Stephen Brooks

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Neutrino Factory Muon Beam Production Studies
m
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Confusing Acronyms

• I am a DPhil student1 with Oxford Particle
  Physics and part of the JAI
• I actually work at RAL (a site of CCLRC) in the
  ASTeC Intense Beams Group
• Nationally, my research contributes to the UKNF
  project2 (funded by PPARC)
• Specifically, WP1 Conceptual Design3
• Internationally, this year it contributes to the
  NF Scoping Study (ISS)4
• Specifically, the accelerator study group5
• 1 Supervisor John Cobb, Oxford PP
• 2 Project leader Ken Long, Imperial College
• 3 WP manager Chris Prior, ASTeC IB Group, RAL
• 4 Project leader Peter Dornan, Imperial
  College
• 5 Group coordinator Mike Zisman, LBNL

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Thesis Title

• Muon Capture and Cooling Schemes for the
  Neutrino Factory
• So far Ive concentrated on muon capture

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Problem

• The neutrino factory is (at least) a tertiary
  beam facility
• p on target ? p ? m ? n,ne,m
• Efficient capture of the pions as they decay to
  muons is a critical step
• Resultant beam must obey constraints
  longitudinally (DE, bunch length) and
  transversely (emittance lt acceptance)

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Research Activity (so far)

• Simulations of pion production in target
• Optimal proton energy (or energies)
• Target material choice
• Tracking of particles up to cooling
• Finding the most efficient capture system
• Comparison, optimisation of schemes
• Also defining what we want from the target
• Cooling modelling preparation

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UKNF Muon Front End
RF phase rotation (reduces energy spread)
Solenoidal decay channel
Target difficult engineering challenge in
itself, covered by UKNF WP2
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Target Simulations
Pions

• Particle production setup
• Used MARS15 code
• Scanned possible proton energies
• Four materials studied so far
• Ta (solid), Hg (liquid jet), C (granular?), Cu
• ? NF International Scoping Study (ISS) also
  GEANT4 benchmarking by K. Walaron

Protons
1cm
Cylinder of material
20cm for Ta 66cm for C
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Target Results
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Particle Tracking Features

• Starts with MARS15 output
• Cannot use paraxial approximation, so 3D
• Nonlinear dynamics e.g. spherical aberration
• (Somewhat) realistic geometry, obstructions
• Includes p ? m and muon, kaon decays
• Supports lattice optimisation ranges
• Novel multi-parameter approach
• Genetic algorithm

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Simulation

• Challenge high emittance of target pions
• Here they come from a 20cm tantalum rod

Evolution of pions from 2.2GeV proton beam on
tantalum rod target
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Optimisation Network

• Internet-based computer grid being used
• 20 million simulations run, 100s of users
• Several lattice-ranges submitted

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Muon Cooling

• G.H. Rees at RAL conceptually designed a cooling
  dogbone lattice
• Future use for tracking/optimising code
• Will compare with John Cobb using ICOOL
• Must include energy absorbers (material)
• At Oxford, the ELMS study has computed the real
  muon cross-sections needed
• Ive studied how to integrate this with my code
• Wade Allison, Simon Holmes speciality (next!)

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Alternative Design
Chicane phase rotation decreases the bunch length
Over 80 caught in linac bucket