LINAC2016 - List of Keywords (experiment)

Paper	Title	Other Keywords	Page
MO2A04	Low Emittance and High Current Electron Linac Development at Tsinghua University	gun, emittance, electron, laser	17
	C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China
	A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.
	Slides MO2A04 [11.413 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO2A04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRC029	Experiment of Plasma Discharge on HWR Cavity for In-Situ Surface Cleaning Study	cavity, plasma, electron, operation	133
	A.D. Wu, Y. He, T.C. Jiang, C.L. Li, Y.M. Li, W.M. Yue, S.H. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China L.M. Chen Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China L. Yang IHEP, Beijing, People's Republic of China
	Hydrocarbons, which migrate from the vacuum bumps system, will absorb on the cavity surface after periods of operation. The contaminants can reduce the surface electron work function to enhance the field emission effect and restrict the cavity accelerating gradient. The room temperature in-situ plasma surface processing to clean the hydrocarbon contaminants can act as a convenient and efficient technology for the accelerator on line performance recovery. For better control of the discharge inside the cavity, the experiment works on a single HWR cavity aims to research the ignition between the swarm parameters (gas flow, pressure, forward power).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC029
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR011	Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration	electron, acceleration, accelerating-gradient, impedance	158
	A.L. Healy, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M.J. Cliffe, D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR037	Study of the Surface and Performance of Single-Cell Nb Cavities After Vertical EP Using Ninja Cathodes	cathode, cavity, polarization, niobium	217
	V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan P. Carbonnier, F. Éozénou, Y. Gasser, L. Maurice, C. Servouin CEA/DSM/IRFU, France F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan K. Ishimi MGI, Chiba, Japan
	A 1.3 GHz single-cell niobium (Nb) coupon cavity was vertically electropolished (VEPed) with three different Ninja cathodes which were specially designed for VEP of 1.3 GHz superconducting RF elliptical (ILC/Tesla type) cavities. The cathodes were fabricated to have different surface areas and different distances between cathode surface and the equator. The Ninja cathode prepared with an enhanced cathode surface area was covered with a meshed shield to avoid bubble attack on the surface of the cavity cell. It has been turned out that the anode-cathode distance and the cathode area affect surface morphology of the equator. A smooth equator surface was obtained in the cases in which the cathode surface was geometrically close to the equator or instead the cathode surface area was sufficiently larger. Two 1.3 GHz ILC/Tesla type single-cell cavities VEPed with the Ninja cathodes and using optimized conditions showed good performance in vertical tests.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR039	Development of New Type "Ninja" Cathode for Nb 9-cell Cavity and Experiment of Vertical Electro-Polishing	cavity, cathode, target, collider	223
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan K. Ishimi MGI, Chiba, Japan
	Marui Galvanizing Co. Ltd. has been improving Vertical Electro-Polishing (VEP) technologies and facilities for Nb 9-cell superconducting accelerator cavity for International Linear Collider (ILC) in collaboration with KEK. This time, we developed new type 'Ninja' cathode in order to improve VEP uniformity of Nb 9-cell cavity inner surface based on the results of 1-cell cavity VEP experiment. In this article, we will report construction of new type "Ninja" cathode for Nb 9-cell cavity and experiment of VEP using this.
	Poster MOPLR039 [0.610 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR063	Development of H⁰ Beam Diagnostic Line in MEBT2 of J-PARC Linac	dipole, linac, diagnostics, vacuum	277
	J. Tamura, A. Miura, T. Morishita JAEA/J-PARC, Tokai-mura, Japan H. Ao FRIB, East Lansing, USA T. Maruta J-PARC, KEK & JAEA, Ibaraki-ken, Japan T. Miyao KEK, Ibaraki, Japan
	In the Japan Proton Accelerator Research Complex (J-PARC) linac, H⁰ particles arising from collisions of accelerated H⁻ beams with residual gas are considered as one of the key factors of the residual radiation in the high energy accelerating section. To analyze the H⁰ and the accelerated H⁻ particles, the bump magnet system was designed and produced. The H⁰ beam diagnostic line consists of four horizontal bending magnets, non-destructive beam position monitor and wire scan beam profile monitor. In the 2015 summer maintenance period of the J-PARC, the new diagnostic line was constructed in the beam transport (MEBT2), which is the matching section from separated-type drift tube linac (SDTL) to annular-ring coupled structure linac (ACS). In the beam commissioning, we experimentally confirmed that the accelerated 190 MeV H⁻ beams are horizontally shifted as expected with the magnetostatic field simulation and the particle tracking simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR063
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP106012	MESA - an ERL Project for Particle Physics Experiments	target, electron, operation, linac	313
	F. Hug, K. Aulenbacher, R.G. Heine, B. Ledroit, D. Simon IKP, Mainz, Germany
