IPAC2016 - List of Keywords (radiation)

Paper	Title	Other Keywords	Page
MOPMB002	First Measurements of Coherent Smith-Purcell Radiation in the SOLEIL Linac	detector, linac, experiment, operation	69
	N. Delerue, J. Barros, S. Jenzer, V. Khodnevych, M.S. Malovytsia LAL, Orsay, France N. Hubert, M. Labat SOLEIL, Gif-sur-Yvette, France V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine M.S. Malovytsia KhNU, Kharkov, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01). An experiment to measure the Coherent Smith-Purcell radiation has been installed in the SOLEIL Linac. Its aim is to produce a map of Smith-Purcell radiation emissions in several planes and compare it with theoretical predictions. Coherent Smith Purcell radiation is produced when a grating is brought close from a sufficiently short charged particles beam. The experiment consist of two detectors with 5 degrees of freedom. These two detectors can be moved around the emission point to measure the intensity of the radiation at different locations. Radiation maps are recorded parasitically by moving the detectors around during normal linac operations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB002
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MOPMB003	Comparison of Coherent Smith-Purcell Radiation and Coherent Transition Radiation	electron, laser, free-electron-laser, simulation	72
	V. Khodnevych, N. Delerue LAL, Orsay, France O.A. Bezshyyko, V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) between France and Ukraine. Smith-Purcell radiation and Transition Radiation are two radiative phenomenon that occur in charged particles accelerators. For both the emission can be significantly enhanced with sufficiently short pulses and both can be used to measure the form factor of the pulse. We compare the yield of these phenomenon in different configurations and look at their application as bunch length monitors, including background filtering and rejection. We apply these calculations to the specific case of the CLIO Free Electron laser.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB003
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MOPMB004	Comparison of the Smith-purcell Radiation Yield for Different Models	electron, simulation, experiment, detector	75
	M.S. Malovytsia, N. Delerue LAL, Orsay, France M.S. Malovytsia KhNU, Kharkov, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) France-Ukraine. Smith-Purcell radiation is used in several applications including the measurement of the longitudinal profile of electron bunches. A correct reconstruction of such profile requires a good understanding of the underlying model. We have compared the leading models of Smith-Purcell radiation and shown that they are in agreement within the experimental errors.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB004
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MOPMB005	Study of Short Bunches at the Free Electron Laser CLIO	cavity, electron, gun, simulation	78
	V. Khodnevych, N. Delerue, S. Jenzer LAL, Orsay, France J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres CLIO/ELISE/LCP, Orsay, France V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01). CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB005
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MOPMB013	Time-resolved Spectral Observation of Coherent THz Pulses at DELTA	laser, electron, detector, simulation	105
	C. Mai, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M. Höner, M.A. Jebramcik, S. Khan, N.M. Lockmann, A. Meyer auf der Heide, R. Molo, R. Niemczyk, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF (05K13PEC), the DFG (INST 212/236-1) and the state of NRW. Coherent THz pulses induced by a laser-electron interac- tion are routinely produced and observed at DELTA, a 1.5- GeV synchrotron light source operated by the TU Dortmund University. At a dedicated THz beamline, measurements using a Fourier-transform spectrometer have been performed between 1 THz and 7 THz. Recently, an ultrafast Schottky- diode detector and a novel polarizing Fourier-transform spec- trometer were installed, which enable turn-by-turn-resolved spectral measurements in the frequency range below 1 THz. The commissioning results of the new spectrometer and simulations are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB013
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MOPMB014	Simultaneous Detection of Longitudinal and Transverse Bunch Signals at ANKA	synchrotron, detector, synchrotron-radiation, timing	109
	B. Kehrer, E. Blomley, M. Brosi, E. Bründermann, N. Hiller, A.-S. Müller, M.J. Nasse, M. Schedler, M. Schuh, P. Schönfeldt, P. Schütze, N.J. Smale, J.L. Steinmann KIT, Karlsruhe, Germany
	Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the BMBF under contract number 05K13VKA. The ANKA storage ring offers different operation modes including the short-bunch mode with bunch lengths tuned down to a few picoseconds. This can lead to the occurrence of micro-bunching instabilities coupled to the emission of coherent synchrotron radiation (CSR) in so-called 'bursts'. To study this CSR instability we use several turn-by-turn enabled detector systems to synchronously measure both the THz signal as well as bunch profiles. The different detectors are placed at different locations around the storage ring. Here we discuss the experimental setup and calibration of the various systems' synchronisation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB014
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MOPMB016	Single-Shot Spectral Analysis of Synchrotron Radiation in THz Regime at ANKA	detector, synchrotron, synchrotron-radiation, bunching	115
	A. Schmid, M. Brosi, E. Bründermann, K.S. Ilin, B. Kehrer, K. Kuzmin, A.-S. Müller, J. Raasch, M. Schuh, P. Schönfeldt, M. Siegel, J.L. Steinmann, S. Wuensch KIT, Karlsruhe, Germany S.A. Kuznetsov NSU, Novosibirsk, Russia
	Funding: This work was supported by BMBF contract number 05K13VK4 and the Ministry of Education and Sci- ence of the Russian Federation (State Assignment Contract No. 3002). Micro-bunching instabilities limit the longitudinal compression of bunches in an electron storage ring. They create substructures on the bunch profile of some hundred micrometer size leading to coherently emitted synchrotron radiation in the THz range. To detect the changing THz spectrum, single-shot bunch-by-bunch and turn-by-turn measurements are necessary. We present recent experiments at ANKA where the spectral information is extracted by simultaneous detection with several narrowband THz detectors, each of them sensitive in a different frequency range.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB016
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MOPMB017	Design Issues for the Optical Transition Radiation Screens for theELI-NP Compton Gamma Source	electron, simulation, linac, laser	118
	M. Marongiu, A. Giribono, A. Mostacci, V. Pettinacci INFN-Roma, Roma, Italy D. Alesini, E. Chiadroni, F. Cioeta, G. Di Pirro, V.L. Lollo, L. Pellegrino, V. Shpakov, A. Stella, C. Vaccarezza, A. Variola INFN/LNF, Frascati (Roma), Italy A. Cianchi INFN-Roma II, Roma, Italy L. Palumbo University of Rome La Sapienza, Rome, Italy
	A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation profile monitors. In order to measure the beam properties along the train, the screens must sustain the thermal stress due to the energy deposited by the bunches; moreover the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the analytical studies as well as numerical simulations to investigate the thermal behaviour of the screens impinged by the nominal bunch; the design and the performance of the optical detection line is discussed as well.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB017
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MOPMB020	Transverse Intensity Distribution Measurement of Ion Beams Using Gafchromic Films	ion, cyclotron, octupole, tandem-accelerator	130
	Y. Yuri, T. Agematsu, T. Ishizaka, K. Narumi, S. Okumura, H. Seito, T. Yuyama JAEA/TARRI, Gunma-ken, Japan
	A possible method of measuring the transverse spatial distribution of energetic ion beams is developed at Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (formerly, Japan Atomic Energy Agency). For this purpose, a radiochromic film, Gafchromic film (Ashland Inc.), is employed since it enables us to easily measure a large-area irradiation field distribution at a high spatial resolution. Gafchromic EBT3 and HD-V2 films are irradiated with ion beams of various species and kinetic energies extracted from a cyclotron and electrostatic accelerators at QST/Takasaki. Then, the coloration response of the films is analyzed in terms of the optical density. It is demonstrated that EBT3 and HD-V2 films are useful for the beam profile measurement at low fluence and at low energy, respectively.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB020
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MOPMB026	Frequency and Time Domain Measurement of Coherent Transition Radiation	electron, laser, vacuum, polarization	143
	K. Kan, M. Gohdo, T. Kondoh, I. Nozawa, J. Yang, Y. Yoshida ISIR, Osaka, Japan
	Ultrashort electron beams are essential for light sources and time-resolved measurements. Electron beams can emit terahertz (THz) pulses using coherent transition radiation (CTR). Michelson interferometer is one of can-didates for analyzing the pulse width of an electron beam based on frequency-domain analysis. Recently, electron beam measurement using a photoconductive antenna (PCA) based on time-domain analysis has been investi-gated. In this paper, to improve beam diagnostics of ul-trashort electron beam, investigation of characteristics of a PCA for generation and frequency and time-domain measurement of THz pulses was conducted. * I. Nozawa et al., Phys. Rev. ST Accel. Beams 17, 072803 (2014). ** K. Kan et al., Appl. Phys. Lett. 102, 221118 (2013).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB026
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MOPMB028	Development of Beam Diagnostic System for the SPring-8 Upgrade	diagnostics, beam-diagnostic, photon, emittance	149
	H. Maesaka, T. Ohshima, Y. Otake RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Dewa, T. Fujita, K. Kobayashi, M. Masaki, S. Matsubara, T. Nakamura, S. Sasaki, S. Takano JASRI/SPring-8, Hyogo-ken, Japan
	The goal of the beam diagnostic system for the SPring-8 upgrade is to deliver brilliant X-rays enabled by the new low-emittance ring to experimental stations with ultimate stability. Developments of accurate electron and photon beam position monitors (EBPM and XBPM, respectively) with both short and long-term stability are the most critical. The EBPM sensitivity is also crucial for low-current beam commissioning to accomplish the first beam storage in the ring. We designed a button electrode to obtain sufficiently high-intensity signals while suppressing high-Q trapped modes leading to impedance and heating issues. We also designed a precise EBPM block and a rigid support to achieve mechanical accuracy and stability. Another challenge is the development of a reliable and stable XBPM, which should be an accurate reference for an orbit feedback without any photon-energy dependences. A significant improvement of a blade-type XBPM or an invention of a novel XBPM detecting the core of an intense X-ray beam are necessary. The other diagnostic instrumentations can be utilized for the new ring with minor improvements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB028
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MOPMB030	Development of an EO Sampling Method for THz Pulse Detection	laser, polarization, electron, experiment	155
	T. Toida, M. Washio, R. Yanagisawa Waseda University, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	We have been studying an S-band Cs-Te photo-cathode rf gun at Waseda Univ. The high quality electron beam produced by the rf gun is used to generate a high-power coherent terahertz pulse via Cherenkov radiation. This terahertz pulse can be applied to terahertz imaging and material analysis. As a preliminary step towards material analysis, we conducted experiments on terahertz time domain spectroscopy by EO sampling method to reveal major parameters of the terahertz pulse such as the pulse form and the spectrum. EO sampling method has high frequency response and suitable for high peak power terahertz pulses. In terahertz time domain spectroscopy, the duration of the probe pulse needs to be much faster than that of the terahertz pulse. Therefore, we developed a mode locked Yb-fiber laser based on nonlinear polarization rotation as a reliable and cost-effective ultra-fast probe light source. The laser generates 3.80 ps chirped pulses which are compressed to 213 fs with a grating pair. In this conference, we will report the performance of the Yb-fiber laser and results of EO sampling experiments.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB030
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MOPMB036	Beam Profile Measurement Using Kirkpatrick Baez Mirror Optics at Shanghai Synchrotron Radiation Facility	synchrotron, synchrotron-radiation, optics, diagnostics	167
	D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue IHEP, Beijing, People's Republic of China J. Chen SINAP, Shanghai, People's Republic of China
	For the third-generation light sources, the vertical emit-tance of a few pico-meter-radians which can be achieved with good coupling correction close to 0.1%, will lead to very small beam size. Several microns vertical beam sizes measurement has presented challenges for diagnostic capability in this region. A few techniques have been developed to make a precise measurement, such as visible light interferometer, x-ray imaging using Fresnel zone plates, compound refractive lenses or pinhole camera. In this paper, an x-ray reflective optics method based on the Kirkpatrick'Baez mirrors will be emphasis on discussed. The K-B mirror system will be installed and tested in SSRF to obtain the vertical beam size close to 20 microns, which is expected to be used for several microns vertical beam size measurement in the future light source named HEPS (High Energy Photon Source) in China.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB036
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MOPMB039	Design of Bunch Length Measurement System at the IRFEL Using a Martin-Puplett Interferometer	electron, detector, polarization, vacuum	178
	T.Y. Zhou, X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, F.F. Wu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by the National Science Foundation of China (11575181, 11175173) Electron bunch length measurement is of great significance for optimizing IRFEL performance. An optical autocorrelation system using coherent transition radiation (CTR) would be set up to measure the electron bunch length at the IRFEL. CTR can be occurred when short electron bunches traverse a vacuum-metal interface. A Martin-Puplett interferometer allowed measurement of the autocorrelation of the CTR signal. The basic principle and the main components of Martin-Puplett interferometer are elaborated in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB039
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MOPMR003	Electron Bunch Length Measurement Using Coherent Radiation Source of fs-THz accelerator at Pohang Accelerator Laboratory	electron, linac, experiment, target	235
	J.H. Ko, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S.H. Jung, H.-S. Kang, I.S. Ko, J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition radiation (CTR) from a 65-MeV electron beam of the fs-THz accelerator. In this paper, we show the how to make a longitudinal distribution of electron bunch and the radiation intensity difference between CTR and Coherent edge radiation (CER) for nondestructive electron bunch length measurement. And we report the measurement methods to get the fine electron bunch length information.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR003
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MOPMR013	Development, Calibration and Application of New-generation Dissectors with Picosecond Temporal Resolution	electron, laser, operation, positron	251
	O.I. Meshkov, O. Anchugov, V.L. Dorohov, G.Y. Kurkin, A.V. Petrozhitskii, D.A. Shvedov, E.I. Zinin BINP SB RAS, Novosibirsk, Russia P.B. Gornostaev, M.Ya. Schelev, E.V. Shashkov, A. V. Smirnov, A.I. Zarovskii GPI, Moscow, Russia
	Funding: The presented experimental results were implemented due to financial support of the Russian Science Foundation (Projects N 14-29-00295) A dissector is an electron-optical device designed for measurement of periodic light pulses of subnanosecond and picosecond duration. LI-602 dissector developed at BINP is widely used for routine measurements of a longitudinal profile of electron and positron beams at BINP electron-positron colliders and other similar installations]. This dissector is a part of many optical diagnostic systems and provides temporal resolution of about 20 ps. Recently* a new generation of picosecond dissectors were created on the basis of the PIF-01/S1 picosecond streak-image tube designed and manufactured at the General Physics Institute Photoelectronics Department (Moscow). The device has demonstrated a temporal resolution of 3-4 ps (FWHM). The procedure of temporal resolution calibration and results of application of the new-generation picosecond dissector are given in this work. *E.I. Zinin, O.I. Meshkov. JINST, 2015 1748-0221 10 P10024 doi:10.1088/1748-0221/10/10/P10024
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR013
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MOPMR015	Optical Fibers as a Tool for Gamma Beam Diagnostics at Medical Electron Accelerators	betatron, target, detector, electron	258
	A.I. Novokshonov, V.I. Bespalov, A. Potylitsyn, D.A. Shkitov, S.R. Uglov, A.V. Vukolov TPU, Tomsk, Russia
	Funding: This work was partially supported by the Russian Ministry of Education and Science within the program "Nauka" Grant № 3.709.2014/K. The existing techniques for gamma beam diagnostics at medical accelerators based on X-ray films have several disadvantages such as insufficient spatial resolution, difficult realization and off-line mode. In the works,* a feasibility of Cherenkov radiation (CR) in glass fibers for charged particle beam diagnostics was demonstrated. An application of glass fibers scanning for gamma beam diagnostics may have a lot advantages including a possibility of on-line measurements. For this goal we used optical fiber with 0.6 mm diameter and length up to 10 m. An efficiency of CR generation in such fibers and signal attenuation in a long fiber were investigated using the Tomsk microtron electron beam. The shape of gamma beam field produced by the medical SL-75-5MT 6 MeV electron accelerator was measured using the proposed technique. It is shown there it is possible to measure not only gamma beam spatial distribution, but also its angular distribution. * Wulf, F. and Korfer, M. 2009 Proc. DIPAC2009 411. ** Murokh, A., Agustsson, R., Boucher, S., Frigola, P., Hodgetts, T., Ovodenko, A., Ruelas, M. and Tikhoplav, R. 2012 Proc. IPAC2012 996.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR015
