Columbia’s Cyclotron Passing into History

The cyclotron that has resided in Pupin for the last seventy years (the first one built in the United States) is about to breath its last breath. Space is needed to house equipment for the new Northwest Science Building next to Pupin. The cyclotron was constructed by John Ray Dunning in 1936 and in 1940, Dunning’s team verified the claim by German physicists (two years earlier) of achieving nuclear fission in uranium.  They further showed that it was the comparatively rare uranium-235 that was fissile, not the abundant uranium-238. Dunning’s team also developed the gaseous diffusion method for separating the two isotopes, which was critical to the Manhattan project to develop the atomic bomb.

After a very long and useful life, the cyclotron was retired in 1965; some pieces were sent to the Smithsonian Institute, but most of the carbon-steel electromagnet weighing over 30 tons remains in Pupin.  During the operation of the cyclotron the magnets became radioactive by activation but now any remaining radioactivity is very small.

cy1 cy2

Left: Recent photo of the Cyclotron in Pupin (2007).
Right: Joe Ray Dunning, Enrico Fermi, and Dana P. Mitchell next to the Cyclotron (late 1930’s).

Recycling Program to Expand

Look for a new recycling station in the lobby of Lerner Hall later this Fall. The recycling station will enable diversion of additional waste from dumpsters and landfills: materials intended for re-use in the community and household items containing materials that are potentially environmentally hazardous.

Item selected for reuse include:

  1. books, and
  2. intact, functioning electronics

Items containing hazardous materials and selected for collection and recycling are:

  1. compact fluorescent lamps (CFLs) containing mercury,
  2. small used electronics containing lead and potentially other hazardous metals, and
  3. batteries containing a wide variety of hazardous metals and corrosive chemicals.

Batteries, in particular, should be collected for recycling due to their widespread use and potential hazards to the environment. Since 2002, CUMC has been successful in recycling batteries in 45 receptacles located throughout campus. Following this model, EH&RS/EH&S will be launching additional battery collection containers at the Morningside campus. Locations for the new battery collection include:

        • B-230 near the Service Center
        • CEPSER lobby
        • Fairchild 7th floor                                 
        • Havemeyer 3rd floor
        • Mudd 4th floor
        • Public Safety Office in Low Library
        • Pupin lobby  

Please help us protect the environment by properly handling these items at the end of their useful life.  For more information on reuse, recycling or environmental issues, please visit: or

If you have additional ideas for reuse or recycling, please send your suggestions to:

Environmental Health & Radiation Safety /Environmental Health & Safety


Medical Center
630 West 168th Street, Mailbox #8
New York, NY  10032
Phone:  (212) 305-6780

Morningside Campus
S.W. Mudd Building, Suite 350
New York, NY  10027
Phone:  (212) 854-8749

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