
- Solenoids alternated in field strength and narrowed according to a
pattern
- 137 parameters
- Varied everything individually
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5
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- Decay channel:
- Original design: 3.1% m+ out per p+ from rod
- 12-parameter optimisation ŕ 6.5% m+/p+
- 137 parameters ŕ 9.6% m+/p+
- Re-optimised for chicane transmission:
- Original design got 1.13%
- 12 parameters ŕ 1.93%
- 137 parameters ŕ 2.41%
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6
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7
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- How do you optimise in 137-dimensional space?
- Hard to calculate gradient due to stochastic noise
- Use genetic algorithm
- Random designs
- Mutation
- Interpolation
- Crossover
- How do you run 3`700`000 simulations?
- Distributed computing
- Internet-based / FTP
- ~130 users active in last week
- Periodically exchange sample results file
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8
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- Original design had alternating (FODO) solenoids
- Optimiser independently chose a FOFO lattice
- Has to do with the stability of off-energy particles
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9
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- Nontrivial optimum found
- Preferred length?
- Narrowing can only be due to nonlinear end-fields
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10
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- Muon1 modified to count lost particle energies
- For a 4MW p+ beam:
- 35kW deposited in S1 (r=10cm)
- Large >1kW amounts deposited up to S5
- Added “collimators” to the simulation
- Decreases losses to 10’s of watts in all but S1 and S2
- S1 needs enlarging to accommodate an entire Larmor rotation
- Consistent target-area layout is needed
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11
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- Decay channel (as before)
- 31.4MHz RF phase rotation
- Reduces energy spread from 190±70 to ±23MeV
- Cooling ring (20 turns)
- Uses H2(l) or graphite absorbers
- Cooling in all 3 planes
- 16% emittance loss per turn?
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