Rubby Sherr

Rubby Sherr, nuclear physicist and emeritus professor of physics at Princeton University, died on July 8 at the Quadrangle in Haverford, Pa. He would have reached age 100 on September 14.

Sherr was one of the last surviving first-hand witnesses of the atomic bomb test at the Trinity site near Alamogordo, New Mexico on July 16, 1945.

He joined the Initiator Group for the Manhattan Project in 1944, working under Charles Critchfield in Los Alamos. His major contribution to this effort was as the co-inventor of the Fuchs-Sherr Polonium-Beryllium neutron initiator which he nicknamed the “urchin”, the portion of the device positioned at the center of the bomb designed to spread the nuclear chain reaction rapidly throughout the fissile plutonium material. He is far less well known for his initial reaction to the test explosion: intensely focused, staring at his instrument to measure the blast’s shock wave in the darkened blockhouse a few miles from ground zero, he angrily shouted “Who the h*** turned on the g** d***** lights!” at the moment of the detonation’s intense brilliance.

The legion of Trinity witnesses has shrunk rapidly. In 2005, on the occasion of the 60^th anniversary of the Trinity blast, Sherr sat on a panel arranged by Wolfgang Panofsky at the National Academy of Sciences in Washington of 14 surviving scientists who worked on the bomb to recall their experiences of the project. With Sherr’s passing, only two of the panelists survive.

Earlier, while at the MIT-Harvard Radiation Laboratory in the early 1940s, he had contributed to the war effort with the invention of a variety of Doppler radar, an air-borne device capable of detecting moving vehicles on the ground. He spoke of testing the device while crammed into the rear fuselage of a small Army aircraft, flying high above a long straight stretch of highway somewhere in New England. The experience so terrified him that a decade passed before he flew again.

Sherr was an experimentalist to the core. His PhD thesis, which he completed in 1937 at age 23, demonstrated the use of gas diffusion for isotope separation. It consisted of twenty-nine glass diffusion pumps, connected one-to-the-next, individually and crafted by hand. Despite the remarkable artisanship he demonstrated in constructing the device, Sherr rarely mentioned his skill at glass blowing.

More often, he liked to recall his construction of a Rube-Goldberg-style “ichthyological culinary” machine designed to enpan and fry a fish, which he built as a young adult at a summer camp. Photographs of the device show a collection of items on a smallish table with a wash tub for the fish at one end and a frying pan on the other. The details of its design and use are now lost to the ages. While the experiment was not a success, he claimed to have learned a key lesson from that effort — always test individually each component of a complex machine.

Sherr’s large publication record, numbering well over 100 journal articles, spanned nine decades dating from September 1936. Sherr dedicated the bulk of his professional career to experimentally exploring the physics of atomic nuclei. He and co-author H. T. Fortune, emeritus professor of physics, University of Pennsylvania, have submitted five papers for publication in 2013.

Among his more widely publicized, if somewhat whimsical achievements, was his reporting while at Harvard in 1941, that he and co-experimentalist Kenneth Bainbridge had finally achieved the alchemists’ dream of transmuting mercury into gold, a feat that captured media attention.

Sherr joined the faculty of the physics department at Princeton University in 1946. There, he helped to shepherd the construction and use of the Princeton cyclotron for most of his career, and mentored the professional development of generations of physicists. Even after his retirement in 1982, he continued with nuclear research focusing on the effects that the electromagnetic force manifests in atomic nuclei.

Most recently, he had begun to explore why the Americans succeeded in constructing the plutonium bomb before the Germans despite their access to great minds and the same body of published research. He strongly suspected that boron impurities in carbon samples may have played a role. This puzzle he left others to solve.

While in Los Alamos, he learned fly fishing and remained an avid fisherman until the 1990s. He loved folk songs, sporting an impressive memory of the lyrics for a very large number of tunes. He and his wife, Pat, often hosted folk song aficionados, artists, and writers at their home in Princeton. Sherr was a lifelong friend of writer Benjamin Appel, and occasionally battled with Alan Lomax over the proper lyrics for folk songs they both knew. He also enjoyed bird watching, which he continued to do frequently until 2011. Late in life, he developed a fondness for growing orchids, accidently demonstrating the surprising hardiness of many species.

Rubby Sherr was born on September 14, 1913 in Long Branch, N.J., of immigrant parents from Lithuania, graduating from Lakewood New Jersey high school, earning his undergraduate degree from New York University in 1934 and a PhD from Princeton University in 1938. In 1936, he married his lifelong partner Rita “Pat” Ornitz. Following graduation and a one-year post-doc at Princeton, he took a position at Harvard to assist in constructing the Harvard cyclotron, continuing there as an instructor for four years. In 1942 as World War II spread, he moved to the MIT-Harvard Radiation Laboratory, focusing on improving the usefulness of radar. In 1944, he and his family were sent to Los Alamos as he began his work on the atomic bomb. Following the war, in 1946, he took a faculty position as an assistant professor in physics at Princeton University, where he spent the remainder of his career. He received a promotion to associate professor in 1949 and to professor in 1955. He retired as emeritus professor in 1982. Sherr moved to the Quadrangle retirement community in Haverford, Pa. in early 1998.

Professional leaves took him in 1953-54 to the Kellogg Radiation Laboratory at California Institute of Technology; in 1958-59 to CERN in Geneva, Switzerland as an NSF senior postdoctoral fellow and to the Weizmann Institute in Rehovoth, Israel; in 1966 again to the Weizmann Institute; in 1969 to Michigan State University as a distinguished visiting professor; in 1970 to the Lawrence Radiation Laboratory in Berkeley, California as a research associate; and in 1975 again to the Weizmann Institute and to the Los Alamos Scientific Laboratory.

From 1955 to 1971, he held the position of principal investigator for an Atomic Energy Commission contract supporting experimental and theoretical research in low energy nuclear physics. Initially, he had primary responsibility for the operation of the Princeton 18 MEV cyclotron. At its peak, the machine employed a staff of 34 faculty, post-doctoral associates, graduate students and technical staff. In 1961, he initiated a nine year effort to finance and construct a more up-to-date accelerator. The Princeton AVF cyclotron became fully operational for research in 1970.

Prof. Sherr is survived by two daughters, Elizabeth Sherr Sklar (Lawrence) of Ann Arbor Mich. and Frances Sherr (Robert Hess) of Wynnewood Pa.; and one granddaughter, Jessica Sklar of Seattle, Wash.