	The Mainz Energy-recovering Superconducting Accelerator (MESA) will be constructed at the Institut für Kernphysik of the Johannes Gutenberg University of Mainz. The accelerator is a low energy continuous wave (CW) recirculating electron linac for particle physics experiments. MESA will be operated in two different modes serving mainly two experiments: the first is the external beam (EB) mode, where the beam is dumped after being used with the external fixed target experiment P2, whose goal is the measurement of the weak mixing angle with highest accuracy. The required beam current for P2 is 150 μA with polarized electrons at 155 MeV. In the second operation mode MESA will be run as an energy recovery linac (ERL). The experiment served in this mode is a (pseudo) internal fixed target experiment named MAGIX. It demands an unpolarized beam of 1 mA at 10⁵ MeV. In a later construction stage of MESA the achievable beam current in ERL-mode shall be upgraded to 10 mA. Within this contribution an overview of the MESA project will be given highlighting the latest accelerator layout and the challenges of operation with high density internal gas targets. Work supported by DFG through cluster of excellence PRISMA, CRC 1044 and RTG 2128
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP106018	Measurement of the Transverse Beam Dynamics in a TESLA-type Superconducting Cavity	cavity, HOM, simulation, alignment	323
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359. Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106018
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP04	On the Acceleration of Rare Isotope Beams in the Reaccelerator (ReA3) at the National Superconducting Cyclotron Laboratory at MSU	ion, rfq, acceleration, linac	390
	A.C.C. Villari, G. Bollen, M. Ikegami, S.M. Lidia, S. Nash, R. Shane, Q. Zhao FRIB, East Lansing, USA D.B. Crisp, A. Lapierre, D.J. Morrissey, R. Rencsok, R.J. Ringle, S. Schwarz, C. Sumithrarachchi, T. Summers NSCL, East Lansing, Michigan, USA
	The ReAccelerator ReA3 is a worldwide unique, state-of-the-art linear accelerator for rare isotope beams. Beams of rare isotopes are produced and separated in-flight at the NSCL Coupled Cyclotron Facility and subsequently stopped in a linear gas cell. The rare isotopes are then continuously extracted as 1+ ions and transported into a beam cooler and buncher. Ion pulses provided by this device are then transported to a charge breeder based on an Electron Beam Ion Trap (EBIT) where they are captured in flight. The 1+ ions are ionized to a charge state suitable for acceleration in the superconducting radiofrequency (SRF) ReA3 linac, extracted in a pulsed mode and mass analyzed. The extracted beam is pre-bunched before injection into the RFQ and SRF linac, both operating at frequency of 80.5 MHz, and then accelerated to energies from 300 keV/u up to 6 MeV/u, depending on the charge-to-mass ratio of the ion. Stable isotopes can alternatively also be injected into the linac from the EBIT in off-line mode (by ionization of residual gas) or from external off-line ion sources. This contribution will focus on the methodology, properties and techniques used to accelerate and control low intensity rare isotope beams. Results obtained during the preparation of various experiments using the ReA facility, including those with the rare ions 46Ar and 37,46,47K will also be presented.
	Slides TUOP04 [1.979 MB]
	Poster TUOP04 [2.602 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP05	First Experiments at the CW-Operated RFQ for Intense Proton Beams	rfq, ion, operation, coupling	394
	P.P. Schneider, D. Born, M. Droba, C. Lorey, O. Meusel, D. Noll, H. Podlech, A. Schempp, B. Thomas, C. Wagner IAP, Frankfurt am Main, Germany
	This contribution describes the first experiments with the cw-operated RFQ, which is designed to accelerate protons from 120keV to 700keV for the FRANZ-Project. The commissioning is done using the RF and ion beam scrubbing technique. In the first phase, the acceptance of the RFQ is scanned and the performance of the RFQ without space-charge effects is evaluated with a 2mA proton beam. The second phase will increase the beam current up to 50mA and a third phase with a machine upgrade for a beam current of up to 200mA is planned. The configuration of a high-current RFQ, transporting beam current increasing from 2mA with no space-charge forces to a beam with high space-charge effects gives an unique insight in the beam optics of the space-charge effects. The measurements are done with a slit-grid emittance scanner for the transversal phase-space, a faraday cup for the transmitted current and a momentum spectrometer to measure the energy spread. The results set the basis for later experiments on variations of the beam current and the future coupling of the RFQ with an IH-structure*. Bechtold, A., et al., MOP001, LINAC08 Meusel, O., et al., MO3A03, LINAC12 * Vossberg, M., et al., WEPFI009, IPAC13 **** Heilmann, M., et al., THPWO017, IPAC13
	Slides TUOP05 [2.435 MB]
	Poster TUOP05 [4.550 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP08	On Magnetic Flux Trapping in Superconductors	solenoid, niobium, cavity, SRF	402
	R.G. Eichhorn, J. Hoke, Z. Mayle Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Magnetic flux trapped on the cool-down has become an important factor in the performance in superconducting cavities. We have conducted flux trapping experiments on samples that reveal a very interesting feature of the mechanism on flux trapping which might impact magnetic shielding concepts of future cryomodules.
	Slides TUOP08 [1.787 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP08
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRC021	Low-Temperature Properties of 2.6-Cell Cryogenic C-Band RF-Gun Cold Model Cavity	cavity, gun, cryogenics, resonance	462
