We have constructed and installed a pressurized straw vertex chamber in the Mark III experiment at the SLAC e+e- storage ring SPEAR. The chamber consists of 12 concentric layers of straws, arrayed at radii between 5.4 cm and 13.0 cm from the interaction point. There are a total of 640 straws, each 8 mm in diameter and 84 cm long. We obtain an overall spatial resolution of 49 μm for argon-ethane ( 50% 50%) at 3 atm absolute using a cosmic ray data sample. The effects of gases on various chamber materials have been investigated. Chamber lifetime studies have been performed. A prototype chamber was used to study the resolution obtained with various gases.
ASJC Scopus subject areas
- Nuclear and High Energy Physics