May 28, 1911-May 16, 1994
By John H. Reynolds
In May 1994 the international scientific community lost one of its most distinguished experimentalists. Alfred Nier, regents professor emeritus at the University of Minnesota, used mass spectrometers of his own design and construction in a manner that can only be likened in breadth and importance to Albert Michelson's use of interferometers to answer scientific questions in numerous and widely diverse fields of inquiry. These questions included how old is the earth; which isotope of uranium is responsible for slow neutron fission; how is the atmosphere of Mars composed; what are the details of nuclide stability in the table of isotopes; what nuclides of great rarity remained to be discovered in nature; how effective are various schemes of isotope separation; and how can mass spectrometry be applied in practical ways to chemical analysis and to leak detection in vacuum systems.
Alfred Nier (''Al" to all who knew him) was born in St. Paul, Minnesota, on May 28, 1911. His parents were German immigrants who came to the United States as youngsters. His father eventually owned and operated a small dry cleaning business. Al had one sister, eleven years his senior,