Is now available on the Digital Innovation Channel, the three-part interview, presented by Paola Catapano, Science Communicator, and Jeffrey Hangst, Senior Physicist and Leader of the ALPHA and ALPHA-g experiments, taking us inside CERN’s Antimatter Factory and its research.

PART 1 - WELCOME TO CERN’S ANTIMATTER FACTORY

In this video, the first of a miniseries of three, science journalist Paola Catapano and Senior Scientists Jeffrey Hangst take us on a virtual tour of the Antimatter Factory at CERN, the European Laboratory for Particle Physics in Geneva (Switzerland). In this world-unique facility, two low-energy antiprotons “create” antiatoms (anti-hydrogen atoms, the simplest form of atomic antimatter) for studies of antimatter. Two synchrotrons, the AD (Antiproton Decelerator) and ELENA (Extra Low Energy Antiproton) decelerate protons to serve several experiments that are studying antimatter and its properties. These experiments are named: AEgIS, ALPHA, ASACUSA, BASE and GBAR. Previous  experiments also hosted in the facility (ATRAP and ACE) have now completed their scientific programme and have been dismantled.

Installed in 2000, the facility made the headlines in 2002 when large numbers of antihydrogen atoms were produced for the first time. Initial attempts were made to store antiatoms for a long enough time to be able to measure their characteristics. In 2011, an experiment announced that it had produced and trapped antihydrogen atoms for sixteen minutes, which was long enough to be able to study their properties in detail. The following year, the first measurement of the antihydrogen spectrum was published. Since 2010, the experiments in the Antimatter Factory have published numerous measurements of antimatter characteristics, comparing them to those of matter.

PART 2 - ALPHA AND ALPHA-g 

In the second video of this mini-series, Jeffrey Hangst tells Paola Catapano about the ALPHA and ALPHA-g experiments he leads in the Antimatter Factory. Set up in late 2005, ALPHA makes, captures and studies atoms of antihydrogen and compares these with hydrogen atoms. Creating antihydrogen depends on bringing together the two component antiparticles, antiprotons and positrons, in a trapping device for charged particles. Since antihydrogen atoms have no electric charge, once they form they can't be confined in such a device.  ALPHA uses a new trapping method to hold the antihydrogen atoms, and is able to keep them for a long time before they annihilate with ordinary atoms.

In November 2025, in a paper published in Nature Communications, researchers at the ALPHA reported a new technique that allows them to produce over 15 000 antihydrogen atoms in a matter of hours. Using this approach for cooling positrons, the ALPHA experiment produced over 2 million antihydrogen atoms over the course of the experimental runs of 2023-24.

The ALPHA-g experiment uses the unprecedented numbers of antihydrogen atoms produced to study the effect of gravity on antimatter. This allows even more precise measurements to be made and makes it possible to probe deeper into the properties and behaviour of atomic antimatter.

PART 3 - THE ANTI PROTON DECELERATOR

Meet Paola and Jeff inside the tunnel of the Antiproton Decelerator (AD), a unique machine that produces low-energy antiprotons for studies of antimatter, and “creates” antiatoms.

Here a proton beam coming from CERN’s PS (Proton Synchrotron) is fired into a block of metal. These collisions create a multitude of secondary particles, including lots of antiprotons. These antiprotons have too much energy to be useful for making antiatoms. They also have different energies and move randomly in all directions. The job of the AD is to tame these unruly particles and turn them into a useful, low-energy beam that can be used to produce antimatter. The antiprotons, which emerge from the block at diverging angles, are focused before they reach the AD. Only a fraction of them have the right energy to be injected into and stored in the AD. The AD is a ring composed of bending and focussing magnets that keep the antiprotons on the same track, while strong electric fields slow them down. The spread in energy of the antiprotons and their deviation from their track is reduced by a technique known as “cooling”. Antiprotons are subjected to several cycles of cooling and deceleration until they are slowed down to around a tenth of the speed of light.

Installed in 2000, the AD made the headlines in 2002 when large numbers of antihydrogen atoms were produced for the first time. Initial attempts were made to store antiatoms for a long enough time to be able to measure their characteristics. In 2011, an experiment announced that it had produced and trapped antihydrogen atoms for sixteen minutes, which was long enough to be able to study their properties in detail. The following year, the first measurement of the antihydrogen spectrum was published. Since 2010, the AD experiments have published numerous measurements of antimatter characteristics, comparing them to those of matter.

Recently, a newer deceleration ring, ELENA (Extra Low Energy Antiproton), was coupled with the AD. But this will be the subject of another video.