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National Museum of American History Acquires Wasserburg Mass Spectrometer

September 11, 2008
The Smithsonian’s National Museum of American History has acquired a Wasserburg mass spectrometer, completed in 1968 by Professor Gerald J. Wasserburg of the California Institute of Technology. Donated by Wasserburg and the California Institute of Technology through Chairman of the Division of Geological and Planetary Sciences Kenneth Farley, the mass spectrometer will join the museum’s History of Modern Physics collection.

One of the most versatile and widely used scientific instruments today, a mass spectrometer separates atoms of a small sample according to their atomic mass. The Wasserburg mass spectrometer is the first fully digital mass spectrometer with computer-controlled magnetic field scanning and rapid switching. The instrument was developed and built to obtain high-precision isotopic measurements from lunar samples acquired by the Apollo missions, earning it the nickname “Lunatic I.”

“The Wasserburg mass spectrometer is an object of high scientific and historical significance,” said Museum Director Brent D. Glass. “The addition of this device to our Modern Physics collection helps the museum represent the ingenuity and success of American science in the 20th century.”

The essential parts of the instrument are an ion source, a curved tube passing through the field of an electromagnet and a detector. These parts, along with auxiliary equipment such as vacuum pumps, make up an assembly seven feet long and weighing more than a ton. The donation also consists of original engineering drawings and data log books, full photo-documentation of the instrument’s construction and other documentary material.

The National Museum of American History collects, preserves and displays American heritage in the areas of social, political, cultural, scientific and military history. After a two-year renovation and a dramatic transformation, the museum will shed new light on American history. A grand reopening festival is scheduled for Nov. 21, 2008. To learn more about the museum and its renovation, check For Smithsonian information, the public may call (202) 633-1000, (202) 633-5285 (TTY).