The first test of the AWAKE experiment at CERN

Scheme of the AWAKE experiment within CERN's structure (Image courtesy CERN)
Scheme of the AWAKE experiment within CERN’s structure (Image courtesy CERN)

At the end of last week at CERN the first particle beam was sent through the AWAKE experiment, a test of a proof-of-concept of a new type of particle accelerator. It’s currently still under construction but when finished it will prove the possibility to build plasma accelerators in which wakefield acceleration allows to build accelerators a hundred times smaller than the current ones.

The concept of this type of particle accelerator was theorized in the ’70s but then it was impossible to build one due to technological limitations. Now, finally things have changed and various experiments are trying to create one. In the experiment at CERN, a packet of protons generated by the Super Proton Synchrotron (SPS) has simply passed through AWAKE in the test carried out in recent days.

The purpose of the test was to verify that all components of the experiment were working properly and that the magnets align the proton beam properly. When working with particle accelerators, the test results need be monitored carefully in detail because every little anomaly could cause huge damage in the later stages of the project.

During the complete operations, the proton beam will pass through a plasma field. The electrons in the plasma are charged negatively so they’ll be attracted to protons, which have a positive charge instead. At that point the protons have got out of the plasma so the electrons keep moving leaving the plasma that will have acquired a positive charge.

This process will continue generating a wave in which it’s possible to send more electrons that will be accelerated to avoid the electrons already present. The process was described as surfing gathering speed on sea waves. In this case the wake field is used to accelerate particles at levels thousands of times faster than conventional accelerators.

This type of technology will offer the opportunity to build much smaller accelerators, even the size of a table rather than kilometers long such as the Large Hadron Collider. As a consequence, they’ll be much cheaper and simple to build. If the analysis of the this test’s results will confirm that everything went well, at CERN they’ll proceed with installing the rest of the system. It will still take a long time to have an operating plasma accelerator but the first step has been taken.

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