0000000000195004
AUTHOR
M. Tonutti
A large proportional drift chamber with two-dimensional read-out
Abstract The construction and performance of a large drift chamber are described, which has a sensitive area of 5 m2 and an average chamber thickness of 0.55 × 10−3 radiation lengths. Simultaneous sense wire- and high voltage read-out gives a good time correlation with ajitter of 2.0 ns fwhm. Measurements with a collimated radioactive α-sources resulted in a time resolution of 4.3 ns fwhm corresponding to a space resolution of 0.20 mm fwhm at the sense wire. The space resolution at the high voltage plane is about 25 mm fwhm.
Measurement ofj/?-decays into channels containing charged and neutral antinucleons
Using the nonmagnetic BONANZA detector for the detection of antineutrons and antiprotons, we measured branching ratios of theJ/ψ into baryonic final states. Our measurements give the new results:\(BR\left( {{J \mathord{\left/ {\vphantom {J {\psi \to \overline {\Sigma ^ - } }}} \right. \kern-\nulldelimiterspace} {\psi \to \overline {\Sigma ^ - } }}\Sigma ^ - } \right) = \left( {0.24 \pm 0.26} \right)\% ;BR\left( {{J \mathord{\left/ {\vphantom {J {\psi \to }}} \right. \kern-\nulldelimiterspace} {\psi \to }}\bar nn\pi ^ + \pi ^ - } \right) = \left( {0.38 \pm 0.36} \right)\% \) and an independent test for the data of the magnetic detectors.