Golden Jubilee photos: A New Class of Detectors



In the 1960s, detection in particle physics mainly meant examining millions of photographs from bubble chambers or spark chambers. This was slow, labour intensive and not suitable for studies into rare phenomena, so there was a bottleneck that could have affected further progress in high energy physics.
The transistor revolution triggered new ideas. While a camera could detect a spark, a detector wire connected to an amplifier could detect a much smaller effect. In 1968, Georges Charpak developed the 'multiwire proportional chamber', a gas-filled box with a large number of parallel detector wires, each connected to individual amplifiers. Linked to a computer, it could achieve a counting rate a thousand times better than existing techniques - without a camera in sight.
Today practically every experiment in particle physics uses some type of track detector that is based on the principle of the multiwire proportional chamber. The technology is also used in many other fields using ionising radiation such as biology, radiology and nuclear medicine.
Georges Charpak, who won the Nobel Prize in 1992 for his work on particle detectors, is pictured on the left along with Fabio Sauli and Jean-Claude Santiard, working on one of CERN's first large multiwire proportional chambers.