In this report we present recent experimental data from the Relativistic Heavy Ion Collider (RHIC) illustrating effects resulting from {approx}10 Hz vibrations of the triplet quadrupole magnets in the interactions regions and evaluate the impact of these vibrations on RHIC collider performance. Measurements revealed modulation of the betatron tunes of appreciable magnitude relative to the total beam-beam parameter. Comparison of the discrete frequencies in the spectra of the measured beam positions and betatron tunes confirmed a common source. The tune modulations were shown to result from feed-down in the sextupole magnets in the interaction regions. In addition we show that the distortions to the closed orbit of the two counter-rotating beams produced a modulated crossing angle at the interaction point(s).

The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

During the acceleration process, heavy ion beams in RHIC cross the transition energy. When RHIC was colliding deuterons and gold ions during Run-8, lattices with different integer tunes were used for the two rings. This resulted in the two rings crossing transition at different times, which proved beneficial for the 'Yellow' ring, the RF system of which is slaved to the 'Blue' ring. For the symmetric gold-gold run in FY2010, lattices with different transition energies but equal tunes were implemented. We report the optics design concept as well as operational experience with this configuration.

Outstanding research potential of electron-hadron colliders (EHC) was clearly demonstrated by first - and the only - electron-proton collider HERA (DESY, Germany). Physics data from HERA revealed new previously unknown facets of Quantum Chromo-Dynamics (QCD). EHC is an ultimate microscope probing QCD in its natural environment, i.e. inside the hadrons. In contrast with hadrons, electrons are elementary particles with known initial state. Hence, scattering electrons from hadrons provides a clearest pass to their secrets. It turns EHC into an ultimate machine for high precision QCD studies and opens access to rich physics with a great discovery potential: solving proton spin puzzle, observing gluon saturation or physics beyond standard model. Access to this physics requires high-energy high-luminosity EHCs and a wide reach in the center-of-mass (CM) energies. This paper gives a brief overview of four proposed electron-hadron colliders: ENC at GSI (Darmstadt, Germany), ELIC/MEIC at TJNAF (Newport News, VA, USA), eRHIC at BNL (Upton, NY, USA) and LHeC at CERN (Geneva, Switzerland). Future electron-hadron colliders promise to deliver very rich physics not only in the quantity but also in the precision. They are aiming at very high luminosity two-to-four orders of magnitude beyond the luminosity demonstrated by the very successful HERA. …

For improved reproducibility of good operating conditions and ramp commissioning efficiency, new dual-plane slow orbit feedback during the energy ramp was implemented during run-10 in the Relativistic Heavy Ion Collider (RHIC). The orbit feedback is based on steering the measured orbit, after subtraction of the dispersive component, to either a design orbit or to a previously saved reference orbit. Using multiple correctors and beam position monitors, an SVD-based algorithm is used for determination of the applied corrections. The online model is used as a basis for matrix computations. In this report we describe the feedback design, review the changes made to realize its implementation, and assess system performance.

Many efforts were made over the last decades to develop a better polarized electron source for the high energy physics. Several laboratories operate DC guns with the Gallium-Arsenide photo-cathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved using a Superconducting RF electron gun, which delivers beams of higher brightness than DC guns does, because the field gradient at the cathode is higher. SRF guns with metal cathodes and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since the cathode will be normal conducting, the problem about the heat load stemming from the cathode arises. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and the verification by measuring the quality factor of the gun with and without cathode.

Precision measurement and control of the betatron tunes and betatron coupling in the Relativistic Heavy Ion Collider (RHIC) are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.

We report measurements of the phonon density of states as measured with inelastic x-ray scattering in SmFeAsO{sub 1-x}F{sub y} powders. An unexpected strong renormalization of phonon branches around 23 meV is observed as fluorine is substituted for oxygen. Phonon dispersion measurements on SmFeAsO{sub 1-x}F{sub y} single crystals allow us to identify the 21 meV A{sub 1g} in-phase (Sm,As) and the 26 meV B{sub 1g} (Fe,O) modes to be responsible for this renormalization, and may reaveal unusual electron-phonon coupling through the spin channel in iron-based superconductors.

To facilitate studies of collisions between polarized electron and protons at {radical}s = 14 GeV; constructing an electron-nucleon collider at the FAIR facility has been proposed. This machine would collide the stored 15 GeV polarized proton beam in the HESR with a polarized 3.3 GeV electron beam circulating in an additional storage ring. We describe the interaction region design of this facility, which utilizes the PANDA detector.

The luminosity of a ring-ring electron-ion collider is limited by the beam-beam effect on the electrons. Simulation studies have shown that for short ion bunches this limit can be significantly increased by head-on beam-beam compensation via an electron lens. However, due to the large beam-beam parameter experienced by the electrons, together with an ion bunch length comparable to the beta-function at the IP, electrons perform a sizeable fraction of a betatron oscillation period inside both the long ion bunches and the electron lens. Recent results of our simulation studies of this effect will be presented.