	T. Sakai, M. Inagaki, K. Nakao, K. Nogami, K. Takatsuka, T. Tanaka LEBRA, Funabashi, Japan M.K. Fukuda, D. Satoh, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). Development of a cryogenic C-band photocathode RF gun cavity has been conducted at Nihon University in collaboration with KEK. Improved dimensions of the RF input coupler and the 2.6-cell accelerating structure from the first cold model were determined using the 3D simulation code CST Studio. The high-purity copper cavity was fabricated at KEK with ultraprecision machining and diffusion bonding technique. The low level RF properties of the cavity measured at room temperature have been in good agreement with the predictions based on the CST Studio calculation. Preparations for the 20-K cooling tests of the cavity are underway in KEK and Nihon University. The design of the improved cavity and the results of the cold test at low temperature will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRC022	UPS Study for CsK2Sb Photocathode	cathode, electron, laser, ion	465
	M. Kuriki, T. Konomi, Y. Seimiya KEK, Ibaraki, Japan L. Guo, M. Urano, A. Yokota HU/AdSM, Higashi-Hiroshima, Japan K. Negishi Iwate University, Morioka, Iwate, Japan
	CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. The material is robust and the typical operational lifetime is more than several months. It is also vital against the high intensity beam extraction. The photo-cathode is generated as a thin film in-situ and the material property and optimized condition for the cathode formation is not understood well. In this article, we present UPS analysis of CsK2Sb cathode for deeper understanding.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLR022	Particulate Study on Materials for Cleanroom Assembly of SRF Cavities	cavity, niobium, SRF, operation	512
	L. Zhao, A.V. Reilly JLab, Newport News, Virginia, USA
	Reducing particulates is an important aspect for clean-room operation. Knowing that it is impossible to completely eliminate all particulates in a clean room, efforts have been made to prevent particulates from entering SRF cavities during high pressure rinsing (HPR) and assembly. At Jefferson Lab, one practice to achieve this goal has been clamping covers to cavity open flanges during assembly. Several cover materials that have been used are examined and alternative candidate materials are under development. Clamps as a known particulate generator are carefully examined and cleaning efficiency of different methods is studied. Cover tests were done on different cavity flanges, including an LCLS-II beam pipe flange, which helps the selection of cover materials for prototype and production of the project. Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project.
	Poster TUPLR022 [1.282 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TH3A01	Making Molecular Movie with MeV Electrons	electron, laser, alignment, detector	725
	X. Shen, X.J. Wang SLAC, Menlo Park, California, USA
	SLAC launched the Ultrafast Electron Diffraction and Imaging (UED&UEM) initiative with the objective of developing the world leading ultrafast electron scattering instrumentation, complementary to the X-ray Free Electron Laser - Linac Coherent Light Source (LCLS). SLAC has developed a UED setup at the Accelerator Structure Test Area (ASTA), with the goal of providing MeV, 100-femtosecond-scale electron pulses to support an ultrafast science program [1]. The first UED ultrafast science experiment published in Nano Letters, where large amplitude wrinkles of monolayer MoS2 generated by the light pulse' more than 15 percent of the layer's thickness, was observed. This is the first time anyone has visualized these ultrafast atomic motions. Ultrafast MeV electrons also made it possible the direct measurement of phonon occupations as energy is transferred from electrons into the lattice in laser-heated gold (APL). The rotational wavepacket dynamics of laser-aligned nitrogen molecules were captured in gas-phase electron diffraction experiment using MeV electrons. We achieved an unprecedented combination of 100-fs (rms) temporal resolution and sub-Angstrom (0.76 Å) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule(Nature Communications). [1] S. Weathersby, et al., Rev. Sci. Instrum. 86, 073702 (2015).
	Slides TH3A01 [6.518 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THOP01	Experimental Study of Nucleation for Nb3Sn Diffusion Coatings on Niobium SRF Cavities	niobium, SRF, background, accelerating-gradient	740
	U. Pudasaini, M.J. Kelley The College of William and Mary, Williamsburg, Virginia, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: Partially authored by Jefferson Science Associates under Contract No. DE-AC05-06OR23177. Work at William & Mary supported by Office of High Energy Physics under grant SC0014475 Nb3Sn has the potential to achieve superior performance both in terms of operating temperature (4.2 K vs 2 K) and accelerating gradient resulting in significant reduction in both initial and operating costs of SRF linacs. Cavity interior surface coatings are obtained by two-step vapor diffusion: nucleation followed by deposition. To gain more understanding of nucleation and its effect on the subsequent coating, we investigated the effect of varying parameters in a typical tin/tin chloride process. We report findings obtained by SEM/EDS, AFM, SAM and other materials characterization approaches.
	Slides THOP01 [2.784 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC011	Single LLRF for Multi-Harmonic Buncher	controls, LLRF, pick-up, radio-frequency	789
	N.R. Usher, D.M. Alt, J.F. Brandon, D.G. Morris, S. Zhao FRIB, East Lansing, Michigan, USA D.M. Alt NSCL, East Lansing, Michigan, USA
	Funding: Work supported by Michigan State University, National Science Foundation: NSF Award Number PHY-1102511. In this paper, a unique low level radio frequency (LLRF) controller designed for a multi-harmonic buncher (MHB) is presented. Different than conventional designs, the single LLRF output contains three RF frequencies (f1, f2 = 2f1, f3 = 3f1) and is fed to a wide band amplifier driving the MHB. The challenge is while driving f1, due to the non-linearity of the amplifier, the f2 and f3 terms will also be generated and will couple into the control of these two modes. Hence an active cancellation algorithm is used to suppress the nonlinear effect of the amplifier. It is demonstrated in a test that the designed LLRF is able to control the amplitude and phase of the three modes in-dependently.
