Gary Kliewer, Los Alamos National Laboratory
(505) 665-2085
[email protected]
FOR RELEASE: 11:00 a.m. PST, MAR. 18, 1998
LOS ALAMOS COMBINES NEUTRON SCATTERING AND HIGH-FIELD MAGNET FOR MATERIALS SCIENCE TESTS
LOS ANGELES, March 18, 1998 -- Los Alamos National Laboratory researchers are building a device that combines the probing power of neutron scattering with insights from materials under high magnetic fields. A powerful magnet will surround samples targeted by the neutron beam at the U.S. Department of Energy's Los Alamos Neutron Science Center, creating a chance to investigate aspects of the structure of condensed matter that are otherwise impossible to study. The new device was described today (March 18) at the annual meeting of the American Physical Society. The $1.1 million magnet is scheduled to be in operation by the end of 1999. It will be available to university researchers. "This instrument will be unique in the world," said Robert Robinson, lead physicist for the project. "Our philosophy is that a pulsed magnet will work best with a pulsed neutron source. We will be able to look at the three- dimensional arrangements of the magnetism in solids at microscopic levels." The new station at LANSCE will send bursts of neutrons -- uncharged magnetic subatomic particles -- through samples of scientific and technological interest, such as the magnets used in motors and loud speakers. As some neutrons are scattered in telltale patterns by the magnetic elements in a sample, three-dimensional "maps" of the sample's atomic magnetic structure will appear. At the same time, the samples will be subjected to intense magnetic pulses firing twice a second. High magnetic fields are one of the most effective and noninvasive scientific tools to probe nature and explore basic science and new materials critical to modern technology. Magnetic field strength is measured in tesla. One tesla is about 20,000 times stronger than Earth's field. The magnet to be installed at LANSCE will reach 30 tesla, offering the most powerful combination of pulsed neutrons and pulsed magnetic field ever attempted. With this device, Los Alamos combines access to its linear accelerator and its unique expertise in materials science with its role as a branch of the National High Magnetic Field Laboratory. The NHMFL has been testing materials for the past year to overcome the considerable problem of building a magnet that can withstand the stress and heat created by such a strong magnetic pulse firing so rapidly. In a single day, the new magnet will endure the structural strain from more pulses than most high-field facilities experience in their operational lifetimes. Researchers have also designed a continuous water-cooled system to keep the magnet from overheating. Other high-field magnets are flushed with liquid nitrogen between pulses, generally requiring half an hour or more between shots. Researchers will use the magnet to study aspects of many magnetic-field- induced phase transitions for the first time. For instance, in some materials the individual atoms behave like little magnets, which alternate in direction from atom to atom. The magnet can align all the atoms, and the neutrons can simultaneously detect the detailed magnetic arrangement, in three dimensions, as the magnetic field is applied. This can be important for studying new permanent magnet materials, materials for the recording industry, new superconductors and other electronic sensors. The NHMFL is operated by a consortium of Los Alamos National Laboratory, the University of Florida and Florida State University, with user facilities in all three locations. While the Florida facilities concentrate on sustained magnetic fields and magnetic resonance imaging, Los Alamos focuses on high-intensity, pulsed magnetic fields. Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.
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