Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Muon opportunists: Detecting the unseen with natural probes

21.02.2005


Earth is showered constantly by particles called muons that are created by cosmic rays, and clever scientists are finding ways to use them as probes of dense objects, including a massive pyramid in Mexico and volcanoes in Japan. American researchers also have proposed using the energetic particles to detect smuggled nuclear materials in vehicles and cargo containers.



Muons are formed when cosmic rays from deep space interact with the atmosphere. The particles, which strike earth’s surface at the rate of about 10,000 per square meter per minute, pass through large amounts of rock or metal with ease, yet their charge makes them easy to track. Researchers described several promising uses for muon radiography, as it is called, at the annual meeting of the American Association for the Advancement of Science (AAAS).

Arturo Menchaca-Rocha, director of the physics institute at the National Autonomous University of Mexico leads a team that is deploying muon detectors in a tunnel 26 feet below the base of the Pyramid of the Sun in Teotihuacan, about 30 miles northeast of Mexico City. The researchers hope to find any hidden burial chambers or other interior features of the massive pyramid, which is about 740 feet on each side and 215 feet tall. Linda Manzanilla, an archaeologist, is collaborating in the research effort.


Menchaca-Rocha’s team has been doing calibration of its instruments in preparation for taking a year’s data on muon flux through the pyramid. The team will be looking for any surplus of muons striking a portion of its detector array compared to the background flux. That would be an indication that voids in the pyramid have allowed more particles to pass through to the detectors than expected. The denser an object, the less likely the muons are to pass through. The detector consists of an array of thin wires immersed in a gas. A muon passing through the detector will create an electric charge in the gas that can be picked up as a localized current in the wires.

Menchaca-Rocha and his colleagues are following in the footsteps of the late Luis Alvarez, a Nobel physics laureate from the University of California, Berkeley. In the late 1960s, Alvarez placed muon detectors in a tunnel beneath the Great Pyramid of Chefren in Egypt in search of hidden burial chambers. None were discovered.

Another speaker at the meeting, Kanetada Nagamine of the KEK Muon Science Laboratory in Japan, reports on his team’s use of cosmic-ray muons to essentially take X-rays of the interior of volcanoes for hints of their eruption potential. Nagamine and his colleagues exploit the fact that some high-energy muons are traveling almost horizontally when they reach Earth’s surface. By placing multiple muon detectors around a mountain, the scientists can measure its shape and look for interior channels where molten rock may be rising, an early sign of a potential eruption. The research team has studied several volcanoes in Japan, including as assessment of the amount of molten rock within the crater of Mt. Asama.

Closer to home, scientists at Los Alamos National Laboratory in New Mexico have been exploring the use of muon radiography to detect illicit nuclear materials in cargo containers or trucks. Existing X-ray devices, already being deployed at ports and border crossings, cannot readily detect a well-shielded cache of highly enriched uranium, material that could be used in a devastating nuclear bomb. Newer scanning methods, using either dual-beam X-rays or neutrons, can pose radiation hazards to security personnel or illegal immigrants who might stow away in a container.

The muon detection method would involve passive monitoring of vehicles and cargo containers, with no artificial dose of radiation involved, according to the Los Alamos researchers. Truck drivers could remain in their vehicles while the scan is underway. "We measure the angle of a muon coming in and the angle going out," said Christopher Morris, a member of the Los Alamos team. "The change in angle tells us how much material was in the path."

It takes about 30 to 60 seconds to track enough muons for each cargo container screened, Morris said. There have been questions on whether the method is quick enough to allow prompt screening of large numbers of vehicles or cargo containers. "We’ve been fighting the general perception that there are not enough muons to measure," Morris said. "There really are." The team is developing better software techniques to allow rapid 3-dimensional images of the volumes being screened. They can reliably detect a small cube of uranium - about 4 inches on a side - within a large metal container full of sheep.

While the Los Alamos research is still in its developmental phase, Morris said he is confident a muon detectors, probably at an initial cost of about $1 million each, could make a significant contribution to efforts to tighten screening of vehicles and cargo containers entering the United States.

This AAAS session was organized by Rick Chartrand of the Los Alamos National Laboratory.

Earl Lane | EurekAlert!
Further information:
http://www.aaas.org
http://www.sciencemag.org

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>