LINAC2016 - List of Keywords (acceleration)

Paper	Title	Other Keywords	Page
MOOP09	Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute	laser, electron, wakefield, accelerating-gradient	62
	S.P. Jamison, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom G. Burt, R. Letizia, C. Paoloni Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work has been funded by STFC Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP09
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MOPLR011	Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration	electron, accelerating-gradient, impedance, experiment	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
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MOPLR050	Study and Development of CW Room Temperature Rebuncher for SARAF Accelerator	cavity, vacuum, linac, impedance	244
	B. Kaizer, Z. Horvitz, A. Perry, J. Rodnizki Soreq NRC, Yavne, Israel M. Di Giacomo, J.F. Leyge, M. Michel, P. Toussaint GANIL, Caen, France A. Friedman Ariel University, Ariel, Israel
	The SARAF 176 MHz accelerator is designed to provide CW proton/deuteron beams up to 5 mA current and 40 MeV accelerated ion energy. Phase I of SARAF (up to 4-5 MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the planning stage and will contain larger MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3 MeV/u RFQ, is 4.5 m long, and contains three 176 MHz rebunchers providing a field integral of 10⁵ kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with a required of 40 mm diameter by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR050
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MOP106002	X-Band Photonic Band Gap Accelerating Structures with Improved Wakefield Suppression	wakefield, HOM, dipole, electron	307
	E.I. Simakov LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by U.S. Department of Energy (DOE) Office of High Energy Physics. We present the design of a novel photonic band gap (PBG) accelerating structure with elliptical rods and improved wakefields suppression. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. The experimental characterization of the wakefield spectrum in a beam test was performed at Argonne Wakefield Accelerator facility in 2015, and the superior wakefield suppression properties of the PBG structure were demonstrated. In 2013 the team from MIT and SLAC demonstrated that the X-band PBG structures with elliptical rods have reduced breakdown rate compared to PBG structures with round rods, presumably due to the reduced surface magnetic fields. However, the structure with elliptical rods designed by MIT confined the dipole higher order mode in addition to the accelerating mode and thus did not have superior wakefield suppression properties. We demonstrate that PBG resonators can be designed with 40% smaller peak surface magnetic fields while preserving and even improving their wakefield suppression properties as compared to the structure with round rods. The design of the new structure is presented. The structure will be fabricated, tuned, and tested for high gradients and for wakefield suppression.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106002
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MOP106021	Superconducting Traveling Wave Cavity Tuning Studies	cavity, accelerating-gradient, feedback, SRF	327
	R.A. Kostin LETI, Saint-Petersburg, Russia P.V. Avrakhov, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US DOE SBIR # DE-SC0006300 Superconducting traveling wave cavity (SCTW) can provide 1.2-1.4 times larger accelerating gradient than conventional standing wave SRF cavities [1]. Firstly, traveling wave opens the way to use other than Pi-mode phase advance per cell which increase transit time factor. Secondly, traveling wave is not so sensitive to cavity length as standing wave, which length is limited to 1 meter because of field flatness degradation. 3 cell SCTW cavity was proposed [2] and built for high gradient traveling wave demonstration and tuning studies. This paper describes analytical model that was used for cavity development. Tuning properties and requirements are also discussed. ' r.kostin@euclidtechlabs.com
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TUOP04	On the Acceleration of Rare Isotope Beams in the Reaccelerator (ReA3) at the National Superconducting Cyclotron Laboratory at MSU	ion, rfq, experiment, 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
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TUPLR054	RFQ Vane Shapes for Efficient Acceleration	rfq, multipole, quadrupole, focusing	581
	Y. Iwashita, Y. Fuwa Kyoto ICR, Uji, Kyoto, Japan R.A. Jameson IAP, Frankfurt am Main, Germany
	RFQ vane shapes for efficient acceleration are under investigation by introducing more terms in addition to the two term potential. They can incorporate with the feature of the trapezoidal shape modulation with less multipole components, while higher acceleration efficiency is expected. The simulation study will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR054
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TUPLR066	High Current Beam Injector for Cancer Therapy	ion, linac, injection, cavity	604
	L. Lu, Y. He, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, L. Yang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China T.L. He USTC/NSRL, Hefei, Anhui, People's Republic of China
	A hybrid single cavity (HSC) linac, which is formed by combining a radio frequency quadrupole (RFQ) and a drift tube (DT) structure into one interdigital-H (IH) cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme (DPIS), which can inject a high intensity heavy ion beam produced by a laser ion source (LIS). The input beam current of the HSC is designed to be 20 mA C⁶⁺ ions. According to numerical simulations, the HSC linac can accelerate a 6-mA C⁶⁺ beam, which meets the requirement of the needed particle number for cancer therapy (108~9 ions/pulse). The HSC injector with the DPIS method makes the existing multi-turn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency (RF) measurements show excellent RF properties for the resonator, with a measured Q equal to 91% of the simulated value. A C⁶⁺ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR066
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THOP11	Ultra-Short Bunch Electron Injector for Awake	plasma, electron, gun, wakefield	770
	S. Döbert CERN, Geneva, Switzerland
	The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.
	Slides THOP11 [2.733 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP11
