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SeongYeol Kim at the PhD Program Physics at UNIST. He is currently involved in the AWAKE collaboration at CERN. Credit: Moses Chung
The Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN), near Geneva, Switzerland, is believed to be the largest particle accelerator in the world. The accelerator occupies a tunnel 27 kilometers in circumference and 175 meters deep under the Franco-Swiss border. The installation helped scientists to discover the Higgs boson, the last particle predicted by the standard model, in 2012.
Following the discovery of Higgs, one of the main scientific objectives of high energy physicists has been to characterize its properties and to discover other phenomena of high energy physics. As a result, high energy particle accelerator technologies have rapidly evolved to support research in high energy physics. However, the technologies used to date can only be improved and expanded at great cost. For this reason, it is urgent to make high energy accelerators more affordable.
An international team of physicists working at CERN (AWAKE), an advanced plasma accelerator experiment in proton-controlled plasma, has announced an innovative experiment demonstrating a new way to accelerate electrons to high particle accelerator energies and reduce their costs. An article describing this important result was published in Nature August 29, 2018.
AWAKE is an international scientific collaboration consisting of engineers and scientists from 18 institutes, including CERN and the Max Planck Institute for Physics in Germany. A UNIST-based research group, led by Professor Moses Chung of the Department of Physics, is also part of this AWAKE collaboration and has made several important contributions to AWAKE. This includes the design of beam lines and the optimization of the injection of electron beams.
"AWAKE's technology will bring a paradigm shift in the development of future high energy particle accelerators, following the LHC," said Professor Chung. "The latest achievement could allow engineers to significantly reduce the size of future particle accelerators, reducing the huge amounts of money normally required to build them." He adds: "The high-energy particle collisions produced by these facilities allow physicists to analyze the fundamental laws of nature, providing the basis for advances in a very wide variety of different fields."
Generally, particle physics experiments use oscillating electric fields, called radiofrequency cavities, and powerful magnets to accelerate high energy particles. But these experiments must become quite large – they must be, in order to accelerate the particles with enough energy to study them properly.
As an alternative cost-saving option to accelerate particles more efficiently, the field-field accelerator has been suggested. Physicists send a beam of electrons, protons or a laser through a plasma. The free electrons in the plasma move towards the beam, but go beyond it and then refreeze, creating a bubble structure behind the beam and intense electric fields. If you inject particles, such as more electrons, in the wake, the injected particles can be accelerated faster with an electric field 10 times more powerful.
In the study, the acceleration of plasma-induced plasma field acceleration has been demonstrated. Powerful electric fields, generated by a series of proton microbubs, were sampled with a group of electrons. These electrons were accelerated up to 2 GeV in about 10 m of plasma and measured with the aid of a magnetic spectrometer. This technique has the potential to accelerate electrons up to the TeV scale in a single step of acceleration.
Although still at the beginning of its program, the AWAKE collaboration has taken an important step towards realizing new experiments in high energy particle physics.
Explore further:
The researchers perform the very first acceleration of electrons in a proton plasma wave
More information:
E. Adli, et al., "Acceleration of electrons in the proton group plasma wakefield" Nature(2018).
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