For years, scientists from different parts of the world have spent time and effort to try and answer one of the most fundamental questions in physics: why all things appear to be made of only one kind of matter when there are in fact two kinds?
In 2016, a team of researchers from CERN (Conseil Européen pour la Recherche Nucléaire) or European Organization for Nuclear Research successfully measured the light spectrum of antimatter, through antihydrogen, for the first time, confirming what has long been predicted by the laws of physics:
Antimatter is an exact mirror image of matter.
The said breakthrough opened up new ways and possibilities for Einstein’s Theory of Relativity to be tested, and the mind boggling question of why there seems to be more matter than antimatter in the Universe to be answered.
Almost eight months after the discovery was first reported, the same team of scientists made another breakthrough by acquiring substantial evidence of antimatter’s existence.Another #CERN #ALPHA experiment captured 'fingerprints' of #Antimatter!Click To Tweet
‘Fingerprints’ of Antimatter Spotted: the Hyperfine Structure
In a paper published in the international weekly journal Nature, the team of researchers under the ALPHA Collaboration at CERN explained how they used the cutting-edge technology spectroscopy to observe a detailed structure of antihydrogen-the counterpart to regular hydrogen-dubbed as ‘hyperfine structure.’
What is hyperfine structure?
Just like the atoms of matter that have electrons orbiting them, positrons are also orbiting around anti-atoms of antimatter. Energizing these particles and antiparticles will make their energy state leap up. However, their energy state will also fall if they lose energy.
A ‘fine structure’ will be seen from a zoomed out perspective, but zooming in to a precise level will show the ‘hyperfine structure.’
Apparently, scientists observed that the spectral lines or ‘fingerprints’ found in antihydrogen’s hyperfine structure are practically the same as those of hydrogen.
‘Fingerprints’ of Antimatter Spotted: The Experiment
Scientists believe that this discovery would provide new insights and explanations about the mysteries of the Big Bang that led to the creation of trillions of galaxies. According to Michael Hayden, a professor at Simon Fraser University in Canada and the research study’s lead author:
“By studying the properties of anti-atoms we hope to learn more about the universe in which we live.”
Observing and finding the difference between two kinds of matter is not an easy task. The physicists need to gather enough antimatter in one place, and that is no easy feat. However, the ALPHA Collaboration team was able to do it by cranking up CERN’s Antiproton Decelerator and churning out about 90,000 antiprotons.
The scientists used a series of high-energy collisions to create the antiprotons. Then, to make the antihydrogen element, they coupled each antiproton with a positron. For every million particle collisions, only about four proton-antiproton pairs were created.
The antiprotons were drawn away using incredibly powerful magnetic fields and were brought to the Antiproton Decelerator. The Decelerator reduced the speed of the antiprotons from 96% to around 10% of the speed of light.
The researchers were only able to make around 25,000 antihydrogen anti-atoms. From that figure, the team only managed to trap and detect 194 atoms over some trials. Justine Munich, an ALPHA Collaboration researcher, said:
“We have to keep them apart. We can’t just put our anti-atoms into an ordinary container. They have to be trapped or held inside a special magnetic bottle.”
While the experiment proves to be difficult, 194 atoms were said to be enough for the researchers to expose samples of antihydrogen with microwave energy burst of varying frequencies and see their reaction.
The patterns produced by the different elements through absorption and emission of their light at specific frequencies enabled physicists to observe with remarkable precision the hyperfine structure of the antimatter.
For the first time, researchers were able to capture the spectral lines of an antimatter using the technique spectroscopy. Spectral lines are said to be similar to ‘fingerprints.’ Every element has its own unique pattern.
“Spectroscopy is a very important tool in all areas of physics. We are now entering a new era as we extend spectroscopy to antimatter.
“With our unique techniques, we are now able to observe the detailed structure of antimatter atoms in hours rather than weeks, something we could not even imagine a few years ago,” says Jeffrey Hangst, spokesperson for the ALPHA experiment.
Currently, spectroscopy proves itself to be an effective technique that would play a significant role in further studying antimatter in the future. Hayden said:
“By studying the properties of anti-atoms we hope to learn more about the Universe in which we live. We can make antimatter in the lab, but it doesn’t seem to exist naturally except in miniscule quantities. Why is this? We simply don’t know. But perhaps antihydrogen can give us some clues.”