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THPLR014	Laser-Driven Dielectric Nano-Beam Accelerator for Radiation Biology Researches	electron, laser, simulation, ion	873
	K. Koyama, M. Yoshida KEK, Ibaraki, Japan Z. Chen, H. Okamoto The University of Tokyo, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by JSPS KAKENHI (B)(Grant-in-Aid for Scientific Research) Grant Number 15H03595. Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR014
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THPLR021	Identification of Emitting Sources of Dark Currents From Gridded Thermionic Electron Gun and Measures to Suppress Dark Currents From Electron Gun in SPring-8 Linear Accelerator	cathode, electron, gun, synchrotron	888
	T. Magome, H. Hanaki, T. Kobayashi, S. Suzuki, T. Taniuchi JASRI/SPring-8, Hyogo-ken, Japan
	The dark current is emitted from a gridded thermionic electron gun although the grid-electrode potential against the cathode is negative enough to suppress the cathode emission current. This dark current in the SPring-8 linear accelerator caused satellite bunches unignorable for precise experiments in the downstream electron storage ring. The dark current has been investigated by means of our electron-gun test equipment applying a DC accelerator voltage to the electron gun. The investigations revealed that the dark current was generated from the wehnelt electrode, the gird electrode, and the cathode surface. The dark current from the wehnelt electrode was decreased under the measurement limit 2·10^-15 A by replacing the wehnelt and the anode electrodes with new electro-polished ones. The dark current from the cathode surface was reduced by lowering the grid-electrode potential against the cathode down to -160 V. To reduce the dark current from the grid electrode, the surface of the grid electrode was significantly smoothed by electro-polishing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR021
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THPLR032	Update on SSR2 Cavity EM Design for PIP-II	cavity, linac, simulation, quadrupole	920
	P. Berrutti, T.N. Khabiboulline, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Proton Improvement Plan II (PIP-II) is the future plan for upgrading the Fermilab proton accelerator complex to a beam power capability of at least 1 MW delivered to the neutrino production target. A room temperature section accelerates H⁻ ions to 2.1 MeV and creates the desired bunch structure for injection into the superconducting (SC) linac. SC linac using five cavity types. One 162.5 MHz half wave resonator, two 325 MHz spoke resonators and two 650 MHz elliptical 5-cell cavities, provide acceleration to 800 MeV. The EM design of the second family of spoke resonator is presented in this paper. The work reported is a thorough electromagnetic study including: the RF parameters, multipacting mitigation and transverse field asymmetry. The cavity is now ready for structural design analysis.
	Poster THPLR032 [1.947 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR032
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THPLR040	First Vertical Test of Superconducting QWR Prototype at RIKEN	ion, cryomodule, coupling, multipactoring	939
	K. Yamada, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, Y. Watanabe RIKEN Nishina Center, Wako, Japan E. Kako, H. Nakai, K. Umemori KEK, Ibaraki, Japan A. Miyamoto, K. Sennyu, T. Yanagisawa MHI-MS, Kobe, Japan
	Development of a superconducting quarter-wavelength resonator (SC-QWR) was started at RIKEN Nishina Center to realize a low-velocity part of high-intensity ion linac. First prototype of the SC-QWR, frequency of which is 75.5 MHz, is fabricating now. Preparation of its partial components such as outer conductor, stem, bottom plate, and top plate was almost completed, and we are now studying a low-power RF property by clamping the every components as an assembly to obtain data for frequency tuning. After the adjustment of geometry of components and welding them, surface treatment by buffered chemical polishing and high-pressure rinsing will be performed in the summer. Preparation of vertical test for the SC-QWR is also in progress at KEK. The first result of vertical test for the prototype of SC-QWR will be presented in this contribution. This work was funded by the ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan). N. Sakamoto et al., Proceedings of SRF2015, WEBA06.
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THPLR061	Research on a Two-beam Type Drift Tube Linac	ion, DTL, heavy-ion, cavity	989
	L. Lu, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China T.L. He USTC/NSRL, Hefei, Anhui, People's Republic of China L. Yang USTC, Hefei, Anhui, People's Republic of China
	The very high intense heavy-ion beam is a high attraction for heavy ion researches and heavy-ion applications, but it is limited by heavy-ion production of ion source and space-charge-effect in acceleration. There is one way, accelerating several heavy-ion beams in one cavity at same time and funneling them, which could achieve the acceleration of very high intense heavy-ion beam with existing ion source and accelerating technology. In this paper, we will introduce our designs, calculations and simulations of a 2-beam type drift tube linac.
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THPLR062	Muon Acceleration Using an RFQ	rfq, linac, experiment, 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.
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FR1A05	Development of a Muon Linac for the G-2/EDM Experiment at J-PARC	rfq, linac, emittance, cavity	1037
	M. Otani, N. Kawamura, T. Mibe, F. Naito, M. Yoshida KEK, Tsukuba, Japan K. Hasegawa, Y. Kondo JAEA, Ibaraki-ken, Japan N. Hayashizaki RLNR, Tokyo, Japan T. Ito JAEA/J-PARC, Tokai-mura, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan Y. Iwata NIRS, Chiba-shi, Japan R. Kitamura University of Tokyo, Tokyo, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Precision measurements of the muon's anomalous magnetic moment (g-2) and electric dipole moment (EDM) are one of the effective ways to test the standard model. An ultra-cold muon beam is generated from a surface muon beam by a thermal muonium production and accelerated to 300 MeV/c by a linac. The muon linac consists of an RFQ, an inter-digital IH, a Disk And Washer structure, and a disk loaded structure. The ultra-cold muons will have an extremely small momentum spread of 0.3 % with a normalized transverse emittance of around 1.5 pi mm-mrad. The design and status of the muon linac at J-PARC will be presented.
	Slides FR1A05 [13.154 MB]
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Paper

