Micro-gap parallel-plate chambers with porous secondary electron emitters

We developed a micro-gap (0.1 mm) parallel-plate chamber with one or more layers of solid converters of radiation. The detector with a one-layer converter was tested with X-rays (6-30 keV) and also at the T9 and T10 beam facilities at CERN. A position resolution better than 30 mu m was achieved. With minimum ionizing particles, an efficiency close to ~20% was achieved with one detector, and it was almost twice as high as the efficiency due to the interaction of minimum ionizing particles with the gas alone. The detectors with a few layers of converter were tested only with X-rays. An efficiency of ~10% could be achieved. The combination of a micro-gap PPC with secondary- electron converters may allow a further improvement of the time resolution of these detectors, which has already reached 50-100 ps at present. (10 refs).