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MOPMR016	A New Approach for the Electron Beam Diagnostic Using Diffraction Radiation Disphase Target	target, detector, simulation, diagnostics	261
	D.A. Shkitov, G.A. Naumenko, A. Potylitsyn TPU, Tomsk, Russia J. Urakawa KEK, Ibaraki, Japan
	Funding: The work was partially supported by the RFBR grant No 15-52-50028. Since 1995, when the diffraction radiation (DR) from relativistic particles was first observed, the development of new approaches using the DR for charged particle beam diagnostics is continued. The DR appears when charged particle moves close to the media and the electromagnetic field interacts with it. A rather well-known non-invasive diagnostic method of transversal bunch size is to use a slit target. In paper the optical DR from disphase target was proposed to use for non-invasive diagnostics of high energy electron beam. Disphase target consists of the two rectangular flat plates inclined with respect to each other at an angle compared with 1/g, where g is the Lorentz-factor. Recently the feasibility of the disphase target usage for the 6 MeV electron beam size diagnostics was investigated*. In this report we present the further research of the disphase target beam diagnostics. The simulations of the spectral-angular DR characteristics from this target and it application for diagnostics aim are shown. These calculations confirm an applicability of this technique for micron size beam measurements for the case of g>1000. Y. Shibata et al. //PRE 52, 6787 (1995) P. Karataev et al. //PRL 93, 244802 (2004) G. Naumenko et al. //Proc. of PAC TOAD004, 404 (2005) ***E.V. Kornoukhova et al. //JPCS, in press (2016)
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR016
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MOPMR021	Lifetime and Operational Criteria of Proton Beam Instrumentation in the ESS Target Station	electron, proton, target, monitoring	276
	Y. Lee, T.J. Shea, C.A. Thomas ESS, Lund, Sweden
	At the European Spallation Source, a 2 GeV, 5 MW proton beam will be delivered from a superconducting linear accelerator to target at a 4% duty factor, which poses demanding requirements on target station design. To tune the beam delivery system and to protect the target station components, the current density, the halo distribution, and the position of the proton beam shall be measured. To provide this functionality, a suite of beam monitoring devices will be deployed in the target monolith, including a multi-wire grid for the beam profile monitoring, thermo-couple assemblies and secondary emission blades for aperture monitoring, and a beam footprint imaging system consisting of optical components and luminescent coatings. Since these devices are exposed to particles that deposit energy and cause a high rate of radiation damage, it is a significant challenge to ensure full functionality. In this paper, material selection, lifetime estimates and operational criteria for these beam-monitoring devices are presented. A number of particle transport and finite-element simulations are performed for analyses, and an empirical validation plan is presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR021
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MOPMR030	Performance of the Upgraded Synchrotron Radiation Diagnostics at the LHC	extraction, synchrotron, synchrotron-radiation, diagnostics	306
	G. Trad, E. Bravin, A. Goldblatt, S. Mazzoni, F. Roncarolo CERN, Geneva, Switzerland T.M. Mitsuhashi KEK, Ibaraki, Japan
	During the LHC long shut down in 2014, the transverse beam size diagnostics based on synchrotron radiation was upgraded in order to cope with the increase of the LHC beam energy to 6.5 TeV. The wavelength used for imaging was shifted to near ultra-violet to reduce the contribution of diffraction to the system resolution, while in parallel, a new diagnostic system based on double slit interferometry was installed to measure the beam size by studying the spatial coherence of the emitted synchrotron radiation. This method has never been implemented before in a proton machine. A Hartmann mask was also installed to identify possible wavefront distortions that could affect the system accuracy. This paper will focus on the comparison of visible and the near ultra-violet imaging and on the first experience with interferometry.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR030
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MOPMR032	Measurement of Beam Size with a SR Interferometer in TPS	synchrotron, synchrotron-radiation, shielding, monitoring	313
	M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, W.Y. Lai, C.J. Lin, S.Y. Perng, C.W. Tsai, T.C. Tseng, H.S. Wang NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) has operated since 2015. An optical diagnostic beamline is constructed in section 40 of TPS for the diagnosis of the properties of the electron beam. One instrument at this beamline is a synchrotron radiation interferometer (SRI), which is operated to monitor the beam size. In this paper, we present the beamline structure and recent results of measurement with the SR interferometer.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR032
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MOPMR034	Precise Betastron Tune Measurement in TPS Storage Ring	betatron, storage-ring, simulation, synchrotron-radiation	319
	C.H. Chen, C.H. Chang, J.Y. Chen, M.-S. Chiu, S. Fann, C.H. Huang, T.Y. Lee, C.C. Liang, Y.-C. Liu, F.H. Tseng NSRRC, Hsinchu, Taiwan
	To acquire precise beam orbits from beam position monitors (BPMs) in storage ring is one of the most significant diagnosis to measure beam parameters. However, the precise spectrum analyses from BPM data acquisitions such as betatron tune, dynamics aperture and frequency map '..etc. that are depended on more accurate discrete Fourier transform (DFT) or the fast Fourier transform (FFT). A method of the fast Fourier transform correction (FFTc) was employed for the more accurate spectrum measurement in Taiwan Photon Source (TPS). We perform the accuracy and error analyses of this method from some spectral lines in two window functions. And the precise spectrum for betatron tune measurements and related results will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR034
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MOPMR036	Using a Single Shot Spectrometer to Determine the Spectral Characteristics of the Beam as a Result of Micro-bunching Instabilities	detector, synchrotron, synchrotron-radiation, storage-ring	327
	A. Finn, P. Karataev JAI, Egham, Surrey, United Kingdom P. Karataev Royal Holloway, University of London, Surrey, United Kingdom G. Rehm DLS, Oxfordshire, United Kingdom
	A single shot spectrometer has been designed and is in operation at the Diamond Light Source (DLS). It is an array of eight Schottky barrier diodes (SBDs) each with a distinct frequency band covering 33-1000 GHz. The aim of the spectrometer is to observe the bursts of coherent synchrotron radiation (CSR) as a result of micro-bunching instabilities (MBI) and stable low alpha modes, where alpha is the momentum compaction factor. In this case, the bursts of CSR occur with wavelengths in the mm regime. SBDs are often implemented as detectors in the millimetre wavelength range and benefit from low noise, excellent sensitivity and ultra-fast responses. The eight SBDs have been individually characterised thus making the results obtained comparable to simulations. Here we present, an analysis of the data obtained via the spectrometer in particular, the bursting nature and spectral characteristics of a sample of beam modes at DLS. Furthermore, the results obtained can be used to confirm simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR036
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MOPMR039	Review of Emittance Diagnostics for Space Charge Dominated Beams for AWAKE e^- Injector	emittance, space-charge, quadrupole, focusing	337
	O. Mete Apsimon, G.X. Xia UMAN, Manchester, United Kingdom S. Döbert CERN, Geneva, Switzerland C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. For a low energy, high intensity beam, total beam emittance is dominated by defocusing space charge force. This is most commonly observed in photo-injectors. In this low energy regime, emittance measurement techniques such as quadrupole scans fail as they consider the beam size only depends on optical functions. The pepper-pot method is used for 2D emittance measurements in a single shot manner. In order to measure the beam emittance in space charge dominated regime by quadrupole scans, space charge term should be carefully incorporated into the transfer matrices. On the other hand, methods such as divergence interferometry via optical transition radiation (OTRI), phase space tomography using 1D projections of quadrupole scans can be suitably applied for such conditions. In this paper, the design of a versatile pepper-pot system for AWAKE experiment at CERN is presented for a wide range of bunch charges from 0.1 to 1nC where the space charge force increases significantly. In addition, other aforementioned methods and respective algorithms are introduced as alternative methods.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR039
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MOPMR040	First Steps Towards a Single-Shot Longitudinal Profile Monitor: Study of the Properties of Coherent Smith-Purcell Radiation Using the Surface Current Model	detector, polarization, background, simulation	340
	H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster JAI, Oxford, United Kingdom A. Aryshev, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: UK STFC, Leverhulme Trust, Photon and Quantum Basic Research Coordinated Development Program (Ministry of Education, Culture, Sports, Science and Technology, Japan)and JSPS KAKENHI. We propose to use the polarization of coherent Smith-Purcell radiation (cSPr) to separate the signal from background radiation in a single-shot longitudinal bunch profile monitor. We compare simulation and experimental results for the degree of polarization of cSPr generated by a grating with a 1mm periodic structure at the LUCX facility, KEK (Japan). Both experiment and simulation show that the majority of the cSPr signal is polarized in the direction parallel to the grating grooves. The degree of polarization predicted by simulation is higher than the measured result, therefore further investigation is needed to resolve this discrepancy.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR040
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MOPMR041	Experimental and Theoretical Studies of the Properties of Coherent Smith-Purcell Radiation	polarization, background, electron, experiment	344
	F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, A. Reichold JAI, Oxford, United Kingdom J. Barros, N. Delerue LAL, Orsay, France R. Bartolini DLS, Oxfordshire, United Kingdom C.I. Clarke SLAC, Menlo Park, California, USA
	Funding: This work was supported (in parts) by the UK Science and Technology Facilities Council (STFC UK) through grant ST/M003590/1 and The Leverhulme Trust through the International Network Grant IN-2015-012 Previous studies have demonstrated that coherent Smith-Purcell radiation (cSPr) can be used for relativistic electron bunch time profile reconstruction at pico-second and femtosecond scales. The E203 experiments undertaken in May 2015 at FACET (SLAC) were dedicated to the study of some properties of cSPr, namely the azimuthal distribution and the polarization of the radiation. The experimental set up description which allowed such studies will be presented along with the results. To understand the experimental data both semi-analytical and numerical models were studied. The semi-analytical approach was based on the surface-current model, and the 3D particle-in-cell code VSim was used for numerical modeling. The experimental and theoretical studies are compared.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR041
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MOPMR043	Optical System Design for The ESS Proton Beam and Target Diagnostics	target, optics, proton, diagnostics	347
	M.G. Ibison, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom E. Adli, H. Gjersdal University of Oslo, Oslo, Norway M.G. Ibison, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom T.J. Shea, C.A. Thomas, N. de la Cour ESS, Lund, Sweden
	Funding: Science and Technology Facilities Council The high power and low emittance of the European Spallation Source (ESS) proton beam require a robust protection strategy for the spallation target and its surroundings. For this, the beam will be imaged on passing through scintillator screens coating both the proton beam window (PBW) on exit from the accelerator, and the entry window to the target (TW). Light from the screens must be transported to remote cameras through a 4m high shielding plug of limited aperture. At the same time, the optical path must not compromise the integrity of the shield against neutrons and interaction products. We present the theory underlying the design of the reflective optics for efficient transmission of high-quality images to provide the desired level of protection to the machine, and describe its implementation in the Zemax software tool, as well as the predicted imaging performance. We also consider how the requirements of environment (thermal and radiation), initial alignment and ongoing maintenance for the optical system will be met. Finally we comment on the applicability of optics of this type for diagnostic systems in similar situations at other neutron sources and elsewhere.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR043
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MOPMR054	Double-slit Interferometer Measurements at SPEAR3	electron, synchrotron, synchrotron-radiation, optics	368
	C.L. Li, W.J. Zhang East China University of Science and Technology, Shanghai, People's Republic of China M.J. Boland SLSA, Clayton, Australia W.J. Corbett, M. Grinberg SLAC, Menlo Park, California, USA T.M. Mitsuhashi KEK, Ibaraki, Japan Y.H. Xu DongHua University, Songjiang, People's Republic of China W.J. Zhang University of Saskatchewan, Saskatoon, Canada
	The resolution of a conventional telescope used to image visible-light synchrotron radiation is often limited by diffraction effects. To improve resolution, the double-slit interferometer method was developed at KEK and has since become popular around the world. Based on the Van Cittert-Zernike theorem relating transverse source profile to transverse spatial coherence, the particle beam size can be inferred by recording fringe contrast as a function of interferometer slit separation. In this paper, we describe the SPEAR3 double-slit interferometer, develop a theoretical framework for the interferometer and provide experimental results. Of note the double-slit system is 'rotated' about the beam axis to map the dependence of photon beam coherence on angle.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR054
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MOPMR055	Radiation-Resistant Fiber Optic Strain Sensors for SNS Target Instrumentation	target, neutron, proton, detector	371
	Y. Liu, W. Blokland, J.D. Bryan, A. Rakhman, B.W. Riemer, R.L. Sangrey, M. Wendel, D.E. Winder ORNL, Oak Ridge, Tennessee, USA A. Rakhman UTK, Knoxville, Tennessee, USA R. Strum San Diego State University, San Diego, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Measurement of stresses and strains in the mercury target vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. Owing to their compactness, easy system integration, and invulnerability to the electromagnetic interference, fiber optic strain sensors have been installed into the SNS target module starting from the fall of 2015. In this talk, we report on the development of radiation-resistant fiber optic strain sensors for subsequent generations of SNS target instrumentation. The sensors are extrinsic Fabry-Perot interferometers (EFPIs) made from fluorine-doped single-mode fibers. The radiation induced loss of the fiber has been measured in the SNS target 13 at the energy-on-target level exceeding 500 MWhr which results in peak doses on fiber of more than 10⁹ Gy. A superluminescent diode laser at 1300 nm is used as the light source and the strain is measured in real-time using quadrature phase shifted signals generated from a local interferometer. We have demonstrated successful measurements of strains from 1 to 1000 με at a kHz frequency range on a test plate using the developed interrogation optical system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR055
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MOPMR056	Single-shot THz Spectrometer for Measurement of RF Breakdown in mm-wave Accelerators	detector, vacuum, alignment, laser	374
	S.V. Kutsaev, A.Y. Murokh, M. Ruelas, E.A. Savin, H.L. To RadiaBeam Systems, Santa Monica, California, USA M. Dal Forno, V.A. Dolgashev SLAC, Menlo Park, California, USA V. Goncharik Logicware Inc, New York, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under contract DE-SC0013684 We present a new instrument designed to detect RF pulse shortening caused by vacuum RF breakdown in mm-wave particle accelerators. RF breakdown limits the performance of high gradient RF accelerators. To understand the properties of these breakdowns, it is necessary to have diagnostics that reliably detect RF breakdowns. In X-band or S-band accelerators, RF breakdowns are detected by measuring RF pulse shortening, vacuum burst, or, if current monitors are available, spikes in the field-emitted currents. In mm-wave accelerators, all of these methods are difficult to use. In our experiments, we could not measure RF pulse shortening directly with a crystal detector because the RF pulse is very short'just a few nanoseconds'and changes in the measured signal were masked by RF amplitude jitter. To overcome this limitation, we built a single-shot spectrometer with a frequency range of 117-125 GHz and a resolution of 0.1 GHz. The spectrometer should be able to measure the widening of the spectrum caused by the shortening of nanosecond-long pulses. We present design considerations, first experimental results obtained at FACET, and planned future improvements for the spectrometer.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR056
