Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Antimatter atoms ready for their close-up

07.02.2011
Controlling antihydrogen atoms using two different methods brings physicists closer to answering quantum and cosmic questions

Two international teams of physicists, including RIKEN researchers, have trapped and manipulated atoms made out of antimatter, in milestone experiments that should help to reveal why the substance is so rare in our Universe.

Since its existence was first predicted by physicist Paul Dirac in 1931, antimatter has become an increasingly common sight. The antiparticle of the electron, for example, is routinely used in positron emission tomography, a clinical imaging technique. Yet despite this routine use of isolated antimatter particles, making ‘anti-atoms’ is extremely difficult because matter and antimatter annihilate each other in a flash of energetic photons when they meet.

The simplest and most abundant atom in the universe—hydrogen—consists of a positive proton and an electron. Its opposite number, antihydrogen, contains a negative antiproton and a positron, and teaming the antiparticles without allowing them to touch any ordinary matter is a ticklish business.

In parallel research efforts, known as ALPHA and ASACUSA, the international teams of physicists have shown how to handle antihydrogen atoms in a way that will soon allow their properties to be investigated precisely, and compared with normal hydrogen.

Physicists are keen to make this comparison because one of the foundations of modern quantum physics—the charge, parity and time reversal symmetry theorem—states that hydrogen and antihydrogen should have identical energy levels, producing matching spectra when probed with light. But this also suggests that at the very beginning of the Universe, both matter and antimatter would have been created in equal quantities. So the fact that our Universe is almost entirely made of matter seems to contradict quantum theory, and poses a fundamental question about how the cosmos works.

Trapped in an asymmetric field

Researchers working on the ATHENA and ATRAP experiments at CERN, the European particle physics facility based in Geneva, Switzerland, first combined positrons and antiprotons to create cold antihydrogen in 2002. The ATHENA project evolved into ALPHA, which relies on electric and magnetic fields—a ‘magnetic bottle’, or Ioffe-Pritchard trap—to control, cool, and mix the particles, and to trap antihydrogen atoms.

“The challenge is the temperature of antihydrogen atoms,” says Yasunori Yamazaki of the RIKEN Advanced Science Institute in Wako, Japan, who is involved with both the ALPHA and ASACUSA experiments. Fast-moving antiprotons as hot as 100,000 kelvin must be chilled to less than 0.5 kelvin to form trappable antihydrogen.

In recent experiments, the ALPHA researchers collided about 30,000 antiprotons with electrons to cool them to roughly 200 kelvin in a cloud about 1.6 millimeters across. They cooled a separate pool of positrons by allowing the hotter particles to ‘evaporate’ away from the rest, leaving a 1.8 millimeter-diameter cloud of about two million particles at roughly 40 kelvin. The strong magnetic field containing the particles was shaped so that the particles collected in the center of the trap, and the researchers slowly coaxed the antiprotons towards the positrons by changing the electric field. After mixing for just a second, they removed any unreacted antiparticles from the trap.

About 0.2 seconds after the removal of antiprotons and positrons, the researchers opened the magnetic bottle to look for trapped antihydrogen atoms. Since antihydrogen atoms are neutral, any that formed were no longer controlled by the electric field. Those not cold enough to be trapped in the magnetic bottle drifted towards the sides of the trap, where they annihilated and formed exotic particles called pions, which were registered by silicon detectors. Studying the energy and the trajectory of the pions allowed the researchers to weed out any signals that had been produced by cosmic rays—high-energy particles from space. Overall, they found 38 atoms of antihydrogen from 335 experimental runs1.

Yamazaki hopes that antihydrogen could be trapped for much longer in future experiments, which would help efforts to study its properties. But “the strong magnetic field gradient of the magnetic bottle would make real high-resolution spectroscopy not straightforward,” he adds.

Synthesized in a symmetrical field

ASACUSA uses a different method of taming antihydrogen. It collects antiprotons and positrons in a cusp trap, which relies on symmetrical magnetic and electric fields, unlike ALPHA's asymmetrical fields. Recent experiments show that ASACUSA researchers can use the cusp trap to combine antiprotons and positrons to produce a beam of antihydrogen atoms2. This approach has unique advantages, says Yamazaki.

“First of all, we can extract antihydrogen atoms as an intensified beam in a magnetic-field free region, which enables high-resolution spectroscopy. Secondly, the temperature of the antihydrogen atoms can be much higher—say 10 kelvin—which makes it orders of magnitude more efficient to synthesize a usable number of antihydrogen atoms,” explains Yamazaki. “We think we can confirm the beam next year, and if everything goes well, we can also get some spectroscopic results for the first time,” he adds. ALPHA, too, is already making plans for its own laser spectroscopy measurements.

Improving supply

Both experiments could benefit from a new project at CERN, called ELENA, which can deliver lower-energy antiprotons. “We really hope this project will be approved as soon as possible,” says Yamazaki. This could provide a continuous supply of much larger numbers of chilled antiprotons for ALPHA and ASACUSA, which “should have a tremendous impact on both antihydrogen projects,” he notes.

Of both projects’ latest results, he adds: “I feel that these two achievements are really big milestones towards realizing low-energy antimatter physics for the first time.”

About the Researcher: Yasunori Yamazaki

Yasunori Yamazaki was born in Osaka, Japan, in 1949. He graduated from the Department of Physics, Osaka University, in 1973, received his master degree in 1975, and obtained his doctoral degree in 1978 from the Department of Applied Physics at the same institute. He was appointed research associate of the Tokyo Institute of Technology in 1978, associate professor of The University of Tokyo in 1988, and professor at the same university in 1993. He was jointly appointed as chief scientist at RIKEN in 1997. From 2010, he has held the title of distinguished senior scientist of RIKEN and professor emeritus of The University of Tokyo. His research interests are cold antimatter science with antihydrogen atoms as well as applications of beam physics to various fields of natural science, including living cell surgery, micromodification of liquid–solid interfaces and virtual x-ray spectroscopy of relativistic highly charged heavy ions channeling through crystalline targets.

Journal information

1.Andresen, G.B., Ashkezari, M.D., Baquero-Ruiz, M., Bertsche, W., Bowe, P.D., Butler, E., Cesar, C.L., Chapman, S., Charlton, M., Deller, A., et al. Trapped antihydrogen. Nature 468, 673–676 (2010).

2.Enomoto, Y., Kuroda, N., Michishio, K., Kim, C.H., Higaki, H., Nagata, Y., Kanai, Y., Torii, H.A., Corradini, M., Leali, M., et al. Synthesis of cold antihydrogen in a cusp trap. Physical Review Letters 105, 243401 (2010).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/hom/6504
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

nachricht Airborne thermometer to measure Arctic temperatures
11.01.2017 | Moscow Institute of Physics and Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>