|
Physicists: After 30 years of study, rare particle confirms prediction
March 11, 2008GAINESVILLE, Fla. - High-energy physicists devoted to recreating the conditions at the beginning of the universe have for the first time observed a new way to produce those basic particles of atoms, protons and neutrons.
Confirming a decades-old prediction, the physicists with the CLEO collaboration say they observed a rare and extremely short-lived subatomic particle with the unusual name of "charmed-strange meson" decay into a proton and anti-neutron.
Detection of the event, which the collaboration made public Sunday at http://arxiv.org/, was attributed to John Yelton, a physicist at the University of Florida, one of many institutions that are part of the CLEO collaboration.
"It's the sort of thing that, for many years, people have known should happen," Yelton said. "What we have done is show that it does, and how often."
The Cornell Electron Storage Ring accelerator, or CESR, collides electrons with positrons at energies ranging from 3 to 5 billion electron volts - producing many short-lived, elementary and rare particles of interest to physicists. CLEO, the large experimental detector designed to detect the accelerator collisions, is a joint project of nearly two dozen institutions in the U.S., Canada and England.
Among the products of the CESR collisions are the charmed-strange mesons, which exist for less than one-trillionth of a second before decaying into other more stable particles. Although charmed mesons have been studied for 30 years, no one had ever observed one decaying into a proton or neutron, as theory had predicted. This is notable because about 10 percent of all the collisions in the accelerator produce protons and neutrons.
Yelton did not detect the anti-neutron directly but rather inferred its presence from data on energy and momentum of other particles.
All told, he found 13 instances of charmed-strange mesons decaying into protons and anti-neutrons, retrieving and identifying those events from data on millions and millions of different collisions and their aftermaths.
Yelton based his analysis on techniques developed at Syracuse University for the detection of two other types of rare subatomic particles, a muon and invisible neutrino.
"Professor Yelton did an extraordinary job of applying our techniques to a new area and extracted an excellent result in record time," said Sheldon Stone, co-spokesman for CLEO and the physics professor at Syracuse who, with graduate student Nabil Meena, first developed the techniques. "This is what working together in an experiment is all about."
David Asner, a physicist with Carleton University and CLEO's other co-spokesperson, said the observation will contribute much to theoretical work on particle decay.
"Observation of these rare decays has the promise of increasing our understanding of the underlying mechanisms of how the world is put together," he said.
When CLEO was first started in 1979, CESR was among the highest energy accelerators operating at the time. More recent accelerators, such as the Tevatron at Fermilab in Chicago and the soon-to-be-completed Large Hadron Collider in Switzerland, operate at far higher energies. Most public attention is focused on research in these colliders - research aimed at, among other things, observing the so-called "God" particle, the Higgs boson.
Yelton said the latest result shows there remains much to be learned from collisions at lower energy in lower energy colliders. "It highlights the fact that there is still physics to be done at lower energy accelerators," he said.
The CLEO collaboration has also submitted a paper on the discovery to the journal Physics Review Letters.
The National Science Foundation funded the bulk of the CESR hardware and operations. The research is funded by the NSF, the U.S. Department of Energy, the Natural Sciences and Engineering Research Council of Canada and the U.K. Science and Technology Facilities Council.
University of Florida
"It's the sort of thing that, for many years, people have known should happen," Yelton said. "What we have done is show that it does, and how often."
The Cornell Electron Storage Ring accelerator, or CESR, collides electrons with positrons at energies ranging from 3 to 5 billion electron volts - producing many short-lived, elementary and rare particles of interest to physicists. CLEO, the large experimental detector designed to detect the accelerator collisions, is a joint project of nearly two dozen institutions in the U.S., Canada and England.
Among the products of the CESR collisions are the charmed-strange mesons, which exist for less than one-trillionth of a second before decaying into other more stable particles. Although charmed mesons have been studied for 30 years, no one had ever observed one decaying into a proton or neutron, as theory had predicted. This is notable because about 10 percent of all the collisions in the accelerator produce protons and neutrons.
Yelton did not detect the anti-neutron directly but rather inferred its presence from data on energy and momentum of other particles.
All told, he found 13 instances of charmed-strange mesons decaying into protons and anti-neutrons, retrieving and identifying those events from data on millions and millions of different collisions and their aftermaths.
Yelton based his analysis on techniques developed at Syracuse University for the detection of two other types of rare subatomic particles, a muon and invisible neutrino.
"Professor Yelton did an extraordinary job of applying our techniques to a new area and extracted an excellent result in record time," said Sheldon Stone, co-spokesman for CLEO and the physics professor at Syracuse who, with graduate student Nabil Meena, first developed the techniques. "This is what working together in an experiment is all about."