We present electron ion collider lattice design for the Relativistic Heavy Ion Collider (eRHIC) where the electrons have multi-passes through recirculating linacs (ERL) and arcs placed in the existing RHIC tunnel. The present RHIC interaction regions (IR's), where the electron ion collisions will occur, are modified to allow for the large luminosity. Staging of eRHIC will bring the electron energy from 4 up to 20 (30) GeV as the superconducting cavities are built and installed sequentially. The synchrotron radiation from electrons at the IR is reduced as they arrive straight to the collision while ions and protons come with 10 mrad crossing angle using the crab cavities.

The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity design, integration, machine protection, and a potential validation test in the SPS.

Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented. The primary goal of the RHIC experiments were execute an on-line measurement of the optics using the tools developed for the LHC. Turn-by-turn BPM trajectories (typically 1000 turns) acquired immediately after an external dipole kick are numerically analyzed to determine the optical parameters at the location of the beam position monitors (BPMs). For chromatic optics, a similar analysis, but on a beam with finite momentum offset(s). Each optical measurement typically is calculated from multiple data sets to capture statistical variations and ensure reproducibility. The procedure of measurement and analysis is detailed in ref [1, 2]. Two dedicated experiments were performed at RHIC with protons during Run 2009. The first at injection energy and optics and the other at 250 GeV and squeezed optics. The basic RHIC parameters relevant for the two experiments are listed in Table 1.

We report recent experimental results on linear optics measurements and corrections using ac dipole. In RHIC 2009 run, the concept of the SVD correction algorithm is tested at injection energy for both identifying the artificial gradient errors and correcting it using the trim quadrupoles. The measured phase beatings were reduced by 30% and 40% respectively for two dedicated experiments. In RHIC 2010 run, ac dipole is used to measure {beta}* and chromatic {beta} function. For the 0.65m {beta}* lattice, we observed a factor of 3 discrepancy between model and measured chromatic {beta} function in the yellow ring.

The Electron Beam Ion Source (EBIS) project at Brookhaven National Laboratory is a new heavy ion preinjector for Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory science programs. Laser Ion Source (LIS), which can supply many heavy ion species using solid targets, is a candidate of a primary ion source provider for RHIC-EBIS. LIS experiment with 5 Hz operation, which is required practically in RHIC-EBIS, was demonstrated to understand the beam property for long operation time. High laser power density decayed the peak current and ion yield with operation time and did not keep the surface of target flat. On the contrary, the beam in low laser power density kept the performance in long operation time.

The Electron Nucleon Collider, proposed as an extension to the High Energy Storage Ring (HESR), is currently investigated and a first layout of the Interaction Region (IR) proposed. The limited size of the machine, the low beam energy and the Lorentz force vector pointing in the same direction for both beams make the IR design demanding. In this paper we present the parameters of the IR magnets, show the boundary conditions given by the beam dynamics and the experiments. We present first 2D designs for the electron and proton triplet magnets along with the separating dipole next to the collision point. Different methods to shield the beam in the spectrometer dipoles are investigated and presented.

A fast transition instability presents a limiting factor for ion beam intensity in RHIC. Several pieces of evidence show that electron clouds play an important role in establishing the threshold of this instability. In RHIC Runs8 the measurements of the instability, using a button BPM, were done in order to observe details of the instability development on the scale over hundreds and thousands turns. The paper presents and discusses the results of those measurements in time and frequency domains.

Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

The effects of microbunching instability for the SPARX accelerator have been analyzed by means of numerical simulations. The laser heater counteracting action has been addressed in order to optimize the parameters of the compression system, either hybrid RF plus magnetic chicane or only magnetic, and possibly enhance the FEL performance.

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Recirculating Linear Accelerators (RLA) are the most likely means to achieve the rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In this paper, we present a novel return-arc optics design based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice that allows 5 and 9 GeV/c muons of both charges to be transported in the same string of magnets. The return arcs are made up of super cells with each super cell consisting of three triplets. By employing combined function magnets with dipole, quadrupole, sextupole and octupole magnetic field components, each super cell is designed to be achromatic and to have zero initial and final periodic orbit offsets for both 5 and 9 GeV/c muon momenta. This solution would reduce the number of arcs by a factor of 2, simplifying the overall design.

Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.

The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

A 56 MHz superconducting RF cavity was designed for a luminosity upgrade of the Relativistic Heavy Ion Collider (RHIC), including requirements for Higher Order Mode (HOM) damping. In this paper, we describe our optimization of the damper's performance, and modifications made to its original design. We also show the effects of the damper geometry on the cavity's HOM impedance. To reduce the likelihood of magnetic breakdown, we lowered the magnetic field enhancement at the ports to a value less than the highest field in the cavity. We simulated all monopole and dipole HOMs up to 1GHz with their frequencies, mode configurations, R/Qs, and shunt impedances, verifying that all modes are well-damped with the optimized design and configuration. The 56 MHz superconducting RF cavity is a quarterwave resonator designed to have a gap voltage of 2.5 MV. Our plans are to place this beam-driven resonator at a common section of RHIC to provide a storage RF potential for both rings. The large bucket of the cavity will reduce spill due to Intra-Beam Scattering (IBS), and thus increase the luminosity for the detectors. It is very important to damp all the cavity's Higher Order Modes (HOMs) to avoid beam instabilities. The design …