A very high light-yield imaging chamber

By operating the parallel-plate imaging chamber in a nonproportional regime it was possible to increase the light yield from the gas avalanches by a factor in excess of 10 4 over the proportional operation. At this higher gain, the avalanches can easily be seen with the naked eye in a moderately lit room and recorded with CCD cameras without any image intensification. The device is continuously operating and is free of sparking. The main limitations are the existence of a detection threshold that is dependent on the primary charge density, and the large amount of current flowing in the high-gain gap, leading to ageing.