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Preview: Recent Articles in Phys. Rev. ST Accel. Beams

Recent Articles in Phys. Rev. Accel. Beams

Recent articles in Physical Review Accelerators and Beams

Published: 2016-10-21T16:19:24-04:00


Experimental measurements and theoretical model of the cryogenic performance of bialkali photocathode and characterization with Monte Carlo simulation


Author(s): Huamu Xie, Ilan Ben-Zvi, Triveni Rao, Tianmu Xin, and Erdong Wang
High-average-current, high-brightness electron sources have important applications, such as in high-repetition-rate free-electron lasers, or in the electron cooling of hadrons. Bialkali photocathodes are promising high-quantum-efficiency (QE) cathode materials, while superconducting rf (SRF) electro…
[Phys. Rev. Accel. Beams 19, 103401] Published Wed Oct 19, 2016

Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes


Author(s): Xiaomei Zhang, Toshiki Tajima, Deano Farinella, Youngmin Shin, Gerard Mourou, Jonathan Wheeler, Peter Taborek, Pisin Chen, Franklin Dollar, and Baifei Shen
Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a …
[Phys. Rev. Accel. Beams 19, 101004] Published Tue Oct 18, 2016

Long term dynamics of the high luminosity Large Hadron Collider with crab cavities


Author(s): J. Barranco García, R. De Maria, A. Grudiev, R. Tomás García, R. B. Appleby, and D. R. Brett
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) aims to achieve an integrated luminosity of 200–300  fb^{−1} per year, including the contribution from the upgrade of the injector chain. For the HL-LHC the larger crossing angle together with a smaller beta function at the collision …
[Phys. Rev. Accel. Beams 19, 101003] Published Tue Oct 11, 2016

Polarization response of RHIC electron lens lattices


Author(s): V. H. Ranjbar, F. Méot, M. Bai, D. T. Abell, and D. Meiser
Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. In particular we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and thresho…
[Phys. Rev. Accel. Beams 19, 101002] Published Mon Oct 10, 2016

Tunable THz radiation source from dielectric loaded waveguide excited by nonrelativistic electron bunch trains


Author(s): Weiwei Li, Zhigang He, Yalin Lu, Ruixuan Huang, Weihao Liu, Qika Jia, and Lin Wang
We propose a novel scheme to generate a tunable narrow-band THz radiation. In this scheme, a train of laser pulses with THz repetition rate is used to drive a photocathode direct current (DC) gun, leading to the emission of a train of electron bunches. The electron bunch train is subsequently accele…
[Phys. Rev. Accel. Beams 19, 104701] Published Thu Oct 06, 2016

Probing half β_{y}^{*} optics in the Accelerator Test Facility 2


Author(s): M. Patecki, D. Bett, E. Marin, F. Plassard, R. Tomás, K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, and N. Terunuma
A nanometer beam size at the interaction point (IP) is required for future linear colliders to achieve the desired rate of particle collisions. KEK Accelerator Test Facility 2 (ATF2), a scaled down implementation of the linear collider beam delivery system, serves for demonstrating the feasibility o…
[Phys. Rev. Accel. Beams 19, 101001] Published Wed Oct 05, 2016

Wake excited in plasma by an ultrarelativistic pointlike bunch


Author(s): G. Stupakov, B. Breizman, V. Khudik, and G. Shvets
We study propagation of a relativistic electron bunch through a cold plasma assuming that the transverse and longitudinal dimensions of the bunch are much smaller than the plasma collisionless skin depth. Treating the bunch as a point charge and assuming that its charge is small, we derive a simplif…
[Phys. Rev. Accel. Beams 19, 101302] Published Wed Oct 05, 2016

Breakdown study based on direct in situ observation of inner surfaces of an rf accelerating cavity during a high-gradient test


Author(s): Tetsuo Abe, Tatsuya Kageyama, Hiroshi Sakai, Yasunao Takeuchi, and Kazuo Yoshino
We have developed normal-conducting accelerating single-cell cavities with a complete higher-order-mode (HOM) heavily damped structure, into which we feed a 508.9-MHz continuous wave. During a high-gradient test of the second production version of the cavity, we performed a breakdown study based on …
[Phys. Rev. Accel. Beams 19, 102001] Published Tue Oct 04, 2016

Transverse to longitudinal phase space coupling in an electron beam for suppression of microbunching instability


Author(s): Dazhang Huang, Chao Feng, Haixiao Deng, Qiang Gu, and Zhentang Zhao
The microbunching instability developed during the beam compression process in the linear accelerator (LINAC) of a free-electron laser (FEL) facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by th…
[Phys. Rev. Accel. Beams 19, 100701] Published Mon Oct 03, 2016

Electron acceleration and generation of high-brilliance x-ray radiation in kilojoule, subpicosecond laser-plasma interactions


Author(s): J. Ferri, X. Davoine, S. Y. Kalmykov, and A. Lifschitz

Comparison through particle-in-cell simulations of self-modulated-high-density and resonant-low-density regimes provides a bridge between the laser-wakefield-acceleration and picosecond-petawatt-laser communities.

[Phys. Rev. Accel. Beams 19, 101301] Published Mon Oct 03, 2016

Efficient computation of coherent synchrotron radiation in a rectangular chamber


Author(s): Robert L. Warnock and David A. Bizzozero
We study coherent synchrotron radiation (CSR) in a perfectly conducting vacuum chamber of rectangular cross section, in a formalism allowing an arbitrary sequence of bends and straight sections. We apply the paraxial method in the frequency domain, with a Fourier development in the vertical coordina…
[Phys. Rev. Accel. Beams 19, 090705] Published Tue Sep 27, 2016

Performance analysis of superconducting rf cavities for the CERN rare isotope accelerator


Author(s): S. Calatroni, A. Miyazaki, G. Rosaz, A. Sublet, W. Venturini Delsolaro, R. Vaglio, and V. Palmieri
The first cryomodule of the new HIE-ISOLDE rare isotope accelerator has recently been commissioned with beam at CERN, with the second cryomodule ready for installation. Each cryomodule contains five superconducting low-beta quarter wave cavities, produced with the technology of sputtering a thin nio…
[Phys. Rev. Accel. Beams 19, 092002] Published Fri Sep 23, 2016

Multiobjective optimizations of a novel cryocooled dc gun based ultrafast electron diffraction beam line


