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As the linac-based X-ray FEL oscillator is actively pursued recently, feasibility of a storage ring based X-ray FEL oscillator is examined. Conditions of the required storage ring parameters such as beam emittance and machine parameters are investigated. Also, the performance and advantages and disadvantages of a storage ring based X-ray FEL oscillator is compared with those of other X-ray FEL sources. [ABSTRACT FROM AUTHOR]

A thermal beam emittance measurement method is developed specifically to measure high power density beams for the ITER neutral beam injection system (NBI)’s. A one-dimensional carbon-fiber composite (CFC) target is utilized to withstand the high current densities of the negative hydrogen beam making the beam emittance measurement possible. Schemes for the emittance measurement were discussed since beam instabilities are present in various stages of the beam phase. The allowable time for the measurement will be less than 2 seconds and it’s necessary to monitor the CFC temperature to not exceed 2000°C. The proposed measurement scheme to minimize beam instabilities is through the constant operation of the arc discharge and pulsed beam extraction. Mechanical structures are also being designed for rapid measurements to select different phases of the beam and for implementing the measurement system to long pulse beam operation. [ABSTRACT FROM AUTHOR]

Laser-plasma accelerators can provide very high acceleration gradients that makes them promising candidates as drivers for compact light sources as well as for high-energy applications. However, the conservation of beam emittance when coupling the beam into and extracting it from the plasma is extremely challenging. We present a concept that employs tapered matching sections to drastically relax the constraints on the matched beamsize at the plasma entrance and to adiabatically reduce the beam divergence at the plasma exit, thereby minimizing the emittance growth. [ABSTRACT FROM AUTHOR]

A laser plasma accelerator-based collider will necessitate chaining of something of the order of hundreds of individual acceleration stages. Matching the electron beam at the entrance of each stage in order to obtain emittance conservation within and during transition between stages is crucial for beam quality preservation along the entire acceleration chain. Previous studies have addressed the matching conditions for two consecutive stages. In this simulation study, we focus on the matching of a short electron beam in a string of stages, using short down-ramps of the order of the electron beam betatron period, demonstrating emittance conservation for up to six consecutive stages. [ABSTRACT FROM AUTHOR]

SC200 is an isochronous cyclotron which generate 200 MeV, 500 nA proton for particle therapy. As an important component of the cyclotron, the ion source chimney needs to be tested and optimized. The simulation results and optimization of ion source in test bench for SC200 are described in this paper. The simulation results show that the extraction slit with different sizes and shapes has an influence on the emittance of the extraction beam. To verify the simulation results, the performance of the designed ion source chimney with optimized slits was measured, including the beam current intensity and the beam emittance. [ABSTRACT FROM AUTHOR]

The H- injector for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory consists of a RF H- ion source and a compact electrostatic low-energy beam transport (LEBT) section. Up to 5 ion sources and up to 4 LEBT assemblies are alternated for the SNS beam operations. The beam current and emittance of the H- beam exiting the LEBT were characterized on the test-stand for different sources and LEBT assemblies in order to understand and minimize their performance variations. [ABSTRACT FROM AUTHOR]

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) 2nd stage requirements of an H- ion beam current of 60mA within normalized emittances of 1.5πmm·mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of more than 50days, a cesiated RF-driven H- ion source using a internal-antenna developed at the Spallation Neutron Source (SNS) was developed. The horizontal and vertical emittances were measured by using two double (W) slit emittance monitors for several different conditions. Although the measured normalized rms emittances are more than 1.4-times larger than those of a J-PARC H- ion source driven with two tungsten (W) filaments probably due to the RF field around extraction gap, the J-PARC 2nd stage requirement of the 60mA beam within 1.5πmm·mrad was satisfied if a beam more than 66mA were extracted. [ABSTRACT FROM AUTHOR]

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) [1, 2] were measured using a photon-counting single-shot pixelated Silicon-based detector [3], providing for the first time single-shot direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse [4, 5, 6, 7, 8]. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray and electron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion. [ABSTRACT FROM AUTHOR]

The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented. [ABSTRACT FROM AUTHOR]

