Welcome to Lawrence Livermore National Laboratory's Center for Accelerator Mass Spectrometry (CAMS) web site.

CAMS performs more than 25,000 accelerator mass spectrometry (AMS) measurements per year to identify the isotopic composition of substances. It is the world's most versatile and productive AMS facility. The research made possible by CAMS is diverse, and includes the following programs, which are vitally important to the Laboratory, the university community, and the nation:

• Archaeology
• Atmospheric chemistry
• Bioavailability and metabolisms of isotopes, toxic compounds, and nutrients
• Carbon-cycle dynamics
• Cell biology and macromolecular turnover
• Combustion mechanisms and alternative fuels
• Detection of signatures of nuclear fuel reprocessing for nonproliferation purposes
• Forensic dating
• Forensic reconstruction of Hiroshima and Chernobyl dosimetry
• Neotectonics
• Oceanic circulation
• Paleoclimatology
• Paleoseismology

Accelerator mass spectrometry (AMS) combines mass spectrometry with high-voltage potential to accelerate ions to velocities sufficient to eliminate molecular isobars. At CAMS, we combine a high intensity cesium-sputter source with a conventional low-energy mass spectrometer injection system as the front end of our system. Negative ions generated from solid targets are extracted, mass selected, and then sequentially injected into the accelerator.

In the accelerator, the ions are accelerated towards a high-positive terminal potential and stripper canal. The stripper may be either a thin metal foil or a region filled with a slightly higher pressure of an inert gas, such as argon. As the negative ions proceed through the stripper region, electrons are stripped off the individual ions and molecular isobars are destroyed. The terminal voltage is chosen to optimize the charge exchange as electrons are stripped from the negative ions. The resulting positive ions exit the accelerator tube and then proceed through the high-energy, mass-spectrometer end of the system. The magnets in the high-energy portion of the beam line mass-select based upon mass-to-charge ratios. For most applications, we use a gas-ionization detector that allows for individual atom counting and particle identification.

Explore this web site to learn more about CAMS's facilities, methods, research, staff, and publications.