ACCELERATOR PHYSICS

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ACCELERATOR PHYSICS AT NORTHERN ILLINOIS
UNIVERSITY Courtlandt L. Bohn Northern Illinois
University Department of Physics (as of 15
August 2005)
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Proximity to Two Major Laboratories
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Aerial View of University (location DeKalb,
Illinois)
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Faraday Hall Home of Physics Department
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Beam Physics and Astrophysics Group Main
Interests

• Production of high-brightness beams (electron,
  hadron)
• High-resolution electron-beam diagnostics
• interferometry (transition radiation)
• electro-optic sampling (electromagnetic fields)
• Theory and simulation of space charge
• chaos in time-dependent systems
• mixing in N-body systems (beams, galaxies)
• multiresolution analysis (wavelet-based
  algorithms)

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Beam Physics and Astrophysics Group People

• Faculty Court Bohn, Bela Erdelyi, Philippe
  Piot
• Postdocs Daniel Mihalcea, Ioannis Sideris,
  Balša Terzic
• Graduate Students Greg Betzel, Marwan Rihaoui,
  Ily Vass
• Many collaborators
• For more information, see http//nicadd.niu.edu/re
  search/beams

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Beam Physics and Astrophysics Group Beowulf PC
Cluster

• 56 dual-processor nodes linked via 100 Mbit
  network
• Server 1GB RAM, 2x Athlon 2600, shared 1.5TB
  raid array
• Worker nodes 1GB RAM/node, Amd Opteron 1800
  (2x15 nodes), Amd Atlon 2400(2x24),
  1800(2x16), shared disk space 4.5TB
• Software
• PV-WAVE (visualization, data analysis)
• ROOT (analysis of large data bases),
• LAM (enables parallel processing)
• CONDOR (managing batch jobs)

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Beowulf PC Cluster
56 nodes ? 112 CPUs in a climate-controlled room
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Status Funding is in hand to build the Lab
equipment is on order Plans Electron gun
(borrowed from Argonne) Titanium-Sapphire
femtosec-class laser (to be purchased) UHV
preparation capability State-of-the-art
electronics and controls
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Context of Accelerator Physics Program

• Electron photoinjectors and linacs for
• Linear Collider (Fermilab)
• X-ray FEL (Argonne)
• high-average-power FEL (Argonne, Jefferson Lab)
• Hadron linear accelerators for
• isotope production (Argonne, Fermilab?)
• neutrino physics (Fermilab)
• Proton booster synchrotron with high current
  for
• neutrino physics (Fermilab)

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Overview of Experiments and Hardware Development
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Longitudinal Density Profile via Interferometry
of Coherent Transition Radiation
Longitudinal density profile of compressed 3 nC
bunches measured (red) vs. PARMELA with 20,000
particles (blue).
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Electro-Optical Sampling
Proof-of-principle experiment (and Univ. of
Rochester Ph.D. dissertation for M. Fitch)
Measured beam-induced wakefield of 6-way
cross. Goal for future work Measure beam field
directly (not wakefield) to infer the beam
density profile. A key need low-impedance
vacuum chamber. Ultimate objective Noninvasive
bunch monitor
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Overview of Theory Program (more information can
be found in Group publications)
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NONEQUILIBRIUM BEAM A CARTOON
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Transient Chaos in a Breathing Bunch
log10f(t) vs. t
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Impact of Unavoidable Noise on Halo
???? 10-3
???? 10-3
Breathing mode Internal mode
(oscillating envelope) (stationary
envelope) Both the topology of the mode(s) and
the strength of the noise are important to halo
formation.
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Wavelets
1D
2D

• Haar wavelet, (b) Morlet wavelet,
• (c) Daubechies wavelet.

Daubechies least symmetric N 10 two-dimensional
wavelet.
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Fermilab/NICADD Photoinjector Simulations
rms beam radius (mm)
rms normalized transverse emittance (µm)
rms bunch length (mm)
rms normalized longitudinal emittance (ps-keV)
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Simulations of AES/JLab Photoinjector
Green Function Fast Fourier Transform
Wavelets Preconditioning
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Summary

• Northern Illinois University is serious about
  accelerator physics
• Focus is basic research, especially as
  concerns
• Production, measurement of high-brightness beams
• Fundamental understanding of space-charge
  dynamics
• Improved simulation codes to include multiscales,
  halo
• In-house facilities are in place for theory,
  computations, and small-scale laboratory work
• Many collaborations are in place, including
  with Fermilab and Argonne
• We seek excellent students who are likewise
  serious!

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Announcement

• We plan shortly to establish a special
  fellowship
• The
• NICADD Fellowship in Accelerator Physics
• Very competitive for especially gifted
  students
• At most 2 recipients per year
• Annual stipend of 30,000
• Full tuition waiver