Antiatoms Bottled for First Time - ScienceNOW: Nevertheless, the ALPHA team managed to catch a few of the things. The physicists again combined positrons and antiprotons in a nested Penning trap, beginning with a puff of 30,000 antiprotons cooled to 200˚ above absolute zero, or 200 kelvin, and 2 million positrons cooled to about 40 kelvin. But this time, they build the Penning trap inside a magnetic trap known as an Ioffe-Pritchard trap, as they report online today in Nature.
That trap was only "deep" enough to capture the slowest-moving antiatoms. To prove that it worked, after mixing the protons and positrons, Hangst and colleagues turned off the Penning trap and used electric fields to sweep any remaining charged particles out their device. They then turned off the magnetic trap and looked for any lingering antiatoms drifting into the material in the trap and annihilating to produce detectable particles. In 335 trials, the physicists saw a total of 38 trapped atoms—about one every 10 trials.