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[en] The linear one-turn map of a storage ring contains coupling information on which a correction algorithm can be based. In principal, the one-turn matrix can be fitted from turn-by-turn data of beam position monitors after a kick was applied. However, the so obtained coupling information often sinks into the noise floor. The signal-to-noise ratio of the coupling information can be greatly enhanced by fitting maps for larger turn numbers N, equal to half the beat period. With the so obtained N-turn map an automated global coupling correction is possible without the need for a tune change. This is demonstrated for the Relativistic Heavy Ion Collider where the algorithm is implemented for operational use at injection
[en] During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Coherent beam-beam modes were observed, and suppressed by tune changes. In this article we summarize the most important beam-beam observations made during stores so far
[en] The goal of nonlinear dynamics experiments is to improve the understanding of single particle effects that increase the particle amplitude and lead to loss. Particle motion in storage rings is nearly conservative and for transverse dynamics the Hamiltonian in action angle variables (Ix,Iy,φx,φy) near an isolated resonance kνx + lνy ∼ p is H = Ixνx0 + Iyνy0 + g(Ix, Iy) + h(Ix, Iy)cos(kφx + lφy - pθ), (1) where k, l, p are integers, θ = 2πs/L is the azimuth, and s and L are the path length and circumference respectively. The amplitude dependent tunes are given by νx,y(Ix,Iy) = νx0,y0 + ∂g(Ix,Iy)/∂Ix,y (2) and h(Ix,Iy) is the resonance driving term (RDT). If the motion is governed by multiple resonances, h(Ix,Iy) has to be replace by a series of terms. The particle motion is completely determined by the terms g and h, which can be calculated from higher order multipoles (Sec. ??), or obtained from simulations. Deviations from pure Hamiltonian motion occur due to synchrotron radiation damping (Sec. ??) in lepton or very high energy hadron rings, parameter variations, and diffusion processes such as residual gas and intrabeam scattering. The time scale of the non-Hamiltonian process determines the applicability of the Hamiltonian analysis. Transverse nonlinearities are introduced through sextupoles or higher order multipoles and magnetic field errors in dipoles and quadrupoles. Sextupoles can already drive all resonances. The beam-beam interaction and space charge also introduce nonlinear fields. Intentionally introduced nonlinearities are used to extract beam on a resonance or through capture in stable islands. Localization and minimization of nonlinearities in a ring is a general strategy to decrease emittance growth and increase the beam lifetime. The minimization of nonlinear effects can be done locally or globally. Except for resonant extraction, amplitude increase and particle loss is the result of chaotic particle motion. Large chaotic regions allow particles to increase their amplitudes, and ensures their ultimate loss. However, chaotic particles can, on average, still survive the time period of interest, i.e. the storage time. Nonlinear dynamics experiments aim to determine either the detuning and driving terms g and h directly, or their effect on other quantities. Nonlinear phenomena observed in experiments include phase space deformations and resonant islands in Poincare surfaces of section, nonlinear phase advances, amplitude detuning g, decoherence (Sec. ??), resonance driving terms h, smear, halo formation, echoes (Sec. ??), the tune response matrix, dynamic aperture (Sec. ??), emittance growth, and particle loss. Nonlinear experiments can also be done in the longitudinal plane.
[en] The Relativistic Heavy Ion Collider (RHIC) operates with either ions or polarized protons. After increasing the heavy ion luminosity by two orders of magnitude since its commissioning in 2000, the current luminosity upgrade program aims for an increase by another factor of 4 by means of 3D stochastic cooling and a new 56 MHz SRF system. An Electron Beam Ion Source is being commissioned that will allow the use of uranium beams. Electron cooling is considered for collider operation below the current injection energy. For the polarized proton operation both luminosity and polarization are important. In addition to ongoing improvements in the AGS injector, the construction of a new high-intensity polarized source has started. In RHIC a number of upgrades are under way to increase the intensity and polarization transmission to 250 GeV beam energy. Electron lenses will be installed to partially compensate the head-on beam-beam effect.
