ATLAS

Abstract:

The DØ detector is a large general purpose detector for the study of short-distance phenomena in high energy antiproton-proton collisions, now in operation at the Fermilab Tevatron collider. The detector focusses upon the detection of electrons, muons, jets and missing transverse momentum. We describe the design and performance of the major elements of the detector, including the tracking chambers, transition radiation detector, liquid argon calorimetry and muon detection. The associated electronics, triggering systems and data acquisition systems are presented. The global mechanical, high voltage, and experiment monitoring and control systems which support the detector are described. We also discuss the design and implementation of software and software support systems that are specific to DØ. © 1994.

Abstract:

The “APC3” is a charge sampling and storage chip designed for high speed readout of silicon detectors. It has 32 channels, each with preamplifier, integrator and storage capacitors. Current from a silicon detector connected to the input is integrated as a charge and stored on a capacitor. There are 128 capacitors per channel which are used sequentially to store the charge. The charge is held on the storage capacitor until it is either read out or discarded. Logic on the chip manages the storage and retrieval of samples. This logic uses a novel architecture based on a system of pointers and read out addresses. This paper describes the operation of the chip and measurements of its performance. © 1994 IEEE

Abstract:

We present the results of a search for the top quark in 19.3 pb-1 of p̄p collisions at s =1.8 TeV. The data were collected at the Fermilab Tevatron collider using the Collider Detector at Fermilab (CDF). The search includes standard model tt̄ decays to final states eeνν̄, eμνν̄, and μμνν̄ as well as e+ν+jets or μ+ν+jets. In the (e,μ)+ν+jets channel we search for b quarks from t decays via secondary vertex identification and via semileptonic decays of the b and cascade c quarks. In the dilepton final states we find two events with a background of 0.56-0.13+0.25 events. In the e,μ+ν+jets channel with a b identified via a secondary vertex, we find six events with a background of 2.3±0.3. With a b identified via a semileptonic decay, we find seven events with a background of 3.1±0.3. The secondary vertex and semileptonic-decay samples have three events in common. The probability that the observed yield is consistent with the background is estimated to be 0.26%. The statistics are too limited to firmly establish the existence of the top quark; however, a natural interpretation of the excess is that it is due to tt̄ production. We present several cross-checks. Some support this hypothesis; others do not. Under the assumption that the excess yield over background is due to tt̄, constrained fitting on a subset of the events yields a mass of 174±10-12+13 GeV/c2 for the top quark. The tt̄ cross section, using this top quark mass to compute the acceptance, is measured to be 13.9-4.8+6.1 pb.

Abstract:

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of p̄p collisions at s =1.8 TeV with an integrated luminosity of 19.3 pb-1. We find 12 events consistent with either two W bosons, or a W boson and at least one b jet. The probability that the measured yield is consistent with the background is 0.26%. Though the statistics are too limited to establish firmly the existence of the top quark, a natural interpretation of the excess is that it is due to tt̄ production. Under this assumption, constrained fits to individual events yield a top quark mass of 174±10-12+13 GeV/c2. The tt̄ production cross section is measured to be 13.9-4.8+6.1 pb. © 1994 The American Physical Society.