In a paper published online by the journal Nature Physics today, the ALPHA experiment at the European Organization for Nuclear Research or CERN1 reports that it has succeeded in trapping antimatter atoms for over 16 minutes: long enough to begin to study their properties in detail. ALPHA is part of a broad programme at CERN's antiproton decelerator (AD)2investigating the mysteries of one of nature's most elusive substances.
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Today, we live in a universe apparently made entirely of matter, yet at the big bang matter and antimatter would have existed in equal quantities. Nature seems to have a slight preference for matter, which allows our universe and everything in it to exist. One way of investigating nature's preference for matter is to compare hydrogen atoms with their antimatter counterparts, and that's what makes today's result important.
"We can keep the antihydrogen atoms trapped for 1000 seconds," explained ALPHA spokesperson Jeffrey Hangst of Aarhus University. "This is long enough to begin to study them -- even with the small number that we can catch so far."
In the paper published today, some 300 trapped antiatoms are reported to have been studied. The trapping of antiatoms will allow antihydrogen to be mapped precisely using laser or microwave spectroscopy so that it can be compared to the hydrogen atom, which is among the best-known systems in physics. Any difference should become apparent under careful scrutiny. Trapping antiatoms could also provide a complementary approach to measuring the influence of gravity on antimatter, which will soon be investigated with antihydrogen by the AEgIS experiment.
What is anti-matter?
Dr. Jeffrey Hangst from CERN describes how they trapped anti-matter.
Another important consequence of trapping antihydrogen for long periods is that the antiatoms have time to relax into their ground state, which will allow ALPHA to conduct the precision measurements necessary to investigate a symmetry known as CPT. Symmetries in physics describe how processes look under certain transformations. C, for example, involves swapping the electric charges of the particles involved in the process. P is like looking in the mirror, while T involves reversing the arrow of time.
Individually, each of these symmetries is broken -- processes do not always look the same. CPT, however, says that a particle moving forward through time in our universe should be indistinguishable from an antiparticle moving backwards through time in a mirror universe, and it is thought to be perfectly respected by nature. CPT symmetry requires that hydrogen and antihydrogen have identical spectra.
"Any hint of CPT symmetry breaking would require a serious rethink of our understanding of nature. But half of the universe has gone missing, so some kind of rethink is apparently on the agenda."
The next step for ALPHA is to start performing measurements on trapped antihydrogen, and this is due to get underway later this year. The first step is to illuminate the trapped anti-atoms with microwaves, to determine if they absorb exactly the same frequencies (or energies) as their matter cousins.
"If you hit the trapped antihydrogen atoms with just the right microwave frequency, they will escape from the trap, and we can detect the annihilation -- even for just a single atom. This would provide the first ever look inside the structure of antihydrogen -- element number 1 on the anti-periodic table."
1. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. One candidate for accession: Romania. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.
A lot of my fans don't know what CERN really is. These YouTube videos should help explain this $10 billion project.
A 3-minute tour of CERN
Theoretical physics professor Michio Kaku talks about CERN's test run after CERN was shutdown for a year and one-half to fix mechanical problems.
An excellent documentary of CERN explaining what it hopes to accomplish (sorry about the poor quality). This is when they thought CERN was going to cost only $6 billion. HA, HA.
2. ALPHA is one of several AD experiments investigating antimatter at CERN. ATRAP has pioneered trapping techniques, and is also investigating antihydrogen. ASACUSA has made measurements of unprecedented precision of the antiproton's mass, so far not revealing any divergence from that of the proton. ASACUSA is also developing complementary techniques for studying antihydrogen. AEgIS studies how antiprotons fall under gravity, and ACE investigates the potential use of antiprotons for cancer therapy.
COMMENTARY: For physicists, antimatter is probably the most valuable substance ever; the slightest bit of it could provide extremely valuable information that can help clear out some of the most stressing issues in modern physics. However, the thing is these little gifts are pretty hard to wrap. However, the ALPHA project at CERN achieved this remarkable feat and took a huge leap towards understanding one of the questions about the Universe: what’s the actual difference between matter and antimatter.
The team had 38 successful attempts to capture single antihydrogen atoms in a magnetic field for about 170 miliseconds. Says Jeffrey Hangs, spokesman for ALPHA collaboration at CERN,
“We’re ecstatic. This is five years of hard work."
And they should be. Since it restarted working, the Large Hadron Collider at CERN had quite a few good moments, but this is the best one so far. Antimatter (or the lakc of it) still poses one of the biggest mysteries ever; according to the theories up to date, at the Big Bang, matter and antimatter were produced in equal amounts, but somehow all the antimatter dissappeared, so now researchers are forced to turn to more and more advanced and delicate methods in order to find it and study it.
As you can guess by its name, antimatter is just like matter, only in reverse. So the antiprotons are just like normal protons, but they are negatively charged, while electrons have a positive charge. The main objective of this stage of the ALPHA project was to compare the relative energy of hydrogen and antihydrogen in order to confirm that antimatter and matter have the same electromagnetic properties, which is a key feature of the standard model.
This is not the first time antimatter was captured, the first time it was in 2002, with the ATHENA project; however, it lasted just several miliseconds, which made it impossible to analyze. What happens is that when you combine matter with antimatter, they vanish with a big boom, releasing high energy photons (gamma rays). In the ATHENA project, antihydrogen combined with hydrogen from the walls of the contained and annihilated each other.
To prevent this from happening, the ALPHA team used a totally different technique, which was way more difficult: capturing the antimatter in a magnetic trap. To capture the 38 atoms, they had to repeat the experiment no less than 335 times.
Of course, achieving these atoms was very costly, but the effort was definitely worth it. However, physicists are looking into other methods that could prove to be more effective in times to come.
I have been poking fun at CERN ever since they built the multi-billion dollar monstrosity and it experienced one problem after another, after another. They cranked it up in 2007, but it didn't work. Finally in 2009 they were able to get the damn thing to finally work.
At the end of 2010, they have accomplished something significant--capturing anti-matter in a vacuum chamber--but what exactly have they started? Have we taken the Genie out of the bottle?
We are venturing into the unknown area where there are a lot of 'ifs'. What will happen when we start working with heavier elements? Let's hope nobody gets hurt and we don't open a time warp or create a black hole in the universe.