In a recent press release, CERN intends to continue the road leading to passing, from fiction to reality, the portable antimatter storage device which serves as the backdrop to Dan Brown's famous novel, Angels and Demons.
The device in question will be based on the technology and achievements already obtained at CERN by members of the Base collaboration ( Baryon Antibaryon Symmetry Experiment ) who have already broken many records in the field of antimatter research. They were thus the first to keep it for over a year. These were antiprotons stored in a Penning trap which holds the particles in place by means of electric and magnetic fields, antiprotons from another machine, the CERN Antiproton Decelerator (AD).
Such a trap, which allows the study of isolated particles and which has earned its developer, Hans Georg Dehmelt, a Nobel Prize in Physics, can also serve as a reservoir containing up to about 10 million million antiprotons.
A Basic presentation. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. © CERN
CERN, an antimatter bomb factory?
However, we should not believe that we could make antimatter bombs with them, contrary to what is staged with physicists from CERN in the novel from which a film was made. The European laboratory has clearly explained this on its website because it is very difficult to produce and capture antiprotons. The processes used with CERN accelerators for decades indeed have a ridiculously low efficiency since the energy stored in the form of the mass of the antiprotons represents only a tenth of a millionth (10 -10 ) of the energy expended and , if all the antiprotons created at CERN since that time have indeed been annihilated with protons, the energy recovered would be just enough to make an electric bulb shine for a few minutes. It would therefore take billions of years for CERN to be able to manufacture an antimatter bomb with the same destructive capacity as a hydrogen bomb.
The recipe used to produce antiprotons is simple. We start by accelerating protons to an energy of about 25 GeV and the resulting beam is sent to a fixed target, a block of metal such as copper or tungsten . Many secondary particles will emerge from collisions between the beam protons and the nucleons of the metal nuclei, and the difficulty lies in purifying the shower of particles obtained by capturing some of the antiprotons produced.
The members of Base therefore now want to develop a device, Base-Step, consisting of several Penning traps inside a superconducting magnet cooled with liquid helium. Base-Step will still measure 1.9 meters in length, 0.8 meters in width and 1.6 meters in height. It will weigh a maximum of 1,000 kg , which will allow it to be moved with a small truck. We can then transport antiprotons to a place in CERN less polluted magnetically by other experiments in order to make more precise measurements on the properties of antiprotons or anti-hydrogen atoms, in search of a new physics.
A similar device but based on another antiproton storage technique will also be produced and it is called Puma (antiProton Unstable Matter Annihilation). It will be used to transport antiprotons to be used for experiments on exotic nuclei of radioactive atoms with very short lifetimes and which are produced with the Isolde installation, the acronym for Isotope mass Separator On-Line.
Antimatter ready for a truck ride?
For ordinary people, antimatter remains a strange object. For physicists, it is now sufficiently mastered that they can consider using it in experiments. And even to imagine transporting it ... in a truck!
For a long time, antimatter seemed elusive. And the researchers had no other idea in producing it than to study it. More recently, they have learned to master it. Enough, believes a team from CERN (Switzerland) today, to consider using antimatter to better understand the strange behavior of certain rare radioactive nuclei. But for that, they will have to transport this antimatter from one laboratory to another ... by truck!
At the heart of the European particle physics laboratory, an experiment produces antimatter. How? 'Or' What ? By hitting a metal target with a proton beam. The emerging antiprotons are then slowed down and CERN researchers intend to trap them in a vacuum using magnetic and electric fields.
The team intends to trap up to a billion antiprotons in this way . A billion antiprotons that will then have to be stored for several weeks in an enclosure maintained at only four degrees above absolute zero and in a vacuum comparable to that which reigns in intergalactic space.
A billion antiprotons is nothing. “The energy released by their sudden annihilation would not equal even a joule. Hardly enough to lift an apple of 20 centimeters ”, assures Alexandre Obertelli, the project manager, to those who are worried just by the idea of knowing antimatter thus carried in nature. In a single gram of hydrogen, in fact, there are a hundred trillion times more protons.
The development of the technology needed to trap and transport antimatter is expected to take almost four years. The first measurements are planned at Cern for 2022. © Cern
Unveiling the secrets of neutron stars
The trap will then be loaded onto a truck to be transported a few hundred meters further. There, another experiment produces rare and radioactive atomic nuclei. They disintegrate so quickly that it is not possible to move them. And they exhibit a neutron / proton imbalance that can be the source of exotic features that are interesting to understand.
However, antiprotons tend to annihilate extremely easily and quickly when they encounter both protons and neutrons . Hence the idea of exploiting these annihilations on very short-lived nuclei. By discriminating the number of times antiprotons annihilate with protons or neutrons, physicists hope to be able to determine the relative densities of these particles and their distribution within these nuclei.
The objective of CERN researchers is to provide some information to astrophysicists who study neutron stars and the formation of heavy elements in the Universe . The nuclei of these super-dense stars indeed constitute a mystery that could be solved by a better understanding of what is happening at the heart of exotic radioactive nuclei .