Author(s): Colwyn Gulliford, Adam Bartnik, and Ivan Bazarov
We present the results of multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line utilizing a 225 kV dc gun with a novel cryocooled photocathode system and buncher cavity. Optimizations of the transverse projected emittance as a function of bunch char…
[Phys. Rev. Accel. Beams 19, 093402] Published Fri Sep 23, 2016

Electron bunch structure in energy recovery linac with high-voltage dc photoelectron gun


Author(s): Y. M. Saveliev, F. Jackson, J. K. Jones, and J. W. McKenzie
The internal structure of electron bunches generated in an injector line with a dc photoelectron gun is investigated. Experiments were conducted on the ALICE (accelerators and lasers in combined experiments) energy recovery linac at Daresbury Laboratory. At a relatively low dc gun voltage of 230 kV,…
[Phys. Rev. Accel. Beams 19, 094002] Published Fri Sep 23, 2016

Longitudinal stability in multiharmonic standing wave linacs


Author(s): L. R. Carver, R. M. Jones, Y. Jiang, and J. L. Hirshfield
Accelerating cavities that excite multiple modes at integer harmonics of the fundamental frequency have the potential to be used to suppress the onset of rf breakdown and reduce the pulsed surface heating at high accelerating gradients. Understanding the effect of an additional harmonic cavity mode …
[Phys. Rev. Accel. Beams 19, 094001] Published Thu Sep 22, 2016

Utilizing the N beam position monitor method for turn-by-turn optics measurements


Author(s): A. Langner, G. Benedetti, M. Carlà, U. Iriso, Z. Martí, J. Coello de Portugal, and R. Tomás
The N beam position monitor method (N-BPM) which was recently developed for the LHC has significantly improved the precision of optics measurements that are based on BPM turn-by-turn data. The main improvement is due to the consideration of correlations for statistical and systematic error sources, …
[Phys. Rev. Accel. Beams 19, 092803] Published Wed Sep 21, 2016

Radiation emitted by transverse-gradient undulators


Author(s): Axel Bernhard, Nils Braun, Verónica Afonso Rodríguez, Peter Peiffer, Robert Rossmanith, Christina Widmann, and Michael Scheer
Conventional undulators are used in synchrotron light sources to produce radiation with a narrow relative spectral width as compared to bending magnets or wigglers. The spectral width of the radiation produced by conventional undulators is determined by the number of undulator periods and by the ene…
[Phys. Rev. Accel. Beams 19, 090704] Published Tue Sep 20, 2016

Factors affecting the output pulse flatness of the linear transformer driver cavity systems with 5th harmonics


Author(s): V. M. Alexeenko, M. G. Mazarakis, A. A. Kim, S. S. Kondratiev, V. A. Sinebryukhov, S. N. Volkov, M. E. Cuneo, M. L. Kiefer, J. J. Leckby, B. V. Oliver, and P. D. Maloney
We describe the study we have undertaken to evaluate the effect of component tolerances in obtaining a voltage output flat top for a linear transformer driver (LTD) cavity containing 3rd and 5th harmonic bricks [A. A. Kim et al., in Proc. IEEE Pulsed Power and Plasma Science PPPS2013 (San Francisco…
[Phys. Rev. Accel. Beams 19, 090401] Published Mon Sep 19, 2016

Design and experimental tests of free electron laser wire scanners


Author(s): G. L. Orlandi, P. Heimgartner, R. Ischebeck, C. Ozkan Loch, S. Trovati, P. Valitutti, V. Schlott, M. Ferianis, and G. Penco
SwissFEL is a x-rays free electron laser (FEL) driven by a 5.8 GeV linac under construction at Paul Scherrer Institut. In SwissFEL, wire scanners (WSCs) will be complementary to view-screens for emittance measurements and routinely used to monitor the transverse profile of the electron beam during F…
[Phys. Rev. Accel. Beams 19, 092802] Published Fri Sep 16, 2016

Measurements and simulations of wakefields at the Accelerator Test Facility 2


Author(s): J. Snuverink, R. Ainsworth, S. T. Boogert, F. J. Cullinan, A. Lyapin, Y. I. Kim, K. Kubo, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa, and G. R. White
Wakefields are an important factor in accelerator design, and are a real concern when preserving the low beam emittance in modern machines. Charge dependent beam size growth has been observed at the Accelerator Test Facility (ATF2), a test accelerator for future linear collider beam delivery systems…
[Phys. Rev. Accel. Beams 19, 091002] Published Thu Sep 15, 2016

Theoretical study of a waveguide THz free electron laser and comparisons with simulations


Author(s): Yoshihiro Shobuda and Yong Ho Chin

This paper fills a gap in the waveguide free electron laser theory by considering transverse distribution and energy spread of the electron beam.

[Phys. Rev. Accel. Beams 19, 094201] Published Wed Sep 14, 2016

Mid-infrared lasers for energy frontier plasma accelerators


Author(s): I. V. Pogorelsky, M. N. Polyanskiy, and W. D. Kimura

Mid-infrared lasers offer an alternative path for plasma acceleration; proposed applications include lepton colliders, gamma colliders, and positron sources.

[Phys. Rev. Accel. Beams 19, 091001] Published Mon Sep 12, 2016

Extremum seeking x-ray position feedback using power line harmonic leakage as the perturbation


Author(s): S. Zohar, D. J. Kissick, N. Venugopalan, C. M. Ogata, O. Makarov, S. Stepanov, and R. F. Fischetti
Small x-ray beam sizes necessary for probing nanoscale phenomena require exquisite stability to prevent data corruption by noise. One source of instability at synchrotron radiation x-ray beamlines is the slow detuning of x-ray optics to marginal alignment where the onset of clipping increases the be…
[Phys. Rev. Accel. Beams 19, 092801] Published Mon Sep 12, 2016

Propagation of elastic pressure waves in a beam window


Author(s): T. R. Davenne and P. Loveridge
As particle accelerator beam power increases, stress on beam windows and targets increases. Many simulations are carried out to model the dynamic stresses that are induced in these critical components by near instantaneous beam heating. However while it is often easy to obtain simulation results the…
[Phys. Rev. Accel. Beams 19, 093501] Published Mon Sep 12, 2016

Tunable polarization plasma channel undulator for narrow bandwidth photon emission


Author(s): S. G. Rykovanov, J. W. Wang, V. Yu. Kharin, B. Lei, C. B. Schroeder, C. G. R. Geddes, E. Esarey, and W. P. Leemans

Undulator field generated by off-axis or crossing injection of laser beam into plasma channel is discussed with appealing properties for practical applications.

