New elements pop in, cousins may linger.

Two new elements, numbers 116 and 118, have winked briefly into existence during high-energy impacts inside a particle accelerator, scientists announced this week. The not-yet-confirmed findings may spark even more element discoveries this year, several researchers say, that may spill from the heavy end of the periodic table of elements like fruit from a cornucopia.

Out of that horn of plenty, experimenters later may pluck long-predicted, extraordinarily stable, superheavy isotopes, the findings suggest. Isotopes are versions of an element that differ only in their numbers of neutrons.

The discoveries are "really very exciting news," comments Sigurd Hofmann of GSI, the German center for heavy-ion research in Darmstadt. Experiments have begun there this week to attempt to duplicate and improve upon the results, he says.

Victor Ninov of Lawrence Berkeley (Calif.) National Laboratory led a team of government and university scientists in the recent experiments. By pummeling a lead target for more than 10 days with roughly a million trillion krypton ions, the team made three atoms of 118, which quickly decayed into 116, 114, and other elements.

Prevailing wisdom held that the approach wouldn't work because it involved hurling unusually heavy particles against the target. The team tried anyway, encouraged by the calculations of Robert Smolanczuk, a Fulbright scholar from the Soltan Institute for Nuclear Studies in Warsaw, Poland, who is working at the Berkeley lab.

"By golly, the miracle did happen. It's really exciting," says the lab's Albert Ghiorso.

Given the surprising success of the approach, Ken Gregorich, also of the Berkeley lab, expects researchers there, at GSI, or in Russia soon to fire krypton at bismuth to make element 119. Because 119 would decay into the yet-undiscovered 117, 115, and 113, science could gain four new elements in one fell swoop. "It will happen somewhere before the end of the year," Gregorich predicts.

In the Berkeley experiments, the isotopes of 116 and 118 lasted only about 1.2 milliseconds and 200 microseconds, respectively. Nonetheless, their lifetimes were long enough to indicate that current investigations are

converging on a cluster of exceptionally stable superheavy isotopes. Such isotopes may survive many years.

Heavy-element researchers say that this cluster inhabits an island of stability in a sea of short-lived isotopes.

The new discoveries follow closely upon the first sighting of element 114 by a Russian-American group (SN: 2/6/99, p. 85). That experiment was hailed as the first to reach the stability island.

"It's exciting, of course, because [the isotopes of 116 and 118 are] also on the edge of this superheavy element island," says Ron Lougheed of Lawrence Livermore (Calif.) National Laboratory, who was a member of the Russian-American team. The island may harbor "a whole new chemistry" that can be explored if its isotopes last long enough, he says.