H. Richard Crane (1907-2007)

H. Richard (Dick) Crane was born (4/11/07) and raised in Turlock, a small farming town in central California. His parents encouraged their young son’s fascination with technology by letting him experiment with mechanical and electrical devices around the house. By age 14, he was licensed for amateur radio, an interest that lasted for the rest of his life.

In 1926 Crane enrolled as a freshman at the California Institute of Technology, but when he graduated in 1930 jobs were hard to find, so he returned to Cal Tech for graduate school. He joined Charles Lauritsen’s group as a graduate assistant and helped build an accelerator used for studies of nuclear properties and for neutron production. Crane also started to look for evidence of the neutrino’s existence. By the time he had finished his thesis (1934) and stayed for a postdoctoral year, Crane, at age 28, was already lead author on seventeen letters and articles in the Physical Review.

191Crane lived for a time in the Athaneum, the Cal Tech faculty club, and it was there that he met his future wife, Florence LeBaron, an Athaneum manager who provided much personal assistance for the Einsteins during their visits to Cal Tech.

In 1935 Harrison Randall at the University of Michigan found the money to hire this bright Californian at the rank of instructor. Upon arriving in Ann Arbor, he began building a 1 MeV accelerator and also undertook experiments with radioactive sources. Over the years 1936-1940, he continued the study of nuclear disintegration, gamma and beta spectra, beta spectra, and mechanisms of electron energy loss.

He also continued to search for evidence of the neutrino. In 1938 he and Jules Halpern published the first convincing, quantitative measurements of neutrino momentum. And, in 1939 Crane searched for neutrino absorption by burying a mesothorium source in a bag of salt and looking for sulfur produced by the inverse beta decay of chlorine; he was able to set an upper limit for the cross section of this process and he also discussed the astrophysical implications of his result. Crane’s last publication on neutrinos, in the 1948 Reviews of Modern Physics, was given lavish credit by Ray Davis in his 2002 Nobel Prize acceptance speech.

During the1940-1945 years of WWII, Crane worked on the development of the proximity fuse at the Carnegie Institution, at the Johns Hopkins Applied Physics Lab, and in Ann Arbor. He also worked briefly at the MIT Radiation Lab and on the Manhattan Project.

In the post-WWII years Crane’s research expanded beyond pure nuclear physics. In 1946 he proposed and then built an 80 MeV electron synchrotron of racetrack form that featured long, straight-line sections of beam path suitable for placement of injectors, targets and detectors. This synchrotron became operational in 1952 and served as the model for many accelerators built at other institutions.

The synchrotron’s electron injector was available before the rest of the accelerator was ready, so graduate student William Louisell used it for Mott scattering in which a magnetic field was used to guide electrons between polarizer and analyzer. Crane realized that measuring the polarization’s dependence on magnetic field could provide an accurate value of the magnetic moment of the free electron; this “g-2” experiment was a way to step around the then widely-held belief, based on the uncertainty principle, that this quantity was not susceptible of meaningful measurement. The first Michigan results drew much attention when they were reported in 1953, and for the next decade Crane continued to improve the experiment with the help of Robert Pidd, Arthur Schupp, David Wilkinson, Arthur Rich and John Wesley.

In the mid-1950’s, with the success of his experimental programs established, Crane stepped more visibly into national leadership roles. He became president (1957-1960) of the Midwest Universities Research Association. In 1965 he was named to the National Academy of Sciences and served on many of its committees. From 1965 to 1972 he was chair of the University of Michigan Physics Department. And from 1971 to 1975, he chaired the Board of Governors of the American Institute of Physics.

In the 1960’s Crane began to devote more time to improving teaching at the university level. This led to his election as president (1965-66) of the American Association of Physics Teachers and his subsequent vice presidency (1967-70) of the Commission on College Physics.

Crane took uncommon pleasure in sharing his understandings with others. His abilities to combine visual reasoning with formal calculation are nicely demonstrated in his expository papers on the principles of biological growth and in his analysis (1956) with Cyrus Levinthal on the unwinding of DNA. He returned to his love of table-top experiments with a model to demonstrate geomagnetic field reversals. He showed how one could build a very short Foucault pendulum. For many years he wrote a column “How Things Work” for The Physics Teacher; seventy of those columns are collected in a best-selling AAPT book.

Having already done much for the teaching of college physics by the mid-1970s, Crane started to direct more of his interest and resources to science education for K-12 schoolchildren and for community college students. He was also a driving force and leading developer of exhibits for the Ann Arbor Hands-On Science Museums.

Crane combined relentless curiosity and quiet intensity with an astonishing intuition for physics, yet he was a modest, reserved man who often described himself as a tinkerer. But the appreciation of his colleagues was clearly expressed: Elected to the National Academy in 1965, he received many honors including the APS Davisson-Germer Prize in 1967, the AAPT’s Oersted Medal in 1977, and the National Medal of Science in 1986.

In his later years, Crane often spoke of having enjoyed a long life in an era when there was so much to discover. There had been time to work in many fields of science, but there had also been time for playing the violin, fishing, raising orchids, artistic painting, and enjoying friends and family.

Dick Crane was an icon of Michigan physics who showed his many friends and colleagues how a balanced life in science could be lived. He died on 19 April, 2007, just months short of his 100th birthday.

JCZ

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We welcome comments and additions from those who knew Dick Crane.

 

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