RIP: Professor Owen Chamberlain

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His credentials as a member of the scholarly classes were further established by
his longstanding devotion to his pipe.



Professor Owen Chamberlain
(Filed: 06/03/2006)

Professor Owen Chamberlain, who died on Shrove Tuesday aged 85,
won the Nobel Prize for Physics for his discovery of the antiproton.

Chamberlain and Emilio Segrè shared the award for their
discovery, in 1955, which came after nuclear physicists had spent more than a
quarter of a century attempting to verify the existence of the antiproton, which
annihilates positive protons and cannot exist for long beside ordinary matter.

Its existence had first been postulated by the English physicist
PAM Dirac in 1928 (and is implicitly suggested by Einstein's equation e=mc2).
But, though stable in a vacuum, antiprotons remained elusive, despite
experiments with cosmic rays to establish their existence in atomic nuclei.

Chamberlain's discovery was that antiprotons existed only outside
the nucleus, in high-energy nuclear collisions such as occurred in cosmic
radiation. At the University of California at Berkeley, where Chamberlain was by
then based, the construction of the Bevatron - then the world's most powerful
"atom-smasher" - in the 1950s allowed him and Segrè to test their
hypothesis.

Firing protons of 6.2 billion electron volts at a copper target,
Chamberlain and his team created, and kept in existence, antiprotons for long
enough to identify them. Taking the secondary beam of protons, neutrons and
mesons presumed to contain antiprotons from the target and feeding them into an
experimental maze of magnetic fields, Chamberlain was able to announce the
existence of the antiproton in October 1955, though the time taken to confirm
his findings meant that there was little initial fanfare about the
discovery.

Though most physicists had already, for theoretical purposes,
assumed the existence of the antiproton, the confirmation that it could be
experimentally verified allowed for an expansion of work in particle physics.
The next decade was dominated by work on protons in accelerators, and on a
steady stream of new particles which emerged from such experiments.

Owen Chamberlain was born on July 10 1920 in San Francisco, where
his father was a radiologist at Stanford University Hospital. The family moved
to Philadelphia when Owen was 10, and he went to school in the city before
attending Dartmouth College, from which he graduated in 1941. He went on to the
University of California at Berkeley for post-graduate work in physics but,
after America entered the war, abandoned his studies to join the scientists
working on the Manhattan project.

Chamberlain began by investigating uranium isotopes under Ernest
Lawrence, a Nobel-prizewinner who had invented the cyclotron, then moved to Los
Alamos in 1943, where he continued his atomic research, at one stage being
compelled to take a leave of absence after exposure to dangerous levels of
radiation. It was during his work on the project that he first met Segrè, with
whom Chamberlain was later to collaborate. He was also present at the first
atomic bomb test, losing a $5 bet that it would not go off.

After the war, Chamberlain concentrated on slow-neutron
diffraction in liquids at the Argonne National Laboratory in Chicago, working
for his doctorate under Enrico Fermi. He then returned to Berkeley to teach
physics in 1948, becoming an assistant professor two years later and an
associate professor in 1954. He took a Guggenheim Fellowship in 1957 and was
appointed a full professor in 1959.

Chamberlain, whose crew cut and glasses gave him the appearance
of the architypal "physics geek" in his early years, took to the laid back
attitude at Berkeley, growing his hair and acquiring a large beard during the
1960s. He demonstrated the frisbee to Chinese schoolchildren, and demonstrated
against nuclear weapons (he had visited Hiroshima shortly after the war). He
also agitated for civil rights and free speech. His credentials as a member of
the scholarly classes were further established by his longstanding devotion to
his pipe.

From the 1960s, his primary work was in pioneering the use of
polarised proton targets, which proved invaluable in the study of high energy
processes. During the late 1970s and early 1980s he transferred his attention to
studying the interactions of energetic light nuclei, before formally retiring
from his post at Berkeley.

But Chamberlain never ceased to take an active interest in his
field, continuing to attend classes and colloquia until days before his
death.

He received numerous academic awards and honours.

Chamberlain married, first, in 1943, (Beatrice) Babette Cooper,
with whom he had three daughters and a son. She died in 1988 and he married,
secondly, June Steingart Greenfield, who died in 1991. He is survived by his
third wife, Senta, and by his children.

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