[Phys. Rev. Accel. Beams 19, 090703] Published Fri Sep 09, 2016

Production of superconducting 1.3-GHz cavities for the European X-ray Free Electron Laser


Author(s): W. Singer, A. Brinkmann, R. Brinkmann, J. Iversen, A. Matheisen, W.-D. Moeller, A. Navitski, D. Reschke, J. Schaffran, A. Sulimov, N. Walker, H. Weise, P. Michelato, L. Monaco, C. Pagani, and M. Wiencek

Analysis and review of the largest production to date of superconducting cavities.

[Phys. Rev. Accel. Beams 19, 092001] Published Fri Sep 09, 2016

Tracing dynamics of laser-induced fields on ultrathin foils using complementary imaging with streak deflectometry


Author(s): F. Abicht, J. Braenzel, G. Priebe, Ch. Koschitzki, A. A. Andreev, P. V. Nickles, W. Sander, and M. Schnürer
We present a detailed study of the electric and magnetic fields, which are created on plasma vacuum interfaces as a result of highly intense laser-matter interactions. For the field generation ultrathin polymer foils (30–50 nm) were irradiated with high intensity femtosecond (10^{19}–10^{20}  W/cm^{…
[Phys. Rev. Accel. Beams 19, 091302] Published Thu Sep 08, 2016

Comment on “Controlling the spectral shape of nonlinear Thomson scattering with proper laser chirping”


Author(s): Balša Terzić and Geoffrey A. Krafft
Rykovanov, Geddes, Schroeder, Esarey and Leemans [Phys. Rev. Accel. Beams 19, 030701 (2016); hereafter RGSEL] have recently reported on the analytic derivation for the laser pulse frequency modulation (chirping) which controls spectrum broadening for high laser pulse intensities. We demonstrate here…
[Phys. Rev. Accel. Beams 19, 098001] Published Thu Sep 08, 2016

Reply to “Comment on ‘Controlling the spectral shape of nonlinear Thomson scattering with proper laser chirping’”


Author(s): S. G. Rykovanov, C. G. R. Geddes, C. B. Schroeder, E. Esarey, and W. P. Leemans
We reply to Terzic and Krafft’s forgoing Comment [Phys. Rev. Accel. Beams, Comment on “Controlling the spectral shape of nonlinear Thomson scattering with proper laser chirping” 19 (2016)]. We disagree with the conclusion of the Comment regarding the novelty of solutions and the citations presented …
[Phys. Rev. Accel. Beams 19, 098002] Published Thu Sep 08, 2016

Generation of large-bandwidth x-ray free-electron-laser pulses


Author(s): Angela Saa Hernandez, Eduard Prat, Simona Bettoni, Bolko Beutner, and Sven Reiche
X-ray free-electron lasers (XFELs) are modern research tools in disciplines such as biology, material science, chemistry, and physics. Besides the standard operation that aims at minimizing the bandwidth of the produced XFEL radiation, there is a strong scientific demand to produce large-bandwidth X…
[Phys. Rev. Accel. Beams 19, 090702] Published Wed Sep 07, 2016

Method to generate a pulse train of few-cycle coherent radiation


Author(s): Bryant Garcia, Erik Hemsing, Tor Raubenheimer, Lawrence T. Campbell, and Brian W. J. McNeil
We develop a method to generate a long pulse train of few-cycle coherent radiation by modulating an electron beam with a high power laser. The large energy modulation disperses the beam in a radiating undulator and leads to the production of phase-locked few-cycle coherent radiation pulses. These pu…
[Phys. Rev. Accel. Beams 19, 090701] Published Tue Sep 06, 2016

Brilliant GeV electron beam with narrow energy spread generated by a laser plasma accelerator


Author(s): Ronghao Hu, Haiyang Lu, Yinren Shou, Chen Lin, Hongbin Zhuo, Chia-erh Chen, and Xueqing Yan
The production of GeV electron beam with narrow energy spread and high brightness is investigated using particle-in-cell simulations. A controlled electron injection scheme and a method for phase-space manipulation in a laser plasma accelerator are found to be essential. The injection is triggered b…
[Phys. Rev. Accel. Beams 19, 091301] Published Tue Sep 06, 2016

Polarized ^{3} He^{+2} ions in the Alternate Gradient Synchrotron to RHIC transfer line


Author(s): N. Tsoupas, H. Huang, F. Méot, V. Ptitsyn, T. Roser, and D. Trbojevic
The proposed electron-hadron collider (eRHIC) to be built at Brookhaven National Laboratory (BNL) will allow the collisions of 20 GeV polarized electrons with 250 GeV polarized protons, or 100  GeV/n polarized ^{3}He^{+2} ions, or other unpolarized ion species. The large value of the anomalous magne…
[Phys. Rev. Accel. Beams 19, 094702] Published Tue Sep 06, 2016

Compton sources for the observation of elastic photon-photon scattering events


Author(s): D. Micieli, I. Drebot, A. Bacci, E. Milotti, V. Petrillo, M. Rossetti Conti, A. R. Rossi, E. Tassi, and L. Serafini
We present the design of a photon-photon collider based on conventional Compton gamma sources for the observation of elastic γγ scattering. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton backscattering with two high …
[Phys. Rev. Accel. Beams 19, 093401] Published Thu Sep 01, 2016

Focusing effects in laser-electron Thomson scattering


Author(s): Chris Harvey, Mattias Marklund, and Amol R. Holkundkar

More realistic laser beams affect spectral properties of Thomson scattering.

