Intense Pulsed Neutron Source

Argonne's Intense Pulsed Neutron Source (IPNS) is one of the world's most productive research facilities. It provides the nation's most reliable source of neutrons for the study of the atomic arrangements and motions in liquids and solids, a field known as condensed-matter physics. The IPNS has produced more than five billion pulses of neutrons since its construction in 1981.

Neutrons are useful for research because of their penetrating power. Neutrons can punch through several centimeters of steel, so IPNS experimenters can study materials inside pressure cells and furnaces. The penetration of X-rays and electrons are measured in ten-thousandths of a centimeter.

Neutrons are also uniquely useful for studying materials containing atoms of the lighter elements, like hydrogen and oxygen. Much of what is known about the atomic motion and structure of high-temperature superconductors - the oxides of various metals - was discovered at neutron sources. In addition, many of the advances in computer technology over the last few decades were made possible by neutron research into modern magnetic materials.

Unlike reactor-based neutron sources, the IPNS delivers a time-dependent range of neutron wavelengths with each pulse, an advantage in designing and conducting certain kinds of experiments.

In addition to magnetic materials and high-temperature superconductors, which lose all resistance to electricity when cooled with liquid nitrogen, IPNS experimenters also investigate polymers for many industrial applications and a wide range of materials for advanced energy technologies.

At the heart of the IPNS, inside a 20-foot-tall, steel-and-concrete "monolith," is a stack of enriched uranium disks about the size of an oatmeal box. This cylinder reacts to a proton beam by releasing an intense pulse of neutrons about one-third of a microsecond long. The neutrons travel through a beam line to instruments and experiments arrayed around the monolith. Readings from the instruments are relayed to a nearby data room, where experimenters can watch the results in "real time" and have their data stored electronically.

IPNS has operated with more than 95 percent reliability since it was first turned on in May 1981. The IPNS has led the world in many scientific and technical innovations for spallation sources, including uranium targets, cryogenic moderators and a wide variety of neutron scattering instruments including time-focused powder diffractometers, chopper spectrometers and reflectometers.

More than 4,000 experiments have been performed at IPNS. More than 3,000 scientists come to the facility for one or more experiments during any given year.

For more information about the IPNS and Argonne's other scientific user facilities, visit the following Web pages:

IPNS home page

Scientific facilities — National user facilities and other resarch facilities that are available for use by qualified scientists

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