Title

Other Keywords

Page

MOOP09

Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute

laser, electron, wakefield, accelerating-gradient

62

S.P. Jamison, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burt, R. Letizia, C. Paoloni
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work has been funded by STFC
Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.

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MOPLR011

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

electron, accelerating-gradient, impedance, experiment

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.

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MOPLR050

Study and Development of CW Room Temperature Rebuncher for SARAF Accelerator

cavity, vacuum, linac, impedance

244

B. Kaizer, Z. Horvitz, A. Perry, J. Rodnizki
Soreq NRC, Yavne, Israel
M. Di Giacomo, J.F. Leyge, M. Michel, P. Toussaint
GANIL, Caen, France
A. Friedman
Ariel University, Ariel, Israel

The SARAF 176 MHz accelerator is designed to provide CW proton/deuteron beams up to 5 mA current and 40 MeV accelerated ion energy. Phase I of SARAF (up to 4-5 MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the planning stage and will contain larger MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3 MeV/u RFQ, is 4.5 m long, and contains three 176 MHz rebunchers providing a field integral of 10⁵ kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with a required of 40 mm diameter by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.

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MOP106002

X-Band Photonic Band Gap Accelerating Structures with Improved Wakefield Suppression

wakefield, HOM, dipole, electron

307

E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by U.S. Department of Energy (DOE) Office of High Energy Physics.
We present the design of a novel photonic band gap (PBG) accelerating structure with elliptical rods and improved wakefields suppression. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. The experimental characterization of the wakefield spectrum in a beam test was performed at Argonne Wakefield Accelerator facility in 2015, and the superior wakefield suppression properties of the PBG structure were demonstrated. In 2013 the team from MIT and SLAC demonstrated that the X-band PBG structures with elliptical rods have reduced breakdown rate compared to PBG structures with round rods, presumably due to the reduced surface magnetic fields. However, the structure with elliptical rods designed by MIT confined the dipole higher order mode in addition to the accelerating mode and thus did not have superior wakefield suppression properties. We demonstrate that PBG resonators can be designed with 40% smaller peak surface magnetic fields while preserving and even improving their wakefield suppression properties as compared to the structure with round rods. The design of the new structure is presented. The structure will be fabricated, tuned, and tested for high gradients and for wakefield suppression.