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MOPMR059	Development of S-band High Power Load	vacuum, klystron, radio-frequency, electron	383
	X.C. Meng, H.B. Chen, C. Cheng, Y.-C. Du, Q. Gao, J. Shi, P. Wang, Z.F. Xiong TUB, Beijing, People's Republic of China
	Several types of S-band high power loads have been designed, manufactured and tested successfully in Tsinghua University. The high power loads, which work at 2856 MHz for 10 MW~100 MW range, are made of all stainless steel. In this paper, we will present the design, fabrication and the high power test results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR059
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MOPMW010	Property Test of the Q-Factor for High Purity Copper at the Temperature of 20K	cavity, electron, linac, cryogenics	417
	A. Iino Sokendai, Ibaraki, Japan K. Endo TOYAMA Co., Ltd., Zama-shi, Kanagawa, Japan S. Yamaguchi KEK, Ibaraki, Japan
	A coherent parametric x-ray radiation (PXR) source based on a cryogenic electron linac has been developed by Toyama Co., Ltd, KEK and Nihon University. This accelerator is a C-band normal-conducting compact linac that requires a high Q factor in the accelerating and de-celerating structures. To obtain a high Q factor, the ac-celerating and decelerating structures are operated around 20 K, and are joined by diffusion bonding and are constructed with high-purity 6N8 copper which has very low resistivity in extremely low temperatures. In this study, we report the measurements and calculation of the residual resistance ratio (RRR) for 6N8 copper and oxy-gen-free copper (Class 1) as well as the Q factor for a pillbox cavity made of 6N8 copper and Class 1. The results of a low-power test of this accelerating structure at low temperature are reported. The Q factor for a 6N8 copper pillbox cavity is not much higher than that of a Class 1 pillbox cavity at low temperatures Moreover, the Q factor is saturated when RRR is greater than 500.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW010
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MOPMW032	Study of RF Breakdown in 805MHz Pillbox Modular Cavity in Strong Magnetic Field	cavity, operation, site, pick-up	466
	A.V. Kochemirovskiy University of Chicago, Chicago, Illinois, USA D.L. Bowring, A. Moretti, K. Yonehara Fermilab, Batavia, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	RF breakdown has a negative impact on a cavity's performance, especially with the presence of strong magnetic fields. This issue can arise in designs of muon ionization cooling channel, RF guns, klystrons and in many other applications. The MuCool Test Area at Fermilab is the facility that allows us to study the effects of static magnetic field on RF cavity operation. As a part of this research program, we have tested an 805MHz pillbox "modular" cavity in strong external magnetic fields. The design of the cavity allowed for a better control over sources of systematic error. "Modular" structure of the cavity enables easy dismounting of the endplates to perform inspection of inner surfaces after each run as well as swapping endplates to study the effects of various materials on breakdown phenomenon. Coupler design ensures maximum electric field enhancement on cavity axis, thus reducing breakdown probability in the coupler region. The results and analysis from high-power runs with zero and non-zero external magnetic fields will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW032
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MOPOR046	Studies on Depolarization by Synchrotron Radiation using Elegant Particle Tracking	synchrotron, synchrotron-radiation, polarization, resonance	695
	J.F. Schmidt, W. Hillert ELSA, Bonn, Germany
	Funding: BMBF Spin dynamics in circular electron accelerators are significantly influenced by the emission of synchrotron light. In storage rings, Sokolov-Ternov polarization build-up and radiative depolarization have crucial impact on equilibrium polarization. On shorter timescales, as in damping rings or synchrotrons with fast energy ramp, the temporal development of polarization depends on spin decoherence caused by stochastic momentum changes. Thus, especially longitudinal beam dynamics affect depolarization. This contribution presents the implementation of particle tracking with synchrotron radiation from Elegant in an in-house developed spin tracking code. Exemplary results on depolarization including synchrotron radiation are shown.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR046
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MOPOW008	Reverse Undulator Tapering for Polarization Control at XFELs	undulator, FEL, resonance, bunching	722
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. We describe a method for such a suppression: an application of the reverse taper in the main undulator. In a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. The scheme was successfully tested at LCLS* and is routinely used in user experiments. In this contribution we present the theoretical description of the method as well as the results of experiments with reverse taper at FLASH2. * E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 16, 110702 (2013) ** H.-D. Nuhn et al., "Commissioning of the DELTA polarizing undulator at LCLS", Proc. of FEL2015 Conf., Daejeon, Korea
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW008
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MOPOW009	Studies of Harmonic Lasing Self-seeded FEL at FLASH2	undulator, FEL, simulation, electron	725
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in,. A gap-tunable undulator is divided into two parts such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is reduced by a significant factor depending on harmonic number but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed. E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702 ** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW009
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MOPOW011	Operation of Free Electron Laser FLASH Driven by Short Electron Pulses	electron, undulator, simulation, laser	732
	V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW011
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MOPOW012	Transverse Coherence and Fundamental Limitation on the Pointing Stability of X-ray FELs	FEL, electron, photon, emittance	735
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	The radiation from SASE FEL has always limited value of the degree of transverse coherence. When transverse size of the electron beam significantly exceeds diffraction limit, the mode competition effect does not provide the selection of the ground mode, and spatial coherence degrades due to contribution of the higher azimuthal modes. An important consequence of this effect are fluctuations of the spot size and pointing stability of the photon beam. These fluctuations are fundamental and originate from the shot noise in the electron beam. The effect of pointing instability becomes more pronouncing for shorter wavelengths. We analyze in detail the case of optimized SASE FEL and derive universal dependencies applicable to all operating and planned x-ray FELs. We show that the hard x-ray FELs driven by low energy beams may exhibit poor spatial coherence and bad pointing stability. * E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 281(2008)1179. ** E.A. Schneidmiller and M.V. Yurkov, Proc. FEL2015 Conference, Daejeon, Korea, 2015, TUP021.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW012
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MOPOW013	Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL	FEL, undulator, electron, photon	738
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH. E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383. ** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW013
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MOPOW016	Status of Design and Development of Delhi Light Source at IUAC, Delhi	laser, electron, undulator, gun	748
	S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu IUAC, New Delhi, India A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa KEK, Ibaraki, Japan A. Deshpande SAMEER, Mumbai, India V. Naik, A. Roy VECC, Kolkata, India T. Rao BNL, Upton, Long Island, New York, USA
	Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW016
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MOPOW020	Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing	FEL, focusing, undulator, electron	760
	G. Zhou, Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China J. Wu SLAC, Menlo Park, California, USA T. Zhang SINAP, Shanghai, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009) Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW020
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MOPOW023	Proposal of an X-band Linearizer for Dalian Coherent Light Source	FEL, laser, electron, undulator	766
	G.L. Wang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China H.X. Deng, C. Feng SINAP, Shanghai, People's Republic of China
	Dalian coherent Light Source (DCLS) is a FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility based on HGHG mode, requires high brightness electron beam with small energy spread and low emittance. To linearise the longitudinal phase space before the bunch compression, an X-band linearizer is considered before the bunch compressor. In this paper, we study the performance improvement of DCLS FEL radiation by using such a harmonic cavity, including the jitter of central wavelength induced by arriving time and a larger bunch compression ratio for femtosecond FEL application.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW023
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MOPOW024	Harmonic Lasing Options for Dalian Coherent Light Source	FEL, laser, electron, undulator	770
	G.L. Wang, X.M. Yang, W.Q. Zhang DICP, Dalian, People's Republic of China H.X. Deng, C. Feng SINAP, Shanghai, People's Republic of China
	Harmonic lasing of the Free Electron Laser can be achieved by disrupting the electron interaction with the usually dominant fundamental while allowing the increasing of a harmonic interaction. It's a cheap and relatively efficient way to extend the photon energy range of a particular FEL. In this paper, we discussed the possibility of harmonic lasing concept at Dalian Coherent Light Source by using the combination of tapered undulators and phase shifters. Our calculation shows that it's feasible with the present layout to provide intense, stable, and narrow-band harmonic radiation, the FEL wavelength could be down to 20 nm and the corresponding pulse energy is about 10 μJ.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW024
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MOPOW026	Status of FELiCHEM, a New IR-FEL in China	FEL, undulator, cavity, electron	774
	H.T. Li, Z.G. He, Q.K. Jia, Q. Luo, L. Wang, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is a FEL oscillator generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 μm. It will be a dedicated light source aiming at energy chemistry research, with the photo excitation, photo dissociation and photo detection experimental stations. We present the brief physical and technical design that delivers the required performance for this device and summarize the status of fabrication. Final assembly is scheduled for early in the next year with first light targeted for July 2017.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW026
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MOPOW027	Generation of Coherent Mode-locked Radiation in a Seeded Free Electron Laser	electron, FEL, laser, simulation	777
	Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	We present the promise of generating mode-locked multichromatic radiations in a seeded free electron laser based on high gain harmonic generation (HGHG). 3D start-to-end simulations have been carried out and analysis & comparisons have been made to have a research on the properties of each system. In these schemes, either the electron beam density or the seed laser intensity is modulated to produce a coherent radiation pulse train that yields multiple spectral lines in FEL output. Stable peak power at gigawatt level can be generated in the undulator finally.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW027
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MOPOW035	A Compact, Wavelength Tunable MW-THz FEL Amplifier	undulator, FEL, electron, laser	789
	C.H. Chen, A.P. Lee NSRRC, Hsinchu, Taiwan F.H. Chao, Y.C. Chiu, Y.-C. Huang, M.H. Wu NTHU, Hsinchu, Taiwan G. Zhao PKU, Beijing, People's Republic of China
	We propose a compact scheme of THz free electron laser (FEL) amplifier within a 3.5 m long beam line. The amplification of a tunable THz seed laser in an FEL amplifier is driven by an rf photoinjector. The THz seed laser is an optical parametric amplifier* pumped by a 1064-nm microchip laser and an external-cavity tunable diode laser. By varying the beam energy and undulator parameter, the radiation frequency of the THz FEL amplifier can be tunable in a broad spectral range between 1.5 and 3.0 THz. Moreover, to extract more radiation power from the electron beam within a short undulator, we employ a linearly tapered undulator in our design. The influence of the seed power on the electron-laser interaction in the undulator is studied in some detail for the FEL amplification. Our simulation results show that the radiation power of the THz FEL amplifier can achieve few MW with a 10-W seed power. * D.T. Palmer et al., in Proceedings of Particle Acceleration Conference, Vancouver, 1997, p. 2687, (1997). ** S. Hayashi et al., SCIENTIFIC REPORTS, 4, 5045-1-6, (2014).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW035
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TUYA01	BEPCII Performance and Beam Dynamics Studies on Luminosity	luminosity, lattice, synchrotron, synchrotron-radiation	1014
	C.H. Yu, Z. Duan, S. Gu, Y.Y. Guo, X.Y. Huang, D. Ji, H.F. Ji, Y. Jiao, Zh.C. Liu, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X.H. Wang, Y. Wei, X.M. Wen, J. Wu, J. Xing, G. Xu, Y. Yue, C. Zhang, Y. Zhang IHEP, Beijing, People's Republic of China
	The upgrade of the Beijing Electron Positron Collider, BEPCII, is now in a good performance for both high energy physics and synchrotron radiation experiments. The luminosity at the design energy of 1.89 GeV reached the design value 1.0*10³³/cm²/s¹ recently. A lot of work, including accelerator physics study and technical progress, has been done for the luminosity enhancement, not only at the design energy, but all the energy region run for HEP experiments from 1.0 to 2.3 GeV. The performance of BEPCII and the process of luminosity enhancement will be described in detail.
	Slides TUYA01 [5.801 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUYA01
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TUZA01	Soft X-ray Free Electron Laser at SINAP	FEL, undulator, laser, electron	1028
	D. Wang SINAP, Shanghai, People's Republic of China
	Shanghai X-ray FEL (SXFEL) is a test facility at Shanghai Institute of Applied Physics, Chinese Academy of Sciences originally designed for studying XFEL principle and technologies. It is composed of a warm linac to provide up to 840 MeV electron beam, an undulator line with cascaded EEHG-HGHG setup and a short diagnostic beamline. The project started the construction by the end of 2014. Recently a proposal to upgrade it to an user facility at the soft x-ray regime got approved. The talk will give an overview of the test facility construction and upgrade plan.
	Slides TUZA01 [9.344 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZA01
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TUXB01	High Power Radiation Sources using the Steady-state Microbunching Mechanism	laser, storage-ring, FEL, focusing	1048
	A. Chao, E. Granados, X. Huang, D.F. Ratner SLAC, Menlo Park, California, USA H.W. Luo NTHU, Hsinchu, Taiwan
	The mechanism of steady-state microbunching (SSMB) was proposed for providing high power coherent radiation using electron storage rings. The mechanism follows closely the RF bunching in conventional storage rings, except that the energy modulation of by an RF system at a microwave wavelength is replaced by a seeded laser in an undulator at an optical wavelength. No FEL mechanism, and thus no FEL energy heating, is invoked. The basic idea is firstly to make the beam microbunched so that its radiation becomes coherent, and secondly to make the microbunching a steady state so that the coherent radiation is maintained at every turn. The combination of the high repetition rate of a storage ring and the enhanced radiation power by a factor of N (the number of electrons in the microbunches within one coherence length) opens the possibility as well as challenges of very high power SSMB sources. To explore its potential reach, we apply SSMB to the infrared, deep ultraviolet and EUV regions and estimate their respective power levels using SPEAR3 as example. Several variants of the SSMB schemes are discussed. A proof-of-principle configuration without an identified testbed is also suggested.
	Slides TUXB01 [1.602 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUXB01
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TUZB01	High Power Proton Beam Targets: Technological Evolution, Current Challenges, and the Future	target, neutron, proton, operation	1075
	J. Galambos ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This talk reviews the history of proton beam target development and the current challenges associated with the operation of high power beam targets. Beyond providing high power proton beams, accelerator facilities must also engineer robust targets to accept the load and satisfy mission needs. Recently some high power facilities are limited by target operations, rather than accelerator capabilities. The outlook for targets for future high power facilities is also considered.
	Slides TUZB01 [8.971 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZB01
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TUZB02	Challenge of In-vacuum and Cryogenic Undulator Technologies	undulator, vacuum, cryogenics, permanent-magnet	1080
