Development of a small high-pressure steamer chamber for charm-lifetime measurements

The spacial resolution in a streamer chamber is investigated as a function of the gas pressure in the chamber. For this purpose a small streamer chamber with a track sensitive volume of 50 mm diameter and 23 mm gap has been constructed and operated between 5 and 20 atm pressure. In this pressure range streamer densities 43 to 67 streamers per centimeter were found. The track width 2sigma is mainly determined by the diffusion of the electrons and shrinks proportionally to 1/√p. In addition, the influence of a magnetic field of 1.8 T on the diffusion was studied. At 20 atm one reaches a sigma of 70 μm in space, which allows a measurement of charmed particle lifetimes as short as 10-13 s. (orig.)