	Poster THPRC011 [1.944 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC028	Deflector Design for Spin Rotator in Muon Linear Accelerator	dipole, simulation, solenoid, vacuum	830
	S. Artikova JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Kondo JAEA, Ibaraki-ken, Japan T. Mibe, M. Otani KEK, Tsukuba, Japan
	A muon g-2/EDM experiment based on muon linear accelerator was proposed for the J-PARC muon facility. In this experiment, the ultra-slow muons created in muonium target region will be accelerated to 210 MeV kinetic energy then will be injected into the muon storage ring to measure the decay products depending on the muon spin. Therefore, a spin rotator (device) is a key component of the muon linac. Spin rotator consists of a pair of combined electrostatic and magnetic deflectors and a pair of solenoids which will be placed in between these two deflectors. In this paper, we report the design of these two dispersion-free deflectors and the simulation results of the device performance will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC028
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR015	Fifth-Order Moment Correction for Beam Position and Second-Order Moment Measurement	linac, simulation, factory, quadrupole	876
	K. Yanagida, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan
	For precise beam position measurement using a beam position monitor (BPM), a recursive correction which is expressed by the higher-order polynomials of beam positions are usually adopted. We recognized that the higher-order polynomials came from the higher-order moments and that beam position measurement is consequently influenced by a transverse beam shape. To investigate what order was required for adequate correction, we performed a successive iteration for the six-electrode BPM holding an inner radius of 16mm (circular cross-section). The successive iteration is a method to obtain a self-consistent solution for the higher-order correction. An amplitude of static electric field due to a beam charge was calculated by two-dimensional mirror charge method. As a result of the successive iteration, the convergence region was large enough for ordinary measurements (from lower than -5mm to higher than 5mm horizontally and vertically). In the convergence region the root mean square of the differences between the set and calculated vertical position were obtained as 0.487mm (without correction), 0.030mm (with third-order correction) and 0.003mm (with fifth-order correction).
	Poster THPLR015 [6.049 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR062	Muon Acceleration Using an RFQ	rfq, linac, acceleration, emittance	992
	Y. Kondo, K. Hasegawa JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Fukao, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, K. Shimomura KEK, Tsukuba, Japan K. Ishida RIKEN Nishina Center, Wako, Japan R. Kitamura University of Tokyo, Tokyo, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	A muon linac development for a new muon g-2 experiment is now going on at J-PARC. Muons from the muon beam line (H-line) at the J-PARC MLF are once stopped in an silica aerojel target and room temperature muoniums are evaporated from the aerogel. They are dissociated with laser (ultra slow muons), then accelerated up to 212 MeV using a linear accelerator. As the first accelerating structure, an RFQ will be used. We are planning to use a spare RFQ of the J-PARC linac for the first acceleration test. For this acceleration test, an degraded muon beam will be used instead of the ultra slow muon sourece. In this paper, present status of this muon acceleration test using the J-PARC RFQ is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR062
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR065	Beam Commissioning Status and Results of the FNAL PIP2IT Linear Accelerator RFQ	rfq, proton, controls, operation	1002
	J. Steimel, C.M. Baffes, P. Berrutti, J.-P. Carneiro, J.P. Edelen, T.N. Khabiboulline, L.R. Prost, V.E. Scarpine, A.V. Shemyakin Fermilab, Batavia, Illinois, USA A.L. Edelen CSU, Fort Collins, Colorado, USA M.D. Hoff, A.R. Lambert, D. Li, T.H. Luo, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA V.L. Sista BARC, Mumbai, India
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. An H⁻ beam was accelerated through a continuous wave (CW) capable, 4-vane, radio frequency quadrupole (RFQ) at Fermilab that was designed and constructed at Berkeley Lab. This RFQ is designed to accelerate up to 10 mA H⁻ beam from 30 keV to 2.1 MeV in a test accelerator (PIP2IT). This paper presents results of specification verification and commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR065
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FR1A04	Ion Effects in High Brightness Electron Linac Beams	ion, linac, radiation, electron	1032
	S.J. Full, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, G.H. Hoffstaetter, K. J. Smith Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Electron beams ionize rest gas particles which then accumulate around them, disturbing beam dynamics and causing background radiation. While this effect has been predicted in the past, linacs have hitherto not suffered from it because of their rather small beam current. The effect of ions increases with larger currents and smaller cross sections of the beam, and it has clearly been observed in Cornell's high-brightness ERL injector for the first time. This presentation will show experimental evidence for ions, demonstrate strategies for their elimination, and will compare the experimental data to theories of beam-ion interactions.
	Slides FR1A04 [5.995 MB]
	Poster FR1A04 [2.630 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-FR1A04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MO2A04