David Asner, a physicist with Carleton University and CLEO's other co-spokesperson, said the observation will contribute much to theoretical work on particle decay.
"Observation of these rare decays has the promise of increasing our understanding of the underlying mechanisms of how the world is put together," he said.
When CLEO was first started in 1979, CESR was among the highest energy accelerators operating at the time. More recent accelerators, such as the Tevatron at Fermilab in Chicago and the soon-to-be-completed Large Hadron Collider in Switzerland, operate at far higher energies. Most public attention is focused on research in these colliders - research aimed at, among other things, observing the so-called "God" particle, the Higgs boson.
Yelton said the latest result shows there remains much to be learned from collisions at lower energy in lower energy colliders. "It highlights the fact that there is still physics to be done at lower energy accelerators," he said.
The CLEO collaboration has also submitted a paper on the discovery to the journal Physics Review Letters.
The National Science Foundation funded the bulk of the CESR hardware and operations. The research is funded by the NSF, the U.S. Department of Energy, the Natural Sciences and Engineering Research Council of Canada and the U.K. Science and Technology Facilities Council.
University of Florida
Particles News and Current Particles Events RSSInvisible waves shape continental slope
A class of powerful, invisible waves hidden beneath the surface of the ocean can shape the underwater edges of continents and contribute to ocean mixing and climate, researchers from The University of Texas at Austin have found.
Metals Shape Up with a Little Help from Friends
For 5,000 years the only way to shape metal has been by the "heat and beat" technique. Even with modern nanotechnology, metalworking involves carving metals with electron beams or etching them with acid.
Physicists create millimeter-sized 'Bohr atom'
Nearly a century after Danish physicist Niels Bohr offered his planet-like model of the hydrogen atom, a Rice University-led team of physicists has created giant, millimeter-sized atoms that resemble it more closely than any other experimental realization yet achieved.
Super atoms turn the periodic table upside down
Researchers at Delft University of Technology (TU Delft) in The Netherlands have developed a technique for generating atom clusters made from silver and other metals. Surprisingly enough, these so-called super atoms (clusters of 13 silver atoms, for example) behave in the same way as individual atoms and have opened up a whole new branch of chemistry. A full account can be read in the new edition of TU Delft magazine Delft Outlook.
Bee disease a mystery
Scientists are one step closer to understanding the recent demise of billions of honey bees after making an important discovery about the transmission of a common bee virus.
New efficiency benchmark for dye-sensitized solar cells
In a paper published online June 29 in the journal Nature Materials, EPFL professor Michael Graetzel, Shaik Zakeeruddin and colleagues from the Changchun Institute of Applied Chemistry at the Chinese Academy of Sciences have achieved a record light conversion efficiency of 8.2% in solvent-free dye-sensitized solar cells.
Air monitoring helps anticipate possible ecosystem changes
When rain settles the atmosphere and brings air pollutants to the ground, it can have a lasting effect on ecosystems, sometimes hundreds of miles away, according to a Texas AgriLife Research agricultural engineer.
Silicon photonic crystals key to optical cloaking, researchers say
In computer simulations, the researchers have demonstrated an approximate cloaking effect created by concentric rings of silicon photonic crystals. The mathematical proof brings scientists a step closer to a practical solution for optical cloaking.
Lavas from Hawaiian volcano contain fingerprint of planetary formation
Hikers visiting the Kilauea Iki crater in Hawaii today walk along a mostly flat surface of sparsely vegetated basalt. It looks like parking lot asphalt, but in November and December 1959, it emitted the orange glow of newly erupted lava.
A promising step towards more effective hydrogen storage
An international research team led by Swedish Professor Rajeev Ahuja, Uppsala University, has demonstrated an atomistic mechanism of hydrogen release in magnesium nanoparticles - a potential hydrogen storage material. The findings have been published in the online edition of Proceedings of the National Academy of Science (PNAS).
More Particles News Articles
 | Blasphemy by Douglas Preston |
 | Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions by Lisa Randall |
 | Nuclear Weapons: What You Need to Know by Jeremy Bernstein |
 | Deep Down Things: The Breathtaking Beauty of Particle Physics by Bruce A. Schumm |
 | All About Particles: A Handbook of Japanese Function Words (Power Japanese Series) (Kodansha's Children's Classics) by Naoko Chino |
 | The Elementary Particles by Michel Houellebecq, Frank Wynne |
 | Schaum's Outline of Engineering Mechanics by E. W. Nelson, Charles L. Best, William G. McLean |
 | The Trouble With Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next by Lee Smolin |
 | Classical Dynamics of Particles and Systems by Stephen T. Thornton, Jerry B. Marion |
 | Schaum's Outline of Quantum Mechanics (Schaum's) by Eliahu Zaarur, Phinik Reuven |
| © 2008 BrightSurf.com |