Tag Archives: matter

Antihydrogen and antimatter

Coldest antimatter yet might help scientists probe its secrets

A novel technique for cooling antimatter down to the point where it might become almost stationary might provide scientists with a better basis for studying one of the greatest modern mysteries today.

Antimatter, as it name implies, is the total opposite of matter and when the two meet they cancel each other out. For instance the opposite of an electron is a positron. It’s because of this fascinating behavior, however, that studying antimatter is extremely difficult, since we’re ubiquitously surrounded by matter. A great puzzling dilemma for physicists today is why is there so little antimatter present in the Universe compared to matter.

Antihydrogen and antimatter

It’s theorized that after the first Big Bang sparks, equal amounts of both matter and antimatter were spewed through out the early Universe, but for some yet unknown reason matter won out. Currently, the only instances antimatter has been observed naturally are those following radioactive decay or cosmic ray collisions, and though the existence of antimatter has been proven since the 1930s only recently could it be artificially produced, and in small quantities to top it over.

With this in mind, scientists have been looking to devise ways to ease antimatter research. A recent technique that has garnered quite a bit of attention was developed by Makoto Fujiwara, a research scientist at Canada’s particle physics lab TRIUMF and an adjunct professor at the University of Calgary, along with colleagues, and is called Doppler cooling. It implies chilling anti-hydrogen (with one positron and one anti-proton) to just a tad over absolute zero Kelvin – 25 times colder than ever attempted.

The technique has yet to be proven, though an advanced prototype experimental setup is in the works, however a computer simulation showed extremely promising results.

“The ultimate goal of antihydrogen experiments is to compare its properties to those of hydrogen,” physicist Francis Robicheaux of Auburn University in Alabama said in a statement. “Colder antihydrogen will be an important step for achieving this.”

“By reducing the antihydrogen energy, it should be possible to perform more precise measurements of all of its parameters,” Robicheaux said. “Our proposed method could reduce the average energy of trapped antihydrogen by a factor of more than 10.”

Fujiwara led in 2011 a team of scientists at CERN that made the first direct measurement of antimatter’s energy and also held particles of anti-hydrogen stable for as long as 15 minutes, still a record. Comparing the properties of hydrogen and anti-hydrogen might allow scientists to explain why there is such a great quantitative gap between the two. If the two are indeed proven to exhibit totally opposite properties then a sounds basis for further study might be built.

The present technique uses precisely targeted lasers on antihydrogen in order to loose energy and chill it down. Remember, however, that antimatter and matter annihilate each other, so the key to their research is trapping antihydrogen – the scientists hope to achieve this through a system of magnetic fields.

“We want anti-hydrogen atoms as cold as possible in our trap, and by cold I mean not moving. In particular, to measure the gravitational properties, antihydrogen in our trap is still moving way too fast. So this paper has shown that the technique called laser cooling can be applied in our experimental set-up,” Mr. Fujiwara said.

The first immediate goals for Fujiwara and colleagues is to study basic properties of antihydrogen like colour, weight, how it reacts to light or gravity and so on. The laser cooling technique was described in a paper published in the Journal of Physics B.


Antimatter captured at CERN

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.

“We’re ecstatic. This is five years of hard work,” says Jeffrey Hangst, spokesman for the ALPHA collaboration at CERN.

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.

Artist depiction of hydrogen and anithydrogen

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.

“This was ten thousand times more difficult” than creating untrapped antihydrogen atoms, says Hangst — ATHENA made an estimated 50,000 of them in one go in 2002. To do spectroscopic measurements, Surko estimates that up to 100 antihydrogen atoms may need to be trapped at once.

“The goal is to study antihydrogen and you can’t do it without trapping it,” says Cliff Surko, an antimatter researcher at the University of California, San Diego. “This is really a big deal.”

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.

“Rather than trying to demonstrate that we can confine 38 antihydrogen atoms for a small fraction of a second, we are working on new methods to produce and trap much larger numbers of colder atoms,” says Gerald Gabrielse, ATRAP’s spokesman. “We shall see which approach is more fruitful.”

via CERN

Large Hadron Collider hints at infant Universe

Despite several setbacks and technical difficulties, the Large Hadrdon Collider is already starting to live up to it’s nickname, the Big Bang machine. Researchers have pinpointed what may very well be the dense, hot state state of matter that is believed to have filled the Universe during its first nanoseconds.

Generally speaking, quarks are bound together in groups of two or three, stuck together by gluons. However, right after the Big Bang, it was so hot that the quarks broke free, and the matter became a free flow of quarks and gluons.

In the snapshots taken from LHC’s detector, a flow similar to this has been observed.

Full report here.