We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool.

Low emittance of not-fully-stripped gold (Z=79) Au{sup +77} Helium-like ion beams from the AGS (Alternating Gradient Synchrotron) injector to the Relativistic Heavy Ion Collider (RHIC) could be attributed to the cooling phenomenon due to inelastic intrabeam scattering [1,2] or due to electron de-excitations from collisions with the residual gas [3]. The low emittance gold beams have always been observed at injection in the Relativistic Heavy Ion Collider (RHIC). There have been previous attempts to attribute the low emittance to a cooling due to the exchange of energy between ions during the inelastic intrabeam scattering. The Fano-Lichten theory [4] of electron promotion might be applied during inelastic collisions between helium like gold ions in the AGS. The two K-shell electrons in gold Au{sup +77} could get promoted if the ions reach the critical distance of the closest approach during intra-beam scattering or collisions with the residual gas. During collisions if the ion energy is large enough, a quasi-molecule could be formed, and electron excitation could occur. During de-excitations of electrons, photons are emitted and a loss of total bunch energy could occur. This would lead to smaller beam size. We propose to inject gold ions with two missing electrons into RHIC, at injection energy, and study the beam behavior with bunched and de-bunched beam, varying the RF voltage and the beam intensity. If the ''cooling'' is observed additional X-ray detectors could be installed to observe emitted photons.

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H- injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation.

The Fortran program TRANFT simulates transverse instabilities in circular accelerators using fast Fourier transform algorithms. It may be used for any particle type. Forces from transverse wakefields, longitudinal wakefields, and transverse detuning wakes are included, with linear transverse space charge forces included as a special case. This note describes the algorithms and their implementation in TRANFT.

The large scale application of non-evaporable getter coating in RHIC has been effective in reducing the electron cloud. Since beams with higher intensity and smaller bunch spacing became possible in operation, the emittance growth is of concern. Study results are reported together with experiences of machine improvements: saturated NEG coatings, anti-grazing ridges in warm sections, and the pre-pumping in cryogenic regions.

Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

In this study, an array of vibration measurements at the undisturbed NSLS II site has been performed in order to establish the 'green-field' vibration environment and its spectral characteristics. The interaction of the green-field vibration environment with the NSLS II accelerator structure and the quantification of the storage ring vibration, both in terms of amplitude and spectral content have been assessed through a state-of-the-art wave propagation and scattering analysis. This paper focuses on the wave propagation and scattering aspect as well as on the filtering effects of accelerator structural parameters.