Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

JLab Completes 100th Experiment

02.06.2004


The experiment, titled "Quark Propagation through Cold QCD Matter," began its run in December 2003 and wrapped up in early March. It probed Quantum Chromodynamics (QCD), a fundamental theory of particle physics that describes the interactions of quarks and gluons — the basic building blocks of matter. A property of QCD, called confinement, states that no quark can ever be found alone. Instead, quarks combine in pairs or triplets to make up larger particles. For instance, every proton and neutron contains three basic quarks.



"You never find a quark by itself, in isolation. That’s really a very bizarre thing and a huge mystery. So what happens when you try to get one quark alone?" asks Will Brooks, JLab Staff Scientist and experiment spokesperson.

Jefferson Lab’s accelerator is helping physicists answer that question. The electron beam is one of the few tools on Earth that can separate quarks. "You can’t pull quarks apart with your fingers, but you can collide something very energetic with a quark and try to knock it out. And we have a rather simple picture of what happens when you do that."


In this experiment, scientists essentially slam an electron into a single quark, knocking it out of the particle it was bound up in. But it doesn’t come out alone — the energy the quark absorbs in the collision is transformed into new clusters of quarks and gluons.

"If you could pull on a single quark, as it gets farther and farther away, the force between that quark and the others remains the same, but the energy you’re putting into that system to move the quark is getting higher and higher. So the farther away you pull, the more energy you’re stuffing in there. And you get so much energy stored up, that a new particle could be produced, because according to Einstein’s E=mc2, energy can be transformed into matter. And so a new particle just mysteriously pops out of the vacuum. And now you’ve got a brand new particle. And if you pull very hard for a very long distance, you can have many of these new particles appear."

Scientists hope that studying this process of creating new quark-based particles, called hadronization, reveals new information about quark confinement. And by studying the new quarks and gluons, experimenters seek to understand how they were created and what happened before they coalesced into new multi-quark particles.

"Normally, all you measure are the particles that come out, long after that other process [hadronization] is done. So the idea is to use the nucleus as a laboratory. If you knew everything about the nucleus, and then you initiated some process inside one that you want to study, then you could use your understanding of the nucleus to understand what’s going on."

To that end, the experiment used five different targets — composed of nuclei with different numbers of protons and neutrons. Deuterium, which holds the simplest nucleus containing both a proton and a neutron, was used, as well as carbon, iron, tin and lead.

Brooks says now that data collection is complete, the next step is to calibrate the data. "Once it’s calibrated and processed, we’ll know whether there’s something very unexpected. And we’ll have preliminary results around 6 months after that. We might have publishable results one to two years after that. It takes a long time."

In the meantime, the experimental team, comprised of CEBAF Large Acceptance Spectrometer (CLAS) Collaboration members, is looking to the future. Brooks says improved beam energies should provide even better data. "The CEBAF 12 GeV Upgrade would be a very fine place to do the ultimate experiment of this kind, and it’s in our plans."

Brooks says JLab’s 100th experiment was run concurrently with its 101st experiment: "Q2 Dependence of Nuclear Transparency for Incoherent ñ0 Electroproduction," a search for color transparency, another prediction of QCD. "In Hall B, you can do more than one experiment at a time. For instance, the first Hall B run had 13 experiments."

Jefferson Lab ran its first experiment in 1995. Titled "The Energy Dependence of Nucleon Propagation in Nuclei as Measured in the (e, e’p) Reaction," the experiment began its run in Hall C and was completed in December 1995.

Kandice Carter | JLab
Further information:
http://www.jlab.org/div_dept/dir_off/public_affairs/news_releases/2004/04100th.html

More articles from Physics and Astronomy:

nachricht A new force for optical tweezers awakens
19.06.2019 | University of Gothenburg

nachricht View of the Earth in front of the Sun
19.06.2019 | Georg-August-Universität Göttingen

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: Successfully Tested in Praxis: Bidirectional Sensor Technology Optimizes Laser Material Deposition

The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.

Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

A new force for optical tweezers awakens

19.06.2019 | Physics and Astronomy

New AI system manages road infrastructure via Google Street View

19.06.2019 | Information Technology

A new manufacturing process for aluminum alloys

19.06.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>