Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268


Thu., September 08, 2011, at 3:00 p.m. (refreshments at 2:40 p.m.)

Confinement and Interrogation of Antihydrogen in the ALPHA Trap

Art Olin, TRIUMF, Vancouver, BC, Canada
Building 6008 Conference Room

ALPHA (Antihydrogen Laser Physics Apparatus) is an international project at the CERN AD. The primary aim is to test fundamental symmetries between matter and antimatter using trapped antihydrogen atoms, the simplest atomic form of neutral antimatter. Cold atoms of antihydrogen promise a unique opportunity to study the properties of atomic antimatter, and via comparisons with its well-studied matter-counterpart, the possibility to test fundamental symmetries of Nature such as CPT invariance. In order to probe matter-antimatter symmetry at the highest possible precision, it is essential that the anti-atoms be suspended in vacuum to allow for detailed interrogation via laser light or microwaves.

Trapping of antihydrogen is a big challenge as the antiprotons needed, which are only available at sufficient low energy at the AD at CERN in Geneva, Switzerland, are created at relativistic energies and therefore need to be decelerated many orders of magnitude. The antihydrogen is formed at, essentially, the temperature of the antiprotons used for the synthesis. ALPHA has implemented a state-of-the-art superconducting multipole magnetic-minimum trap which for antihydrogen in the ground state forms a trap only deep enough to trap anti-atoms with energies less than about 0.6 K. As no atom cooling is readily available the constituent antiprotons and positrons must be cold for the creation of antihydrogen. Before synthesis the antiprotons and positrons are kept in separate wells in a Penning-Malmberg trap. The introduction of the multipole trapping fields for the neutral atoms may perturb the charged particle plasmas used for the formation, such that they heat to well beyond the 0.5 K limit for trapping of the neutral atoms. This presentation will describe the techniques ALPHA employs to generate antihydrogen and the evidence that it has been successfully trapped. Finally, I will offer an outlook towards the future spectroscopic studies that could be carried out on a trapped antihydrogen sample using the techniques of laser and microwave spectroscopy.