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PULSTAR Reactor (Image 1)

July 13, 2010
The PULSTAR reactor at North Carolina State University produces the world's most intense low-energy positron beam. Through the use of this National Science Foundation Major Research Instrumentation program-funded instrument, researchers will have better measurements of a material's porosity to improve the development of nano materials and nanotechnology. [See related image Here.] More about this Image Anti-matter, no longer the stuff of Star Trek, will improve the development of nanomaterials and nanotechnology. With funding from the National Science Foundation, a team of researchers from North Carolina State University, the University of Michigan and Oak Ridge National Laboratory have constructed a low-energy positron beam at the PULSTAR nuclear reactor with the highest positron output of any such facility worldwide. Positrons have the same mass as electrons, but have a positive instead of negative change, and are the antiparticle of electrons. Positrons are generated using the intense radiation in the vicinity of the reactor core. Ayman Hawari, associate professor of nuclear engineering and director of the Nuclear Reactor Program at North Carolina State, reports positron output of over 600 million positrons per second. "These numbers are two orders of magnitude higher than those available using regular lab sources and exceed intensities currently reported by other international facilities," he says. Once the stuff of science fiction, these anti-matter, or positron, beams have a multitude of uses in nanoscience and materials engineering because of the positron's ability to gravitate toward and get trapped in material defects or pores with sizes as small as a single atom. Positrons are used to detect damage from radiation in nuclear reactors and are impacting the emerging field of nanoengineered materials where nanometer-sized voids control properties such as he dielectric constant in microelectronic devices and hydrogen storage in fuel cells. An intense positron beam means that researchers will have better measurements of a material's porosity, especially in high-tech thin film applications where traditional techniques falter. The PULSTAR Reactor is a 1 Megawatt pool-type research reactor with four percent enriched, pin-type fuel consisting of uranium dioxide pellets in zircaloy cladding. This fuel gives the PULSTAR Reactor response characteristics that are very similar to commercial light water power reactors. The PULSTAR has a variety of irradiation facilities used for teaching and analytical services. Neutron Activation Analysis (NAA) is provided to academic institutions, federal and state agencies, and commercial companies across the country. Fixed beam facilities are used for prompt neutron capture gamma analysis and neutron radiography. Training services in radiation measurements and isotopic analysis are also provided. Funding for PULSTAR was provided by a grant from the National Science Foundation's Major Research Instrumentation program, a federal investment in state-of-the-art research instrumentation at U.S. higher education, research museums, and non profit research organizations. [Story written for LiveScience by Steve Buhneing, National Science Foundation.] (Date of Image: 2006)


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