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MOP106021

Superconducting Traveling Wave Cavity Tuning Studies

cavity, accelerating-gradient, feedback, SRF

327

R.A. Kostin
LETI, Saint-Petersburg, Russia
P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by US DOE SBIR # DE-SC0006300
Superconducting traveling wave cavity (SCTW) can provide 1.2-1.4 times larger accelerating gradient than conventional standing wave SRF cavities [1]. Firstly, traveling wave opens the way to use other than Pi-mode phase advance per cell which increase transit time factor. Secondly, traveling wave is not so sensitive to cavity length as standing wave, which length is limited to 1 meter because of field flatness degradation. 3 cell SCTW cavity was proposed [2] and built for high gradient traveling wave demonstration and tuning studies. This paper describes analytical model that was used for cavity development. Tuning properties and requirements are also discussed.
' r.kostin@euclidtechlabs.com

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TUOP04

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

ion, rfq, experiment, 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]

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TUPLR054

RFQ Vane Shapes for Efficient Acceleration

rfq, multipole, quadrupole, focusing

581

Y. Iwashita, Y. Fuwa
Kyoto ICR, Uji, Kyoto, Japan
R.A. Jameson
IAP, Frankfurt am Main, Germany

RFQ vane shapes for efficient acceleration are under investigation by introducing more terms in addition to the two term potential. They can incorporate with the feature of the trapezoidal shape modulation with less multipole components, while higher acceleration efficiency is expected. The simulation study will be presented.

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TUPLR066

High Current Beam Injector for Cancer Therapy

ion, linac, injection, cavity

604

L. Lu, Y. He, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, L. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
T.L. He
USTC/NSRL, Hefei, Anhui, People's Republic of China

A hybrid single cavity (HSC) linac, which is formed by combining a radio frequency quadrupole (RFQ) and a drift tube (DT) structure into one interdigital-H (IH) cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme (DPIS), which can inject a high intensity heavy ion beam produced by a laser ion source (LIS). The input beam current of the HSC is designed to be 20 mA C⁶⁺ ions. According to numerical simulations, the HSC linac can accelerate a 6-mA C⁶⁺ beam, which meets the requirement of the needed particle number for cancer therapy (108~9 ions/pulse). The HSC injector with the DPIS method makes the existing multi-turn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency (RF) measurements show excellent RF properties for the resonator, with a measured Q equal to 91% of the simulated value. A C⁶⁺ ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.

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THOP11

Ultra-Short Bunch Electron Injector for Awake

plasma, electron, gun, wakefield

770

S. Döbert
CERN, Geneva, Switzerland

The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.

Slides THOP11 [2.733 MB]

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THPLR014

Laser-Driven Dielectric Nano-Beam Accelerator for Radiation Biology Researches

electron, laser, simulation, ion

873

K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Z. Chen, H. Okamoto
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by JSPS KAKENHI (B)(Grant-in-Aid for Scientific Research) Grant Number 15H03595.
Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique.

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THPLR021

Identification of Emitting Sources of Dark Currents From Gridded Thermionic Electron Gun and Measures to Suppress Dark Currents From Electron Gun in SPring-8 Linear Accelerator

cathode, electron, gun, synchrotron

888

T. Magome, H. Hanaki, T. Kobayashi, S. Suzuki, T. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

The dark current is emitted from a gridded thermionic electron gun although the grid-electrode potential against the cathode is negative enough to suppress the cathode emission current. This dark current in the SPring-8 linear accelerator caused satellite bunches unignorable for precise experiments in the downstream electron storage ring. The dark current has been investigated by means of our electron-gun test equipment applying a DC accelerator voltage to the electron gun. The investigations revealed that the dark current was generated from the wehnelt electrode, the gird electrode, and the cathode surface. The dark current from the wehnelt electrode was decreased under the measurement limit 2·10^-15 A by replacing the wehnelt and the anode electrodes with new electro-polished ones. The dark current from the cathode surface was reduced by lowering the grid-electrode potential against the cathode down to -160 V. To reduce the dark current from the grid electrode, the surface of the grid electrode was significantly smoothed by electro-polishing.

