James
Chadwick
Childhood
in Manchester
On
20th October 1891 James Chadwick was born in Bollington
near Macclesfield, Cheshire. When his father left to
open a laundry business in Manchester, Chadwick remained
with his grandmother, was educated locally and later
entered Manchester Municipal Secondary School. Chadwick
specialised in applied mathematics and at the age of
16 succeeded in gaining two scholarships to attend Manchester
University.
Chadwick
was immature and very shy. He applied to Manchester
to read mathematics, but was accidentally interviewed
as a potential physics student. He was too shy to mention
the mistake, but was so impressed by the interviewer
that he decided to do physics.
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Manchester
University
Chadwick
found the first year classes large and noisy, but in
his second year he met the Professor, Ernest
Rutherford. When Rutherford set Chadwick his third
year research project he left a deliberate mistake in
the method to see if Chadwick was alert. Chadwick noticed
the mistake but didn't dare correct the Professor, so
Rutherford thought he had missed it!
Chadwick
got his First Class Honours degree in 1911 and began
research for a Masters degree. He stayed in Manchester
and was interested in Geiger and Marsden's scattering
of alpha particles, research that led to Rutherford's
discovery of the nucleus. In 1913 Chadwick received
his Masters, and Rutherford recommended him for an 1851
Exhibition scholarship.
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Berlin
and the War
The
scholarship required that Chadwick move from Manchester.
He wanted to speacialise in radioactivity, so went with
Geiger to the Reichsanstalt in Berlin where he quickly
learnt German. Geiger supervised Chadwick and introduced
him to other leading German scientists, including Albert
Einstein.
The
First World War brought a sudden end to this way of
life. Geiger was called away as a reserve officer, but
Chadwick stayed in Germany. When war was declared it
was too late for Chadwick to leave, and soon afterwards
he was imprisoned at a racecourse at Ruhleben. He lived
with five others in a stable built to hold two horses,
and suffered from inadequate food and bitter cold.
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The
Cavendish Laboratory
In
1918 the War ended. After four years of imprisonment,
poor and in bad health, Chadwick was free to return
to England and Manchester, where Rutherford offered
him a job. A year later Rutherford became the Cavendish
Professor, and invited Chadwick to join him in Cambridge.
From the start Chadwick played a very important part
in the running of the Cavendish Laboratory, which Rutherford
had decided would concentrate on the experimental study
of the atomic nucleus.
Chadwick
was offered a Wollaston Studentship of £120 a
year by Gonville and Caius College. In 1921 he was elected
as a research fellow by the college, increasing his
income to £350 a year. The following year Chadwick
was funded by the Department of Scientific and Industrial
Research to become the Assistant Director of Research
in the Cavendish.
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Assistant
Director
Chadwick
now concentrated solely on research, and no longer had
to teach or lecture. He and Rutherford would allocate
research problems, and each morning at 11 o'clock Chadwick
reported any progress to the Professor. Their close
friendship lasted for sixteen years.
Chadwick
was married in 1925 and arranged to have a house built
by October 1926. The building actually took longer,
and the Chadwicks spent some time living in a cold and
draughty house. At the time Chadwick was revising Rutherford's
book on radioactivity, and is said to have worked each
night until midnight, wrapped up in an overcoat and
wearing gloves!
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The
Neutron
In
1932 Chadwick discovered the neutron. He and Rutherford
had discussed the possibility of the particle for more
than ten years, and had tried many 'silly' experiments
to find it. The successful discovery changed the world,
and won Chadwick a Nobel Prize in Physics in 1935. Soon
after the discovery Cockcroft and Walton's accelerator
split nuclei of lithium and Chadwick was keen to build
a more powerful accelerator in the Cavendish.
But
Rutherford was reluctant to ask for money and refused
Chadwick's request. Chadwick had to look elsewhere for
his accelerator, so in 1935 was delighted to accept
the Lyon Jones Chair of Physics at Liverpool University.
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Liverpool
When
Chadwick moved to Liverpool its physics department was
run down and lacking equipment, but by the time he left
he had built up a high level of teaching and research.
In 1936 he began by starting the construction of a '37-inch
cyclotron', a circular particle accelerator nearly a
metre across, using £2000 from the Warren Fund
of the Royal Society.
Chadwick
had asked Cockcroft to design the magnet for his cyclotron.
This annoyed Rutherford, who was still opposed to building
expensive accelerators. When Chadwick visited Cambridge
in June 1936, Rutherford attacked him about the cyclotron
and for encouraging his new director of research, Mark
Oliphant, to leave for a chair at Birmingham. Chadwick
was surprised and shocked, and returned to Liverpool
on bad terms with Rutherford.
Rutherford
didn't bear any lasting grudge, and even allowed Cockcroft
to build his accelerator, but in October 1937 Rutherford
died of a strangulated hernia. Although he had resumed
writing to Chadwick on good terms the two men had not
met since their argument. Chadwick always regretted
this sad ending to their long friendship. Chadwick was
not elected as a successor to the Cavendish Chair.