	J.C. Huang, C.-H. Chang, C.H. Chang, T.Y. Chung, C.-S. Hwang, C.K. Yang, Y.T. Yu NSRRC, Hsinchu, Taiwan H. Kitamura RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	An in-vacuum undulator (IVU) opens the utilization of high-brilliance X-rays in the medium energy storage rings. The development of a short-period undulator with low phase error becomes important to bring X-ray into a new unprecedented brilliant light source in an ultimate storage ring (USR). NdFeB or PrFeB cryogenic permanent magnet undulators (CPMUs) with a short period have been developed worldwide to obtain high brilliance of undulator radiation. A CPMU has high resistance against beam-induced heat load and allow to operate at a narrow gap. In a low emittance or ultimate storage ring, not only the performance of an undulator but the choice of the lattice functions is very important to obtain high bril-liance of synchrotron radiation. The optimum betatron functions and zero dispersion function shall be given for a straight section at IVU/CPMUs. In this paper, the relevant factors and design issues for IVU/CPMU will be discussed. Many technological challenges of a short-period undulator associated with beam induced-heat load, phase errors, and the deformation of in-vacuum girders will also be presented herein.
	Slides TUZB02 [5.204 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZB02
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TUPMB007	Research and Development of the Pulse Bump Magnet for the Injection System in CSNS/RCS	injection, neutron, high-voltage, synchrotron	1118
	L. Huo, M.Y. Huang, W. Kang, Y.Q. Liu, J. Qiu, L. Wang, S. Wang IHEP, Beijing, People's Republic of China
	The H⁻ stripping painting injection is adopted in the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS). Painting injection is realized by eight pulse bump magnets. The pulse bump magnet is the key of the performance of painting, as well as the beam loss control. The manufacture and the field measurement of the eight pulse bump magnets have been completed. In the development of the magnets, some key technical problems on fabrication of coil were solved, and the field measurement results show that the magnets fulfil the design specification.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB007
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TUPMB010	Magnetic Center Position and Tilt Angle of Quadrupole by Vibration Wire Method	quadrupole, experiment, alignment, superconductivity	1127
	L. Wu, X. Guan, X.W. Wang, S.X. Zheng TUB, Beijing, People's Republic of China B.C. Wang NINT, Xi'an, People's Republic of China G. Xialing CIAE, Beijing, People's Republic of China
	Vibrating wire method and device are described to locate the magnetic center of a Quadrupole theoretically and experimentally. With rotating 180 degrees method, it is convenience to measure the position magnetic center from mechanical center. Tilt angle can also be measured because tilt of magnetic axis will cause the difference of measured magnetic center in different harmonic driving current frequency. Errors analysis shows that tilt of Quadrupole will cause the main error and improved device is described to adjust and measure the tilt angle to fix the errors caused by tilt.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB010
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TUPMB015	Compact Rare-Earth Permanent Magnet Material System for Industrial Electron Accelerators Irradiation Field Formation	electron, quadrupole, permanent-magnet, simulation	1139
	D.S. Yurov, A.N. Ermakov, V.V. Khankin, N.V. Shvedunov, V.I. Shvedunov M.V. Lomonosov Moscow State University (MSU), Skobeltsyn Institute of Nuclear Physics, Moscow, Russia
	A compact system for industrial electron accelerators irradiation field formation is described. This system permits to get uniform distribution of electron beam current along the direction perpendicular to product movement with the width 50 - 100 cm. Its main element is a non-linear quadrupole lens, based on rare-earth permanent magnet material. This system can be used instead of an electromagnet of the conventional beam scanning systems, making much more comfortable conditions for products irradiation. Operation principles, results of calculations and test results of the system for CW 1 MeV and pulse 10 MeV electron linear accelerators are described.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB015
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TUPMB034	Design and Manufacture of a Superconducting Solenoid for D-Line of J-PARC Muon Facility	solenoid, operation, vacuum, interface	1177
	T. Semba, Y. Hagiwara, S. Kido, S. Nakajima, Y. Tanaka Hitachi Ltd., Ibaraki-ken, Japan N. Kawamura, Y. Makida, Y. Miyake, H. Ohhata, K. Sasaki, K. Shimomura KEK, Ibaraki, Japan N. Kurosawa KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan Y. Murata Hitachi, Ltd., Energy and Environmental System Laboratory, Hitachi-shi, Japan P. Strasser High Energy Accelerator Research Organization (KEK), Institute of Materials Structure Science (IMSS), Ibaraki, Japan
	A superconducting solenoid for J-PARC muon facility was newly designed and manufactured. High Energy Accelerator Research Organization (KEK) has been operating the J-PARC Muon Science Establishment (MUSE) since 2008. Among its four muon beam lines, the decay muon line (D-Line) has been extracting and providing surface muons and positive decay muons up to a momentum of 50 MeV/c for various users, utilizing a superconducting solenoid. The D-Line as well as the other J-PARC facility suffered severe damages from the earthquake on March 11, 2011. It necessitated rebuilding of the damaged superconducting solenoid. New design parameter of the solenoid is as follows: length of solenoid: 6 m, diameter of warm bore: 0.2 m, magnetic field of bore center: 3.5 T, rated current: 415 A, superconducting wire: NbTi/Cu, quench protection: quench back heaters. The six-meter-long solenoid consists of twelve pieces of 0.5-meter-long superconducting coils. The entire solenoid is forced-indirectly cooled by supercritical helium flow. This report describes the design and manufacturing process of the newly built superconducting solenoid for D-Line of J-PARC muon facility.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB034
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TUPMB049	Development of Separator Cooling System for Helium	cryogenics, experiment, controls, vacuum	1209
	W.R. Liao, S.-H. Chang, W.-S. Chiou, P.S.D. Chuang, F. Z. Hsiao, H.C. Li, T.F. Lin, H.H. Tsai NSRRC, Hsinchu, Taiwan
	A helium phase separator with a condenser is under fabrication and assembled at National Synchrotron Radiation Research Centre (NSRRC). The objective of a helium phase separator with its condenser is to separate two-phase helium flow and to re-condense vaporized gaseous helium with a cryocooler of Gifford-McMahon type. We developed a 100 litre (ltr) helium phase separator with a small heat loss as a prototype. The experimental results for the total cooling capacity of the phase separator are 0.73 W at 1.67 bara, which includes the effect of thermal conduction and thermal radiation from the environment. The helium liquefaction rate is 2 ltr/day with a 100 ltr vessel. The mechanism of heat transfer in phase separator was investigated and discussed. This paper presents the experiment of helium liquefaction process of 100 ltr separator with condenser, which was a key component of the helium phase separator.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB049
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TUPMB050	Development of Multi-channel Line for the NSRRC Cryogenic System	cryogenics, vacuum, photon, synchrotron	1212
	P.S.D. Chuang, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H.C. Li, W.R. Liao, T.F. Lin, H.H. Tsai NSRRC, Hsinchu, Taiwan
	For the past few years, the technology of X-ray photon source is getting more and more advanced, more and more countries are now striving to build the biggest synchrotron facility to meet its' need. In Taiwan, the construction of an electron accelerator with the energy of up to 3.5 GeV is constructed to fulfill the strong demands for an X-ray photon source with high brilliance and flux. Thus, to let the TPS be under stable operation, the cryogenic system is therefore very important. The refrigerant of the TPS Cryogenic System is Liquid Helium, to maintain liquid helium in its state, the temperature has to be maintained under 4.5K, however to let liquid helium turn into gas helium, only 20 W is needed. Therefore, the Multi-Channel Line is developed in our system to prevent heat from conduction in and letting liquid helium vaporize. Several mechanical parts have been designed to reduce heat loss and meet its needs, for example the Spacer. The paper presents a design methodology of long multi-channel helium cryogenic transfer lines. It describes some aspects thermo-mechanical calculation, supporting structure and contraction protection.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB050
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TUPMB052	High Intensity Beam Test of Low Z Materials for the Upgrade of SPS-to-LHC Transfer Line Collimators and LHC Injection Absorbers	experiment, simulation, injection, proton	1218
	F.L. Maciariello, O. Aberle, M.E.J. Butcher, M. Calviani, R. Folch, V. Kain, K. Karagiannis, I. Lamas Garcia, A. Lechner, F.-X. Nuiry, G.E. Steele, J.A. Uythoven CERN, Geneva, Switzerland
	In the framework of the LHC Injector Upgrade (LIU) and High-Luminosity LHC (HL-LHC) project, the collimators in the SPS-to LHC transfer lines will undergo important modifications. The changes to these collimators will allow them to cope with beam brightness and intensity levels much increased with respect to their original design parameters: nominal and ultimate LHC. The necessity for replacement of the current materials will need to be confirmed by a test in the High Radiation to Materials (HRM) facility at CERN. This test will involve low Z materials (such as Graphite and 3-D Carbon/Carbon composite), and will recreate the worst case scenario those materials could see when directly impacted by High luminosity LHC (HL-LHC) or Batch Compression Merging and Splitting (BCMS) beams. Thermo-structural simulations used for the material studies and research, the experiment preparation phase, the experiment itself, pre irradiation analysis (including ultrasound and metrology tests on the target materials), the results and their correlation with numerical simulations will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB052
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TUPMW002	LHC Luminosity Modeling for RUNII	luminosity, emittance, scattering, proton	1403
	F. Antoniou, G. Arduini, M. Hostettler, M. Lamont, S. Papadopoulou, Y. Papaphilippou, G. Papotti, M. Pojer, B. Salvachua, M. Wyszynski CERN, Geneva, Switzerland
	Funding: Research supported by the High Luminosity LHC project After a long shut-down (LS1), LHC restarted its operation on April 2015 at a record energy of 6.5TeV, achieving soon a good luminosity performance. In this paper, a luminosity model based on the three main components of the LHC luminosity degradation (intrabeam scattering, synchrotron radiation and luminosity burn-off), is compared with data from runII. Based on the observations, other sources of luminosity degradation are discussed and the model is refined. Finally, based on the experience from runI and runII, the model is used for integrated luminosity projections for the HL-LHC beam parameters.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW002
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TUPMW005	Characterization of the Radiation Field in the FCC-hh Detector	detector, shielding, neutron, dipole	1414
	M.I. Besana, F. Cerutti, A. Ferrari, W. Riegler, V. Vlachoudis CERN, Geneva, Switzerland
	As part of the post-LHC high-energy program, a study is ongoing to design a new 100 km long hadron collider, which is expected to operate at a centre-of-mass energy of 100 TeV and to accumulate up to 30 ab−1, with a peak instantaneous luminosity that could reach 30 1034cm−2s−1. In this context, the evaluation of the radiation load on the detector is a key step for the choice of materials and technologies. In this contribution, a first detector concept will be presented. At the same time, fluence distributions, relevant for detector occupancy, and accumulated damage on materials and electronics will be shown. The effectiveness of a possible shielding configuration, intended to minimise the background in the muon chambers and tracking stations, will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW005
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TUPMW009	Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders	emittance, simulation, synchrotron, collider	1430
	X. Buffat, T. Pieloni, C. Tambasco CERN, Geneva, Switzerland J. Barranco, A. Florio EPFL, Lausanne, Switzerland
	The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW009
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TUPMW018	Radiation Load Optimization in the Final Focus System of FCC-hh	shielding, quadrupole, luminosity, optics	1462
	R. Martin, M.I. Besana, F. Cerutti, R. Tomás CERN, Geneva, Switzerland
	With a center-of-mass energy of up to 100 TeV, FCC-hh will produce highly energetic collision debris at the Interaction Point (IP). Protecting the final focus quadrupoles from this radiation is challenging, since the required amount of shielding placed inside the magnets will reduce the free aperture, thereby limiting the β^* reach and luminosity. Hence, radiation mitigation strategies that make best use of the available aperture are required. In this paper, we study the possibility to split the first quadrupole Q1 into two quadrupoles with individual apertures, in order to distribute the radiation load more evenly and reduce the peak dose.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW018
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TUPMW022	Modelling and Measurements of Bunch Profiles at the LHC Flat Bottom	emittance, lattice, scattering, damping	1477
	S. Papadopoulou, F. Antoniou, J.E. Muller, Y. Papaphilippou, G. Trad CERN, Geneva, Switzerland
	At the LHC flat bottom the interplay between a series of effects (i.e. intrabeam scattering, longitudinal beam manipulations, non-linearities of the machine, etc) can lead to a population of the tails of the beam distributions, which may become non-Gaussian. This paper presents observations of the evolution of particle distributions in the LHC flat bottom. Novel distribution functions are employed to represent the beam profiles, and used as a guideline for generalising emittance growth rate estimations due to IBS. Finally, an attempt is made to benchmark an IBS Monte-Carlo simulation code, able to track 3D particle distributions, with the measured beam profile evolutions.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW022
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TUPMY017	Laser Driven Dielectric Accelerator in the Non-relativistic Energy Region	laser, acceleration, electron, vacuum	1585
	K. Koyama, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan S. Kurimura NIMS, Ibaraki, Japan H. Okamoto, S. Otsuki The University of Tokyo, Tokyo, Japan M. Yoshida KEK, Ibaraki, Japan
	Laser-driven dielectric accelerator (LDA) is suitable for delivering a submicron-size ultra-short electron beam, which is useful for studying basic processes of the radiation effect in a biological cell. Both the oblique incidence and the normal incidence configurations of LDA were studied. The oblique incidence configuration of LDA relaxes the synchronization condition as v_e=¥pm c L_G/¥left(¥λ+ L_G n ¥sin ¥theta ¥right) and is somewhat suitable for accelerating the non-relativistic electrons. The required energy to accelerate electrons in the oblique incidence configuration is smaller than that in the normal incidence configuration by a factor of ¥cos ¥theta, where ¥theta is the incidence angle of the laser beam. Two gratings each were made of different material structure of silica ({¥rm SiO₂}) were fabricated by the electron beam lithography. When a crystal silica was adopted, many large humps of several hundred nm size were observed in grooves of the grating. On the other hand, a glass silica had smoother grooves.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY017
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TUPMY026	Electron Beam Generation and Injection From a Pyroelectric Crystal Array	acceleration, electron, laser, injection	1604
	R.B. Yoder, Z. Kabilova, B. Saeks Goucher College, Baltimore, Maryland, USA
	Novel acceleration structures (e.g. dielectric laser accelerators [DLAs]) powered by lasers have the potential to greatly reduce the footprint and cost of both industrial linacs and colliders. As these devices have dimensions comparable to optical wavelengths, they require injection of a sub-micron-scale electron bunch to generate high-quality output beams, which are well beyond the capability of conventional rf photocathodes. Photoexcitation and field emission from an array of nanotips, followed by further acceleration and focusing, is a promising approach to achieving the requisite small beam sizes for successful injection. Pyroelectric crystals can provide electrostatic fields of sufficient magnitude and uniformity to enable emission and acceleration. We present an initial design for a low-energy injection module using the accelerating electrostatic fields provided by pyroelectric crystals. The approach is modeled numerically and supported by direct benchtop measurements of pyroelectric fields from a 2-crystal array. R. J. England et al., Rev. Mod. Phys. 86, p. 1337 (2014).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY026
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TUPMY032	Radiation from Open Ended Waveguide with a Dielectric Loading	vacuum, electron, controls, simulation	1617
	S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin, V.V. Vorobev Saint-Petersburg State University, Saint-Petersburg, Russia S. Baturin LETI, Saint-Petersburg, Russia S. Baturin Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913). Terahertz radiation is considered as a promising tool for a number of applications. One possible way to emit THz waves is to pass short electron bunch through a waveguide structure loaded with dielectric. In our previous papers, we have analyzed this problem in both approximate* and rigorous*** formulation. However, we have encountered certain difficulties with calculations. In the present report, we are starting to develop another rigorous approach based on mode-matching technique and modified residue-calculus technique. We consider the radiation from the open-ended dielectrically loaded cylindrical waveguide placed inside regular cylindrical waveguide with larger radius. We present structure of reflected and transmitted modes and typical radiation patterns from the open end of larger radius waveguide. * S. Antipov et al., Appl. Phys. Lett., vol. 100, p. 132910, 2012. S.N. Galyamin et al., Opt. Express, vol. 22, No. 8, p. 8902, 2014. * S.N. Galyamin et al., in Proc. IPAC'15, pp. 2578-2580.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY032
