WASHINGTON — Riccardo Levi-Setti, an Italian-born Holocaust survivor who became a path-breaking physicist at the University of Chicago, uncovering subatomic particles while traveling the world in search of trilobites, ancient arthropods he called ‘‘the butterflies of the seas,’’ died Nov. 8 at a nursing home in Chicago. He was 91.
His son, Emile Levi Setti, said the precise cause was not immediately known.
Raised in an aristocratic Jewish family in Milan, Dr. Levi-Setti was a teenager during World War II, when he hid from the Nazis and their fascist collaborators in a remote farmhouse, mountain caves, and an empty underground fuel container near Genoa.
While on the run, he also developed a lifelong interest in fossils — possibly the result of scrambling across a fossil-filled rock pile while evading German patrols, his son said — and in physics.
Dr. Levi-Setti joined the University of Chicago in 1956 as a research associate, and over the next decade conducted experiments that set the stage for the discovery of strange quarks, one of the ‘‘fundamental building blocks of matter,’’ according to Chicago physicist Henry Frisch. His work centered on hyperons and mesons, a pair of subatomic particles, as well as cosmic rays, high-energy radiation that he studied using flights of balloons.
At the same time, Dr. Levi-Setti developed new techniques to track the paths of particles through space, sometimes using a superheated vessel known as a bubble chamber.
In the early 1980s, Dr. Levi-Setti turned from particle physics to develop a scanning ion microprobe, an instrument that enabled him to take extraordinarily high-resolution images of teeth, DNA, and almost anything else that struck researchers’ fancy.
Sometimes called the scanning ion microscope, it was not simply a viewing device, but could ‘‘see, taste and write,’’ Dr. Levi-Setti boasted, analyzing the chemical composition of objects, arranging individual atoms and even etching lines so tiny ‘‘that it could write 100 books, each containing 1,000 pages, on the head of a pin,’’ according to one account in the Chicago Tribune.
Amid his work at the University of Chicago, where he led the Enrico Fermi Institute for experimental physics from 1992 to 1998, Dr. Levi-Setti traveled across the Czech Republic, Wales, Newfoundland and Morocco to collect thousands of trilobite fossils.
He published his book ‘‘Trilobites’’ in 1975; it was republished in 1993.
Riccardo Paolo Levi was born in Milan on July 11, 1927. His father was a furrier and decorated World War I veteran, and his mother was a homemaker. With anti-Semitism on the rise under fascist leader Benito Mussolini, the family converted to Catholicism in 1934, and later fled.
Dr. Levi-Setti had just turned 16 when, in July 1943, the Mussolini regime fell. Two months later, German forces swept into the northern half of Italy. By his count, 11 of his relatives were killed by the Nazis.
With his older brother, he gave himself the hyphenated name Levi-Setti, in honor of the woman, Elisa Setti, who helped their parents survive. (His children do not use a hyphen in their last name.)
His first marriage, to Katharine McCarthy, ended in divorce. He leaves his wife of 41 years, Nika Semkoff Levi-Setti of Chicago; two children from his first marriage, Emile Levi Setti of Santa Monica, Calif., and Matteo Levi Setti of San Diego; and two granddaughters.