62 research outputs found
Stability, stabilisation and design of multidimensional recursive digital filters
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Feasibility Conditions for Interference Alignment
The degrees of freedom of MIMO interference networks with constant channel
coefficients are not known in general. Determining the feasibility of a linear
interference alignment solution is a key step toward solving this open problem.
Our approach in this paper is to view the alignment problem as a system of
bilinear equations and determine its solvability by comparing the number of
equations and the number of variables. To this end, we divide interference
alignment problems into two classes - proper and improper. An interference
alignment problem is called proper if the number of equations does not exceed
the number of variables. Otherwise, it is called improper. Examples are
presented to support the intuition that for generic channel matrices, proper
systems are almost surely feasible and improper systems are almost surely
infeasible.Comment: 6 pages. Submitted to IEEE Globecom March 31 200
A Large Hadron Electron Collider at CERN
This document provides a brief overview of the recently published report on
the design of the Large Hadron Electron Collider (LHeC), which comprises its
physics programme, accelerator physics, technology and main detector concepts.
The LHeC exploits and develops challenging, though principally existing,
accelerator and detector technologies. This summary is complemented by brief
illustrations of some of the highlights of the physics programme, which relies
on a vastly extended kinematic range, luminosity and unprecedented precision in
deep inelastic scattering. Illustrations are provided regarding high precision
QCD, new physics (Higgs, SUSY) and electron-ion physics. The LHeC is designed
to run synchronously with the LHC in the twenties and to achieve an integrated
luminosity of O(100) fb. It will become the cleanest high resolution
microscope of mankind and will substantially extend as well as complement the
investigation of the physics of the TeV energy scale, which has been enabled by
the LHC
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Superconducting Photoinjector
One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at up to a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders.
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