[Phys. Rev. Accel. Beams 19, 094701] Published Thu Sep 01, 2016

High power experimental studies of hybrid photonic band gap accelerator structures


Author(s): JieXi Zhang, Brian J. Munroe, Haoran Xu, Michael A. Shapiro, and Richard J. Temkin
This paper reports the first high power tests of hybrid photonic band gap (PBG) accelerator structures. Three hybrid PBG (HPBG) structures were designed, built and tested at 17.14 GHz. Each structure had a triangular lattice array with 60 inner sapphire rods and 24 outer copper rods sandwiched betwe…
[Phys. Rev. Accel. Beams 19, 081304] Published Wed Aug 31, 2016

Dependence of trapped-flux-induced surface resistance of a large-grain Nb superconducting radio-frequency cavity on spatial temperature gradient during cooldown through T_{c}


Author(s): Shichun Huang, Takayuki Kubo, and R. L. Geng
Recent studies by Romanenko et al. revealed that cooling down a superconducting cavity under a large spatial temperature gradient decreases the amount of trapped flux and leads to reduction of the residual surface resistance. In the present paper, the flux expulsion ratio and the trapped-flux-induce…
[Phys. Rev. Accel. Beams 19, 082001] Published Fri Aug 26, 2016

Optimization of positrons generation based on laser wakefield electron acceleration


Author(s): Yuchi Wu, Dan Han, Tiankui Zhang, Kegong Dong, Bin Zhu, Yonghong Yan, and Yuqiu Gu
Laser based positron represents a new particle source with short pulse duration and high charge density. Positron production based on laser wakefield electron acceleration (LWFA) has been investigated theoretically in this paper. Analytical expressions for positron spectra and yield have been obtain…
[Phys. Rev. Accel. Beams 19, 081303] Published Tue Aug 23, 2016

Ultrafast harmonic rf kicker design and beam dynamics analysis for an energy recovery linac based electron circulator cooler ring


Author(s): Yulu Huang, Haipeng Wang, Robert A. Rimmer, Shaoheng Wang, and Jiquan Guo
An ultrafast kicker system is being developed for the energy recovery linac (ERL) based electron circulator cooler ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously named MEIC). In the CCR, the injected electron bunches can be recirculated while performing ion cooling…
[Phys. Rev. Accel. Beams 19, 084201] Published Mon Aug 22, 2016

Asymmetric dual axis energy recovery linac for ultrahigh flux sources of coherent x-ray and THz radiation: Investigations towards its ultimate performance


Author(s): R. Ainsworth, G. Burt, I. V. Konoplev, and A. Seryi
In order for sources of coherent high brightness and intensity THz and x-ray radiation to be accepted by university or industrial R laboratories, truly compact, high current and efficient particle accelerators are required. The demand for compactness and efficiency can be satisfied by superconductin…
[Phys. Rev. Accel. Beams 19, 083502] Published Fri Aug 19, 2016

Explicit symplectic orbit and spin tracking method for electric storage ring


Author(s): Kilean Hwang and S. Y. Lee
We develop a symplectic charged particle tracking method for phase space coordinates and polarization in all electric storage rings. Near the magic energy, the spin precession tune is proportional to the fractional momentum deviation δ_{m} from the magic energy, and the amplitude of the radial and l…
[Phys. Rev. Accel. Beams 19, 084001] Published Thu Aug 18, 2016

Generation of subterawatt-attosecond pulses in a soft x-ray free-electron laser


Author(s): Senlin Huang, Yuantao Ding, Zhirong Huang, and Gabriel Marcus
We propose a novel scheme to generate attosecond soft x rays in a self-seeded free-electron laser (FEL) suitable for enabling attosecond spectroscopic investigations. A time-energy chirped electron bunch with additional sinusoidal energy modulation is adopted to produce a short seed pulse through a …
[Phys. Rev. Accel. Beams 19, 080702] Published Mon Aug 15, 2016

Case study of a magnetic system for low-energy machines


Author(s): Daniel Schoerling
The extra low-energy antiproton ring (ELENA) is a CERN particle decelerator with the purpose to deliver antiprotons at lowest energies aiming to enhance the study of antimatter. The hexagonal shaped ring with a circumference of about 30 m will decelerate antiprotons from momenta of 100 to 13.7  MeV/…
[Phys. Rev. Accel. Beams 19, 082401] Published Wed Aug 10, 2016

Short electron bunch generation using single-cycle ultrafast electron guns


Author(s): Arya Fallahi, Moein Fakhari, Alireza Yahaghi, Miguel Arrieta, and Franz X. Kärtner
We introduce a solution for producing ultrashort (∼fs) high charge (∼pC) from ultracompact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20  μJ are sufficient to generate multi-10 keV electron bunches. Moreover, it is demonstrated that …
[Phys. Rev. Accel. Beams 19, 081302] Published Tue Aug 09, 2016

Efficiency of feedbacks for suppression of transverse instabilities of bunched beams


Author(s): Alexey Burov
Which gain and phase have to be set for a bunch-by-bunch transverse damper, and at which chromaticity is it better to stay? These questions are considered for three models: the two-particle model with possible quadrupole wake, the author’s nested head-tail (NHT) model with the broadband impedance, a…
[Phys. Rev. Accel. Beams 19, 084402] Published Fri Aug 05, 2016

X-ray characterization by energy-resolved powder diffraction


Author(s): G. Cheung and S. M. Hooker

Single-shot, nondestructive measurements can characterize x-ray beams arising from betatron oscillations in a plasma accelerator.

[Phys. Rev. Accel. Beams 19, 082801] Published Thu Aug 04, 2016

Common operation metrics for storage ring light sources


Author(s): A. Lüdeke, M. Bieler, R. H. A. Farias, S. Krecic, R. Müller, M. Pont, and M. Takao
Storage ring light sources aim for high operational reliability. Very often beam availability is used as an operation metric to measure the reliability. A survey of several light sources reveals that the calculation of availability varies significantly between facilities. This complicates useful com…
[Phys. Rev. Accel. Beams 19, 082802] Published Thu Aug 04, 2016

Systematic neutron guide misalignment for an accelerator-driven spallation neutron source


Author(s): C. Zendler and P. M. Bentley
The European Spallation Source (ESS) is a long pulse spallation neutron source that is currently under construction in Lund, Sweden. A considerable fraction of the 22 planned instruments extend as far as 75–150 m from the source. In such long beam lines, misalignment between neutron guide segments c…
[Phys. Rev. Accel. Beams 19, 083501] Published Thu Aug 04, 2016

Analytical formulas for short bunch wakes in a flat dechirper


Author(s): Karl Bane, Gennady Stupakov, and Igor Zagorodnov
We develop analytical models of the longitudinal and transverse wakes, on and off axis for a flat, corrugated beam pipe with realistic parameters, and then compare them with numerical calculations, and generally find good agreement. These analytical “first order” formulas approximate the droop at th…
[Phys. Rev. Accel. Beams 19, 084401] Published Thu Aug 04, 2016

Beam induced hydrodynamic tunneling in the future circular collider components


Author(s): N. A. Tahir, F. Burkart, R. Schmidt, A. Shutov, D. Wollmann, and A. R. Piriz
A future circular collider (FCC) has been proposed as a post-Large Hadron Collider accelerator, to explore particle physics in unprecedented energy ranges. The FCC is a circular collider in a tunnel with a circumference of 80–100 km. The FCC study puts an emphasis on proton-proton high-energy and el…
[Phys. Rev. Accel. Beams 19, 081002] Published Wed Aug 03, 2016

