Muon identification with the event filter of the ATLAS experiment at CERN LHC's

The Large Hadron Collider at CERN offers unprecedented challenges to the design and construction of detectors and trigger/data acquisition systems. For ATLAS, a three level trigger system has been developed to extract interesting physics signatures with a 106 rate reduction. To accomplish this, components of physics analysis traditionally deferred to off-line physics analysis must be embedded within the on-line trigger system. For the Muon trigger, the specific off-line algorithms MOORE (Muon Object Oriented REconstruction) and MuId (Muon Identification) have been adopted so far for the on-line use, imposing an operation in a Bayesian-like environment where only specific hypotheses must be validated. After a short review of the ATLAS trigger, the paper shows the general strategy of the Muon Identification and Selection accessing the full event data, or being seeded from results derived at a previous stage of the trigger chain. © 2006 IEEE

The BaBar silicon vertex tracker

The silicon vertex tracker (SVT) for the BaBar experiment at the PEP-II asymmetric B factory is a 5-layers device based on double sided, AC coupled silicon strip detectors. It is read out by a custom IC, the AToM chip, that can simultaniously acquire, digitze and transmit data. The main purpose of the SVT is to accurately measure the decay position of the B mesons that are produced, which is essential for extracting CP asymmetries. Here, we report on the SVT design as well as progress on its fabrication and assembl

Measurement of the tau polarization at LEP

The polarisation of τ 's produced in Z decay is measured using 160 pb −1 of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters Ae=0.1504±0.0068 and Aτ=0.1451±0.0059 which are consistent with the hypothesis of e- τ universality. Assuming universality, the value Ae-τ=0.1474±0.0045 is obtained from which the effective weak mixing angle sin2θeffW=0.23147±0.00057 is derived