Jun 14 2024Reviewed by Lexie Corner
An international team of scientists, including researchers from the University of Rochester's Laboratory for Laser Energetics, generated high-density relativistic electron-positron pair-plasma beams by creating two to three orders of magnitude more pairs than previously reported. The research was published in the journal Nature Communications.
Artist’s rendering of a black hole emitting a jet of hot gas known as plasma. An international team of scientists, including Rochester researchers, has generated plasma “fireballs” experimentally, opening a new frontier in laboratory astrophysics. Image Credit: (NASA/JPL-Caltech)
Two of the universe's densest known objects are black holes and neutron stars. Alongside solids, liquids, and gases, plasmas are the fourth fundamental state of matter, which exists within and around these extreme astrophysical environments.
Plasmas at these extreme conditions are called relativistic electron-position pair plasmas because they consist of a mixture of electrons and positrons traveling at almost the speed of light.
Although these plasmas are common in deep-space environments, creating them in a lab setting has proven difficult.
The discovery paves the way for additional research that may reveal important details about the functioning of the cosmos.
The laboratory generation of plasma ‘fireballs’ composed of matter, antimatter, and photons is a research goal at the forefront of high-energy-density science, but the experimental difficulty of producing electron-positron pairs in sufficiently high numbers has, to this point, limited our understanding to purely theoretical studies.
Charles Arrowsmith, Physicist and Study Lead Author, University of Oxford
Arrowsmith will join LLE this fall.
The HiRadMat facility at the Super Proton Synchrotron (SPS) accelerator at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is being used to design a novel experiment.
Arrowsmith and other scientists worked with LLE researchers Dustin Froula, the Division Director for Plasma and Ultrafast Laser Science and Engineering, and Daniel Haberberger, a Staff Scientist at LLE and Rochester.
That experiment used over 100 billion protons from the SPS accelerator to produce very high yields of quasi-neutral electron-positron pair beams. The kinetic energy of a single proton is 440 times greater than its resting energy.
Due to its enormous momentum, a proton can smash an atom with enough energy to release its quarks and gluons, which instantly recombine to form a shower that eventually decays into electrons and positrons.
In simpler terms, the beam generated in the lab contained enough particles to exhibit characteristics similar to those of a genuine astrophysical plasma.
Arrowsmith says, “This opens up an entirely new frontier in laboratory astrophysics by making it possible to experimentally probe the microphysics of gamma-ray bursts or blazar jets.”
Additionally, the group has created methods for altering pair beam emittance, which enables controlled investigations of plasma interactions in scaled-down equivalents of astrophysical systems.
Satellite and ground telescopes are not able to see the smallest details of those distant objects and so far we could only rely on numerical simulations. Our laboratory work will enable us to test those predictions obtained from very sophisticated calculations and validate how cosmic fireballs are affected by the tenuous interstellar plasma.
Gianluca Gregori, Professor and Study Co-Author, Department of Physics, University of Oxford
Further, Gregori added, “The achievement highlights the importance of exchange and collaboration between experimental facilities around the world, especially as they break new ground in accessing increasingly extreme physical regimes.”
In addition to LLE, the University of Oxford, and CERN, along with the Science and Technology Facilities Council Rutherford Appleton Laboratory (STFC RAL), the University of Strathclyde, the Atomic Weapons Establishment in the UK, the Lawrence Livermore National Laboratory, the Max Planck Institute for Nuclear Physics, the University of Iceland, and the Instituto Superior Técnico in Portugal participated in this research.
The team's discoveries are related to current initiatives to enhance plasma science through ultrahigh-intensity laser collisions, a field of study that will be investigated using the NSF OPAL Facility.
This study was funded by the European Union’s Horizon Europe Research and Innovation program.
Journal Reference:
Arrowsmith, C. D., et al. (2024) Laboratory realization of relativistic pair-plasma beams. Nature Communications. doi.org/10.1038/s41467-024-49346-2