In ALPHA, charged particles are trapped using a Penning-Malmberg trap. The most commonly trapped particles in our trap are the antiproton and the positron - the two ingredients to produce antihydrogen. Antihydrogen is electrically neutral, so it cannot be confined with the electric fields used to confine the charged positrons and antiprotons. Instead we use an ‘Ioffe-Pritchard trap’.

With the exception of modes, presently we can only detect antimatter in our apparatus by destructive methods (we either need to splat our particles onto a detector surface or annihilate the antimatter into the trap wall). While working with antimatter makes almost everything very difficult, fortunately detection is often very efficient.

We either detect the charge of particles in our apparatus (Faraday Cup, MCP, temperature measurements), or the annihilation products. When antimatter comes in contact with matter, it annihilates. This annihilation releases lots of energy and subatomic particles. These products are then detected either with the Plastic Scintillators, TPC, SVD.

In order to synthesize antihydrogen, we need to combine antiprotons with positrons. We call this delicate process ‘Mixing’. We want to keep the antihydrogen for study, so we use a magnetic trap to confine (trap) it. The mixing process has been carefully planned such that the magnetic trap does not interfere with it. This allows us to repeat the ‘Mixing’ step inside our magnetic trap to ‘Stack’ (accumulate) antihydrogen in the trap.