Last year marked the 30th anniversary of the inception of the scientific research programme of the Mirabelle liquid-hydrogen bubble chamber, which was a joint effort between the Institute for High-Energy Physics in Protvino, Russia, CERN and CEA-Saclay in France.
A superb technological achievement in its time, Mirabelle was at that time the largest electrophysics structure of its kind in the world. Measuring 11 x 5 x 14 m, representing about 3000 tons of instrumentation and a useful volume of 6 m3, it was designed, prepared and experimented on by a Saclay research team under the leadership of Pierre Prugne.
Nicknamed “the little prune”, the chamber became the apple of Prugne’s eye. In 1970-1971 it was installed on the 70 GeV proton beam accelerator at Protvino, which was at that time the most powerful accelerator in the world.
The fast ejection system and, in particular, the particle beam separator for Mirabelle were created at Protvino with the assistance of specialists from CERN . The first photographs were obtained in June 1971. From then on, physicists from Protvino, Saclay and CERN carried out investigations into photon and meson interactions.
Recently at Protvino, specialists from Saclay (many now pensioners), members of their families and their Russian colleagues celebrated Mirabelle’s 30th anniversary. At the official ceremony, Pierre Prugne received the honorary degree of doctor of science.
As a souvenir, the chamber’s cold piston – which was the heart of the Mirabelle chamber – was symbolically erected in the town centre, in a square that was appropriately renamed Mirabelle Square.