The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.

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Experiments performed very deep underground in the gold mines in India and in South Africa are analyzed to yield r , , > 1 . 8~ lo3' yr and r , > lo3' yr for the baryon-number-nonconserving decay of bound nucleons into muonic and kaonic channels, respectively. New experiments capable of improving these limits by more than an order of magnitude are suggested.

Estimation of azimuth and elevation angles of both Angle of Arrival and Angle of Departure is a challenging research topic in 5G smart antenna technology. The key contributions of this work involve two novel algorithms implemented in a uniform planar array for the estimation of the arrival and departure angles using the received signal from the coherent users. One of the two algorithms reduces search complexity without any reduction in the angular resolution of the estimated angles. This is done through selection of active antennas in the uniform planar array to make it sparse without creating angle ambiguity. The second method improves the angular resolution in estimating the angles through reduction in the subspace leakage that occurs between the signal and noise subspace. Numerical simulations prove the proposed two algorithms producing a high angular resolution with reduced complexity.