Number 11 (Story #3), December 3, 1990 by Phillip F. Schewe and Ben Stein A PROTON ACCELERATOR FOR CANCER THERAPY was recently installed at the Loma Linda University Medical Center in southern California. The $30-million clinical instrument, a direct descendent of accelerators used in particle physics research, is presently the world's most costly medical machine. Protons--unlike x rays, which do not stop once they reach the tumor--give up their energy mostly at the tumor site, where they help to kill tumor cells, while doing much less damage to surrounding tissue. (Scientific American, December 1990.)