LEP2: present and future performance and limitations

A brief review of the performance in 1997 is given where LEP was operated up to 92 GeV per beam. The upgrading in the past and next winter shut-down is described which allows to raise the beam energy to 94.5 GeV in 1998 and to gradually approach 100 GeV from 1999 onwards. Preparatory work and studies are summarized which aim at this further increase in beam energy with adequate luminosity. The ini tial performance in 1998 and the expected performance in the following years are reviewed

Future accelerators

An overview of the various schemes for electron-positron linear colliders is given and the status of the development of key components and the various test facilities is given. The present studies of muon-muon colliders and very large hadron colliders are summarized including the plans for component development and tests. Accelerator research and development to achieve highest gradients in linear accelerators is outlined. (44 refs)

Status of CERN

An overview of the present CERN facilities is given and their planned development is outlined as required by the approved physics programme. Although the main task of CERN in the next years will be the construction of LHC, a small but significant programme for accelerator R&D has been defined. It comprises a multi-TeV linear collider, advanced neutrino beams and the upgrading of LHC

Accelerator-based neutrino beams

The design principles of accelerator-based neutrino beams are outlined and the beams currently in operation or under construction are briefly described. The concepts and basic features of the different types of advanced neutrino beams which are under study are summarize

The LEP Superconducting RF System

The basic components and the layout of the LEP RF system for the year 2000 are presented. The superconducting system consisted of 288 four-cell cavities operating at 352 MHz powered by 36 klystrons providing on average of 0.6 MW of RF power. This system was complemented by 56 cavities of the original copper RF system. A total accelerating voltage of 3630 MV could be provided routinely allowing operation up to 104 GeV. The installation schedule of the superconducting cavities is shown and comments are made about the evolution of the system over the years. The performance and the reliability of the final system are described.<br

A Scheme to Numerically Evolve Data for the Conformal Einstein Equation

This is the second paper in a series describing a numerical implementation of the conformal Einstein equation. This paper deals with the technical details of the numerical code used to perform numerical time evolutions from a "minimal" set of data. We outline the numerical construction of a complete set of data for our equations from a minimal set of data. The second and the fourth order discretisations, which are used for the construction of the complete data set and for the numerical integration of the time evolution equations, are described and their efficiencies are compared. By using the fourth order scheme we reduce our computer resource requirements --- with respect to memory as well as computation time --- by at least two orders of magnitude as compared to the second order scheme.Comment: 20 pages, 12 figure

Color Screening and Quark-Quark Interactions in Finite Temperature QCD

We analyze the screening of static diquark sources in 2-flavor QCD and compare results with the screening of static quark-antiquark pairs. We show that a two quark system in a fixed color representations is screened at short distances like a single quark source in the same color representation whereas at large distances the two quarks are screened independently. At high temperatures we observe that the relative strength of the interaction in diquark and quark-antiquark systems, respectively, obeys Casimir scaling. We use this result to examine the possible existence of heavy quark-quark bound states in the high temperature phase of QCD. We find support for the existence of $bb$ states up to about $2T_c$ while $cc$ states are unlikely to be formed above $T_c$.Comment: 8 pages, 6 figure