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 Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>