[en] The RHIC beam lifetime in polarized proton operation is dominated by the beam-beam effect, parameter modulations, and nonlinear magnet errors in the interaction region magnets. Sextupole and skew sextupole errors have been corrected deterministically for a number of years based on tune shift measurements with orbit bumps in the triplets. During the most recent polarized proton run 10- and 12- pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors and estimate their effect on the integrated luminosity.
[en] The prospects for greater economic cooperation between eastern and western Europe have increased considerably since the break up of the USSR. This has set the context for the decision to construct the East-West high-power Transmission System (EWPTS) with the aim of exchanging electrical energy economically and efficiently between east, central and west European utilities. The 4000MW, 1800km long system will run from Borken, near Frankfurt-am-Main, across the former East Germany, through Poland into Belarus and on to Smolensk in western Russia. It will traverse three different distribution systems with four interconnections to national alternating current networks. A HVDC system has been chosen as the most practicable and economic. Among the anticipated advantages of the EWPTS are: long-term energy exchange and the possibility of closure and replacement of old and environmentally hazardous eastern European power plants; the pooling of reserve capacity and a saving of 1600MW thereby; investment in the system by the five utilities involved will be considerably less than the cost of additional plant; the telecommunications circuits used to control EWPTS could carry commercial data and raise revenue to reduce operating overheads. The system is expected to be operating in 2010. (UK)
[en] In proton synchrotrons a high field quality for bending fields is needed. Therefore, the control system for the dipole magnet current has to be of good performance. One way to tackle the problem is a digital control system. A digital control system is resistant to ageing and variations of temperature and voltage. An integration to a more complex digital control system is easy made. The tolerances for field and current of the proton synchrotron DESY III are derived. A short introduction to controller theory is given and some specialities of digital controllers are described. A digital controller for dipole current control, whose main component is not a standard controller with proportional, integral and derivative part, is designed, built and tested with a software and a hardware model. The results are compared with the presently used analog controller for the dipole current of DESY III and show that the digital controller should be a good alternative. (orig.)
[en] Diffusion counteracts cooling and the knowledge of diffusion rates is important for the calculation of cooling times and equilibrium beam sizes. Echo measurements are a potentially sensitive method to determine diffusion rates, and longitudinal measurements were done in a number of machines. We report on transverse echo measurements in RHIC and the observed dependence of echo amplitudes on a number of parameters for beams of gold and copper ions, and protons. In particular they examine the echo amplitudes of gold and copper ion bunches of varying intensity, which exhibit different diffusion rates from intrabeam scattering
[en] Since 2000 RHIC has collided, at 8 energies, 4 combinations of ion species, ranging from gold ions to polarized protons, and including the collisions of deuterons with gold ions. During that time the heavy ion and polarized proton peak luminosities increased by two orders and one order of magnitude respectively. The average proton polarization in store reached 65%. Planned upgrades include the evolution to the Enhanced Design parameters by about 2008, the construction of an Electron Beam Ion Source (EBIS) by 2009, the installation of electron cooling for RHIC II, and the implementation of the electron-ion collider eRHIC. We review the current performance, and the expected performance with these upgrades
[en] The basic outlines of non-proliferation policy, its instruments, the position of the protagonists' interests and the fundamental fields of conflict are to the fore. The history and structure of international non-poliferation policy and, in particular, of the NPT, are described, the instruments for verifying the purely peaceful use of nuclear power (safeguards) are analysed, and important future technological and political challenges of the Treaty are listed. (orig./HP)
[de]Die Grundzuege der Entwicklung der Nichtverbreitungspolitik, ihre Instrumente, die Interessenpositionen der Akteure und die grundlegenden Konfliktfelder stehen im Vordergrund. Es werden die Geschichte und Struktur der internationalen Nichtverbreitungspolitik und insbesondere des NPT beschrieben, die Instrumente zur Ueberwachung der ausschliesslich friedlichen Nutzung von Kernkraft (Safeguards) analysiert und einige wichtige kuenftige technische, aber auch politische Herausforderungen des Vertrages aufgezeigt. (orig./HP)