The injector will produce experimental beams by the end of 1996. This process would be extremely useful for studying nuclear reactions with isotopes whose half-lives may be just fractions of a second. Visiting scientists were involved in more than 90 percent of the experiments on the machine. Argonne physicists and scientists from Northwestern University, the University of Wisconsin and the Hebrew University in Jerusalem have succeeded in simulating some of the processes that occur in star-destroying explosions called supernovae, answering a fundamental question about how the heavier elements are formed. Lighter elements form in cores of stars as their fusion fires quietly light the night sky.
Young stars convert hydrogen to helium, a reaction that liberates vast amounts of heat.
When the hydrogen has been used up, stars begin fusing helium to lithium, and so on up the periodic table. But the process ends with element 26 - iron won't undergo fusion spontaneously at the temperatures inside normal stars. Stars like our sun will just cool off slowly. But much larger stars can explode in a supernova that can outshine an entire galaxy for several days. Just before the supernova explosion, temperatures at the center of the doomed star reach billions of degrees, fueling thousands of exotic fusion reactions that produce all the naturally occurring elements in the universe heavier than iron.