Antimatter

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Antimatter
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Congratulations and Thanks Ron!

• Plasma Fusion Center, MIT

• Physics of Plasmas

• 95 Plasma Study

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New Tools for Antimatter Studies -Positron
Plasmas and Trap-Based Beams
Cliff Surko
James Danielson Toby Weber Tom ONeil Mike
Anderson
Supported by NSF, DOE/NSF Partnership
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Antimatter in our world of Matter
Plasma Physics- enabling the study and use
low-energy antimatter
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The real reason we are making antihydrogen...
But the real reason were making antimatter
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Why Trap and Cool Antimatter?

• Isolate interactions with matter
• - Atomic/molecular physics
• - Laboratory astrophysics
• Density dependent processes
• - Pulsed, bright beams
• (e.g., plasma diagnostics, materials
  analysis)
• - Antihydrogen production
• - Electron-positron plasmas
• - BEC positronium

e
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A Near-Perfect Antimatter Bottle The
Penning-Malmberg Trap
E x B plasma rotation fE cne/B
John Malmberg

• Angular Momentum
• No torques Lz is constant No
  expansion!

(Malmberg deGrassie 75 ONeil 80)
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Buffer-Gas Positron Trap
? Trap using a N2-CF4 gas mixture ?
Positrons cool to 300K (25meV) in 0.1s
30 trapping efficiency
Surko PRL 88 Murphy, PR 92
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Buffer-gas Accumulator
Positron plasma
Gas in
1.8 m
Positrons in (flux 1 pA)
Cryopumps
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Trapping Antimatter Goals Long-term
storage High capacity Cold, dense
plasmas Portable antimatter traps Considerations
Space charge 10 kV ? 1011 e/cm
Confinement at high plasma densities? Cooling
tcool 0.2 s _at_ 5 tesla
cylindrical plasma
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Overview of Positron Trapping
Improved trap
trapped positrons
Stacking ATHENA
Solid neon moderator
Computerized optimization
Improve B-field
Improve vacuum
Year
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New Tools for Antimatter Physics

• Increase positron storage capacity
• Plasma compression for lifetime and
• density control
• Extraction of finely focused beams

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Multicell Trap for Large Ntot Many beaded
rods in parallel
Design Parameters

• B 5T
• n 3x1010 cm-3
• Lp 5 cm
• Rp 0.14 cm
• T 2 eV
• Ntot 1010 (1 cell)
• fc 1 kV

B
L
Side View
Lp
Positron Plasma
2Rp
Total number of cells 100 Ntot 1012
RF Electrodes
DC Electrode
Surko and Greaves, Radiation Physics and
Chemistry (2003)
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Multicell Positron Trap Electrodes
master cell
2 banks of 19 storage cells
Danielson, Phys. Plasmas (2006)
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D/Rw 0.8
fD fDo1 - (D/Rw)2-1
Danielson, Phys. Plasmas (2006)
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Rotating-Wall Compression of Positron Plasmas
Applications - infinite confinement times -
increase plasma density - create bright
antiparticle beams

• Compress radially using a rotating electric
  field.
• Good coupling over broad range of frequencies.

(Huang, et al., Anderegg, et al., Hollmann, et
al., 95 - 00)
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Transition/bifurcation
_________________________________________________
electron plasma
Danielson PRL (05) Phys. Pl. (06)
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(No Transcript)
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Zero-Frequency-Mode (ZFM) Drag is Key to the
Dynamics Dependence on fRW
Danielson, ONeil, Surko, PRL, submitted
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RW Compression in the Strong Drive Regime

• Good physical model of transitions,
• upper and lower fixed points.
• Now explore limits, high densities
• and low temperatures for applications

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Brightness Enhancement Using Traps

• Rotating wall compressed plasma
• Slow release creates beam narrower than plasma
• RW and inward transport fill hole created by
  positron release

Danielson, APL (2007)
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Beam Extraction
Plasma
(10 ms pulses)
electron plasma
Small-beam limit
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(No Transcript)
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Whats Next - Some Near-term Goals

• Explore the density limits of RW compression
• Create a 1 meV positron beam
• Develop a multicell trap

Long-term challenge a portable antimatter trap
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For references see http//positrons.ucsd
.edu/