Quasilinear theory of terahertz free-electron lasers based on Compton scattering of incoherent pump wave by intense relativistic electron beam


Author(s): N. S. Ginzburg and E. R. Kocharovskaya
The use of incoherent broadband pump radiation for improving the electron efficiency in the free-electron lasers (FEL) based on stimulated backscattering is considered. On the basis of a quasilinear approach, it is shown that the efficiency increases in proportion to the width of the pump spectrum. …
[Phys. Rev. Accel. Beams 19, 080701] Published Tue Aug 02, 2016

Beam-induced wakefield observation in X-band choke-mode cavities


Author(s): Hao Zha, Chunguang Jing, Jiaqi Qiu, Eric E. Wisniewski, Manoel Conde, John G. Power, Darrell S. Doran, Wanming Liu, Jiaru Shi, Chen Li, Wei Gai, and Huaibi Chen
The X-band choke-mode structure is currently being studied as an alternative design for the accelerating structure of the compact linear collider (CLIC) main linac. The geometry of the choke-mode structure is designed to ensure the strong suppression of the beam-induced long-range transverse wakefie…
[Phys. Rev. Accel. Beams 19, 081001] Published Mon Aug 01, 2016

Higher order mode damping in a five-cell superconducting rf cavity with a photonic band gap coupler cell


Author(s): Sergey A. Arsenyev, Richard J. Temkin, Dmitry Yu. Shchegolkov, Evgenya I. Simakov, Chase H. Boulware, Terry L. Grimm, and Adam R. Rogacki
We present a study of higher order mode (HOM) damping in the first multicell superconducting radio-frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-…
[Phys. Rev. Accel. Beams 19, 081301] Published Mon Aug 01, 2016

Amplitude dependent closest tune approach


Author(s): R. Tomás, T. H. B. Persson, and E. H. Maclean
Recent observations in the LHC point to the existence of an amplitude dependent closest tune approach. However this dynamical behavior and its underlying mechanism remain unknown. This effect is highly relevant for the LHC as an unexpected closest tune approach varying with amplitude modifies the fr…
[Phys. Rev. Accel. Beams 19, 071003] Published Thu Jul 28, 2016

Theory of electromagnetic insertion devices and the corresponding synchrotron radiation


Author(s): Muhammad Shumail and Sami G. Tantawi
Permanent magnet insertion devices (IDs), which are the main radiation generating devices in synchrotron light sources and free-electron lasers, use a time-invariant but space-periodic magnetic field to wiggle relativistic electrons for short-wavelength radiation generation. Recently, a high power m…
[Phys. Rev. Accel. Beams 19, 074001] Published Wed Jul 27, 2016

Simple model of the slingshot effect


Author(s): Gaetano Fiore and Sergio De Nicola
We present a detailed quantitative description of the recently proposed “slingshot effect.” Namely, we determine a broad range of conditions under which the impact of a very short and intense laser pulse normally onto a low-density plasma (or matter locally completely ionized into a plasma by the pu…
[Phys. Rev. Accel. Beams 19, 071302] Published Thu Jul 21, 2016

Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch


Author(s): S. Kuschel, D. Hollatz, T. Heinemann, O. Karger, M. B. Schwab, D. Ullmann, A. Knetsch, A. Seidel, C. Rödel, M. Yeung, M. Leier, A. Blinne, H. Ding, T. Kurz, D. J. Corvan, A. Sävert, S. Karsch, M. C. Kaluza, B. Hidding, and M. Zepf
We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we intr…
[Phys. Rev. Accel. Beams 19, 071301] Published Wed Jul 20, 2016

Superconducting resonator used as a phase and energy detector for linac setup


Author(s): Nikolai R. Lobanov
Booster linacs for tandem accelerators and positive ion superconducting injectors have matured into standard features of many accelerator laboratories. Both types of linac are formed as an array of independently-phased resonators operating at room temperature or in a superconducting state. Each acce…
[Phys. Rev. Accel. Beams 19, 072801] Published Tue Jul 19, 2016

Rotating system for four-dimensional transverse rms-emittance measurements


Author(s): C. Xiao, M. Maier, X. N. Du, P. Gerhard, L. Groening, S. Mickat, and H. Vormann
Knowledge of the transverse four-dimensional beam rms parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the elimination of interplane correlations to reduce the projected emittances. A dedicated r…
[Phys. Rev. Accel. Beams 19, 072802] Published Tue Jul 19, 2016

Design of general apochromatic drift-quadrupole beam lines


Author(s): C. A. Lindstrøm and E. Adli

Correcting chromatic errors without sextupoles may have important practical applications in future accelerators.

[Phys. Rev. Accel. Beams 19, 071002] Published Fri Jul 15, 2016

CERN antiproton target: Hydrocode analysis of its core material dynamic response under proton beam impact


Author(s): Claudio Torregrosa Martin, Antonio Perillo-Marcone, Marco Calviani, and José-Luis Muñoz-Cobo
Antiprotons are produced at CERN by colliding a 26  GeV/c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, m…
[Phys. Rev. Accel. Beams 19, 073402] Published Fri Jul 15, 2016

rf traveling-wave electron gun for photoinjectors


Author(s): Mattia Schaer, Alessandro Citterio, Paolo Craievich, Sven Reiche, Lukas Stingelin, and Riccardo Zennaro

Novel traveling-wave rf gun for compact high-brightness photoinjectors is designed by joint optimization of beam dynamics and 3D rf calculations.

