Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Pentaquark: The Strongest Confirmation to Date

26.01.2004


An international team of physicists has provided the best evidence to date of the existence of a new form of atomic matter, dubbed the “pentaquark.” The research team confirmed the existence of pentaquarks by using a different approach that greatly increased the rate of detection compared to previous experiments. The results are published as the cover story in today’s issue of the journal Physical Review Letters.



“The latest, and most conclusive evidence of this five-quark particle — the ‘pentaquark’ — could bring immense insight in understanding the laws and structure of universal matter in its most fundamental form,” said lead author Valery Kubarovsky, a Research Scientist at Rensselaer Polytechnic Institute in Troy, N.Y.

The research was carried out at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility (Jefferson Lab) by the CLAS (CEBEF Large Acceptance Spectrometer) collaboration, which consists of physicists from universities and laboratories in seven nations.


Nearly all matter on Earth is held in the nuclei of atoms. An atomic nucleus is composed of protons and neutrons, with the number of protons determining the chemical element. In the last four decades, physicists have discovered that these subatomic particles are composed of even smaller particles, called quarks, which are held together by a strong nuclear force called “glue.” Each proton and neutron is composed of three quarks, for example.

For years, scientists have predicted that five-quark particles also could exist under unusual conditions. Yet, no proof surfaced until late 2002 when a Japanese team announced its discovery of the pentaquark in particle-smashing experiments. When the researchers zapped carbon atoms with high-energy gamma rays, they observed that, after gamma ray photons “crashed” into the neutrons, a few neutrons “grew” into five-quark particles. The Jefferson Lab team then corroborated this finding using a deuteron target.

The team announced the initial discovery of a pentaquark on a proton target at an international physics conference in New York City in May 2003. The findings were soon corroborated by researchers at Bonn University in Germany. Kubarovsky presented the CLAS team’s results at the first conference on pentaquarks, hosted by Jefferson Lab in November 2003.

Still, the results of subsequent experiments by researchers globally have been mixed until now.

“Detection is difficult because we are unable to ‘see’ the pentaquark itself, which lives less than one hundredth of a billionth of a billionth of a second, before decaying into two separate particles,” said Paul Stoler, Rensselaer physics professor and chair of the Jefferson Lab Users Board of Directors. “But even the two-particle, tell-tale sign is difficult to detect because of the many irrelevant reactions, or ‘debris,’ that also occur in the same experiments.”

To limit the debris, CLAS team members searched for a simpler mode of production. Since they could not isolate a single neutron — stable neutrons cannot exist freely — they turned to the single proton as a target.

One proton makes up the entire nucleus of the simplest element known in the universe: hydrogen. In the experiment, the Jefferson Lab team liquefied the hydrogen at a temperature that reached a few degrees above absolute zero before zapping the element with gamma rays.

“Shifting our focus from neutrons to protons dramatically altered our results,” Kubarovsky said. “We strongly increased the previous success rates for detecting pentaquarks.”

According to CLAS researchers, further experimentation is needed to increase the pentaquark detection rate per particle explosion, to better understand the details of how the pentaquark is produced, and its internal characteristics. Several follow-up experiments will be conducted at Jefferson Lab within the next year.

“Consider that, out of several billion collisions, scientists have found a few dozen pentaquarks. We need to find at least a thousand events that result in the creation of pentaquarks to have more valuable information on the nature of this new state of matter,” Kubarovsky says. “Right now we have a sample of about 45, which is the most significant in the world.”

About Rensselaer

Rensselaer Polytechnic Institute, founded in 1824, is the nation’s oldest technological university. The school offers degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of research centers that are characterized by strong industry partnerships. The Institute is especially well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

Jodi Ackerman | Rensselaer PI
Further information:
http://www.rpi.edu/web/News/press_releases/2004/pentaquark.htm

More articles from Physics and Astronomy:

nachricht NASA's Fermi catches gamma-ray flashes from tropical storms
25.04.2017 | NASA/Goddard Space Flight Center

nachricht DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science 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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>