First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.
In the scope of the COMPASS experiment a multi-purpose, high rate capable TDC with digitisation width of 60 ps has been developed. The integration into the readout system and the flexible input of the CATCH readout driver is presented.Key words: TDC; readout driver; front-end electronics; VMEThe COMPASS experiment at CERN will investigate the hadron structure by deep inelastic muon scattering and hadronic production processes. One central issue of the experimental effort will be the measurement of the contribution of gluons to the nucleon spin. To reach this objective a demanding stateof-the-art double-stage spectrometer with large geometrical and dynamical acceptance is being set-up and commissioned through the year 2000.
COMPASS is a fixed target experiment at CERN's SPS. In 2002, a first physics run was completed with 260 TB of data recorded, corresponding to 5 billion events. The data acquisition architecture is based on custom frontends, buffers based on PCI cards, and server PCs networked via Gigabit Ethernet. A custom timing and trigger distribution system provides unique event identification and time synchronization. Results on the performance of the system and an outlook to improvements using online filtering will be given.
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