Low Emittance and High Current Electron Linac Development at Tsinghua University

gun, emittance, electron, laser

17

C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou
TUB, Beijing, People's Republic of China

A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.

Slides MO2A04 [11.413 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO2A04

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRC029

Experiment of Plasma Discharge on HWR Cavity for In-Situ Surface Cleaning Study

cavity, plasma, electron, operation

133

A.D. Wu, Y. He, T.C. Jiang, C.L. Li, Y.M. Li, W.M. Yue, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
L.M. Chen
Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
L. Yang
IHEP, Beijing, People's Republic of China

Hydrocarbons, which migrate from the vacuum bumps system, will absorb on the cavity surface after periods of operation. The contaminants can reduce the surface electron work function to enhance the field emission effect and restrict the cavity accelerating gradient. The room temperature in-situ plasma surface processing to clean the hydrocarbon contaminants can act as a convenient and efficient technology for the accelerator on line performance recovery. For better control of the discharge inside the cavity, the experiment works on a single HWR cavity aims to research the ignition between the swarm parameters (gas flow, pressure, forward power).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC029

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR011

Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration

electron, acceleration, accelerating-gradient, impedance

158

A.L. Healy, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M.J. Cliffe, D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR037

Study of the Surface and Performance of Single-Cell Nb Cavities After Vertical EP Using Ninja Cathodes

cathode, cavity, polarization, niobium

217

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
P. Carbonnier, F. Éozénou, Y. Gasser, L. Maurice, C. Servouin
CEA/DSM/IRFU, France
F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi
MGI, Chiba, Japan

A 1.3 GHz single-cell niobium (Nb) coupon cavity was vertically electropolished (VEPed) with three different Ninja cathodes which were specially designed for VEP of 1.3 GHz superconducting RF elliptical (ILC/Tesla type) cavities. The cathodes were fabricated to have different surface areas and different distances between cathode surface and the equator. The Ninja cathode prepared with an enhanced cathode surface area was covered with a meshed shield to avoid bubble attack on the surface of the cavity cell. It has been turned out that the anode-cathode distance and the cathode area affect surface morphology of the equator. A smooth equator surface was obtained in the cases in which the cathode surface was geometrically close to the equator or instead the cathode surface area was sufficiently larger. Two 1.3 GHz ILC/Tesla type single-cell cavities VEPed with the Ninja cathodes and using optimized conditions showed good performance in vertical tests.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR039

Development of New Type "Ninja" Cathode for Nb 9-cell Cavity and Experiment of Vertical Electro-Polishing

cavity, cathode, target, collider

223

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
K. Ishimi
MGI, Chiba, Japan

Marui Galvanizing Co. Ltd. has been improving Vertical Electro-Polishing (VEP) technologies and facilities for Nb 9-cell superconducting accelerator cavity for International Linear Collider (ILC) in collaboration with KEK. This time, we developed new type 'Ninja' cathode in order to improve VEP uniformity of Nb 9-cell cavity inner surface based on the results of 1-cell cavity VEP experiment. In this article, we will report construction of new type "Ninja" cathode for Nb 9-cell cavity and experiment of VEP using this.

Poster MOPLR039 [0.610 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLR063

Development of H⁰ Beam Diagnostic Line in MEBT2 of J-PARC Linac

dipole, linac, diagnostics, vacuum

277

J. Tamura, A. Miura, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
H. Ao
FRIB, East Lansing, USA
T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Miyao
KEK, Ibaraki, Japan

In the Japan Proton Accelerator Research Complex (J-PARC) linac, H⁰ particles arising from collisions of accelerated H⁻ beams with residual gas are considered as one of the key factors of the residual radiation in the high energy accelerating section. To analyze the H⁰ and the accelerated H⁻ particles, the bump magnet system was designed and produced. The H⁰ beam diagnostic line consists of four horizontal bending magnets, non-destructive beam position monitor and wire scan beam profile monitor. In the 2015 summer maintenance period of the J-PARC, the new diagnostic line was constructed in the beam transport (MEBT2), which is the matching section from separated-type drift tube linac (SDTL) to annular-ring coupled structure linac (ACS). In the beam commissioning, we experimentally confirmed that the accelerated 190 MeV H⁻ beams are horizontally shifted as expected with the magnetostatic field simulation and the particle tracking simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP106012

