For just a small number of days each year, the Large Hadron Collider gets to experiment in ways it wouldn’t normally be able to, and on July 25 it injected lead atoms with just one electron straight into the LHC to see what would happen.
According to CERN, the new experiment is all par for the course and a way of investigating if the scope of CERN could be broadened in the future, as LHC engineer Michaela Schaumann explained.
“We’re investigating new ideas of how we could broaden the present CERN research program and infrastructure. Finding out what’s possible is the first step.”
As part of its routine operations over the course of the year, the LHC normally runs proton-proton collisions and smashes up atomic nuclei. Then, of course, there is the shutdown each winter of the Large Hadron Collider. However, on days like July 25, accelerator physicists get to have some fun when there is machine development happening.
While they recently injected lead atoms into the LHC, in the past they have done things like accelerate xenon nuclei in the Large Hadron Collider and use lead ions that have been partially stripped to inject into the SPS accelerator. As physicist Witold Krasny noted, “This special LHC run was really the last step in a series of tests.”
CERN’s recent experiment at the LHC was a challenging one as it can be extremely tricky to accelerate lead nuclei with just one electron due to the fragility of these atoms, according to Schaumann.
“When that happens, the nucleus crashes into the wall of the beam pipe because its charge is no longer synchronized with the LHC’s magnetic field.”
During their first run of the experiment, physicists took 24 groups of atoms and for a period of around one hour obtained a low-energy, yet stable beam. After this experiment worked, they then ran the LHC at its normal operating power and were able to keep the beam stable for two hours before it fell into the beam dump. As Michaela Schaumann noted, this is what happens when large amounts of particles end up running off course.
“If too many particles go off course, the LHC automatically dumps the beam. Our main priority is to protect the LHC and its magnets.”
During their second run, operators used just six groups of atoms and were able to keep the beam running for two hours again, but this time chose to dump it themselves in the end. Krasny was then able to determine that this beam could last for as long as 40 hours in the Large Hadron Collider.
“We predicted that the lifetime of this special kind of beam inside the LHC would be at least 15 hours. We were surprised to learn the lifetime could be as much as about 40 hours. Now the question is if we can preserve the same beam lifetime at a higher intensity by optimizing the collimator settings, which were still set-up for protons during this special run.”
Now that physicists at CERN have successfully accelerated lead atoms, they will be conducting further experiments to learn whether the LHC could be used as a gamma-ray factory one day in the future.