We present a novel method of controlled electron injection from the background plasma into a laser driven plasma wave using a μm-scale density transition. Substantial quality improvements on the monoenergetic electron beam are demonstrated. Furthermore we discuss the rms transverse emittance measurement results of the generated electron bunch. [ABSTRACT FROM AUTHOR]

Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications. [ABSTRACT FROM AUTHOR]

Decoupling injection from acceleration is a key challenge to achieve compact, reliable, tunable laser-plasma accelerators (LPA) [1, 2]. In colliding pulse injection the beat between multiple laser pulses can be used to control energy, energy spread, and emittance of the electron beam by injecting electrons in momentum and phase into the accelerating phase of the wake trailing the driver laser pulse [3, 4, 5, 6, 7]. At LBNL, using automated control of spatiotemporal overlap of laser pulses, two-pulse experiments showed stable operation and reproducibility over hours of operation. Arrival time of the colliding beam was scanned, and the measured timing window and density of optimal operation agree with simulations [8]. The accelerator length was mapped by scanning the collision point. [ABSTRACT FROM AUTHOR]

High-brightness electron beam sources play a crucial role in many advanced acceleration schemes as well as linac-based light sources such as Energy Recovery Linac (ERL) based light sources and FELs. Three varieties electron sources (photo, thermionic, and field emission) the photoinjector is especially attractive due to its innate ability to control the time structure of intense electron bunches with low transverse and longitudinal emittance. In all cases, the quality of the bunch begins with the intrinsic emittance and time response of the photocathode, and we discuss the trade-offs involved between the various material choices. A variety of longitudinal laser pulse-shaping techniques are currently being developed to linearize space charge forces or create trains of ultra-short bunches. The emittance compensation technique mitigates the growth of the projected emittance due to the linear space charge force while the bunch is accelerated and compressed in an injector. While the normal conducting rf photoinjector is the workhorse of this field, the dc photoinjector is being pushed to its high-voltage limits, and the year 2010 promises to be a critical year for the superconducting rf photoinjector. Parallel to the development of the hardware, rapid progress has also been made with modeling codes, theory, and bench marking of diagnostics. We attempt to give both a tutorial of photoinjectors and a review of the current state of the art in this rapidly developing field. [ABSTRACT FROM AUTHOR]

The use of colliding laser pulses to control the injection of plasma electrons into the plasma wake of a laser-plasma accelerator is a promising approach to obtaining GeV scale electron bunches with reduced emittance and energy spread. Colliding Pulse Injection (CPI) experiments are being performed by groups around the world. We present recent particle-in-cell simulations, using the parallel VORPAL framework, of CPI for physical parameters relevant to ongoing experiments of the LOASIS program at LBNL. We perform parameter scans in order to optimize the quality of the bunch, and compare the results with experimental data. Effect of non-ideal gaussian pulses and laser self-focusing in the plasma channel on the trapped bunch are evaluated. For optimized parameters accessible in the experiment, a 20 pC electron beam can be accelerated to 300 MeV with percent level energy spread. [ABSTRACT FROM AUTHOR]

Electron injection and trapping in a laser wakefield accelerator by high-order field ionization is studied theoretically and by particle-in-cell simulations. To obtain low energy spread beams we use a short region of gas mixture (H+N) near the start of the stage to trap electrons, while the remainder of the stage uses pure H and is injection-free. Effects of gas mix parameters, such as concentration and length, on the final electron injection number and beam quality are studied. Laser polarization and shape effects on injection number and final electron emittance are also shown. [ABSTRACT FROM AUTHOR]

We demonstrate by means of electronic structure calculations, how ultrathin MgO films on Ag(001) surfaces can be used to control the emittance properties of photocathodes. In addition to substantially reducing the work-function of the metal surface, the MgO layers also favorably influence the shape of the surface bands resulting in the generation of well collimated high-brightness electron beams in which the transverse momenta of the electrons are extremely small compared to the longitudinal ones. As the number of MgO surface layers varies from 0 to 3, the emitted electron beam becomes gradually brighter, reducing its transverse emittance to the extremely small value of 0.06 mm-mrad. We suggest the use of such photocathodes for the development of free-electron x-ray lasers and energy-recovery linac x-ray sources. A practical implementation and further tunability through nanophotonics means is also discussed. [ABSTRACT FROM AUTHOR]

