Five-MeV antiprotons provided by the CERN Antiproton Decelerator are slowed in a beryllium foil and captured in a Penning trap where they are further cooled by collisions with cold trapped photoelectrons produced using an excimer laser. Positrons from sodium-22 are cooled with gas molecules and are trapped in a separate Penning trap and then transferred through a small aperture into the 1-Tesla field of the main Penning trap. 60 million positrons and 0.5 million antiprotons are collected within 15 minutes. Antihydrogen is formed as the positrons and antiprotons are mixed in a slowly-ramped nested well, and is detected by Stark-field ionization. The Ioffe trap, which has a magnetic-field minimum at its center, is intended to ultimately confine extremely cold, ground-state anti-H atoms.
Argonne Physics Division Colloquium Schedule