nickel foil, enclosed
in a helium-filled container, and placed in the heavy-ion linear
accelerator (Hilac) beam. Positively charged atoms of element 102 are
knocked off the foil by the beam, which is of carbon-12 or carbon-13
nuclei, and are deposited on a negatively charged conveyor apron. But
element 102 doesn't live long enough to be actually measured. As it
decays, its daughter product, {100}Fm<250>, is attracted onto a charged
aluminum foil where it can be analyzed. The researchers have decided
that the hen really did come first: they have the egg; therefore the hen
must have existed. By measuring the time distance between target and
daughter product, they figure that the hen-mother (element 102) must
have a half-life of three seconds.

[Illustration: Fig. 4. The experimental arrangement used in the
discovery of element 102.]

In an experiment completed in 1961, researchers at the University of
California at Berkeley unearthed similar "footprints" belonging to
element 103 (named lawrencium in honor of Nobel prizewinner Ernest O.
Lawrence). They found that the bombardment of californium with boron
ions released [alpha] particles which had an energy of 8.6 MeV and
decayed with a half-life of 8 +- 2 seconds. These particles can only be
produced by element 103, which, according to one scientific theory, is a
type of "dinosaur" of matter that died out a few weeks after creation of
the universe.

The half-life of lawrencium (Lw) is about 8 seconds, and its mass number
is thought to be 257, although further research is required to establish
this conclusively.

Research on lawrencium is complicated. Its total [alpha] activity
amounts to barely a few counts per hour. And, since scientists had the
[alpha]-particle "footprints" only and not the beast itself, the
complications increased. Therefore no direct chemical techniques could
be used, and element 103 was the first to be discovered solely by
nuclear methods.[A]

For many years the periodic system was considered closed at 92. It has
now been extended by at least eleven places (Table I), and one of the
extensions (plutonium) has been made in truckload lots. Its production
and use affect the life of everyone in the United States and most of the
world.

Surely the end is again in sight, at least for ordinary matter, although
persistent scientists may shift their search to the other-world "anti"
particles. These, too, will call for very special techniques for
detecti