Fundamental limitations in acceleration gradient, emittance, alignment and polarization in acceleration schemes are considered in application for novel schemes of acceleration, including laser-plasma and structure-based schemes. Problems for each method are underlined whenever it is possible. Main attention is paid to the scheme with a tilted laser bunch. [ABSTRACT FROM AUTHOR]

Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at the A0 photoinjector. [ABSTRACT FROM AUTHOR]

Phase space manipulation techniques with two degrees of freedom could be essential to the enhancement of the performance of next generation accelerators such as high energy colliders and accelerator-based light sources. At the Fermilab A0 Photoinjector, a proof-of-principle experiment to demonstrate the exchange of the transverse and longitudinal emittance is ongoing. The emittance exchange (EEX) beamline consists of a 3.9 GHz normal conducting deflecting mode cavity positioned between two doglegs as proposed by Kim and Sessler. The experiment is performed using electron bunches with charge of 250 pC and energy of 14.3 MeV. The incoming electron beam has transverse emittance of 2-4 mm mrad and longitudinal emittance of 10-14 mm mrad. After the EEX the measured horizonal emittance is blown up to 13-15 mm mrad while the measured vertical emittance (Non EEX plane) stays the same. At the same time the longitudinal emittance is reduced to 7-9 mm mrad as measued by the current longitudinal diagnostic tools. A linear optics model is established using the beam matrix calculated and measured. A first order simulation based on this model is performed to compare to our experiment results for both EEX measurement and the phase space manipulation experiment. [ABSTRACT FROM AUTHOR]

We describe here the laser assisted emittance exchange (LAEE) technique. A laser operating in the transverse mode (TEM10 or TEM01) is used to interact with the electron beam in a dispersive region and to initiate the transverse-to-longitudinal emittance exchange. It is shown that with the LAEE one can generate an electron beam with ultralow transverse emittance, which allows one to significantly bring down the size of an X-ray free electron laser (FEL) and greatly extend the availability of these light sources. The technique can also be used to enhance the performances of X-ray FELs in storage rings. The timing and energy jitter problems for the standard emittance exchange and LAEE techniques are also discussed. [ABSTRACT FROM AUTHOR]

We propose combining a transverse-to-longitudinal emittance exchange beam line and a conventional modulator to generate high harmonics with short-wavelength free-electron lasers. The key point of this scheme is the use of a multi-slit mask to create a transverse-shaped beam. In an emittance exchange beam line, the transverse-shaped bunch will produce a longitudinal-shaped one, resulting in separated energy bands. The modulator that follows this step will generate micro-bunches containing high harmonics. A coherent synchrotron radiation effect is also considered in this paper; compared to the two-modulator scheme, the method investigated here is more flexible and can be used to relax the coherent synchrotron radiation effect. [ABSTRACT FROM AUTHOR]

The University of Maryland electron ring (UMER) is a low-energy, high current recirculator for beam physics research with relevance to any applications that rely on intense beams of high quality. We review the space-charge physics issues, both in transverse and longitudinal beam dynamics, which are currently being addressed with UMER: emittance growth and halo formation, strongly asymmetric beams, Montague resonances, equipartitioning, bunch capture and shaping, etc. Furthermore, we report on recent developments in experiments, simulations, and improved diagnostics for space-charge dominated beams. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

