The largest of the LEP experiments, by far, is L3, a collaboration
led by Nobel Laureate Sam Ting. L3 brought together institutes
from 17 countries spread throughout the World.
L3 aimed to specialize in measuring electrons, positrons, and
photons emerging at small angles to LEP's colliding beams with
the best possible precision. To achieve this, special crystals
made from Bismuth Germanate, BGO, were chosen. Such crystals
had previously only been made in small quantities, a few cubic
centimetres, and never with the purity required by L3. The experiment
would need a massive 12 tons of BGO crystals.
A group of about a hundred physicists and engineers from China,
France, Germany, Holland, Hungary, Italy, Switzerland, the USA
and the USSR was set up to find a solution. It soon became clear
that only the Shanghai Institute of Ceramics (SIC) would be capable
of producing such a large number of crystals, some 11 000 in total,
with the needed quality, within the timescale, and at an affordable
National sensibilities were quickly forgotten as Russia agreed
to furnish five tons of Germanium Oxide, a highly strategic material,
China supplied the highly pure Bismuth Oxide and French industry
developed new machines for crystal cutting and polishing.
Industrial production of BGO crystals started in 1985, and the
finished crystals were delivered to CERN in June 1987. More than
95% passed the most critical quality control tests on arrival
at the Laboratory. Final assembly, testing, and mounting was enthusiastically
performed by all the teams in L3's BGO group, and the detector
was fully operational when LEP started up in 1989.