Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Record-breaking detector may aid nuclear inspections

15.03.2006


Scientists at the Commerce Department’s National Institute of Standards and Technology (NIST) have designed and demonstrated the world’s most accurate gamma ray detector, which is expected to be useful eventually in verifying inventories of nuclear materials and detecting radioactive contamination in the environment.


Silicon chip built by NIST researchers with 16 tiny gamma ray detectors that may help nuclear inspectors improve analysis of plutonium and other radioactive materials. Each detector is one millimeter square. Image credit: National Institute of Standards and Technology


The data plots above show detection of gamma rays with specific energies. Arrows point to energies identified with the new detector that are difficult to detect in the red plot made with a conventional detector. Image credit: National Institute of Standards and Technology, National Nuclear Security Agency, Los Alamos National Laboratory



The tiny prototype detector, described today at the American Physical Society national meeting in Baltimore, can pinpoint gamma ray emissions signatures of specific atoms with 10 times the precision of the best conventional sensors used to examine stockpiles of nuclear materials. The NIST tests, performed with different forms of plutonium at Los Alamos National Laboratory,* also show the prototype greatly clarifies the complex X-ray and gamma-ray emissions profile of plutonium.

Emissions from radioactive materials such as uranium or plutonium provide unique signatures that, if accurately measured, can indicate the age and enrichment of the material and sometimes its intended purpose or origin.


The 1-square-millimeter (mm) prototype collects only a small amount of radiation, but NIST and Los Alamos researchers are collaborating to make a 100-sensor array that could be deployed in the field, perhaps mounted on a cart or in a vehicle.

"The system isn’t planned as a primary detection tool," says NIST physicist Joel Ullom. "Rather, it is intended for detailed analysis of material flagged by other detectors that have larger collection area but less measurement accuracy." An array could be used by inspectors to determine, for example, whether plutonium is of a dangerous variety, whether nuclear fuel was made for energy reactors or weapons, or whether what appears to be radium found naturally in the environment is actually explosive uranium.

"People at Los Alamos are very excited about this work," says Michael Rabin, a former NIST post-doc who now leads a collaborating team at Los Alamos. The Los Alamos National Laboratory operates and improves the capability to handle nuclear materials and sends scientists to participate in United Nations nuclear inspection teams.

An array of the new sensors might give inspectors new capabilities, such as enabling them to determine the plutonium content of spent reactor fuel without handling the fuel or receiving reliable information from the reactor’s operators. Plutonium content can indicate whether a reactor is being used to produce weapons or electrical power.

The gamma ray detector is a variation on superconducting "transition edge" sensor technology pioneered at NIST laboratories in Boulder, Colo., for analysis of X-rays (for astronomy and semiconductor analysis applications) and infrared light (for astronomy and quantum communications). The cryogenic sensors absorb individual photons (the smallest particles of light) and measure the energy based on the resulting rise in temperature. The temperature is measured with a bilayer of normal metal (copper) and superconducting metal (molybdenum) that changes its resistance to electricity in response to the heat from the radiation.

To stop gamma rays, which have higher energy than infrared light and X-rays, the sensors need to be topped with an absorbent material. A layer of tin, 0.25 mm thick, is glued on top of each sensor to stop the gamma rays. The radiation is converted to heat, or vibrations in the lattice of tin atoms, and the heat drains into the sensor, where the temperature change is measured. NIST researchers have developed microfabrication techniques to attach absorbers across an array.

Researchers expect the 100-detector array to measure 1 square centimeter in size. The NIST team has already developed multiplexed readout systems to measure the signals from large sensor arrays, and recent advances in commercial refrigeration technology are expected to allow pushbutton operation of the system without liquid cryogens.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics 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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>