This is a numerical study of the effects of a rotational mismatch of a beam at injection. A closely related type of mismatch is the presence of a skew quadrupole at some place in the transporting channel. In both cases, the initial mismatch implies that the emittance of the beam will increase as the beam is transported through an alternating focusing channel. In our simulations, we used the WARP computer code to simulate the University of Maryland Electron Ring (UMER) beam and we have indeed seen a substantial emittance growth (by a factor of 2–3) for mismatches of 10 degrees. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

elegant is a general-purpose code for electron accelerator simulation that has a worldwide user base. Recently, many of the time-intensive elements were parallelized using MPI. Development has used modest Linux clusters and the BlueGene/L supercomputer at Argonne National Laboratory. This has provided very good performance for some practical simulations, such as multiparticle tracking with synchrotron radiation and emittance blow-up in the vertical rf kick scheme. The effort began with development of a concept that allowed for gradual parallelization of the code, using the existing beamline-element classification table in elegant. This was crucial as it allowed parallelization without major changes in code structure and without major conflicts with the ongoing evolution of elegant. Because of rounding error and finite machine precision, validating a parallel program against a uniprocessor program with the requirement of bitwise identical results is notoriously difficult. We will report validating simulation results of parallel elegant against those of serial elegant by applying Kahan’s algorithm to improve accuracy dramatically for both versions. The quality of random numbers in a parallel implementation is very important for some simulations. Some practical experience with generating parallel random numbers by offsetting the seed of each random sequence according to the processor ID will be reported. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Particle diffusion and emittance growth induced by numerical discrete-particle effects are analyzed in two-dimensional self-consistent numerical simulations of high-intensity beam dynamics. In particular, an analytical model is presented which describes the slow-time-scale variation of edge emittance for a perfectly matched beam in a periodic (quadrupole or solenoidal) magnetic focusing field. A scaling law for edge emittance growth is obtained. The scaling law is tested in both self-consistent Green-function-based simulations and particle-in-cell (PIC) simulations, and good agreement between theory and simulations is obtained. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Measurement of the beam quadrupole moment at several locations can be used to reconstruct the beam envelope and emittance parameters. The measurements can be performed in a non-intercepting way using a set of quadrupole-mode cavities. We present a cavity design with an optimized quadrupole moment shunt impedance. The cavity properties can be characterized using a wire test method to insure symmetry about the central axis, and alignment to nearby position sensing cavities. The design and characterization of the prototype structure is discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Production of high-brightness x- and γ-ray beams using Compton-scattering schemes requires high-brightness electron beams; to minimize the output photon bandwidth, the electron beam emittance must also be minimized. This emittance minimization is in conflict with the desire to increase the electron bunch charge and maximize the number of scatterers at the interaction point. We study here, using a combination of PARMELA and well-benchmarked, Compton-scattering codes, the impact of laser temporal and spatial profiles on the emittance produced in a photoinjector, and the trade-off between charge and emittance in scattered photon brightness and flux. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We discuss the design of and initial results from an experiment in space-charge dominated beam dynamics which explores a new regime of high-brightness electron beam generation at the SPARC photoinjector. The scheme under study employs the tendency of intense electron beams to rearrange to produce uniform density, giving a nearly ideal beam from the viewpoint of space charge-induced emittance. The experiments are aimed at testing the marriage of this idea with a related concept, emittance compensation. We show that this new regime of operating photoinjector may be the preferred method of obtaining highest brightness beams with lower energy spread. We discuss the design of the experiment, including developing of a novel time-dependent, aerogel-based imaging system. This system has been installed at SPARC, and first evidence for nearly uniformly filled ellipsoidal charge distributions recorded. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In order to understand the charged particle dynamics, e.g. the halo formation, emittance growth, x-y energy transfer and coupling, knowledge of the actual phase space is needed. Other the past decade there is an increasing number of articles who use tomography to map the beam phase space and measure the beam emittance. These studies where performed at high energy facilities where the effect of space charge was neglible and therefore not considered in the analysis. This work extends the tomography technique to beams with space charge. In order to simplify the analysis linear forces where assumed. By carefully modeling the tomography process using the particle-in-cell code WARP we test the validity of our assumptions and the accuracy of the reconstructed phase space. Finally, we report experimental results of phase space mapping at the University of Maryland Electron Ring (UMER) using tomography. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present studies of transverse emittances and electron beam pulse length for various operating points of the electron source: electron beam charge, laser length and spot size, and solenoid settings. We especially study the impact, on transverse emittance, of short Gaussian versus long square temporal distributions of the photocathode drive-laser. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

