3.
Kick Sorter
The
nuclear physics group in Cambridge no longer had the
high-energy machines needed to produce novel elementary
particles. The cost of such machines was now too much
for any single university to afford! These machines
were built instead at large international research centres,
such as the European Centre of Nuclear Research (or
CERN) in Geneva and Fermilab in the United States. These
expensive particle accelerators were funded by many
organisations from several nations, and the results
shared internationally.
These
experiments would produce a huge number of results,
too many to measure by hand. Frisch began to concentrate
on making counters which could measure and record these
results automatically.
Scintillation
counters were becoming used in 1947, designed to detect
gamma rays. Before these counters, experimenters had
to count the rays individually as they produced tiny
spots on a fluorescent screen! Frisch's 'kick sorter'
was a device for measuring the strength of pulses from
the counters.
The
'kick sorter' worked by rolling ball-bearings into different
channels cut in a polystyrene block. Each ball-bearing
would be held above the channels until it was 'kicked'
by the signal, with the strength of the signal determining
the force of the kick. A very strong signal would kick
the ball a long way, allowing it to fall into one of
the furthest channels, while a weak signal would only
kick it into the nearer channels. This mechanical device
built up an automatic histogram, a chart showing the
number of pulses of different energies.
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