swings halfway around; the field
then becomes negative in front of the particle again, and again attracts
it. As the particle moves faster and faster it spirals outward in an
ever increasing circle, something like a tether ball unwinding from a
pole. The energies achieved would have seemed fantastic to earlier
scientists. The Bevatron, a modern offspring of the first cyclotron,
accelerates protons to 99.13% the speed of light, thereby giving them
6.2 billion electron volts (BeV).

Another instrument, the heavy-ion linear accelerator (Hilac),
accelerates ions as heavy as neon to about 15% the speed of light. It is
called a linear accelerator because it accelerates particles in a
straight line. Stanford University is currently (1963) in the process of
building a linear accelerator approximately two miles long which will
accelerate charged particles to 99.9% the speed of light.

But highly accelerated charged particles did not solve all of science's
questions about the inner workings of the nucleus.

In 1932, during the early search for more efficient ways to bombard
nuclei, James Chadwick discovered the neutron. This particle, which is
neutral in charge and is approximately the same mass as a proton, has
the remarkable quality of efficiently producing nuclear reactions even
at very low energies. No one exactly knowns why. At low energies,
protons, alpha particles, or other charged particles do not interact
with nuclei because they cannot penetrate the electrostatic energy
barriers. For example, slow positive particles pick up electrons, become
neutral, and lose their ability to cause nuclear transformations. Slow
neutrons, on the other hand, can enter nearly all atomic nuclei and
induce fission of certain of the heavier ones. It is, in fact, these
properties of the neutron which have made possible the utilization of
atomic energy.

With these tools, researchers were not long in accurately identifying
the missing elements 43, 61, 85, and 87 and more--indeed, the list of
new elements, isotopes, and particles now seems endless.

Element 43 was "made" for the first time as a result of bombarding
molybdenum with deuterons in the Berkeley cyclotron. The chemical work
of identifying the element was done by Emilio Segre and others then
working at Palermo, Sicily, and they chose to call it technetium,
because it was the element first made by artificial technical methods.

Element 61 was made for the first time from the fissi