LACARA (laser cyclotron auto-resonance accelerator) is a vacuum laser accelerator of electrons that is under construction at the Accelerator Test Facility (ATF), Brookhaven National Laboratory. It is expected that the experiment will be assembled by September 2006; this paper presents progress towards this goal. According to numerical studies, as an electron bunch moves along the LACARA solenoidal magnetic field (∼5.2 T, length ∼1 m), it will be accelerated from 50 to ∼75 MeV by interacting with a 0.8 TW Gaussian-mode circularly polarized optical pulse provided by the ATF CO2 10.6μm laser system. The LACARA laser transport optics must handle 10 J and be capable of forming a Gaussian beam inside the solenoid with a 1.4 mm waist and a Rayleigh range of 60 cm. The electron optics must transport a bunch having input emittance of 0.015 mm-mrad and 100 μm waist through the magnet. Precision alignment between the electron beam and the solenoid magnetic axis is required, and a method to achieve this is described in detail. Emittance- filtering may be necessary to yield an accelerated bunch having a narrow (∼1%) energy-spread. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Tevatron in Collider Run II (2001-present) is operating with six times more bunches and many times higher beam intensities and luminosities than in Run I (1992–1995). Beam diagnostics were crucial for the machine start-up and the never-ending luminosity upgrade campaign. We present the overall picture of the Tevatron diagnostics development for Run II, outline machine needs for new instrumentation, present several notable examples that led to Tevatron performance improvements, and discuss the lessons for the next big machines — LHC and ILC. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The emittance is an important characteristic of propagating charged particle beams, because it allows the prediction of focus size and beam losses. After introducing the concept and various definitions of the emittance and Twiss parameters, useful applications of this representation will be explored for the transverse emittances of charged particle beams. This is followed by a presentation of different measuring methods, together with their advantages and disadvantages. The second part discusses the analysis of emittance data, and possible mitigations for effects introduced by noise, bias, and other artifacts. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The planned FAIR (Facility for Antiproton and Ion Research) project consists of two heavy ion synchrotrons and four large storage rings, the existing GSI facility together with a new high-current proton linac will be used as the injector chain. The fast cycling, superconducting synchrotrons are build for high current operation with the aim of secondary ion and antiproton production. A large variety of low current secondary beams as well as the antiprotons are stored and cooled in the four storage rings. A complex operation scheme with multiple use of transport lines is foreseen. This demands an exceptional high dynamic range for the beam instrumentation. Due to the enormous beam power, non-destructive methods are mandatory for high currents as well as for the low current secondary beams due to the low repetition rate. Precise measurements of all beam parameters and automatic steering or feedback capabilities are required due to the necessary exploitation of the full ring acceptances. Moreover, online beam-corrections with short response times are mandatory for the fast ramping super-conducting magnets. An overview of the challenges and projected innovative solutions for various diagnostic installations will be given. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Emittance is one of the major characteristics of charged particle beams. In this paper, we will present techniques used for measuring emittance for the sources, linear and circular accelerators. Invasive and non-invasive methods are described and their advantages and limitations are discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In designing an ionization profile monitor system for the Tevatron some novel approaches were taken, in particular for the readout electronics. This was motivated by the desire to resolve the individual bunches in both proton and pbar beams simultaneously. For this purpose, custom-made electronics originally developed for Particle Physics experiments was used to provide a fast charge integration with very low noise. The various parts of the readout electronics have been borrowed or adapted from the KTev, CMS, MINOS and BTev experiments. The detector itself also had to be modified to provide clean signals with sufficient bandwidth. The system design will be described along with the initial results. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The International Linear Collider (ILC) is a proposed facility for the study of high energy physics through electron-positron collisions at center-of-mass energies up to 500 GeV and luminosities up to 2 × 1034 cm-2 sec-1. Meeting the ILC’s goals will require an extremely sophisticated suite of beam instruments for the preservation of beam emittance, the diagnosis of optical errors and mismatches, the determination of beam properties required for particle physics purposes, and machine protection. The instrumentation foreseen for the ILC is qualitatively similar to equipment in use at other accelerator facilities in the world, but in many cases the precision, accuracy, stability, or dynamic range required by the ILC exceed what is typically available in today’s accelerators. In this paper we survey the beam instrumentation requirements of the ILC and describe the system components which are expected to meet those requirements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Multi-bunch instabilities deteriorate beam quality, increasing beam emittance, or even causing beam loss in the synchrotron light source. The feedback system is essential to suppress multi-bunch instabilities caused by the impedances of beam ducts, and trapped ions. A new FPGA based transverse and longitudinal bunch-by-bunch feedback system have been commissioned at the Taiwan Light Source recently, A single feedback loop is used to simultaneously suppress the horizontal and the vertical multi-bunch instabilities. Longitudinal instabilities caused by cavity-like structures are suppressed by the longitudinal feedback loop. The same FPGA processor is employed in the transverse feedback and the longitudinal feedback system respectively. Diagnostic memory is included in the system to capture the bunch oscillation signal, which supports various studies. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