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TUPMY033	Radiation of Charged Particle Flying into Chiral Isotropic Medium	polarization, vacuum, plasma, interface	1620
	S.N. Galyamin, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia A.A. Peshkov HIJ, Jena, Germany
	Funding: Work is supported by the Grant of the Russian Foundation for Basic Research (No. 15-32-20985). In recent years, the interest to radiation of moving charged particles in media with chiral properties is connected with relatively new and prospective method for diagnostics of biological objects which uses the Cherenkov radiation ' Cherenkov luminescence imaging. Optical activity (chirality, gyrotropy) is typical or biological matter and is caused by mirrorless structure of molecules. Contrary to such gyrotropic medium as magnetized ionospheric plasma, aforementioned media are isotropic. One distributed model describing the frequency dispersion of isotropic chiral media is Condon model. In this report, we continue the investigation performed in our previous paper* where we dealt with the field produced by uniformly moving charge in infinite chiral isotropic medium. Moreover, we perform generalization of early paper**, where the problem with half-space was considered in the specific case of slow charge motion. We present typical radiation patterns in vacuum area and corresponding ellipses of polarization which allows determination of the chiral parameter of the medium. Spinelli A.E. et al. // NIM A. 2011. V. 648. P. S310. Galyamin S.N. et al. // Phys. Rev. E. 2013. V. 88. P. 013206. * Engheta N., Mickelson A.R. // IEEE Trans. AP. 1982. V. 30. P. 1213.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY033
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TUPMY034	On Bunch Diagnostics with use of Surface Waves Generated on Planar Wire Grid	vacuum, electronics, diagnostics, electromagnetic-fields	1623
	V.V. Vorobev, S.N. Galyamin, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia
	Funding: Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913). Periodic structures can be used for non-destructive diagnostics of charged particle bunches. We consider structures which consist of thin conducting parallel wires. It is assumed that the structure period is much less than the typical wavelength under consideration. Therefore the influence of the structure on the electromagnetic field can be described with help of the averaged boundary conditions. We consider radiation of bunches which move along the grid but transversely to wires. Unlike previous works the bunch is assumed to have essential transversal dimensions along with definite longitudinal charge distribution. In particular we analyze the effect of reflection of the surface wave from the structure edge. For all considered situations, analytical and numerical results demonstrate that analysis of the surface waves allows estimating the size and the shape of the bunch. A.V. Tyukhtin et al., Phys. Rev. ST AB 17, 122802 (2014); A.V. Tyukhtin et al., Phys. Rev. E 91, 063202 (2015). ** M.I. Kontorovich et al., Electrodynamics of Grid Structures (Moscow, 1987).
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TUPMY035	Short-wavelength Radiation of a Small Charged Bunch in Presence of a Dielectric Prism	target, optics, polarization, vacuum	1626
	A.V. Tyukhtin, S.N. Galyamin Saint-Petersburg State University, Saint-Petersburg, Russia E.S. Belonogaya LETI, Saint-Petersburg, Russia
	Funding: Work is supported by the Grant from Russian Foundation for Basic Research (No. 15-02-03913). Investigation of radiation of a charged particle bunch in the presence of a large (compared with wavelengths under consideration) dielectric object can be performed using certain approximate methods. We develop here the method based on the known Stratton-Chu formulae which allows calculating the field everywhere outside the object including the Fresnel and Fraunhofer areas, as well as neighborhoods of focal points. The main problem considered here consists in investigation of radiation of a small bunch moving along boundary of a dielectric prism or in channel inside a prism. Approximate analytical solutions of the problem are obtained and typical numerical results are given. S.N. Galyamin and A.V. Tyukhtin, Phys. Rev. Lett. 113, 064802, 2014.
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TUPOR003	CSR-Driven Longitudinal Single Bunch Instability with Negative Momentum Compaction Factor	synchrotron, shielding, damping, electron	1651
	P. Kuske HZB, Berlin, Germany
	Acceptable agreement is found between experimental results obtained at the Metrology Light Source (MLS) operated with negative momentum compaction factor, α, and theoretical estimates of the CSR-driven threshold currents. Theoretical instability thresholds are estimated by numerically solving the Vlasov-Fokker-Planck equation and/or by multi particle tracking and taking into account the shielded CSR-interaction. Some of the issues with the calculations, the determination of the theoretical thresholds as well as the derivation of a general scaling law will be presented
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TUPOR006	Systematic Studies of Short Bunch-Length Bursting at ANKA	synchrotron, shielding, synchrotron-radiation, electron	1662
	M. Brosi, E. Blomley, E. Bründermann, N. Hiller, B. Kehrer, A.-S. Müller, M. Schedler, M. Schuh, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	Funding: Supported by the German Federal Ministry of Education and Research (05K13VKA), the Helmholtz Association (VH-NG-320) and by the Helmholtz International Research School for Teratronics (HIRST). At ANKA, the Karlsruhe synchrotron radiation source, the so called short bunch-length operation mode allows the reduction of the bunch length down to a few picoseconds. The micro-bunching instability resulting from the high degree of longitudinal compression leads to fluctuations in the emitted intensity in the THz regime, referred to as bursting. For extremely compressed bunches at ANKA bursting also occurs, in a certain current range, below the main bursting threshold. This contribution shows measurements of this short bunch-length bursting and makes first comparisons with theory.
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TUPOR012	THz Coherent Synchrotron Radiation from Ultra-low Alpha Operating Mode at Diamond Light Source	simulation, storage-ring, impedance, electron	1682
	T. Chanwattana, M. Atay, R. Bartolini JAI, Oxford, United Kingdom R. Bartolini, G. Cinque, M. Frogley, E. Koukovini-Platia, I.P.S. Martin DLS, Oxfordshire, United Kingdom
	Diamond Light Source is regularly operated in low-alpha mode to provide THz coherent synchrotron radiation (CSR) and short X-ray pulses for users. In order to maintain the wide frequency range of the coherent radiation whilst improving the signal to noise ratio, an ultra-low alpha mode has been considered to shorten the bunch length even further. In order to study this mode, the analysis of single bunch dynamics resulting from a variety of wakefield sources has been investigated using a single bunch multiparticle tracking code. These results are compared with measurements recorded using a Fourier transform infrared (FTIR) interferometer on the MIRIAM beam-line at Diamond.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR012
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TUPOR020	Combination of Density and Energy Modulation in Microbunching Analysis	electron, collective-effects, synchrotron-radiation, synchrotron	1703
	C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA R. Li JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Microbunching instability (MBI) has been one of the most challenging issues in the transport of high-brightness electron beams for modern recirculating or energy recovery linac machines. Recently we have developed and implemented a Vlasov solver* to calculate microbunching gain for an arbitrary beamline lattice design, based on the extension of early theoretical formulation for the microbunching amplification from an initial density perturbation to the final density modulation. For more thorough analyses, in addition to the case of (initial) density to (final) density amplification, we in this paper extend the previous formulation to more general cases, including energy-to-density, density-to-energy and energy-to-energy amplifications for a recirculation machine. Such semi-analytical formulae are then incorporated into our Vlasov solver, and reasonable agreement is obtained when the semi-analytical results are benchmarked with particle tracking simulation using ELEGANT. C.Y. Tsai et al, FEL'15 S. Heifets et al, PRSTAB 5, 064401 (2002), Z. Huang and K. Kim, PRSTAB 5, 074401 (2002), M. Vneturini, PRSTAB 10, 104401 (2007) * M. Borland, APS LS-287, 2000
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TUPOR031	Trapped Ion Effects and Mitigation During High Current Operation in the Cornell DC Photoinjector	ion, experiment, linac, vacuum	1735
	S.J. Full, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: U.S. Department of Energy (Grant No. DE-SC0012493), National Science Foundation (Award No. NSF-DMR 0807731) The Cornell high intensity photoinjector reaches a new regime of linac beam parameters where high continuous-wave electron beam currents lead to ion trapping. Above 10 mA, we have observed beam trips that limit stable machine operation to approximately 10^-15 minutes. By applying known ion clearing methods, the machine lifetime increases to at least 24 hours of continuous operation, suggesting that trapped ions are the most likely cause of the trips. In this paper we share some of our observations ion trapping in the photoinjector, as well as experimental tests of three common ion mitigation methods: clearing electrodes, beam shaking and bunch gaps.
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TUPOW008	Generation of Short Bunch Electron Beam from Compact Accelerator for Terahertz Radiation	laser, electron, injection, detector	1757
	S. Suphakul, T. Kii, K. Masuda, K. Morita, H. Ohgaki, K. Torgasin, H. Zen Kyoto University, Kyoto, Japan
	We are developing a new compact accelerator system to generate a high power terahertz (THz) radiation at the Institute of Advanced Energy, Kyoto University. THz radiations are produced by injecting ultra-short and intense electron pulses to a short plannar undulator. The bunch compression characteristic by the newly installed chicane was investigated by observation of a coherent part of an optical transition radiation (OTR). As the result, the chicane can compress the electron bunch at the laser injection phase from 10 to 40 degree. The beam energy and relative rms energy spread were also measured and the results were 4.6 MeV and 1.3 %, respectively.
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TUPOW009	Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University	undulator, electron, bunching, injection	1760
	S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW009
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TUPOW010	Production of Ultra-short Electron Pulse and Observation of Coherent Transition Radiation at t-ACTS, Tohoku University	electron, bunching, detector, injection	1763
	T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	A test-Accelerator as Coherent Terahertz Source (t-ACTS) project has been under development at Research Center for Electron Photon Science, Tohoku University. In order to generate a coherent radiation in terahertz (THz) region, it is necessary to produce sub-picosecond electron pulses. Velocity bunching scheme is employed for the short electron pulse production in t-ACTS. We experimentally confirmed the production of short electron pulse under 500 fs by measuring the bunch length using a streak camera. Coherent transition radiation in THz region was produced by which the short electron pulses pass through a vacuum-metal interface. Several radiation properties including　spatial distribution, polarization and spectrum were measured and compared with theoretical calculations. The details of the beam experiment at t-ACTS are described.
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TUPOW018	Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation	electron, experiment, space-charge, gun	1782
	Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China W. Gai ANL, Argonne, Illinois, USA
	High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.
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TUPOW026	Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory	undulator, electron, linac, emittance	1803
	N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai Chiang Mai University, Chiang Mai, Thailand
	Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand. Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution. The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.
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TUPOW038	Measurement and Control of Beam Losses Under High Average-current Operation of the Compact ERL at KEK	operation, beam-losses, recirculation, optics	1839
	S. Sakanaka, K. Haga, Y. Honda, H. Matsumura, T. Miyajima, T. Nogami, T. Obina, H. Sagehashi, M. Shimada, M. Yamamoto KEK, Ibaraki, Japan
	The compact ERL (cERL)* is a superconducting accelerator aimed at demonstrating excellent ERL technologies for the future light source. The cERL comprises a 5 MeV injector, a main linac, and a recirculation loop. In the cERL, production and transportation of low-emittance and high average-current beams (tentative goals: 1 mm-mrad and 10 mA) is primarily important. At this moment (in December 2015), beam currents of up to 80 uA (CW) have successfully been transported through the recirculation loop at a beam energy of 20 MeV. Before such high-current operations, we carefully tuned up the machine so that beam losses became very small. The beam losses were watched using fast beam-loss detectors and radiation monitors while absolute losses were estimated from measured radiation levels on the roof of the shield. After careful beam-optics corrections and elimination of beam halos / tails at low-energy section, we achieved the beam losses of at most a few nA level at several locations along the loop, and those below 1 nA elsewhere in the loop. We will report these results together with the result of higher-current operation which is planned early in 2016. * S. Sakanaka et al., IPAC'15, TUBC1; T. Obina et al., to be presented at IPAC'16.
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TUPOW040	UH-FLUX: Compact, Energy Efficient Superconducting Asymmetric Energy Recovery LINAC for Ultra-high Fluxes of X-ray and THz Radiation	cavity, HOM, electron, coupling	1847
	I.V. Konoplev, A. Seryi JAI, Oxford, United Kingdom R. Ainsworth Fermilab, Batavia, Illinois, USA G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Funding: This work was supported (in part) by The Leverhulme Trust through the International Network Grant IN-2015-012. The conventional ERLs have limited peak beam current because increasing the beam charge and repetition rate leads to appearance of the beam break-up instabilities. At this stage the highest current, from the SRF ERL, is around 300 mA. A single turn (the beam will be transported through the accelerating section, interaction point and deceleration section of the AERL only once) Asymmetric Energy Recovery LINAC (AERL) is proposed. The RF cells in different sections of the cavity are tuned in such a way that only operating mode is uniform inside all of the cells. The AERL will drive the electron beams with typical energies of 10 - 30 MeV and peak currents above 1 A, enabling the generation of high flux UV/X-rays and high power coherent THz radiation. We aim to build a copper prototype of the RF cavity for a compact AERL to study its EM properties. The final goal is to build AERL based on the superconducting RF cavity. Preliminary design for AERL's cavity has been developed and will be presented. The results of numerical and analytical models and the next steps toward the AERL operation will also be discussed.
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TUPOW044	Experimental Investigation of THz Smith-Purcell Radiation From Composite Corrugated Capillary	simulation, detector, electron, vacuum	1861
	K. Lekomtsev, A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan A. Ponomarenko, A.A. Tishchenko MEPhI, Moscow, Russia
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Terahertz part of electromagnetic spectrum has a variety of potential applications ranging from fundamental to security applications. Further advances in development of a linac based, tunable, and narrow band coherent source of THz radiation are very important. Mechanisms of Cherenkov radiation and Smith-Purcell radiation (SPR) [] may be used for generation of THz radiation via coherent emission [, ]. In this report we will present experimental investigations of the SPR generated from the corrugated capillary with a reflector, using the femtosecond multi-bunch electron beam of LUCX accelerator at KEK, Japan [*]. LUCX is capable to generate a train of 4 bunches each with 200 femtosecond (60 micrometer) duration and 200 micrometer transverse size. We will discuss the composite design of the capillary, measurements of the SPR angular distributions and the comparison of these measurements with PIC simulations. In addition, we will discuss SPR spectral characteristics; bunch energy modulation, introduced by the corrugated capillary; and the way in which the bunch spacing changes the spectrum and angular distributions of SPR. K.Lekomtsev et al., NIMB 355 (2015) 164 A. M. Cook et al., PRL 103, (2009) 095003. S. E. Korbly et al., PRL 94, (2005) 054803. ***A. Aryshev, arXiv:1507.03302 [physics.acc-ph]
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TUPOW045	Pre-bunched Electron Beam Emittance Simulation and Measurement	electron, simulation, emittance, gun	1864
	Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.