While
the cyclotron was being built, Chadwick took a keen
interest in teaching and medical physics. During the
first few months of 1939 he spent half his time organising
classes and reorganising cancer therapy. He was an able
Department Head and brilliant researcher.
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The
Second World War
History
came close to repeating itself as Chadwick almost found
himself behind enemy lines at the start of the Second
World War. In September 1939 he was on a fishing holiday
in Sweden, and when he got back to Stockholm found no
immediate way home. Fortunately he obtained a flight
to Amsterdam, and after a few days was able to return
to England.
The
Liverpool cyclotron became operational at the start
of the Second World War. Uranium fission had been discovered
by Hahn and Strassmann at the start of 1939, and a few
months later the possibility of a nuclear chain reaction
had been demonstrated.
E.V.
Appleton, the Secretary of the Department of Scientific
and Industrial Research, asked Chadwick if a nuclear
bomb was a possibility. It appeared that such a bomb
would need more than a ton of uranium to explode, but
Chadwick wasn't sure, and decided to use the Liverpool
cyclotron for a feasibility study.
By
the end of 1940 Chadwick and others found that the first
American experiments had underestimated the sizes needed
to maintain a chain reaction, and found that only a
few kilograms of uranium would be needed to create a
nuclear weapon. Chadwick and many of Britain's other
leading physicists joined to form 'the Maud Committee',
and produced a report saying that a nuclear bomb could
be ready by 1943. Only P.M.S. Blackett doubted this
timescale. The power plant needed to produce the nuclear
material was built in Canada.
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The
Manhattan Project
America
entered the war after the Japanese attack on Pearl Harbour
in December 1941. It became clear that the Amercian
nuclear weapons project could quickly overshadow the
British efforts, and Chadwick expressed that every effort
should be made to allow complete cooperation between
the two allied nations. On 19 August 1943 the Quebec
Agreement on Anglo-American collaboration was signed
by Prime Minister Churchill and President Roosevelt,
and British scientists were transferred to the United
States.
Chadwick
quickly established a friendly relationship with Major
General Groves, the executive officer in charge of America's
nuclear bomb projects, collectively called the Manhattan
Project. Groves and Chadwick respected each other, were
wholly straightforward and honest. Chadwick was determined
to keep Anglo-American relations as strong as possible.
He helped draft agreements to provide uranium for the
Project, maintained the morale of British scientists
during their time in America, and was responsible for
British observers being present at the bombing of Nagasaki.
After
the War Chadwick encouraged cooperation with the United
States on nuclear energy matters, and considered the
construction of reactors capable of producing plutonium
to be the first priority. This cooperation weakened,
and by 1955 was extremely limited.
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Return
to Liverpool
In
1946 Chadwick returned to Britain and Liverpool, physically,
mentally and spiritually tired. He became involved with
Britain's nuclear energy programme, continued his work
on fundamental research in universities, and advised
the British delegation to the United Nations in 1947.
At Liverpool he made plans to produce a new synchrocyclotron,
so that by the time he left in 1948 Liverpool had the
most powerful accelerator outside America.
When
a European research centre into nuclear physics was
proposed, Chadwick was keen that Britain should be involved,
seeing it as the only way British scientists could stay
competitive with the large accelerators in the United
States. He recommended that European scientists be allowed
to gain experience on the Liverpool accelerator, and
in 1952 recommended that Britain join the Council of
Representatives for the European project. Meeting at
Cambridge with eleven other physicists, it was decided
that Britain should contribute £250,000 a year
for eight years. At the end of 1952 Britain agreed to
set up C.E.R.N., contributing nearly a quarter of the
required resources.
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Gonville
and Caius
In
1948 Chadwick returned to Cambridge to become the Master
of Gonville and Caius College, a move which surprised
many of his friends in Liverpool. He missed his laboratory,
but was pleased to have more contact with undergraduates.
The College Bursar was absent through illness on Chadwick's
arrival, so he handled the finances, managing to make
a good return by investing in equities rather than securities.
Chadwick was also responsible for building a new court,
and relaxing the rules about arriving back late at night!
Chadwick
accepted the post of Vice-Chancellor at Cambridge, but
was overcome with exhaustion before he could take up
the role.
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Retirement
In
1958 Chadwick became unhappy with the emotional and
personal criticism levelled at him as Master, so he
resigned from Gonville and Caius and retired to a cottage
in North Wales.
Chadwick
was happy to be back near Liverpool again, and stayed
in Liverpool for eleven years. The Chadwicks returned
to Cambridge in 1969 to be near their two daughters,
and James Chadwick died on 24th July, 1974. More than
four hundred attended his funeral at Great Saint Mary's
on the 26th October.
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