LANSCE builds on 2001 successes as it readies for new run

As researchers at the world’s most powerful linear accelerator prepare for the upcoming run cycle, they look back on a successful 2001 run cycle that produced scores of experimental results for basic and defense science, built key new facilities and instruments and set records for operating efficiency.

These are remarkable achievements for the venerable Los Alamos Neutron Science Center, whose 800-million-electron-volt accelerator celebrates its 30th birthday next month.

LANSCE’s unique value to the nation is found in the breadth of science that can be done there. Scientists come to LANSCE to study and make use of neutrons over the largest energy range in the world to solve a broad variety of issues in nuclear science, condensed matter physics, material science and nuclear weapon physics.

“Last year’s run cycle at LANSCE was an outstanding success,” said LANSCE Division Leader Paul Lisowski. “We’re excited about both the large number and high quality of proposals for experiments in this summer’s running period. Response from the basic and applied research communities shows that after nearly 30 years of operation, LANSCE is still one of the world's premier research facilities.”

Recently completed analyses of the seven-month, round-the-clock run cycle for 2001 showed LANSCE achieved 92 percent operational efficiency, far better than any previous run cycle, with significantly fewer long outages. The 92-percent figure measures the amount of time the accelerator delivered beam to its many users, taking into account scheduled maintenance and replacements. Generally, large accelerators and associated target stations operate at about 85-percent efficiency.

About 250 users ran more than 200 experiments at LANSCE during 2001, many of them from top universities and from industry. Their work has resulted in or will lead to dozens of publications and doctoral dissertations.

“LANSCE has once again shown its value to the international scientific community while delivering on its commitment to its major sponsor, the National Nuclear Security Administration,” Lisowski said. “The quality of research done by our users proves LANSCE’s value as a magnet facility to attract young scientists who will reinvigorate our fundamental research and national security work.”

LANSCE has always attracted an extensive and diverse community of outside users from industry, universities, other government laboratories and foreign research institutions, providing a base for collaboration and scientific advance, Lisowski said.

The LANSCE user facility comprises the half-mile-long proton accelerator, a proton storage ring, production targets at the Manuel Lujan Jr. Neutron Scattering Center, the Weapons Neutron Research Facility and a variety of associated experimental areas and spectrometers. Both the Lujan Center, which provides low-energy neutrons, and the WNR, which provides high-energy neutrons, are designated by the Department of Energy as National User Facilities. At the Lujan Center and WNR, defense and academic researchers can use 18 separate instruments simultaneously.

“By providing an exciting experimental tool to address basic science and stockpile issues, we are continuing to attract early-career scientists who bring fresh approaches to Los Alamos National Laboratory’s mission,” Los Alamos Director John Browne recently told Congress.

During 2001, researchers at LANSCE used new and existing instruments to do important science and seek solutions to problems that affect national security.

Among those were work on a new nuclear physics instrument at the Lujan Center’s DANCE, the Detector for Advanced Neutron Capture Experiments. Using the instrument, astrophysicists are studying how heavy elements are made in stars, and weapons designers and engineers are analyzing past nuclear test data to improve their understanding of how robust the nation’s nuclear stockpile is. Their work ultimately will help improve the sophisticated, three-dimensional computer codes that integrate the past test data with new fundamental experiments to provide full-physics simulations of weapons phenomena.

Another major breakthrough at LANSCE was a new technique for production of ultra-cold neutrons that can be kept bottled up and studied to provide clues to the fundamental nature of matter and the origins of the universe. Construction has begun on a facility to take advantage of the new technique.

Laboratory researchers and industrial engineers used Lujan Center instruments to study the molecular fundamentals of creep — deformations or changes in the shape of metals or alloys caused by constant stress, pressures or high temperatures. Their findings could lead to machine tools that last longer and make even better drill bits for millions of home handymen.

Using the Germanium Array for Neutron-Induced Excitations, or GEANIE, researchers made the first accurate measurement over a wide energy range of the cross section, or probability of reaction, linking two key isotopes of plutonium: plutonium 239, the isotope used in nuclear weapons, and plutonium 238. By recreating this neutron reaction experimentally at LANSCE’s Weapons Neutron Research Facility and combining their measurements of gamma rays produced from plutonium 238 with detailed theoretical models, they were able to use past nuclear test data to improve their understanding of nuclear weapons performance.

Researchers from LANSCE and the Physics (P) and Dynamic Experimentation (DX) divisions ran dozens of experiments using proton beams for radiography in 2001, providing new insights into the behavior of nuclear weapon components and metals at high temperatures and pressures.

Nearing completion at LANSCE is the Isotope Production Facility, funded by DOE’s Office of Nuclear Energy, which will produce a variety of short-lived isotopes for research, medical diagnosis and therapy, including isotopes used with Positron Emission Tomography to pinpoint.