A 3-TON LIQUID ARGON TIME PROJECTION CHAMBER

We have constructed and operated a 3 ton liquid argon time projection chamber for the R&D programme of the ICARUS project. The chamber has been in operation since May 1991 collecting events from cosmic rays and a monochromatic gamma ray source. We describe the construction of the different detector components and their assembly; we report the solutions found to the major technological problems and the operation of the detector. The detector can be built in large masses and is continually sensitive providing bubble chamber quality images of ionising events; some examples will be shown. The energy resolution is a few per cents in the MeV region. The space resolution is of the order of 100 mum. The novel technique we have developed provides a basis for building superior detectors in underground and accelerator experiments.