obituaries: Kai Manne Börje Siegbahn

Hagstrom presents an obituary for Kai Manne Börje Siegbahn, a 1981 Nobel laureate internationally recognized for his foundational contributions to electron spectroscopy, particularly to electron spectroscopy for chemical analysis (ESCA), who died Jul 20, 2007 of a heart attack at his summer residence in Angelholm, Sweden. Kai devoted much of his career to developing sophisticated instrumentation with ever-increasing resolution to study beta decay. He often said, "Increase the resolution, and you will surely discover new phenomena." He documented his own discoveries in nuclear spectroscopy and electron spectroscopy as editor of the classic text Alpha-, Beta-, and Gamma-Ray Spectroscopy (North-Holland, 1965), a compendium of articles by 77 internationally recognized authors whom Kai knew personally and had recruited.