Kenneth Johns

The run IIb trigger upgrade for the DO experiment

The increase in instantaneous luminosity anticipated in Run IIb of the Tevatron collider at Fermilab requires increased background rejection capabilities from the trigger system of the DO detector. A set of upgrades is under way to improve triggering at level 1 in the calorimeter and tracker, and at level 2 in the silicon track trigger and software triggers. Reductions of up to a factor of ten on the rates of high transverse momentum triggers are anticipated with the upgrades described.

Cathode Strip Chambers in ATLAS: Installation, Commissioning and in Situ Performance

The Muon Spectrometer of the ATLAS detector at the LHC is designed to provide high quality stand-alone muon identification, momentum measurement and trigger capabilities with high pseudorapidity coverage. Precision tracking at the inner-most station in the high pseudorapidity regions, 2.3 < |eta| < 2.7, is performed by 16 four-layered Cathode Strip Chambers on each end-cap. These are multi-wire proportional chambers with segmented cathodes providing excellent spatial resolution and high counting rate capability. The second cathode of each layer is coarsely segmented, providing the transverse coordinate. The detector level performance of the system is presented. The installation and commissioning effort for the Cathode Strip Chambers is described. Finally, the in situ performance is briefly discussed.

Top Quark Physics at DØ

For the next ten years, top quark physics will be aggressively pursued by experiments at both the Fermilab Tevatron and CERN Large Hadron Collider. There are many reasons why top quark physics is compelling physics. Radiative corrections to the W-boson mass link the W-boson mass with the top quark mass and Higgs boson mass. Precise measurements of the top quark mass and W-boson mass provide an indirect measurement of the Standard Model (SM) Higgs boson mass. If, or when, the Higgs boson is discovered, comparison of the measured Higgs boson mass with this indirect method will be a crucial test for the Standard Model.

Production polarization and magnetic moment of anti-XI+ anti-hyperons produced by 800-GeV/c protons

The polarization of {bar {Xi}}{sup +} hyperons produced by 800-GeV/{ital c} protons in the inclusive reaction {ital p}+Be{r arrow}{bar {Xi}}{sup +}+{ital X} has been measured. The average polarization of the {bar {Xi}}{sup +}, at a mean {ital x}{sub {ital F}}=0.39 and {ital p}{sub {ital t}}=0.76 GeV/{ital c}, is {minus}0.097{plus minus}0.012{plus minus}0.009. The magnetic moment of the {bar {Xi}}{sup +} is 0.657{plus minus}0.028{plus minus}0.020 nuclear magneton.