Scientist Christopher Lavelle of the Johns Hopkins University Applied Physics Laboratory, together with a team of researchers from the University of Maryland and the National Institute of Standards and Technology, has successfully shown that boron-coated vitreous carbon foam can be used in the detection of neutrons emitted by radioactive materials -- of critical importance to homeland security. Lavelle is lead author of the paper "Demonstration of Neutron Detection Utilizing Open Cell Foam and Noble Gas Scintillation" released today in the journal Applied Physics Letters.
Detecting neutrons is key to counterterrorism activities, such as screening cargo containers, as well as other vital applications in nuclear power instrumentation, workplace safety and industry. The demand for detectors has risen dramatically over the past decade while at the same time the usual detection material, helium-3, has become harder to obtain. An advantage of the approach outlined in the paper is that boron is abundant and relatively low cost compared to helium-3. The use of a coated foam, in particular, disperses the boron evenly throughout the detector volume, increasing efficiency by filling in otherwise empty space.
Lavelle and his colleagues' work builds on a series of experiments conducted with scientists at NIST and the University of Maryland that had demonstrated that a process called noble gas scintillation can be controlled and characterized precisely enough to detect the neutrons emitted by radioactive materials. Scintillation refers to a process where energetic particles produce flashes of light when passing through certain materials, in this case xenon gas. Sensitive light detectors record the rate at which these light flashes occur to measure the presence and intensity of neutrons in the environment.
In a follow-on experiment, the research team obtained samples of "carbon foam" coated with boron carbide and placed them in xenon gas. The boron-10 isotope in the coating readily absorbs neutrons. Following neutron absorption, energetic particles are released into the gas and create flashes of light. In this experiment, researchers determined that neutrons captured deep within the coated foam produce large enough flashes to be detected by light detectors outside the foam. Previously, there had been some doubt as to whether the light flashes would actually escape foam, or if the foam would completely shadow them from the light detector.
The next steps in the series of experiments include investigating other unique detector geometries, such as multiple layers of boron-coated thin films, the use of optically transparent neutron absorbers, and finalizing a design for a potential prototype detector.
Media contact: Gina Ellrich, 443-778-7796, Gina.Ellrich@jhuapl.edu
The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit http://www.
Gina Ellrich | EurekAlert!
New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State
Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy