In order to study antimatter it has to be kept separate from matter, to prevent it from annihilating. Electrically-charged antimatter can be trapped in a device called a Penning trap.
The Penning trap requires an ultrahigh vacuum. Inside the trap, magnetic fields force the charged antiparticles to spiral around the magnetic field lines, and electric fields confine them along the magnetic axis.
In June 2011 the ALPHA experiment at CERN reported that it had succeeded in trapping antimatter atoms for over 16 minutes: long enough to begin to study their properties in detail.
This Penning trap has been used to trap electrically charged antiparticles (antiprotons) at CERN. The antiprotons were combined with positrons to produce antihydrogen atoms.
The world record for storing antiparticles is held by the TRAP experiment at CERN: it kept a single antiproton in a Penning trap for 57 days! The scientists performed very precise measurements of its mass and charge before the trap was switched off and the antiproton ... annihilated.