Los Alamos Neutron Science Center (LANSCE)
In October 1995, with the closeout of the nuclear physpics program and the increased need for neutron research, Los Alamos National Laboratory refocused the mission of its linear accelerator complex. The new mission calls for the development and use of spallation neutron sources for research and applications. As a result, the accelerator complex formerly known as the Los Alamos Meson Physics Facility (LAMPF) is now called the Los Alamos Neutron Science Center (LANSCE). LANSCE, an acronym that formerly referred to the Manuel Lujan Jr. Neutron Scattering Center (now the Lujan Center), comprises a high-power, 800-MeV proton linear accelerator (linac); a Proton Storage Ring (PSR); neutron production targets at the Lujan Center and the Weapons Neutron Research (WNR) facility; a proton radiography facility; a high-power materials irradiation area called the Los Alamos Spallation Effects Facility (LASEF); an isotope production facility (IPF); and a variety of spectrometers.
LANSCE has two spallation neutron sources: the Manuel Lujan Jr. Neutron Scattering Center and the Weapons Neutron Research facility. Together they provide neutrons over an unprecedented range of energies—extending from sub-millielectronvolts to hundreds of megaelectronvolts—that are used for both neutron scattering and nuclear physics research. In addition, LANSCE provides protons for radiography of dynamically evolving systems as well as for materials irradiation and isotope production. Users of the facility span a broad spectrum of institutions in the U.S. and abroad and scientific disciplines.
What is Neutron Production?
The spallation process occurs when protons strike heavy-metal targets such as tungsten and drive neutrons from the nuclei of the target atoms. For the 800-MeV proton beams used at LANSCE, about 20 neutrons per proton are ejected. The short, highly intense bursts of spallation neutrons are used in neutron scattering and nuclear science experiments. The neutrons produced have energies up to hundreds of million electronvolts, which are the right energies for nuclear physics experiments at WNR and some experiments at the Lujan Center.
As a national facility for defense and civilian research in radiography, nuclear science, and condensed-matter science, LANSCE hosts scientists from universities, industry, the Laboratory, and other research facilities from around the world. Scientists may apply for beam time by completing a proposal, which is subjected to appropriate peer review before beam time is granted. Once beam time is granted, the experiment is reviewed for technical and safety issues. Information about LANSCE and a blank proposal form are available on the LANSCE Web Site.
Most of the flight paths at the Lujan Center are equipped with spectrometers for determining the atomic, molecular, and magnetic structures as well as the vibrational and magnetic excitations of materials. Of the sixteen flight paths, which currently provide seventeen independent neutron beams, seven have instruments for condensed-matter science and engineering, three are used for nuclear science research, and the remainder are being instrumented.
At the WNR facility, high-energy, unmoderated neutrons and protons are used for basic and applied research in nuclear science and weapons-related measurements. The WNR facility consists of two target areas: Target 2 and Target 4, and their associated flight paths. The neutron beams produced at WNR complement those produced at the Lujan Center because they are of much higher energy and have shorter pulse duration. With both capabilities, LANSCE is able to deliver neutrons with energies ranging from small fractions of an electron volt to 800 MeV.
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