True muonium was first theorized more than 50 years ago, but until now no one had uncovered an unambiguous method by which it could be created and observed.
"We don't usually work in this area, but one day we were idly talking about how experimentalists could create exotic states of matter," says SLAC theorist Stanley Brodsky, who worked with Arizona State's Richard Lebed on the result. "As our conversation progressed, we realized 'Gee…we just figured out how to make true muonium.'"
True muonium is made of a muon and an anti-muon, and is distinguished from what's also been called "muonium" — an atom made of an electron and an anti-muon. Both muons and anti-muons are created frequently in nature when energetic particles from space — cosmic rays — strike the Earth's atmosphere. Yet both have a fleeting existence, and their combination, “true muonium,” decays naturally into other particles in a few trillionths of a second. This makes observation of the exotic atom quite difficult.
“The true muonium system is unique,” says Lebed, an associate professor in ASU’s Department of Physics in the College of Liberal Arts and Sciences.
“It’s the smallest possible atom whose physics is determined by electricity and magnetism, The same forces that hold ordinary atoms together; but it’s 100 times smaller,” Lebed says. “I was astonished to discover not only that no one has ever produced true muonium atoms, but moreover that the methods we proposed just off-the-cuff turned out to be both novel and immediately doable.”
In a paper published May 26 in Physical Review Letters — “Production of the Smallest QED Atom: True Muonium (µ+µ-) — Brodsky and Lebed describe two methods by which electron-positron accelerators could detect the signature of true muonium's formation and decay.
In the first method, an accelerator's electron and positron beams are arranged to merge, crossing at a glancing angle. Such a collision would produce a single photon, which would then transform into a single true muonium atom that would be thrown clear of the other particle debris. Because the newly created true muonium atoms would be traveling so fast that the laws of relativity govern, they would decay much slower than they would otherwise, making detection easier.
In the second method, the electron and positron beams collide head-on, producing a true muonium atom and a photon, tangled up in a cloud of particle debris. Yet simply by recoiling against each other, the true muonium and the photon would push one another out of the debris cloud, creating a unique signature not previously searched for.
"It's very likely that people have already created true muonium in this second way," Brodsky says. "They just haven't detected it."
In their paper, Lebed and Brodsky also describe a possible but more difficult means by which experimentalists could create “true tauonium,” a bound state of a tau lepton and its antiparticle. The tau was first created at SLAC's SPEAR storage ring, a feat for which SLAC physicist Martin Perl received the 1995 Nobel Prize in physics.
“Once you make some of these atoms, you can study their detailed structure using incredibly fast laser pulses,” says Lebed. “It makes for a truly natural interdisciplinary project combining particle physics, atomic physics and cutting-edge optics.”
Brodsky attributes their finding to a confluence of events: various unrelated lectures, conversations and ideas over the years, pieces of which came together suddenly during his conversation with Lebed.
"Once you pull all of the ideas together, you say 'Of course! Why not?' That's the process of science — you try to relate everything new to what you already know, creating logical connections," Brodsky says.
Now that those logical connections are firmly in place, Brodsky says he hopes that one of the world's colliders will perform the experiments he and Lebed describe, asking, "Who doesn't want to see a new form of matter that no one's ever seen before?"
SLAC National Accelerator Laboratory is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science.SOURCES:
Carol Hughes | Newswise Science News
Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences
Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy