Laboratory realization of relativistic pair-plasma beams

Area of Science:

• Plasma Physics
• Astrophysics
• Particle Physics

Background:

• Relativistic electron-positron plasmas are crucial in astrophysical phenomena like black hole magnetospheres and pulsar winds.
• Understanding these plasmas is limited by the difficulty in producing high-yield, quasi-neutral positron beams experimentally.
• The matter-antimatter symmetry of electron-positron plasmas leads to unique behaviors compared to electron-ion plasmas.

Purpose of the Study:

• To experimentally confirm the generation of high-density, quasi-neutral, relativistic electron-positron pair beams.
• To enable direct investigation of pair plasma microphysics in previously inaccessible regimes.
• To bridge the gap between theoretical models and experimental observations of these extreme astrophysical plasmas.

Main Methods:

• Utilized the 440 GeV/c beam at CERN's Super Proton Synchrotron (SPS) accelerator.
• Generated and characterized relativistic electron-positron pair beams.
• Employed Monte Carlo simulations to validate experimental data and analyze plasma properties.

Main Results:

• Successfully generated high-density, quasi-neutral, relativistic electron-positron pair beams.
• Experimental data aligned well with Monte Carlo simulations.
• Confirmed that the produced pair beams exceed characteristic scales (Debye length, collisionless skin depth) required for collective plasma behavior.

Conclusions:

• This experiment marks the first successful generation of relativistic electron-positron pair beams.
• The results open new avenues for studying pair plasma microphysics beyond quasi-linear evolution.
• Enables experimental probing of conditions relevant to astrophysical jets and pulsar winds.