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MOPMB002

First Measurements of Coherent Smith-Purcell Radiation in the SOLEIL Linac

detector, linac, experiment, operation

69

N. Delerue, J. Barros, S. Jenzer, V. Khodnevych, M.S. Malovytsia
LAL, Orsay, France
N. Hubert, M. Labat
SOLEIL, Gif-sur-Yvette, France
V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
M.S. Malovytsia
KhNU, Kharkov, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01).
An experiment to measure the Coherent Smith-Purcell radiation has been installed in the SOLEIL Linac. Its aim is to produce a map of Smith-Purcell radiation emissions in several planes and compare it with theoretical predictions. Coherent Smith Purcell radiation is produced when a grating is brought close from a sufficiently short charged particles beam. The experiment consist of two detectors with 5 degrees of freedom. These two detectors can be moved around the emission point to measure the intensity of the radiation at different locations. Radiation maps are recorded parasitically by moving the detectors around during normal linac operations.

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MOPMB003

Comparison of Coherent Smith-Purcell Radiation and Coherent Transition Radiation

electron, laser, free-electron-laser, simulation

72

V. Khodnevych, N. Delerue
LAL, Orsay, France
O.A. Bezshyyko, V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) between France and Ukraine.
Smith-Purcell radiation and Transition Radiation are two radiative phenomenon that occur in charged particles accelerators. For both the emission can be significantly enhanced with sufficiently short pulses and both can be used to measure the form factor of the pulse. We compare the yield of these phenomenon in different configurations and look at their application as bunch length monitors, including background filtering and rejection. We apply these calculations to the specific case of the CLIO Free Electron laser.

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MOPMB004

Comparison of the Smith-purcell Radiation Yield for Different Models

electron, simulation, experiment, detector

75

M.S. Malovytsia, N. Delerue
LAL, Orsay, France
M.S. Malovytsia
KhNU, Kharkov, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) France-Ukraine.
Smith-Purcell radiation is used in several applications including the measurement of the longitudinal profile of electron bunches. A correct reconstruction of such profile requires a good understanding of the underlying model. We have compared the leading models of Smith-Purcell radiation and shown that they are in agreement within the experimental errors.

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MOPMB005

Study of Short Bunches at the Free Electron Laser CLIO

cavity, electron, gun, simulation

78

V. Khodnevych, N. Delerue, S. Jenzer
LAL, Orsay, France
J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres
CLIO/ELISE/LCP, Orsay, France
V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01).
CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).

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MOPMB013

Time-resolved Spectral Observation of Coherent THz Pulses at DELTA

laser, electron, detector, simulation

105

C. Mai, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M. Höner, M.A. Jebramcik, S. Khan, N.M. Lockmann, A. Meyer auf der Heide, R. Molo, R. Niemczyk, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF (05K13PEC), the DFG (INST 212/236-1) and the state of NRW.
Coherent THz pulses induced by a laser-electron interac- tion are routinely produced and observed at DELTA, a 1.5- GeV synchrotron light source operated by the TU Dortmund University. At a dedicated THz beamline, measurements using a Fourier-transform spectrometer have been performed between 1 THz and 7 THz. Recently, an ultrafast Schottky- diode detector and a novel polarizing Fourier-transform spec- trometer were installed, which enable turn-by-turn-resolved spectral measurements in the frequency range below 1 THz. The commissioning results of the new spectrometer and simulations are presented.

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MOPMB014

Simultaneous Detection of Longitudinal and Transverse Bunch Signals at ANKA

synchrotron, detector, synchrotron-radiation, timing

109

B. Kehrer, E. Blomley, M. Brosi, E. Bründermann, N. Hiller, A.-S. Müller, M.J. Nasse, M. Schedler, M. Schuh, P. Schönfeldt, P. Schütze, N.J. Smale, J.L. Steinmann
KIT, Karlsruhe, Germany

Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the BMBF under contract number 05K13VKA.
The ANKA storage ring offers different operation modes including the short-bunch mode with bunch lengths tuned down to a few picoseconds. This can lead to the occurrence of micro-bunching instabilities coupled to the emission of coherent synchrotron radiation (CSR) in so-called 'bursts'. To study this CSR instability we use several turn-by-turn enabled detector systems to synchronously measure both the THz signal as well as bunch profiles. The different detectors are placed at different locations around the storage ring. Here we discuss the experimental setup and calibration of the various systems' synchronisation.

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MOPMB016

Single-Shot Spectral Analysis of Synchrotron Radiation in THz Regime at ANKA

detector, synchrotron, synchrotron-radiation, bunching

115

A. Schmid, M. Brosi, E. Bründermann, K.S. Ilin, B. Kehrer, K. Kuzmin, A.-S. Müller, J. Raasch, M. Schuh, P. Schönfeldt, M. Siegel, J.L. Steinmann, S. Wuensch
KIT, Karlsruhe, Germany
S.A. Kuznetsov
NSU, Novosibirsk, Russia

Funding: This work was supported by BMBF contract number 05K13VK4 and the Ministry of Education and Sci- ence of the Russian Federation (State Assignment Contract No. 3002).
Micro-bunching instabilities limit the longitudinal compression of bunches in an electron storage ring. They create substructures on the bunch profile of some hundred micrometer size leading to coherently emitted synchrotron radiation in the THz range. To detect the changing THz spectrum, single-shot bunch-by-bunch and turn-by-turn measurements are necessary. We present recent experiments at ANKA where the spectral information is extracted by simultaneous detection with several narrowband THz detectors, each of them sensitive in a different frequency range.

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MOPMB017

Design Issues for the Optical Transition Radiation Screens for theELI-NP Compton Gamma Source

electron, simulation, linac, laser

118

M. Marongiu, A. Giribono, A. Mostacci, V. Pettinacci
INFN-Roma, Roma, Italy
D. Alesini, E. Chiadroni, F. Cioeta, G. Di Pirro, V.L. Lollo, L. Pellegrino, V. Shpakov, A. Stella, C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
L. Palumbo
University of Rome La Sapienza, Rome, Italy

A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation profile monitors. In order to measure the beam properties along the train, the screens must sustain the thermal stress due to the energy deposited by the bunches; moreover the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the analytical studies as well as numerical simulations to investigate the thermal behaviour of the screens impinged by the nominal bunch; the design and the performance of the optical detection line is discussed as well.

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MOPMB020

Transverse Intensity Distribution Measurement of Ion Beams Using Gafchromic Films

ion, cyclotron, octupole, tandem-accelerator

130

Y. Yuri, T. Agematsu, T. Ishizaka, K. Narumi, S. Okumura, H. Seito, T. Yuyama
JAEA/TARRI, Gunma-ken, Japan

A possible method of measuring the transverse spatial distribution of energetic ion beams is developed at Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology (formerly, Japan Atomic Energy Agency). For this purpose, a radiochromic film, Gafchromic film (Ashland Inc.), is employed since it enables us to easily measure a large-area irradiation field distribution at a high spatial resolution. Gafchromic EBT3 and HD-V2 films are irradiated with ion beams of various species and kinetic energies extracted from a cyclotron and electrostatic accelerators at QST/Takasaki. Then, the coloration response of the films is analyzed in terms of the optical density. It is demonstrated that EBT3 and HD-V2 films are useful for the beam profile measurement at low fluence and at low energy, respectively.

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MOPMB026

Frequency and Time Domain Measurement of Coherent Transition Radiation

electron, laser, vacuum, polarization

143

K. Kan, M. Gohdo, T. Kondoh, I. Nozawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron beams are essential for light sources and time-resolved measurements. Electron beams can emit terahertz (THz) pulses using coherent transition radiation (CTR). Michelson interferometer is one of can-didates for analyzing the pulse width of an electron beam based on frequency-domain analysis. Recently, electron beam measurement using a photoconductive antenna (PCA) based on time-domain analysis has been investi-gated. In this paper, to improve beam diagnostics of ul-trashort electron beam, investigation of characteristics of a PCA for generation and frequency and time-domain measurement of THz pulses was conducted.
* I. Nozawa et al., Phys. Rev. ST Accel. Beams 17, 072803 (2014).
** K. Kan et al., Appl. Phys. Lett. 102, 221118 (2013).

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MOPMB028

Development of Beam Diagnostic System for the SPring-8 Upgrade

diagnostics, beam-diagnostic, photon, emittance

149

H. Maesaka, T. Ohshima, Y. Otake
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Dewa, T. Fujita, K. Kobayashi, M. Masaki, S. Matsubara, T. Nakamura, S. Sasaki, S. Takano
JASRI/SPring-8, Hyogo-ken, Japan

The goal of the beam diagnostic system for the SPring-8 upgrade is to deliver brilliant X-rays enabled by the new low-emittance ring to experimental stations with ultimate stability. Developments of accurate electron and photon beam position monitors (EBPM and XBPM, respectively) with both short and long-term stability are the most critical. The EBPM sensitivity is also crucial for low-current beam commissioning to accomplish the first beam storage in the ring. We designed a button electrode to obtain sufficiently high-intensity signals while suppressing high-Q trapped modes leading to impedance and heating issues. We also designed a precise EBPM block and a rigid support to achieve mechanical accuracy and stability. Another challenge is the development of a reliable and stable XBPM, which should be an accurate reference for an orbit feedback without any photon-energy dependences. A significant improvement of a blade-type XBPM or an invention of a novel XBPM detecting the core of an intense X-ray beam are necessary. The other diagnostic instrumentations can be utilized for the new ring with minor improvements.

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MOPMB030

Development of an EO Sampling Method for THz Pulse Detection

laser, polarization, electron, experiment

155

T. Toida, M. Washio, R. Yanagisawa
Waseda University, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

We have been studying an S-band Cs-Te photo-cathode rf gun at Waseda Univ. The high quality electron beam produced by the rf gun is used to generate a high-power coherent terahertz pulse via Cherenkov radiation. This terahertz pulse can be applied to terahertz imaging and material analysis. As a preliminary step towards material analysis, we conducted experiments on terahertz time domain spectroscopy by EO sampling method to reveal major parameters of the terahertz pulse such as the pulse form and the spectrum. EO sampling method has high frequency response and suitable for high peak power terahertz pulses. In terahertz time domain spectroscopy, the duration of the probe pulse needs to be much faster than that of the terahertz pulse. Therefore, we developed a mode locked Yb-fiber laser based on nonlinear polarization rotation as a reliable and cost-effective ultra-fast probe light source. The laser generates 3.80 ps chirped pulses which are compressed to 213 fs with a grating pair. In this conference, we will report the performance of the Yb-fiber laser and results of EO sampling experiments.