MESA - an ERL Project for Particle Physics Experiments

target, electron, operation, linac

313

F. Hug, K. Aulenbacher, R.G. Heine, B. Ledroit, D. Simon
IKP, Mainz, Germany

The Mainz Energy-recovering Superconducting Accelerator (MESA) will be constructed at the Institut für Kernphysik of the Johannes Gutenberg University of Mainz. The accelerator is a low energy continuous wave (CW) recirculating electron linac for particle physics experiments. MESA will be operated in two different modes serving mainly two experiments: the first is the external beam (EB) mode, where the beam is dumped after being used with the external fixed target experiment P2, whose goal is the measurement of the weak mixing angle with highest accuracy. The required beam current for P2 is 150 μA with polarized electrons at 155 MeV. In the second operation mode MESA will be run as an energy recovery linac (ERL). The experiment served in this mode is a (pseudo) internal fixed target experiment named MAGIX. It demands an unpolarized beam of 1 mA at 10⁵ MeV. In a later construction stage of MESA the achievable beam current in ERL-mode shall be upgraded to 10 mA. Within this contribution an overview of the MESA project will be given highlighting the latest accelerator layout and the challenges of operation with high density internal gas targets.
Work supported by DFG through cluster of excellence PRISMA, CRC 1044 and RTG 2128

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP106018

Measurement of the Transverse Beam Dynamics in a TESLA-type Superconducting Cavity

cavity, HOM, simulation, alignment

323

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP04

On the Acceleration of Rare Isotope Beams in the Reaccelerator (ReA3) at the National Superconducting Cyclotron Laboratory at MSU

ion, rfq, acceleration, linac

390

A.C.C. Villari, G. Bollen, M. Ikegami, S.M. Lidia, S. Nash, R. Shane, Q. Zhao
FRIB, East Lansing, USA
D.B. Crisp, A. Lapierre, D.J. Morrissey, R. Rencsok, R.J. Ringle, S. Schwarz, C. Sumithrarachchi, T. Summers
NSCL, East Lansing, Michigan, USA

The ReAccelerator ReA3 is a worldwide unique, state-of-the-art linear accelerator for rare isotope beams. Beams of rare isotopes are produced and separated in-flight at the NSCL Coupled Cyclotron Facility and subsequently stopped in a linear gas cell. The rare isotopes are then continuously extracted as 1+ ions and transported into a beam cooler and buncher. Ion pulses provided by this device are then transported to a charge breeder based on an Electron Beam Ion Trap (EBIT) where they are captured in flight. The 1+ ions are ionized to a charge state suitable for acceleration in the superconducting radiofrequency (SRF) ReA3 linac, extracted in a pulsed mode and mass analyzed. The extracted beam is pre-bunched before injection into the RFQ and SRF linac, both operating at frequency of 80.5 MHz, and then accelerated to energies from 300 keV/u up to 6 MeV/u, depending on the charge-to-mass ratio of the ion. Stable isotopes can alternatively also be injected into the linac from the EBIT in off-line mode (by ionization of residual gas) or from external off-line ion sources. This contribution will focus on the methodology, properties and techniques used to accelerate and control low intensity rare isotope beams. Results obtained during the preparation of various experiments using the ReA facility, including those with the rare ions 46Ar and 37,46,47K will also be presented.

Slides TUOP04 [1.979 MB]

Poster TUOP04 [2.602 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP04

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP05

First Experiments at the CW-Operated RFQ for Intense Proton Beams

rfq, ion, operation, coupling

394

P.P. Schneider, D. Born, M. Droba, C. Lorey, O. Meusel, D. Noll, H. Podlech, A. Schempp, B. Thomas, C. Wagner
IAP, Frankfurt am Main, Germany

This contribution describes the first experiments with the cw-operated RFQ*, which is designed to accelerate protons from 120keV to 700keV for the FRANZ-Project**. The commissioning is done using the RF and ion beam scrubbing technique. In the first phase, the acceptance of the RFQ is scanned and the performance of the RFQ without space-charge effects is evaluated with a 2mA proton beam. The second phase will increase the beam current up to 50mA and a third phase with a machine upgrade for a beam current of up to 200mA is planned. The configuration of a high-current RFQ***, transporting beam current increasing from 2mA with no space-charge forces to a beam with high space-charge effects gives an unique insight in the beam optics of the space-charge effects. The measurements are done with a slit-grid emittance scanner for the transversal phase-space, a faraday cup for the transmitted current and a momentum spectrometer to measure the energy spread. The results set the basis for later experiments on variations of the beam current and the future coupling of the RFQ with an IH-structure****.
* Bechtold, A., et al., MOP001, LINAC08
** Meusel, O., et al., MO3A03, LINAC12
*** Vossberg, M., et al., WEPFI009, IPAC13
**** Heilmann, M., et al., THPWO017, IPAC13

Slides TUOP05 [2.435 MB]

Poster TUOP05 [4.550 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP05

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOP08

On Magnetic Flux Trapping in Superconductors

solenoid, niobium, cavity, SRF

402

R.G. Eichhorn, J. Hoke, Z. Mayle
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Magnetic flux trapped on the cool-down has become an important factor in the performance in superconducting cavities. We have conducted flux trapping experiments on samples that reveal a very interesting feature of the mechanism on flux trapping which might impact magnetic shielding concepts of future cryomodules.

