Context of the Neutrino
Factory
|
|
|
|
Neutrino factory (2018) |
|
4MW proton driver |
|
p+ ŕ p+ ŕ m+ ŕ e+nenm |
|
Linear e+e−
collider (2014/5) |
|
Leptons at 0.4 to 1TeV |
|
Muon collider (2023) |
|
p+ ŕ p+,p− ŕ m+,m− ŕ |
|
Multi-TeV lepton collision |
|
and others… |
Pion Capture and Muon
Front-End
Muon1 Particle Tracking
Code
|
|
|
|
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) |
|
|
Decay Channel Lattice
|
|
|
|
12 parameters |
|
Solenoids alternated in field strength
and narrowed according to a pattern |
|
137 parameters |
|
Varied everything individually |
Improved Transmission
|
|
|
|
|
Decay channel: |
|
Original design: 3.1% m+ out
per p+ from rod |
|
12-parameter optimisation ŕ 6.5% m+/p+ |
|
1.88% through chicane |
|
137 parameters ŕ 9.6% m+/p+ |
|
2.24% through chicane |
|
Re-optimised for chicane transmission: |
|
Original design got 1.13% |
|
12 parameters ŕ 1.93% |
|
137 parameters ŕ 2.41% |
Optimised Design for the
Decay Channel (137 parameters)
Optimiser Architecture
|
|
|
|
|
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 |
|
>75`000 results sent in |
|
Periodically exchange sample results
file |
Why did it make all the
solenoid fields have the same sign?
|
|
|
Original design had alternating (FODO)
solenoids |
|
Optimiser independently chose a FOFO
lattice |
|
Has to do with the stability of
off-energy particles |
Design Optimised for
Transmission Through Chicane
|
|
|
Nontrivial optimum found |
|
Preferred length? |
|
Narrowing can only be due to nonlinear
end-fields |
Recent Work on Losses
|
|
|
|
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 |
New Design with Muon
Cooling
|
|
|
|
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? |
|
|