While protons are not generally associated with synchrotron radiation, they do emit visible light at high enough energies. This paper presents an overview of the use of synchrotron radiation in the Tevatron to measure transverse emittances and to monitor the amount of beam in the abort gap. The latter is necessary to ensure a clean abort and prevent quenches of the superconducting magnets and damage to the silicon detectors of the collider experiments. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

At HERA a proton synchrotron radiation beam emittance monitor has been installed which utilizes the radiation produced in the fringe field of a vertical deflecting dipole magnet. The beam spot is imaged onto the chip of a standard CCD camera by means of a concave mirror. An interference filter together with a polarization filter serve for resolution improvements. While the monitor was used for the first time in standard operational mode during the previous HERA run period, the set-up was improved in the last shut-down. With start of the new run period the monitor is in a stage of re-commissioning and the first results are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The beam position monitoring system is an important part of a synchrotron light source that supports its routine operation and studies of beam physics. The Taiwan light source is equipped with 59 BPMs. Highly precise closed orbits are measured by multiplexing BPMs. Data are acquired using multi-channel 16-bit ADC modules. Orbit data are sampled every millisecond. Fast orbit data are shared in a reflective memory network to support fast orbit feedback. Averaged data were updated to control database at a rate of 10 Hz. A few new generation digital BPMs were tested to evaluate their performance and functionality. This report summarizes the system structure, the software environment and the preliminary beam test of the BPM system. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A high resolution Beam Position Monitor (BPM) is necessary for the beam-based alignment systems of high energy and low emittance electron linacs. Such a monitor is developed in the framework of the European CARE/SRF programme, in a close collaboration between DESY and CEA/DSM/DAPNIA. This monitor is a radiofrequency re-entrant cavity, which can be used either at room or cryogenic temperature, in an environment where dust particle contamination has to be avoided, such as superconducting cavities in a cryomodule. A first prototype of a re-entrant BPM has already delivered measurements at 2K. inside the first cryomodule (ACC1) on the TESLA Test Facility 2 (TTF2). The performances of this BPM are analyzed both experimentally and theoretically, and the limitations of this existing system clearly identified. A new cavity and new electronics have been designed in order to improve the position resolution down to 1 μm and the damping time down to 10 ns. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The perfect matching of the injecting beam phase space with the accelerator lattice is a very important problem. Its successful solution allows excluding possible mismatch emittance blow-up and worsening of the beam characteristics, that is necessary to get the highest possible luminosity in hadron accelerators. The mismatch can be controlled by measuring sizes oscillation on the first revolutions of the injected beam at a certain orbit point. Designed for this purpose the construction, acquisition electronics, software controlling of the operation and data processing of such a monitor are described. A first test result with beam is presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The kinematically complete measurements of the 7Li(9Be,ααt)5He reaction at Ebeam = 55 and 70 MeV have been performed and the reconstructed 11B excitation energy spectra were compared with the 7Li(9Be,α7Li)5He results obtained at the same beam energies. Evidence was found for the t+8Be(g.s.) decay of the 11B excited states at 13.1 and 14.4 MeV, the α+7Li*(4.652 MeV) decay of the states at 14.4 and 17.5 MeV and for the t+8Be*(3.03 MeV) decay of the 17.5 MeV state in 11B. A study of the relative yields for the decay of the 14.4 MeV state indicates that significant part of α-decay strength goes into the 2α+t three-body decay channel. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Rare Isotope Accelerator (RIA) facility utilizes the concept of simultaneous acceleration of two charge states from the ion source. We are building a prototype two charge-state (2Q) injector of the RIA Driver Linac, which includes an ECR ion source, a LEBT and one-segment of the prototype RFQ. Currently, the 2Q-LEBT Facility consists of Berkeley Ion Equipment Corporation BIE-100 ECR ion source. The rf transmitters, high voltage power supplies, turbo pumps and other related equipment were received with the source. BIE-100 is an all-permanent-magnet source and has the highest magnetic field strengths for an ECR ion source of this type ever built. The magnetic field achieves a maximum strength of 11 kG at the plasma chamber surface and 13 kG on the axis. The source can operate with two-frequency plasma heating of 12.75 and 14.5 GHz. The reassembly of the source has been completed and beam production was achieved in the June 2004. This report includes measured beam current and emittance for 16O from the source along with the beam dynamics simulations. Detailed design of the 2Q-LEBT and the current project status are also presented. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