Slides TUOP08 [1.787 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP08

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRC021

Low-Temperature Properties of 2.6-Cell Cryogenic C-Band RF-Gun Cold Model Cavity

cavity, gun, cryogenics, resonance

462

T. Sakai, M. Inagaki, K. Nakao, K. Nogami, K. Takatsuka, T. Tanaka
LEBRA, Funabashi, Japan
M.K. Fukuda, D. Satoh, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
Development of a cryogenic C-band photocathode RF gun cavity has been conducted at Nihon University in collaboration with KEK. Improved dimensions of the RF input coupler and the 2.6-cell accelerating structure from the first cold model were determined using the 3D simulation code CST Studio. The high-purity copper cavity was fabricated at KEK with ultraprecision machining and diffusion bonding technique. The low level RF properties of the cavity measured at room temperature have been in good agreement with the predictions based on the CST Studio calculation. Preparations for the 20-K cooling tests of the cavity are underway in KEK and Nihon University. The design of the improved cavity and the results of the cold test at low temperature will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRC022

UPS Study for CsK2Sb Photocathode

cathode, electron, laser, ion

465

M. Kuriki, T. Konomi, Y. Seimiya
KEK, Ibaraki, Japan
L. Guo, M. Urano, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan

CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. The material is robust and the typical operational lifetime is more than several months. It is also vital against the high intensity beam extraction. The photo-cathode is generated as a thin film in-situ and the material property and optimized condition for the cathode formation is not understood well. In this article, we present UPS analysis of CsK2Sb cathode for deeper understanding.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLR022

Particulate Study on Materials for Cleanroom Assembly of SRF Cavities

cavity, niobium, SRF, operation

512

L. Zhao, A.V. Reilly
JLab, Newport News, Virginia, USA

Reducing particulates is an important aspect for clean-room operation. Knowing that it is impossible to completely eliminate all particulates in a clean room, efforts have been made to prevent particulates from entering SRF cavities during high pressure rinsing (HPR) and assembly. At Jefferson Lab, one practice to achieve this goal has been clamping covers to cavity open flanges during assembly. Several cover materials that have been used are examined and alternative candidate materials are under development. Clamps as a known particulate generator are carefully examined and cleaning efficiency of different methods is studied. Cover tests were done on different cavity flanges, including an LCLS-II beam pipe flange, which helps the selection of cover materials for prototype and production of the project.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project.

Poster TUPLR022 [1.282 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TH3A01

Making Molecular Movie with MeV Electrons

electron, laser, alignment, detector

725

X. Shen, X.J. Wang
SLAC, Menlo Park, California, USA

SLAC launched the Ultrafast Electron Diffraction and Imaging (UED&UEM) initiative with the objective of developing the world leading ultrafast electron scattering instrumentation, complementary to the X-ray Free Electron Laser - Linac Coherent Light Source (LCLS). SLAC has developed a UED setup at the Accelerator Structure Test Area (ASTA), with the goal of providing MeV, 100-femtosecond-scale electron pulses to support an ultrafast science program [1]. The first UED ultrafast science experiment published in Nano Letters, where large amplitude wrinkles of monolayer MoS2 generated by the light pulse' more than 15 percent of the layer's thickness, was observed. This is the first time anyone has visualized these ultrafast atomic motions. Ultrafast MeV electrons also made it possible the direct measurement of phonon occupations as energy is transferred from electrons into the lattice in laser-heated gold (APL). The rotational wavepacket dynamics of laser-aligned nitrogen molecules were captured in gas-phase electron diffraction experiment using MeV electrons. We achieved an unprecedented combination of 100-fs (rms) temporal resolution and sub-Angstrom (0.76 Å) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule(Nature Communications).
[1] S. Weathersby, et al., Rev. Sci. Instrum. 86, 073702 (2015).

Slides TH3A01 [6.518 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A01

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THOP01

Experimental Study of Nucleation for Nb3Sn Diffusion Coatings on Niobium SRF Cavities

niobium, SRF, background, accelerating-gradient

740

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates under Contract No. DE-AC05-06OR23177. Work at William & Mary supported by Office of High Energy Physics under grant SC0014475
Nb3Sn has the potential to achieve superior performance both in terms of operating temperature (4.2 K vs 2 K) and accelerating gradient resulting in significant reduction in both initial and operating costs of SRF linacs. Cavity interior surface coatings are obtained by two-step vapor diffusion: nucleation followed by deposition. To gain more understanding of nucleation and its effect on the subsequent coating, we investigated the effect of varying parameters in a typical tin/tin chloride process. We report findings obtained by SEM/EDS, AFM, SAM and other materials characterization approaches.

Slides THOP01 [2.784 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP01

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC011

Single LLRF for Multi-Harmonic Buncher

controls, LLRF, pick-up, radio-frequency

789

N.R. Usher, D.M. Alt, J.F. Brandon, D.G. Morris, S. Zhao
FRIB, East Lansing, Michigan, USA
D.M. Alt
NSCL, East Lansing, Michigan, USA

Funding: Work supported by Michigan State University, National Science Foundation: NSF Award Number PHY-1102511.
In this paper, a unique low level radio frequency (LLRF) controller designed for a multi-harmonic buncher (MHB) is presented. Different than conventional designs, the single LLRF output contains three RF frequencies (f1, f2 = 2*f1, f3 = 3*f1) and is fed to a wide band amplifier driving the MHB. The challenge is while driving f1, due to the non-linearity of the amplifier, the f2 and f3 terms will also be generated and will couple into the control of these two modes. Hence an active cancellation algorithm is used to suppress the nonlinear effect of the amplifier. It is demonstrated in a test that the designed LLRF is able to control the amplitude and phase of the three modes in-dependently.