[Phys. Rev. Accel. Beams 19, 072001] Published Tue Jul 12, 2016

Beam induced electron cloud resonances in dipole magnetic fields


Author(s): J. R. Calvey, W. Hartung, J. Makita, and M. Venturini
The buildup of low energy electrons in an accelerator, known as electron cloud, can be severely detrimental to machine performance. Under certain beam conditions, the beam can become resonant with the cloud dynamics, accelerating the buildup of electrons. This paper will examine two such effects: mu…
[Phys. Rev. Accel. Beams 19, 074401] Published Tue Jul 12, 2016

Publisher’s Note: High intensity neutrino oscillation facilities in Europe [Phys. Rev. Accel. Beams 16, 021002 (2013)]


Author(s): T. R. Edgecock et al.
[Phys. Rev. Accel. Beams 19, 079901] Published Fri Jul 08, 2016

Conceptual design of a 10^{13} -W pulsed-power accelerator for megajoule-class dynamic-material-physics experiments


Author(s): W. A. Stygar et al.
We have developed a conceptual design of a next-generation pulsed-power accelerator that is optimized for megajoule-class dynamic-material-physics experiments. Sufficient electrical energy is delivered by the accelerator to a physics load to achieve—within centimeter-scale samples—material pressures…
[Phys. Rev. Accel. Beams 19, 070401] Published Thu Jul 07, 2016

Storage ring two-color free-electron laser


Author(s): J. Yan, H. Hao, J. Y. Li, S. F. Mikhailov, V. G. Popov, N. A. Vinokurov, S. Huang, J. Wu, S. Günster, and Y. K. Wu
We report a systematic experimental study of a storage ring two-color free-electron laser (FEL) operating simultaneously in the infrared (IR) and ultraviolet (UV) wavelength regions. The two-color FEL lasing has been realized using a pair of dual-band high-reflectivity FEL mirrors with two different…
[Phys. Rev. Accel. Beams 19, 070701] Published Tue Jul 05, 2016

Channeling, volume reflection, and volume capture study of electrons in a bent silicon crystal


Author(s): T. N. Wistisen, U. I. Uggerhøj, U. Wienands, T. W. Markiewicz, R. J. Noble, B. C. Benson, T. Smith, E. Bagli, L. Bandiera, G. Germogli, V. Guidi, A. Mazzolari, R. Holtzapple, and S. Tucker
We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5 …
[Phys. Rev. Accel. Beams 19, 071001] Published Tue Jul 05, 2016

Ion wave breaking acceleration


Author(s): B. Liu, J. Meyer-ter-Vehn, K-U. Bamberg, W. J. Ma, J. Liu, X. T. He, X. Q. Yan, and H. Ruhl
Laser driven ion wave breaking acceleration (IWBA) in plasma wakefields is investigated by means of a one-dimensional (1D) model and 1D/3D particle-in-cell (PIC) simulations. IWBA operates in relativistic transparent plasma for laser intensities in the range of 10^{20}–10^{23}  W/cm^{2}. The thresho…
[Phys. Rev. Accel. Beams 19, 073401] Published Tue Jul 05, 2016

High-power free-electron maser operated in a two-mode frequency-multiplying regime


Author(s): N. Yu. Peskov, I. V. Bandurkin, A. K. Kaminsky, S. V. Kuzikov, E. A. Perelstein, A. V. Savilov, S. N. Sedykh, and A. A. Vikharev
The frequency multiplication effects in high-power free-electron masers (FEM) with Bragg cavities were studied to provide the advance of the oscillators into short-wavelength bands. Theoretical analysis of frequency-multiplying FEMs was carried out within the framework of the averaged coupled-wave a…
[Phys. Rev. Accel. Beams 19, 060704] Published Wed Jun 29, 2016

Dosimetric response of radiochromic films to protons of low energies in the Bragg peak region


Author(s): M. C. Battaglia, D. Schardt, J. M. Espino, M. I. Gallardo, M. A. Cortés-Giraldo, J. M. Quesada, A. M. Lallena, H. Miras, and D. Guirado
One of the major advantages of proton or ion beams, applied in cancer treatment, is their excellent depth-dose profile exhibiting a low dose in the entrance channel and a distinct dose maximum (Bragg peak) near the end of range in tissue. In the region of the Bragg peak, where the protons or ions ar…
[Phys. Rev. Accel. Beams 19, 064701] Published Tue Jun 21, 2016

Laser mode complexity analysis in infrared waveguide free-electron lasers


Author(s): Rui Prazeres
We analyze an optical phenomenon taking place in waveguide free-electron lasers, which disturbs, or forbids, operation in far infrared range. Waveguides in the optical cavity are used in far-infrared and THz ranges in order to avoid diffraction optical losses, and a hole coupling on output mirror is…
[Phys. Rev. Accel. Beams 19, 060703] Published Mon Jun 20, 2016

Toward high-energy laser-driven ion beams: Nanostructured double-layer targets


Author(s): M. Passoni, A. Sgattoni, I. Prencipe, L. Fedeli, D. Dellasega, L. Cialfi, Il Woo Choi, I Jong Kim, K. A. Janulewicz, Hwang Woon Lee, Jae Hee Sung, Seong Ku Lee, and Chang Hee Nam
The development of novel target concepts is crucial to make laser-driven acceleration of ion beams suitable for applications. We tested double-layer targets formed of an ultralow density nanostructured carbon layer (∼7  mg/cm^{3}, 8–12  μm–thick) deposited on a μm–thick solid Al foil. A systematic i…
[Phys. Rev. Accel. Beams 19, 061301] Published Mon Jun 20, 2016

Pressurized rf cavities in ionizing beams


Author(s): B. Freemire, A. V. Tollestrup, K. Yonehara, M. Chung, Y. Torun, R. P. Johnson, G. Flanagan, P. M. Hanlet, M. G. Collura, M. R. Jana, M. Leonova, A. Moretti, and T. Schwarz
A muon collider or Higgs factory requires significant reduction of the six dimensional emittance of the beam prior to acceleration. One method to accomplish this involves building a cooling channel using high pressure gas filled radio frequency cavities. The performance of such a cavity when subject…
[Phys. Rev. Accel. Beams 19, 062004] Published Mon Jun 20, 2016

Compact rf polarizer and its application to pulse compression systems


Author(s): Matthew Franzi, Juwen Wang, Valery Dolgashev, and Sami Tantawi
We present a novel method of reducing the footprint and increasing the efficiency of the modern multi-MW rf pulse compressor. This system utilizes a high power rf polarizer to couple two circular waveguide modes in quadrature to a single resonant cavity in order to replicate the response of a tradit…
[Phys. Rev. Accel. Beams 19, 062002] Published Fri Jun 17, 2016

Conceptual design of X band waveguide dual circular polarizer


Author(s): Chen Xu, Sami Tantawi, and Juwen Wang
A new design of dual circular polarizer is presented in this paper. This innovative design converts radiofrequency (rf) energy from TE10 mode in a rectangular waveguide to two polarized TE11 modes in a circular waveguide. A reflection less than −20  db is achieved and breakdown field is less than 42…
[Phys. Rev. Accel. Beams 19, 062003] Published Fri Jun 17, 2016

