0000000000651069
AUTHOR
H. Rieseberg
The RICH counter in the CERN hyperon beam experiment
Abstract The hyperon beam experiment WA89 at the CERN-SPS uses a ring imaging Cherenkov counter (RICH) for identification of secondaries from ∑ − N reactions. Cherenkov photons are generated in a 5 m long radiator volume filled with nitrogen at atmospheric pressure and detected in drift chambers. The drift chambers cover an active surface of 1.6 × 0.75 m 2 , with a maximum drift path of 41 cm. Photoelectrons are counted on 1280 wires with a pitch of 2.54 mm, equipped with multihit TDCs. The counting gas is ethane saturated with TMAE at 30°C. The counter was operated in two beam periods in 1990 and 1991. The spatial resolution of the chambers is better than 2 mm and under normal running cond…
Measurement of the polarization of $$\Lambda ^0 , \overline \Lambda ^0 , \Sigma ^ + $$ and ?? produced in a ?? beam of 330 GeV/c
The polarization of Lambda0 , AntiLambda0 , Sigma+ and Xi- inclusively produced in Sigma- induced interactions at 330 GeV has been measured in the experiment WA89 at CERN. This is the first measurement of polarization of baryons produced by a hyperon beam. No polarization of AntiLambda is observed, as was also the case in proton beam data. At transverse momenta of about 1~GeV/c Lambda0 and Sigma+ show little polarization, significantly lower than in the proton beam data, while Xi- have a polarization comparable to the polarization of Lambda0 produced in proton beams. The polarization of Lambda0, AntiLambda0, Sigma+ and Xi- inclusively produced in Sigma- induced interactions at 330 GeV has b…