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MOPMB036

Beam Profile Measurement Using Kirkpatrick Baez Mirror Optics at Shanghai Synchrotron Radiation Facility

synchrotron, synchrotron-radiation, optics, diagnostics

167

D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue
IHEP, Beijing, People's Republic of China
J. Chen
SINAP, Shanghai, People's Republic of China

For the third-generation light sources, the vertical emit-tance of a few pico-meter-radians which can be achieved with good coupling correction close to 0.1%, will lead to very small beam size. Several microns vertical beam sizes measurement has presented challenges for diagnostic capability in this region. A few techniques have been developed to make a precise measurement, such as visible light interferometer, x-ray imaging using Fresnel zone plates, compound refractive lenses or pinhole camera. In this paper, an x-ray reflective optics method based on the Kirkpatrick'Baez mirrors will be emphasis on discussed. The K-B mirror system will be installed and tested in SSRF to obtain the vertical beam size close to 20 microns, which is expected to be used for several microns vertical beam size measurement in the future light source named HEPS (High Energy Photon Source) in China.

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MOPMB039

Design of Bunch Length Measurement System at the IRFEL Using a Martin-Puplett Interferometer

electron, detector, polarization, vacuum

178

T.Y. Zhou, X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, F.F. Wu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (11575181, 11175173)
Electron bunch length measurement is of great significance for optimizing IRFEL performance. An optical autocorrelation system using coherent transition radiation (CTR) would be set up to measure the electron bunch length at the IRFEL. CTR can be occurred when short electron bunches traverse a vacuum-metal interface. A Martin-Puplett interferometer allowed measurement of the autocorrelation of the CTR signal. The basic principle and the main components of Martin-Puplett interferometer are elaborated in this paper.

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MOPMR003

Electron Bunch Length Measurement Using Coherent Radiation Source of fs-THz accelerator at Pohang Accelerator Laboratory

electron, linac, experiment, target

235

J.H. Ko, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Jung, H.-S. Kang, I.S. Ko, J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition radiation (CTR) from a 65-MeV electron beam of the fs-THz accelerator. In this paper, we show the how to make a longitudinal distribution of electron bunch and the radiation intensity difference between CTR and Coherent edge radiation (CER) for nondestructive electron bunch length measurement. And we report the measurement methods to get the fine electron bunch length information.

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MOPMR013

Development, Calibration and Application of New-generation Dissectors with Picosecond Temporal Resolution

electron, laser, operation, positron

251

O.I. Meshkov, O. Anchugov, V.L. Dorohov, G.Y. Kurkin, A.V. Petrozhitskii, D.A. Shvedov, E.I. Zinin
BINP SB RAS, Novosibirsk, Russia
P.B. Gornostaev, M.Ya. Schelev, E.V. Shashkov, A. V. Smirnov, A.I. Zarovskii
GPI, Moscow, Russia

Funding: The presented experimental results were implemented due to financial support of the Russian Science Foundation (Projects N 14-29-00295)
A dissector is an electron-optical device designed for measurement of periodic light pulses of subnanosecond and picosecond duration. LI-602 dissector developed at BINP is widely used for routine measurements of a longitudinal profile of electron and positron beams at BINP electron-positron colliders and other similar installations]. This dissector is a part of many optical diagnostic systems and provides temporal resolution of about 20 ps. Recently* a new generation of picosecond dissectors were created on the basis of the PIF-01/S1 picosecond streak-image tube designed and manufactured at the General Physics Institute Photoelectronics Department (Moscow). The device has demonstrated a temporal resolution of 3-4 ps (FWHM). The procedure of temporal resolution calibration and results of application of the new-generation picosecond dissector are given in this work.
*E.I. Zinin, O.I. Meshkov. JINST, 2015 1748-0221 10 P10024 doi:10.1088/1748-0221/10/10/P10024

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MOPMR015

Optical Fibers as a Tool for Gamma Beam Diagnostics at Medical Electron Accelerators

betatron, target, detector, electron

258

A.I. Novokshonov, V.I. Bespalov, A. Potylitsyn, D.A. Shkitov, S.R. Uglov, A.V. Vukolov
TPU, Tomsk, Russia

Funding: This work was partially supported by the Russian Ministry of Education and Science within the program "Nauka" Grant № 3.709.2014/K.
The existing techniques for gamma beam diagnostics at medical accelerators based on X-ray films have several disadvantages such as insufficient spatial resolution, difficult realization and off-line mode. In the works*,** a feasibility of Cherenkov radiation (CR) in glass fibers for charged particle beam diagnostics was demonstrated. An application of glass fibers scanning for gamma beam diagnostics may have a lot advantages including a possibility of on-line measurements. For this goal we used optical fiber with 0.6 mm diameter and length up to 10 m. An efficiency of CR generation in such fibers and signal attenuation in a long fiber were investigated using the Tomsk microtron electron beam. The shape of gamma beam field produced by the medical SL-75-5MT 6 MeV electron accelerator was measured using the proposed technique. It is shown there it is possible to measure not only gamma beam spatial distribution, but also its angular distribution.
* Wulf, F. and Korfer, M. 2009 Proc. DIPAC2009 411.
** Murokh, A., Agustsson, R., Boucher, S., Frigola, P., Hodgetts, T., Ovodenko, A., Ruelas, M. and Tikhoplav, R. 2012 Proc. IPAC2012 996.

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MOPMR016

A New Approach for the Electron Beam Diagnostic Using Diffraction Radiation Disphase Target

target, detector, simulation, diagnostics

261

D.A. Shkitov, G.A. Naumenko, A. Potylitsyn
TPU, Tomsk, Russia
J. Urakawa
KEK, Ibaraki, Japan

Funding: The work was partially supported by the RFBR grant No 15-52-50028.
Since 1995, when the diffraction radiation (DR) from relativistic particles was first observed*, the development of new approaches using the DR for charged particle beam diagnostics is continued. The DR appears when charged particle moves close to the media and the electromagnetic field interacts with it. A rather well-known non-invasive diagnostic method of transversal bunch size is to use a slit target**. In paper*** the optical DR from disphase target was proposed to use for non-invasive diagnostics of high energy electron beam. Disphase target consists of the two rectangular flat plates inclined with respect to each other at an angle compared with 1/g, where g is the Lorentz-factor. Recently the feasibility of the disphase target usage for the 6 MeV electron beam size diagnostics was investigated****. In this report we present the further research of the disphase target beam diagnostics. The simulations of the spectral-angular DR characteristics from this target and it application for diagnostics aim are shown. These calculations confirm an applicability of this technique for micron size beam measurements for the case of g>1000.
*Y. Shibata et al. //PRE 52, 6787 (1995)
**P. Karataev et al. //PRL 93, 244802 (2004)
***G. Naumenko et al. //Proc. of PAC TOAD004, 404 (2005)
****E.V. Kornoukhova et al. //JPCS, in press (2016)

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MOPMR021

Lifetime and Operational Criteria of Proton Beam Instrumentation in the ESS Target Station

electron, proton, target, monitoring

276

Y. Lee, T.J. Shea, C.A. Thomas
ESS, Lund, Sweden

At the European Spallation Source, a 2 GeV, 5 MW proton beam will be delivered from a superconducting linear accelerator to target at a 4% duty factor, which poses demanding requirements on target station design. To tune the beam delivery system and to protect the target station components, the current density, the halo distribution, and the position of the proton beam shall be measured. To provide this functionality, a suite of beam monitoring devices will be deployed in the target monolith, including a multi-wire grid for the beam profile monitoring, thermo-couple assemblies and secondary emission blades for aperture monitoring, and a beam footprint imaging system consisting of optical components and luminescent coatings. Since these devices are exposed to particles that deposit energy and cause a high rate of radiation damage, it is a significant challenge to ensure full functionality. In this paper, material selection, lifetime estimates and operational criteria for these beam-monitoring devices are presented. A number of particle transport and finite-element simulations are performed for analyses, and an empirical validation plan is presented.

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MOPMR030

Performance of the Upgraded Synchrotron Radiation Diagnostics at the LHC

extraction, synchrotron, synchrotron-radiation, diagnostics

306

G. Trad, E. Bravin, A. Goldblatt, S. Mazzoni, F. Roncarolo
CERN, Geneva, Switzerland
T.M. Mitsuhashi
KEK, Ibaraki, Japan

During the LHC long shut down in 2014, the transverse beam size diagnostics based on synchrotron radiation was upgraded in order to cope with the increase of the LHC beam energy to 6.5 TeV. The wavelength used for imaging was shifted to near ultra-violet to reduce the contribution of diffraction to the system resolution, while in parallel, a new diagnostic system based on double slit interferometry was installed to measure the beam size by studying the spatial coherence of the emitted synchrotron radiation. This method has never been implemented before in a proton machine. A Hartmann mask was also installed to identify possible wavefront distortions that could affect the system accuracy. This paper will focus on the comparison of visible and the near ultra-violet imaging and on the first experience with interferometry.

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MOPMR032

Measurement of Beam Size with a SR Interferometer in TPS

synchrotron, synchrotron-radiation, shielding, monitoring

313

M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, W.Y. Lai, C.J. Lin, S.Y. Perng, C.W. Tsai, T.C. Tseng, H.S. Wang
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) has operated since 2015. An optical diagnostic beamline is constructed in section 40 of TPS for the diagnosis of the properties of the electron beam. One instrument at this beamline is a synchrotron radiation interferometer (SRI), which is operated to monitor the beam size. In this paper, we present the beamline structure and recent results of measurement with the SR interferometer.

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MOPMR034

Precise Betastron Tune Measurement in TPS Storage Ring

betatron, storage-ring, simulation, synchrotron-radiation

319

C.H. Chen, C.H. Chang, J.Y. Chen, M.-S. Chiu, S. Fann, C.H. Huang, T.Y. Lee, C.C. Liang, Y.-C. Liu, F.H. Tseng
NSRRC, Hsinchu, Taiwan

To acquire precise beam orbits from beam position monitors (BPMs) in storage ring is one of the most significant diagnosis to measure beam parameters. However, the precise spectrum analyses from BPM data acquisitions such as betatron tune, dynamics aperture and frequency map '..etc. that are depended on more accurate discrete Fourier transform (DFT) or the fast Fourier transform (FFT). A method of the fast Fourier transform correction (FFTc) was employed for the more accurate spectrum measurement in Taiwan Photon Source (TPS). We perform the accuracy and error analyses of this method from some spectral lines in two window functions. And the precise spectrum for betatron tune measurements and related results will be presented.

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MOPMR036

Using a Single Shot Spectrometer to Determine the Spectral Characteristics of the Beam as a Result of Micro-bunching Instabilities

detector, synchrotron, synchrotron-radiation, storage-ring

327

A. Finn, P. Karataev
JAI, Egham, Surrey, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
G. Rehm
DLS, Oxfordshire, United Kingdom

A single shot spectrometer has been designed and is in operation at the Diamond Light Source (DLS). It is an array of eight Schottky barrier diodes (SBDs) each with a distinct frequency band covering 33-1000 GHz. The aim of the spectrometer is to observe the bursts of coherent synchrotron radiation (CSR) as a result of micro-bunching instabilities (MBI) and stable low alpha modes, where alpha is the momentum compaction factor. In this case, the bursts of CSR occur with wavelengths in the mm regime. SBDs are often implemented as detectors in the millimetre wavelength range and benefit from low noise, excellent sensitivity and ultra-fast responses. The eight SBDs have been individually characterised thus making the results obtained comparable to simulations. Here we present, an analysis of the data obtained via the spectrometer in particular, the bursting nature and spectral characteristics of a sample of beam modes at DLS. Furthermore, the results obtained can be used to confirm simulations.

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MOPMR039

Review of Emittance Diagnostics for Space Charge Dominated Beams for AWAKE e^- Injector

emittance, space-charge, quadrupole, focusing

337

O. Mete Apsimon, G.X. Xia
UMAN, Manchester, United Kingdom
S. Döbert
CERN, Geneva, Switzerland
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This work is supported by the Cockcroft Institute Core Grant and STFC.
For a low energy, high intensity beam, total beam emittance is dominated by defocusing space charge force. This is most commonly observed in photo-injectors. In this low energy regime, emittance measurement techniques such as quadrupole scans fail as they consider the beam size only depends on optical functions. The pepper-pot method is used for 2D emittance measurements in a single shot manner. In order to measure the beam emittance in space charge dominated regime by quadrupole scans, space charge term should be carefully incorporated into the transfer matrices. On the other hand, methods such as divergence interferometry via optical transition radiation (OTRI), phase space tomography using 1D projections of quadrupole scans can be suitably applied for such conditions. In this paper, the design of a versatile pepper-pot system for AWAKE experiment at CERN is presented for a wide range of bunch charges from 0.1 to 1nC where the space charge force increases significantly. In addition, other aforementioned methods and respective algorithms are introduced as alternative methods.

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MOPMR040

First Steps Towards a Single-Shot Longitudinal Profile Monitor: Study of the Properties of Coherent Smith-Purcell Radiation Using the Surface Current Model

detector, polarization, background, simulation

340

H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster
JAI, Oxford, United Kingdom
A. Aryshev, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: UK STFC, Leverhulme Trust, Photon and Quantum Basic Research Coordinated Development Program (Ministry of Education, Culture, Sports, Science and Technology, Japan)and JSPS KAKENHI.
We propose to use the polarization of coherent Smith-Purcell radiation (cSPr) to separate the signal from background radiation in a single-shot longitudinal bunch profile monitor. We compare simulation and experimental results for the degree of polarization of cSPr generated by a grating with a 1mm periodic structure at the LUCX facility, KEK (Japan). Both experiment and simulation show that the majority of the cSPr signal is polarized in the direction parallel to the grating grooves. The degree of polarization predicted by simulation is higher than the measured result, therefore further investigation is needed to resolve this discrepancy.

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MOPMR041

Experimental and Theoretical Studies of the Properties of Coherent Smith-Purcell Radiation

polarization, background, electron, experiment

344

F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, A. Reichold
JAI, Oxford, United Kingdom
J. Barros, N. Delerue
LAL, Orsay, France
R. Bartolini
DLS, Oxfordshire, United Kingdom
C.I. Clarke
SLAC, Menlo Park, California, USA

Funding: This work was supported (in parts) by the UK Science and Technology Facilities Council (STFC UK) through grant ST/M003590/1 and The Leverhulme Trust through the International Network Grant IN-2015-012
Previous studies have demonstrated that coherent Smith-Purcell radiation (cSPr) can be used for relativistic electron bunch time profile reconstruction at pico-second and femtosecond scales. The E203 experiments undertaken in May 2015 at FACET (SLAC) were dedicated to the study of some properties of cSPr, namely the azimuthal distribution and the polarization of the radiation. The experimental set up description which allowed such studies will be presented along with the results. To understand the experimental data both semi-analytical and numerical models were studied. The semi-analytical approach was based on the surface-current model, and the 3D particle-in-cell code VSim was used for numerical modeling. The experimental and theoretical studies are compared.

