CERN will carry the antimatter on the truck for the annihilation experiment

Antiproton inhibitor at CERN

Antimatter is a very fragile substance (more precisely, antimatter). But physicists have learned so well to control it, that now for the first time in history they decided to take a chance and transport a small amount of antiprotons to a distance of several hundred meters.

Antimatter is mined at the Large Hadron Collider, collecting clouds of antiprotons after a collision of a proton beam with a metal target and a careful deceleration of scattering particles, so that they can be used in subsequent experiments. In this case, CERN is preparing for an experiment to annihilate the antiprotons PUMA (anti-Proton Unstable Matter Annihilation), writes the journal Nature .

To carry out annihilation, it is required to deliver antiprotons from the “factory” to the venue of the neighboring experiment ISOLDE, where rare radioactive atomic nuclei are mined. They break up too fast to be transported somewhere. Therefore, for the experiment on annihilation it is necessary to transport precisely the antimatter.


Equipment in the laboratory of particle physics CERN to obtain radioactive atomic nuclei. Photo: CERN

The experiment will take place in the CERN particle physics laboratory. “Antimatter has long been studied on its own, but now its properties are well known enough to start using it as a probe for matter,” said Alexandre Obertelli, a physicist from the Technical University of Darmstadt (Germany), project manager for PUMA.

To stabilize a cloud of about 1 billion antiprotons in a vacuum, scientists will use a trap of magnetic and electric fields. Then this trap will be loaded onto a truck - and transported to as far as hundreds of meters to the place of the ISOLDE experiment.

The illustration below shows how the trap is arranged and how annihilation will proceed in the event of a collision with rare isotopes of radioactive elements. As you can see, the trap inside a superconducting magnet has a length of 700 mm, and isotopes enter it through a tube with a diameter of 10 nanometers. The antiproton collision zone of isotopes is equipped with a detector for the registration of flying particles.


PUMA Experiment Scheme

“Carrying antimatter in a truck is practically science fiction,” says Charles Horowitz, an expert in theoretical nuclear physics from Indiana University in Bloomington. “This is a great idea.”

PUMA experiment

As written in the description of the European grant for the PUMA experiment , it is put to “study one of the most remarkable quantum phenomena in nuclear physics — the appearance of a neutron halo and neutron shells in atomic nuclei that are very neutron-rich. Thick neutron shells, which until now have never been fixed in nuclei of average mass, will become laboratory neutron matter of low density. It is also known that the structure of the nuclear shell varies with the number of protons and neutrons. The nuclear structure of very heavy nuclei with Z = 100 or more is almost unknown, and the existence of new long-lived heavy isotopes is still an open question. This fundamental phenomenon associated with the imbalance of neutrons and protons in unstable nuclei is important for understanding the complex nature of nuclei and the associated astrophysical processes. ”

For example, an excess amount of neutrons in the lithium-11 isotope creates a neutron halo around the core of the nucleus and inflates its size (see illustration).



It is assumed that the same forces, only on a larger scale, act in neutron stars - it is these forces that create a solid shell saturated with neutrons.


Neutron star structure

The structure of the nuclei of superdense stars is still a mystery to scientists. But studying the properties of nuclear halos in the “microcosm” of radioactive isotopes will help to come closer to a solution in astrophysics.

So, within the framework of the PUMA experiment, such neutron halos are “probed” by antiprotons - and they will look at the result of annihilation. To do this, to the place of production of isotopes and carry antimatter. However, before this we have to solve several technical problems - we need to design equipment for storing a billion antiprotons for several weeks in a trap at a temperature 4 degrees above absolute zero. The task is difficult, but achievable. Scientists expect to begin the first experiments on the annihilation of antimatter with neutron halos of radioactive nuclei in 2022.

There is enough antimatter on the truck for other experiments, not only at CERN, so there is a possibility that subsequently the van with antimatter will go to other regions of Europe.

“As soon as they can take a billion antiprotons and hold them for several weeks, then many other experiments will join. People will have new ideas for what can be done here, ”says anti-matter physicist Chloé Malbrunot of CERN. “I think this will really open up a new area of ​​research.”