Poster THPRC011 [1.944 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC028

Deflector Design for Spin Rotator in Muon Linear Accelerator

dipole, simulation, solenoid, vacuum

830

S. Artikova
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Kondo
JAEA, Ibaraki-ken, Japan
T. Mibe, M. Otani
KEK, Tsukuba, Japan

A muon g-2/EDM experiment based on muon linear accelerator was proposed for the J-PARC muon facility. In this experiment, the ultra-slow muons created in muonium target region will be accelerated to 210 MeV kinetic energy then will be injected into the muon storage ring to measure the decay products depending on the muon spin. Therefore, a spin rotator (device) is a key component of the muon linac. Spin rotator consists of a pair of combined electrostatic and magnetic deflectors and a pair of solenoids which will be placed in between these two deflectors. In this paper, we report the design of these two dispersion-free deflectors and the simulation results of the device performance will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR015

Fifth-Order Moment Correction for Beam Position and Second-Order Moment Measurement

linac, simulation, factory, quadrupole

876

K. Yanagida, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan

For precise beam position measurement using a beam position monitor (BPM), a recursive correction which is expressed by the higher-order polynomials of beam positions are usually adopted. We recognized that the higher-order polynomials came from the higher-order moments and that beam position measurement is consequently influenced by a transverse beam shape. To investigate what order was required for adequate correction, we performed a successive iteration for the six-electrode BPM holding an inner radius of 16mm (circular cross-section). The successive iteration is a method to obtain a self-consistent solution for the higher-order correction. An amplitude of static electric field due to a beam charge was calculated by two-dimensional mirror charge method. As a result of the successive iteration, the convergence region was large enough for ordinary measurements (from lower than -5mm to higher than 5mm horizontally and vertically). In the convergence region the root mean square of the differences between the set and calculated vertical position were obtained as 0.487mm (without correction), 0.030mm (with third-order correction) and 0.003mm (with fifth-order correction).

Poster THPLR015 [6.049 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR062

Muon Acceleration Using an RFQ

rfq, linac, acceleration, emittance

992

Y. Kondo, K. Hasegawa
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Fukao, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, K. Shimomura
KEK, Tsukuba, Japan
K. Ishida
RIKEN Nishina Center, Wako, Japan
R. Kitamura
University of Tokyo, Tokyo, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

A muon linac development for a new muon g-2 experiment is now going on at J-PARC. Muons from the muon beam line (H-line) at the J-PARC MLF are once stopped in an silica aerojel target and room temperature muoniums are evaporated from the aerogel. They are dissociated with laser (ultra slow muons), then accelerated up to 212 MeV using a linear accelerator. As the first accelerating structure, an RFQ will be used. We are planning to use a spare RFQ of the J-PARC linac for the first acceleration test. For this acceleration test, an degraded muon beam will be used instead of the ultra slow muon sourece. In this paper, present status of this muon acceleration test using the J-PARC RFQ is presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR065

Beam Commissioning Status and Results of the FNAL PIP2IT Linear Accelerator RFQ

rfq, proton, controls, operation

1002

J. Steimel, C.M. Baffes, P. Berrutti, J.-P. Carneiro, J.P. Edelen, T.N. Khabiboulline, L.R. Prost, V.E. Scarpine, A.V. Shemyakin
Fermilab, Batavia, Illinois, USA
A.L. Edelen
CSU, Fort Collins, Colorado, USA
M.D. Hoff, A.R. Lambert, D. Li, T.H. Luo, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
V.L. Sista
BARC, Mumbai, India

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
An H⁻ beam was accelerated through a continuous wave (CW) capable, 4-vane, radio frequency quadrupole (RFQ) at Fermilab that was designed and constructed at Berkeley Lab. This RFQ is designed to accelerate up to 10 mA H⁻ beam from 30 keV to 2.1 MeV in a test accelerator (PIP2IT). This paper presents results of specification verification and commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FR1A04

Ion Effects in High Brightness Electron Linac Beams

ion, linac, radiation, electron

1032

S.J. Full, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, G.H. Hoffstaetter, K. J. Smith
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Electron beams ionize rest gas particles which then accumulate around them, disturbing beam dynamics and causing background radiation. While this effect has been predicted in the past, linacs have hitherto not suffered from it because of their rather small beam current. The effect of ions increases with larger currents and smaller cross sections of the beam, and it has clearly been observed in Cornell's high-brightness ERL injector for the first time. This presentation will show experimental evidence for ions, demonstrate strategies for their elimination, and will compare the experimental data to theories of beam-ion interactions.

Slides FR1A04 [5.995 MB]

Poster FR1A04 [2.630 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-FR1A04

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)