Verre au plomb et photomultiplicateur pour OPAL

Reflections from a lead-glass block measuring about 10 x 10 x 40 cm. Some 10000 blocks of the same type will be put together in the OPAL experiment, one of the four scheduled LEP experiments. It should be possible, using pho- tomultipliers with these blocks, to measure the energy of the particles penetrating them. A score of laboratories are taking part in OPAL, including the University of Tokyo, which explains why Tatsuo Kawamoto appears in photo 572.