This item probably did not make the front page of your local newspaper, but researchers at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University recently produced the heaviest silicon isotope ever observed. After slamming a beam of calcium ions into a tungsten target, scientists analyzed the reaction products and identified three silicon 44 ions, each with 14 protons and 30 neutrons. (Ordinary silicon has 14 neutrons.) Given that the hefty nuclei survived for only a tiny fraction of a second before decaying, the achievement may not sound earthshaking, but this kind of nuclear research is vitally important. Studying the properties of rare isotopes can help astrophysicists explain how the reactions in exploding stars generated the elements that make up Earth and all the other planets. Isotopes with the appropriate chemical and radiological characteristics could be incorporated into new cancer treatments. And a better understanding of exotic nuclei could even explain why the universe is rich in matter but almost devoid of antimatter.
For the past several years, scientists at the NSCL (where I have been the director since 1992) and the Argonne National Laboratory in DuPage County, Illinois, have sought to build a more powerful ion accelerator that could unlock the secrets of the nucleus. In February 2006 the U.S. Department of Energy delayed the proposed $1-billion Rare Isotope Accelerator and asked the physics community to consider planning a cheaper facility. Last December a National Academy of Sciences committee released a 124-page report concluding that a slimmed-down $550-million ion accelerator could still perform valuable work and should be considered a high priority. Scientists in Japan recently fired up the $380-million Radioactive Isotope Beam Factory, and researchers in Germany and France plan to complete similar facilities within the next four years. The National Academy’s report warned that “failure to pursue such a capability will not only lead to the forfeiture of U.S. leadership but will likely erode our current capability and curtail the training of future American nuclear scientists.”