Scientists transport protons in trucks, paving the way for antimatter transport

Antimatter may sound like the stuff of science fiction, but at the CERN Antiproton Decelerator (AD), scientists create and trap antiprotons every day. BASE experiments can even house them for more than a year. This is an amazing feat considering that antimatter and matter annihilate when they come into contact.

CERN AD Hall is the only place in the world where scientists can store and study antiprotons. But this is something scientists working on the BASE experiment hope to one day change with BASE-STEP, a subproject designed to store and transport antimatter.

Just recently, a team of scientists and engineers took an important step toward this goal by transporting a cloud of 70 protons by truck to CERN’s main site.

“If it can be done with protons, it will work with antiprotons,” said BASE-STEP leader Christian Smola. “The only difference is that we need a much better vacuum chamber for the antiprotons.”

This is the first time that loose particles can be transported in a reusable trap, allowing scientists to open the trap at a new location and transfer its contents to another experiment. The ultimate goal is to create an antiproton delivery service from CERN to experiments at other labs.

Antimatter is a naturally occurring particle that is almost identical to normal matter, except that its charge and magnetic properties are reversed. This has puzzled scientists for decades, because according to the laws of physics, the Big Bang should have produced equal amounts of matter and antimatter. These equal but opposite particles would have quickly annihilated each other, leaving a smoldering but empty universe. Physicists think there may be hidden differences that explain why matter survived and antimatter nearly disappeared.

The BASE experiment aims to answer this question by precisely measuring properties of antiprotons, such as their intrinsic magnetic moment, and comparing these measurements with those for protons. However, the accuracy that can be achieved in experiments is limited by location.

“AD Hall’s accelerator equipment generates fluctuations in the magnetic field, which limits how far we can push the precision measurements,” said BASE spokesperson Stefan Ulmer. “If you want to understand more deeply the fundamental properties of antiprotons, you need to move away from that.”

This is where BASE-STEP comes into play. The goal is to capture the antiprotons and transport them to a facility where scientists can study them with greater precision. Achieving this requires equipment that is small enough to be loaded onto a truck and able to withstand the shock and vibration that is inevitable during ground transportation.

The current device, which includes a superconducting magnet, a cryogenic cooler, a power storage device, and a vacuum chamber that traps particles using magnetic and electric fields, weighs 1,000 kilograms and requires two units to be loaded onto a truck from the experiment hall. crane is required. Although it weighs a ton, BASE-STEP is much more compact than existing systems used to study antimatter. For example, the footprint is one-fifth the size of the original BASE experiment, as it needs to be narrow enough to fit through a regular lab door.

During rehearsals, scientists used trapped protons as a substitute for antiprotons. Protons are important components of all atoms, the simplest being hydrogen (one proton and one electron). But storing protons as loose particles and transferring them to trucks is difficult. This is because the unbound protons are pulled back into their original atoms by the slightest disturbance. nuclear.

“When transported by road, our trapping systems are exposed to acceleration and vibrations, which laboratory experiments are typically not designed with these things in mind,” Smola said. . “We needed to build a trap system robust enough to withstand these forces, and now we’ve actually tested this for the first time.”

But Smola pointed out that the biggest potential obstacle right now is not the bumps in the road, but the traffic congestion.

“If shipping takes too long, we’ll eventually run out of helium,” he says. Liquid helium keeps the trap’s superconducting magnets below their maximum operating temperature of 8.2 Kelvin. If the drive takes too long, the magnetic field will be lost, and the trapped particles will be released and disappear as soon as they touch normal matter.

“Eventually, we hope to be able to transport antimatter to a dedicated precision laboratory at the Heinrich Heine University in Düsseldorf, where we will be able to study antimatter with at least a 100-fold increase in precision. ,” Smola said. “In the long term, we would like to transport it to any laboratory in Europe. This would mean we would have to have a generator on board the truck. We are currently investigating this possibility. .”

After the experiment is successful, including sufficient monitoring and data acquisition, the team will refine the procedure with the goal of transporting antimatter next year.

“This is a completely new technology and will open the door to new possibilities for studying not only antiprotons, but also other exotic particles such as ultrahighly charged ions,” Ulmer said.

In another experiment, Puma is preparing a portable trap. Next year, scientists plan to transport the antiprotons to CERN’s ISOLDE facility, 600 meters from the ADH Hall, where they will be used to study the properties and structure of exotic nuclei.