Temporal characterization of ultrashort linearly chirped electron bunches generated from a laser wakefield accelerator


Author(s): C. J. Zhang, J. F. Hua, Y. Wan, B. Guo, C.-H. Pai, Y. P. Wu, F. Li, H.-H. Chu, Y. Q. Gu, W. B. Mori, C. Joshi, J. Wang, and W. Lu
A new method for diagnosing the temporal characteristics of ultrashort electron bunches with linear energy chirp generated from a laser wakefield accelerator is described. When the ionization-injected bunch interacts with the back of the drive laser, it is deflected and stretched along the direction…
[Phys. Rev. Accel. Beams 19, 062802] Published Fri Jun 17, 2016

Possible emittance growth induced by nonlinear space charge fields for arbitrary particle distributions


Author(s): Takashi Kikuchi (菊池 崇志) and Kazuhiko Horioka (堀岡 一彦)
A procedure to obtain a ratio of beam radii at final and initial states in arbitrary particle distributions is proposed, and is applied to the estimation of possible emittance growth for Gaussian and thermal equilibrium distributions. The ratios are estimated for Gaussian and thermal equilibrium dis…
[Phys. Rev. Accel. Beams 19, 064201] Published Thu Jun 16, 2016

Uncoupled thermoelasticity solutions applied on beam dumps


Author(s): A. Ouzia and T. Antonakakis
In particle accelerators the process of beam absorption is vital. At CERN particle beams are accelerated at energies of the order of TeV. In the event of a system failure or following collisions, the beam needs to be safely absorbed by dedicated protecting blocks. The thermal shock caused by the rap…
[Phys. Rev. Accel. Beams 19, 063501] Published Mon Jun 13, 2016

Three-dimensional analysis of the surface mode supported in Čerenkov and Smith-Purcell free-electron lasers


Author(s): Yashvir Kalkal and Vinit Kumar
In Čerenkov and Smith-Purcell free-electron lasers (FELs), a resonant interaction between the electron beam and the copropagating surface mode can produce a copious amount of coherent terahertz radiation. We perform a three-dimensional (3D) analysis of the surface mode, taking the effect of attenuat…
[Phys. Rev. Accel. Beams 19, 060702] Published Fri Jun 10, 2016

Plasma-driven ultrashort bunch diagnostics


Author(s): I. Dornmair, C. B. Schroeder, K. Floettmann, B. Marchetti, and A. R. Maier

High fields available in a plasma can be exploited to streak an electron bunch injected off-axis, pushing temporal resolution down to sub-fs in a mm-scale device.

[Phys. Rev. Accel. Beams 19, 062801] Published Fri Jun 10, 2016

Improving Touschek lifetime in ultralow-emittance lattices through systematic application of successive closed vertical dispersion bumps


Author(s): J. Breunlin, S. C. Leemann, and Å. Andersson
In present ultralow-emittance storage ring designs the emittance coupling required for the production of vertically diffraction-limited synchrotron radiation in the hard x-ray regime is achieved and in many cases surpassed by a correction of the orbit and the linear optics alone. However, operating …
[Phys. Rev. Accel. Beams 19, 060701] Published Thu Jun 09, 2016

Advanced simulation study on bunch gap transient effect


Author(s): Tetsuya Kobayashi and Kazunori Akai
Bunch phase shift along the train due to a bunch gap transient is a concern in high-current colliders. In KEKB operation, the measured phase shift along the train agreed well with a simulation and a simple analytical form in most part of the train. However, a rapid phase change was observed at the l…
[Phys. Rev. Accel. Beams 19, 062001] Published Thu Jun 09, 2016

Design of a triple-bend isochronous achromat with minimum coherent-synchrotron-radiation-induced emittance growth


Author(s): M. Venturini
Using a 1D steady-state free-space coherent synchrotron radiation (CSR) model, we identify a special design setting for a triple-bend isochronous achromat that yields vanishing emittance growth from CSR. When a more refined CSR model with transient effects is included in the analysis, numerical simu…
[Phys. Rev. Accel. Beams 19, 064401] Published Thu Jun 09, 2016

Intrinsic nonlinear effects of dipole magnets in small rings


Author(s): H. S. Xu, W. H. Huang, C. X. Tang, and S. Y. Lee
We find that dynamic aperture depends significantly on the bending radii of dipole magnets when designing a small storage ring for Tsinghua Thomson scattering X-ray source (TTX) mainly because of the nonlinearity of the dipole field. In this paper, we present systematic studies on the intrinsic-geom…
[Phys. Rev. Accel. Beams 19, 064001] Published Fri Jun 03, 2016

High-energy in-beam neutron measurements of metal-based shielding for accelerator-driven spallation neutron sources


Author(s): D. D. DiJulio, C. P. Cooper-Jensen, H. Björgvinsdóttir, Z. Kokai, and P. M. Bentley
Metal-based shielding plays an important role in the attenuation of harmful and unwanted radiation at an accelerator-driven spallation neutron source. At the European Spallation Source, currently under construction in Lund, Sweden, metal-based materials are planned to be used extensively as neutron …
[Phys. Rev. Accel. Beams 19, 053501] Published Tue May 31, 2016

Seeded free electron laser operating with two colors: Comments on experimental results


Author(s): M. Carpanese, F. Ciocci, G. Dattoli, A. Petralia, V. Petrillo, and A. Torre
Free electron lasers operating with two colors are promising devices for applications. The relevant modelization has provided a good understanding of the underlying physics. In this paper we present an analysis of the experimental results obtained at SPARC_LAB concerning seeded two-colors free elect…
[Phys. Rev. Accel. Beams 19, 050703] Published Thu May 26, 2016

Energy enhancement and spectrum narrowing in terahertz electron sources due to negative mass instability


Author(s): Yu. Lurie, V. L. Bratman, and A. V. Savilov
Simulations of coherent spontaneous undulator radiation in a waveguide demonstrate that the use of negative mass instability (NMI) for retaining longitudinal sizes of dense electron bunches, which are formed in laser-driven photoinjectors, allows one to increase power capabilities of a terahertz rad…
[Phys. Rev. Accel. Beams 19, 050704] Published Thu May 26, 2016

