ALPHA is an international collaboration based at CERN, and whose aim is stable trapping of antihydrogen atoms, the antimatter counterpart of the simplest atom, hydrogen. By precise comparisons of hydrogen and antihydrogen, the experiment hopes to study fundamental symmetries between matter and antimatter.
In a paper published online at Nature Physics, ALPHA announces confinement of antihydrogen atoms for at least 1000s.
Last November, we announced in Nature that we had successfuly trapped 38 antihydrogen atoms for at least 172 ms. In fact, 172 ms is the shortest time we can trap atoms and be sure that we've removed all of the other particles that can be around. By simply leaving the magnetic atom trap on, we can easily make measurements for longer times.
Our complete data set from last year is made up of 309 annihilation events consistent with antihydrogen annihilation, 19 of which occur after holding the trap for at least 1000s. In the figure here, we show the number of atoms trapped as a function of the confinement time.
These results strongly imply that the antihydrogen atoms have reached their lowest-energy (ground) state while in the trap, which is important for the ground-state spectroscopy that ALPHA plans to perform on the trapped atoms. In addition, the large number of atoms allow us to compare the time and position at which the atoms escape the trap to simulations and shed light on the energy distribution of the trapped atoms.
The first beam of the 2011 season was delivered to ALPHA from the AD (Antiproton Decelerator) on the night of May 9th.
The image here shows some of the first antiprotons captured in the trap. It's produced by dumping the particles onto an MCP/phosphor -- the bright circular shape is the electron plasma used to cool the antiprotons from a few keV (kiloelectron volts = 1000 electron volts) to a few eV. The more diffuse cloud off to an angle on the left is the antiproton cloud. There are about 30,000 antiprotons here, which is what we get from one shot (cycle) of the AD.
Here's to another great run!
The Low Energy Antiproton Physics Conference, held every two years, is one of the most important conferences for the antihydrogen community. This year, more than fifteen members of the ALPHA Collaboration travelled to TRIUMF, in Vacouver, Canada to present results and discuss with the rest of the community. The conference, which had ALPHA member Makoto Fujiwara as the chairman of the local organising committee was very successful. You can find more details about LEAP 2011 here, as well as some of the ALPHA presentations in the program.
Physics World, the international physics magazine produced by the Institute of Physics, has named ALPHA's recent trapping of antihydrogen as part of the #1 physics breakthrough of 2010, jointly with the ASACUSA Collaboration's formation of antihydrogen in a 'cusp' trap. The complete list of ten breakthroughs from 2010 includes measurements of the atmosphere of an exoplanet 130 light-years away, a Bose-Einstein condenstate of photons, a new measurement of the proton size, and the first proton collisions at the LHC. Read the article and see the fill list here.