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THPLR032

Update on SSR2 Cavity EM Design for PIP-II

cavity, linac, simulation, quadrupole

920

P. Berrutti, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Proton Improvement Plan II (PIP-II) is the future plan for upgrading the Fermilab proton accelerator complex to a beam power capability of at least 1 MW delivered to the neutrino production target. A room temperature section accelerates H⁻ ions to 2.1 MeV and creates the desired bunch structure for injection into the superconducting (SC) linac. SC linac using five cavity types. One 162.5 MHz half wave resonator, two 325 MHz spoke resonators and two 650 MHz elliptical 5-cell cavities, provide acceleration to 800 MeV. The EM design of the second family of spoke resonator is presented in this paper. The work reported is a thorough electromagnetic study including: the RF parameters, multipacting mitigation and transverse field asymmetry. The cavity is now ready for structural design analysis.

Poster THPLR032 [1.947 MB]

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THPLR040

First Vertical Test of Superconducting QWR Prototype at RIKEN

ion, cryomodule, coupling, multipactoring

939

K. Yamada, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, Y. Watanabe
RIKEN Nishina Center, Wako, Japan
E. Kako, H. Nakai, K. Umemori
KEK, Ibaraki, Japan
A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan

Development of a superconducting quarter-wavelength resonator (SC-QWR) was started at RIKEN Nishina Center to realize a low-velocity part of high-intensity ion linac. First prototype of the SC-QWR, frequency of which is 75.5 MHz, is fabricating now*. Preparation of its partial components such as outer conductor, stem, bottom plate, and top plate was almost completed, and we are now studying a low-power RF property by clamping the every components as an assembly to obtain data for frequency tuning. After the adjustment of geometry of components and welding them, surface treatment by buffered chemical polishing and high-pressure rinsing will be performed in the summer. Preparation of vertical test for the SC-QWR is also in progress at KEK. The first result of vertical test for the prototype of SC-QWR will be presented in this contribution. This work was funded by the ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan).
* N. Sakamoto et al., Proceedings of SRF2015, WEBA06.

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THPLR061

Research on a Two-beam Type Drift Tube Linac

ion, DTL, heavy-ion, cavity

989

L. Lu, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
T.L. He
USTC/NSRL, Hefei, Anhui, People's Republic of China
L. Yang
USTC, Hefei, Anhui, People's Republic of China

The very high intense heavy-ion beam is a high attraction for heavy ion researches and heavy-ion applications, but it is limited by heavy-ion production of ion source and space-charge-effect in acceleration. There is one way, accelerating several heavy-ion beams in one cavity at same time and funneling them, which could achieve the acceleration of very high intense heavy-ion beam with existing ion source and accelerating technology. In this paper, we will introduce our designs, calculations and simulations of a 2-beam type drift tube linac.

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THPLR062

Muon Acceleration Using an RFQ

rfq, linac, experiment, 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.

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FR1A05

Development of a Muon Linac for the G-2/EDM Experiment at J-PARC

rfq, linac, emittance, cavity

1037

M. Otani, N. Kawamura, T. Mibe, F. Naito, M. Yoshida
KEK, Tsukuba, Japan
K. Hasegawa, Y. Kondo
JAEA, Ibaraki-ken, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
T. Ito
JAEA/J-PARC, Tokai-mura, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
Y. Iwata
NIRS, Chiba-shi, Japan
R. Kitamura
University of Tokyo, Tokyo, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Precision measurements of the muon's anomalous magnetic moment (g-2) and electric dipole moment (EDM) are one of the effective ways to test the standard model. An ultra-cold muon beam is generated from a surface muon beam by a thermal muonium production and accelerated to 300 MeV/c by a linac. The muon linac consists of an RFQ, an inter-digital IH, a Disk And Washer structure, and a disk loaded structure. The ultra-cold muons will have an extremely small momentum spread of 0.3 % with a normalized transverse emittance of around 1.5 pi mm-mrad. The design and status of the muon linac at J-PARC will be presented.

Slides FR1A05 [13.154 MB]

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