Approach to combined-function magnets via symplectic slicing


Author(s): M. Titze
In this article we describe how to obtain symplectic “slice” maps for combined-function magnets, by using a method of generating functions. A feature of this method is that one can use an unexpanded and unsplit Hamiltonian. From such a slice map we obtain a first-order map which is symplectic at the…
[Phys. Rev. Accel. Beams 19, 054002] Published Thu May 26, 2016

Two-color beam generation based on wakefield excitation


Author(s): S. Bettoni, E. Prat, and S. Reiche
Several beam manipulation methods have been studied and experimentally tested to generate two-color photon beams in free electron laser facilities to accommodate the user requests. We propose to use the interaction of the beam with an oscillating longitudinal wakefield source to obtain a suitable el…
[Phys. Rev. Accel. Beams 19, 050702] Published Wed May 25, 2016

Adaptive robust control of longitudinal and transverse electron beam profiles


Author(s): Amin Rezaeizadeh, Thomas Schilcher, and Roy S. Smith
Feedback control of the longitudinal and transverse electron beam profiles are considered to be critical for beam control in accelerators. In the feedback scheme, the longitudinal or transverse beam profile is measured and compared to a desired profile to give an error estimate. The error is then us…
[Phys. Rev. Accel. Beams 19, 052802] Published Wed May 25, 2016

New method of calculating the wakefields of a point charge in a waveguide of arbitrary cross section


Author(s): S. S. Baturin and A. D. Kanareykin

The high-frequency limit of electromagnetic fields is derived for a relativistic point-charge passing through a waveguide of arbitrary cross section with an arbitrary material boundary.

[Phys. Rev. Accel. Beams 19, 051001] Published Mon May 23, 2016

Sub-fs electron bunch generation with sub-10-fs bunch arrival-time jitter via bunch slicing in a magnetic chicane


Author(s): J. Zhu, R. W. Assmann, M. Dohlus, U. Dorda, and B. Marchetti
The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs) and bunch arrival-time jitte…
[Phys. Rev. Accel. Beams 19, 054401] Published Thu May 19, 2016

Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements


Author(s): R. Voutta, S. Gerstl, S. Casalbuoni, A. W. Grau, T. Holubek, D. Saez de Jauregui, R. Bartolini, M. P. Cox, E. C. Longhi, G. Rehm, J. C. Schouten, R. P. Walker, M. Migliorati, and B. Spataro
The beam heat load is an important input parameter needed for the cryogenic design of superconducting insertion devices. Theoretical models taking into account the different heating mechanisms of an electron beam to a cold bore predict smaller values than the ones measured with several superconducti…
[Phys. Rev. Accel. Beams 19, 053201] Published Wed May 18, 2016

Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection of ^{23} Na^{1+} ions


Author(s): O. Tarvainen, H. Koivisto, A. Galatà, J. Angot, T. Lamy, T. Thuillier, P. Delahaye, L. Maunoury, D. Mascali, and L. Neri
This work describes the utilization of an injected ^{23}Na^{1+} ion beam as a diagnostics of the helium plasma of a charge breeder electron cyclotron resonance ion source. The obtained data allows estimating the upper limit for the ion-ion collision mean-free path of the incident sodium ions, the lo…
[Phys. Rev. Accel. Beams 19, 053402] Published Mon May 16, 2016

High gradient quadrupoles for low emittance storage rings


Author(s): G. Le Bec, J. Chavanne, C. Benabderrahmane, L. Farvacque, L. Goirand, S. Liuzzo, P. Raimondi, and F. Villar
High gradient quadrupoles are key components for the coming generation of storage ring based light sources. The typical specifications of these magnets are: almost 100  T/m gradient, half a meter long, and a vertical aperture for the extraction of the x-ray beam. This paper presents the preparation …
[Phys. Rev. Accel. Beams 19, 052401] Published Mon May 09, 2016

Performance of a first generation X-band photoelectron rf gun


Author(s): C. Limborg-Deprey, C. Adolphsen, D. McCormick, M. Dunning, K. Jobe, H. Li, T. Raubenheimer, A. Vrielink, T. Vecchione, F. Wang, and S. Weathersby
Building more compact accelerators to deliver high brightness electron beams for the generation of high flux, highly coherent radiation is a priority for the photon science community. A relatively straightforward reduction in footprint can be achieved by using high-gradient X-band (11.4 GHz) rf tech…
[Phys. Rev. Accel. Beams 19, 053401] Published Wed May 04, 2016

Experimental measurements of rf breakdowns and deflecting gradients in mm-wave metallic accelerating structures


Author(s): Massimo Dal Forno, Valery Dolgashev, Gordon Bowden, Christine Clarke, Mark Hogan, Doug McCormick, Alexander Novokhatski, Bruno Spataro, Stephen Weathersby, and Sami G. Tantawi
We present an experimental study of a high gradient metallic accelerating structure at sub-THz frequencies, where we investigated the physics of rf breakdowns. Wakefields in the structure were excited by an ultrarelativistic electron beam. We present the first quantitative measurements of gradients …
[Phys. Rev. Accel. Beams 19, 051302] Published Tue May 03, 2016

Harmonically resonant cavity as a bunch-length monitor


Author(s): B. Roberts, F. Hannon, M. M. Ali, E. Forman, J. Grames, R. Kazimi, W. Moore, M. Pablo, M. Poelker, A. Sanchez, and D. Speirs
A compact, harmonically resonant cavity with fundamental resonant frequency 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Electron Beam Accelerator Facility (CEBAF) photoinject…
[Phys. Rev. Accel. Beams 19, 052801] Published Tue May 03, 2016

Using ac dipoles to localize sources of beam coupling impedance


Author(s): N. Biancacci and R. Tomás
The beam coupling impedance is one of the main sources of beam instabilities and emittance blow up in circular accelerators. A refined machine impedance evaluation is therefore required in order to understand and model intensity dependent effects and instabilities that may limit the machine performa…
[Phys. Rev. Accel. Beams 19, 054001] Published Tue May 03, 2016

Microbunching-instability-induced sidebands in a seeded free-electron laser


Author(s): Zhen Zhang, Ryan Lindberg, William M. Fawley, Zhirong Huang, Jacek Krzywinski, Alberto Lutman, Gabriel Marcus, and Agostino Marinelli
Measurements of the multishot-averaged, soft x-ray, self-seeding spectrum at the LCLS free-electron laser often have a pedestal-like distribution around the seeded wavelength, which limits the spectral purity and can negatively affect some user applications not employing a post-undulator monochromat…
[Phys. Rev. Accel. Beams 19, 050701] Published Mon May 02, 2016