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 detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>