With the development of Electron Cyclotron Resonance Ion Source (ECRIS), very high performance ECRIS nowadays have been set up one by one around the world, such as the GTS in Grenoble, SERSE in Catania, LECR3 in Lanzhou and etc, which can produce very intense Multiply Charged Ion (MCI) beam. But till now, the study of the extracted MCI beam from an ECRIS remains open. In this article, we present a theoretical and experimental study of the extracted MCI beam. In the theoretical part, the influences of the extraction system on the extracted ion beam quality are mainly analyzed. The aspects that have influences on the extracted ion beam quality have been analyzed. With the instruction of the analysis, the PBGUNS code is used to simulate the influences of some important aspects concerning the extraction system. The influences of the extraction system geometry design, magnetic field, and the space charge effect will be detailedly presented in this article. In the experimental part, with an Electric-Sweep Scanner (ESS) emittance detection system, the influences on the extracted ion beam emittance of some typical parameters of ECRIS have been researched, such as the injected RF power, the RF frequency, the magnetic field and etc. The obtained results and the corresponding explanations are presented. Some of the results are well in accord with some empirical laws, but some other results seem to be disputed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The previous two SAMPLE experiments yielded a measurement of the axial e-N form factor G[sub A][sup e] substantially different from the theoretical estimate. In order to confirm this observation, a third SAMPLE experiment was carried out at a lower beam energy of 125 MeV (Q2 = 0.038 (GeV/c)2) on a deuterium target. The data analysis is now at the final stage and the results are consistent with the theoretical prediction of the axial form factor G[sub A][sup e]. Also, reevaluation of the background dilution factor and the electromagnetic radiative correction for the 200 MeV deuterium data lead to updated results, which are also consistent with the theoretical prediction. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A halo generation mechanism in the non-periodic lattices such as the SNS linac MEBT (Medium-Energy Beam-Transport between RFQ and DTL) is reported. We find that the nonlinear space charge force resulting from large transverse beam eccentricity ∼2:1 in the ∼1.6-m-long MEBT chopper section is responsible for halo formation. As a result, the beam distribution, based on the Front End (FE) emittance measurements and multiparticle simulation studies, develops halo that leads to beam loss and radio activation of the SNS linac. Designing lattices with transverse beam eccentricity close to 1:1 suppresses this kind of halo generation. Modifying the MEBT optics and introducing adjustable collimators in the MEBT significantly reduced beam losses in the CCL, which is a preferred scheme for mitigating halo. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

In high intensity proton linacs, beam halo can be observed as early as the very first stages of acceleration. The inital population of halo particles found in the output distribution of the RFQ, increases in chopper lines, which interrupt the regular focusing pattern of RFQ and DTL. The resulting emittance growth and halo development contributes to beam loss in the low-energy accelerator sections and partly defines the beam quality in the high-energy sections. Using the examples of the ESS and Linac4 (CERN) front ends (RFQ to 20 MeV) we investigate emittance growth and beam halo due to statistically distributed field and gradient errors. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]