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MOPMR043

Optical System Design for The ESS Proton Beam and Target Diagnostics

target, optics, proton, diagnostics

347

M.G. Ibison, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
E. Adli, H. Gjersdal
University of Oslo, Oslo, Norway
M.G. Ibison, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
T.J. Shea, C.A. Thomas, N. de la Cour
ESS, Lund, Sweden

Funding: Science and Technology Facilities Council
The high power and low emittance of the European Spallation Source (ESS) proton beam require a robust protection strategy for the spallation target and its surroundings. For this, the beam will be imaged on passing through scintillator screens coating both the proton beam window (PBW) on exit from the accelerator, and the entry window to the target (TW). Light from the screens must be transported to remote cameras through a 4m high shielding plug of limited aperture. At the same time, the optical path must not compromise the integrity of the shield against neutrons and interaction products. We present the theory underlying the design of the reflective optics for efficient transmission of high-quality images to provide the desired level of protection to the machine, and describe its implementation in the Zemax software tool, as well as the predicted imaging performance. We also consider how the requirements of environment (thermal and radiation), initial alignment and ongoing maintenance for the optical system will be met. Finally we comment on the applicability of optics of this type for diagnostic systems in similar situations at other neutron sources and elsewhere.

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MOPMR054

Double-slit Interferometer Measurements at SPEAR3

electron, synchrotron, synchrotron-radiation, optics

368

C.L. Li, W.J. Zhang
East China University of Science and Technology, Shanghai, People's Republic of China
M.J. Boland
SLSA, Clayton, Australia
W.J. Corbett, M. Grinberg
SLAC, Menlo Park, California, USA
T.M. Mitsuhashi
KEK, Ibaraki, Japan
Y.H. Xu
DongHua University, Songjiang, People's Republic of China
W.J. Zhang
University of Saskatchewan, Saskatoon, Canada

The resolution of a conventional telescope used to image visible-light synchrotron radiation is often limited by diffraction effects. To improve resolution, the double-slit interferometer method was developed at KEK and has since become popular around the world. Based on the Van Cittert-Zernike theorem relating transverse source profile to transverse spatial coherence, the particle beam size can be inferred by recording fringe contrast as a function of interferometer slit separation. In this paper, we describe the SPEAR3 double-slit interferometer, develop a theoretical framework for the interferometer and provide experimental results. Of note the double-slit system is 'rotated' about the beam axis to map the dependence of photon beam coherence on angle.

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MOPMR055

Radiation-Resistant Fiber Optic Strain Sensors for SNS Target Instrumentation

target, neutron, proton, detector

371

Y. Liu, W. Blokland, J.D. Bryan, A. Rakhman, B.W. Riemer, R.L. Sangrey, M. Wendel, D.E. Winder
ORNL, Oak Ridge, Tennessee, USA
A. Rakhman
UTK, Knoxville, Tennessee, USA
R. Strum
San Diego State University, San Diego, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Measurement of stresses and strains in the mercury target vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. Owing to their compactness, easy system integration, and invulnerability to the electromagnetic interference, fiber optic strain sensors have been installed into the SNS target module starting from the fall of 2015. In this talk, we report on the development of radiation-resistant fiber optic strain sensors for subsequent generations of SNS target instrumentation. The sensors are extrinsic Fabry-Perot interferometers (EFPIs) made from fluorine-doped single-mode fibers. The radiation induced loss of the fiber has been measured in the SNS target 13 at the energy-on-target level exceeding 500 MWhr which results in peak doses on fiber of more than 10⁹ Gy. A superluminescent diode laser at 1300 nm is used as the light source and the strain is measured in real-time using quadrature phase shifted signals generated from a local interferometer. We have demonstrated successful measurements of strains from 1 to 1000 με at a kHz frequency range on a test plate using the developed interrogation optical system.

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MOPMR056

Single-shot THz Spectrometer for Measurement of RF Breakdown in mm-wave Accelerators

detector, vacuum, alignment, laser

374

S.V. Kutsaev, A.Y. Murokh, M. Ruelas, E.A. Savin, H.L. To
RadiaBeam Systems, Santa Monica, California, USA
M. Dal Forno, V.A. Dolgashev
SLAC, Menlo Park, California, USA
V. Goncharik
Logicware Inc, New York, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under contract DE-SC0013684
We present a new instrument designed to detect RF pulse shortening caused by vacuum RF breakdown in mm-wave particle accelerators. RF breakdown limits the performance of high gradient RF accelerators. To understand the properties of these breakdowns, it is necessary to have diagnostics that reliably detect RF breakdowns. In X-band or S-band accelerators, RF breakdowns are detected by measuring RF pulse shortening, vacuum burst, or, if current monitors are available, spikes in the field-emitted currents. In mm-wave accelerators, all of these methods are difficult to use. In our experiments, we could not measure RF pulse shortening directly with a crystal detector because the RF pulse is very short'just a few nanoseconds'and changes in the measured signal were masked by RF amplitude jitter. To overcome this limitation, we built a single-shot spectrometer with a frequency range of 117-125 GHz and a resolution of 0.1 GHz. The spectrometer should be able to measure the widening of the spectrum caused by the shortening of nanosecond-long pulses. We present design considerations, first experimental results obtained at FACET, and planned future improvements for the spectrometer.

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MOPMR059

Development of S-band High Power Load

vacuum, klystron, radio-frequency, electron

383

X.C. Meng, H.B. Chen, C. Cheng, Y.-C. Du, Q. Gao, J. Shi, P. Wang, Z.F. Xiong
TUB, Beijing, People's Republic of China

Several types of S-band high power loads have been designed, manufactured and tested successfully in Tsinghua University. The high power loads, which work at 2856 MHz for 10 MW~100 MW range, are made of all stainless steel. In this paper, we will present the design, fabrication and the high power test results.

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MOPMW010

Property Test of the Q-Factor for High Purity Copper at the Temperature of 20K

cavity, electron, linac, cryogenics

417

A. Iino
Sokendai, Ibaraki, Japan
K. Endo
TOYAMA Co., Ltd., Zama-shi, Kanagawa, Japan
S. Yamaguchi
KEK, Ibaraki, Japan

A coherent parametric x-ray radiation (PXR) source based on a cryogenic electron linac has been developed by Toyama Co., Ltd, KEK and Nihon University. This accelerator is a C-band normal-conducting compact linac that requires a high Q factor in the accelerating and de-celerating structures. To obtain a high Q factor, the ac-celerating and decelerating structures are operated around 20 K, and are joined by diffusion bonding and are constructed with high-purity 6N8 copper which has very low resistivity in extremely low temperatures. In this study, we report the measurements and calculation of the residual resistance ratio (RRR) for 6N8 copper and oxy-gen-free copper (Class 1) as well as the Q factor for a pillbox cavity made of 6N8 copper and Class 1. The results of a low-power test of this accelerating structure at low temperature are reported. The Q factor for a 6N8 copper pillbox cavity is not much higher than that of a Class 1 pillbox cavity at low temperatures Moreover, the Q factor is saturated when RRR is greater than 500.

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MOPMW032

Study of RF Breakdown in 805MHz Pillbox Modular Cavity in Strong Magnetic Field

cavity, operation, site, pick-up

466

A.V. Kochemirovskiy
University of Chicago, Chicago, Illinois, USA
D.L. Bowring, A. Moretti, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

RF breakdown has a negative impact on a cavity's performance, especially with the presence of strong magnetic fields. This issue can arise in designs of muon ionization cooling channel, RF guns, klystrons and in many other applications. The MuCool Test Area at Fermilab is the facility that allows us to study the effects of static magnetic field on RF cavity operation. As a part of this research program, we have tested an 805MHz pillbox "modular" cavity in strong external magnetic fields. The design of the cavity allowed for a better control over sources of systematic error. "Modular" structure of the cavity enables easy dismounting of the endplates to perform inspection of inner surfaces after each run as well as swapping endplates to study the effects of various materials on breakdown phenomenon. Coupler design ensures maximum electric field enhancement on cavity axis, thus reducing breakdown probability in the coupler region. The results and analysis from high-power runs with zero and non-zero external magnetic fields will be presented.

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MOPOR046

Studies on Depolarization by Synchrotron Radiation using Elegant Particle Tracking

synchrotron, synchrotron-radiation, polarization, resonance

695

J.F. Schmidt, W. Hillert
ELSA, Bonn, Germany

Funding: BMBF
Spin dynamics in circular electron accelerators are significantly influenced by the emission of synchrotron light. In storage rings, Sokolov-Ternov polarization build-up and radiative depolarization have crucial impact on equilibrium polarization. On shorter timescales, as in damping rings or synchrotrons with fast energy ramp, the temporal development of polarization depends on spin decoherence caused by stochastic momentum changes. Thus, especially longitudinal beam dynamics affect depolarization. This contribution presents the implementation of particle tracking with synchrotron radiation from Elegant in an in-house developed spin tracking code. Exemplary results on depolarization including synchrotron radiation are shown.

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MOPOW008

Reverse Undulator Tapering for Polarization Control at XFELs

undulator, FEL, resonance, bunching

722

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. We describe a method for such a suppression: an application of the reverse taper in the main undulator*. In a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. The scheme was successfully tested at LCLS** and is routinely used in user experiments. In this contribution we present the theoretical description of the method as well as the results of experiments with reverse taper at FLASH2.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 16, 110702 (2013)
** H.-D. Nuhn et al., "Commissioning of the DELTA polarizing undulator at LCLS", Proc. of FEL2015 Conf., Daejeon, Korea

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MOPOW009

Studies of Harmonic Lasing Self-seeded FEL at FLASH2

undulator, FEL, simulation, electron

725

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in*,**. A gap-tunable undulator is divided into two parts such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is reduced by a significant factor depending on harmonic number but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702
** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA

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MOPOW011

Operation of Free Electron Laser FLASH Driven by Short Electron Pulses

electron, undulator, simulation, laser

732

V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany
E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.

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MOPOW012

Transverse Coherence and Fundamental Limitation on the Pointing Stability of X-ray FELs

FEL, electron, photon, emittance

735

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

The radiation from SASE FEL has always limited value of the degree of transverse coherence*. When transverse size of the electron beam significantly exceeds diffraction limit, the mode competition effect does not provide the selection of the ground mode, and spatial coherence degrades due to contribution of the higher azimuthal modes. An important consequence of this effect are fluctuations of the spot size and pointing stability of the photon beam**. These fluctuations are fundamental and originate from the shot noise in the electron beam. The effect of pointing instability becomes more pronouncing for shorter wavelengths. We analyze in detail the case of optimized SASE FEL* and derive universal dependencies applicable to all operating and planned x-ray FELs. We show that the hard x-ray FELs driven by low energy beams may exhibit poor spatial coherence and bad pointing stability.
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 281(2008)1179.
** E.A. Schneidmiller and M.V. Yurkov, Proc. FEL2015 Conference, Daejeon, Korea, 2015, TUP021.

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MOPOW013

Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL

FEL, undulator, electron, photon

738

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam*. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time**. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH.
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383.
** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.

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MOPOW016

Status of Design and Development of Delhi Light Source at IUAC, Delhi

laser, electron, undulator, gun

748

S. Ghosh, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, P. Patra, B.K. Sahu, A.S. Sharma, A.S. Sthuthikkatt Reghu
IUAC, New Delhi, India
A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa, J. Urakawa
KEK, Ibaraki, Japan
A. Deshpande
SAMEER, Mumbai, India
V. Naik, A. Roy
VECC, Kolkata, India
T. Rao
BNL, Upton, Long Island, New York, USA

Funding: The project is supported jointly by Board of Research in Nuclear Sciences (BRNS) and IUAC
The demand for the photon beams for basic research is growing in India. To address the requirements, a project to develop a compact Light Source based on the principle of Free Electron Laser has been initiated at the Inter University Accelerator Centre (IUAC). In the first phase of the project, a normal conducting RF gun will be used to produce electron beam of energy ~ 8 MeV by using copper photocathode and subsequently by Cs2Te photocathode. A high power fiber laser with short pulse length is planned to be used to produce the pre-bunched electron beam by splitting the single laser pulse in to 16 pulses ("comb beam"). The electron beam will be injected in to a compact, variable gap undulator magnet to produce the THz radiation whose frequency can be tuned by varying the undulator field strength and the time separation of the comb beam. In the second and third phases of the project, superconducting RF gun and superconducting accelerating structure will be used to increase the energy of the electron beam up to ~ 40 MeV which will be used to produce IR radiation by using long undulator magnets and to produce X-rays by colliding the electron beam with another high power laser beam.

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MOPOW020

Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing

FEL, focusing, undulator, electron

760

G. Zhou, Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China
J. Wu
SLAC, Menlo Park, California, USA
T. Zhang
SINAP, Shanghai, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009)
Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.

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MOPOW023

Proposal of an X-band Linearizer for Dalian Coherent Light Source

FEL, laser, electron, undulator

766

G.L. Wang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

Dalian coherent Light Source (DCLS) is a FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility based on HGHG mode, requires high brightness electron beam with small energy spread and low emittance. To linearise the longitudinal phase space before the bunch compression, an X-band linearizer is considered before the bunch compressor. In this paper, we study the performance improvement of DCLS FEL radiation by using such a harmonic cavity, including the jitter of central wavelength induced by arriving time and a larger bunch compression ratio for femtosecond FEL application.

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MOPOW024

Harmonic Lasing Options for Dalian Coherent Light Source

FEL, laser, electron, undulator

770

G.L. Wang, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China
H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

Harmonic lasing of the Free Electron Laser can be achieved by disrupting the electron interaction with the usually dominant fundamental while allowing the increasing of a harmonic interaction. It's a cheap and relatively efficient way to extend the photon energy range of a particular FEL. In this paper, we discussed the possibility of harmonic lasing concept at Dalian Coherent Light Source by using the combination of tapered undulators and phase shifters. Our calculation shows that it's feasible with the present layout to provide intense, stable, and narrow-band harmonic radiation, the FEL wavelength could be down to 20 nm and the corresponding pulse energy is about 10 μJ.

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MOPOW026

Status of FELiCHEM, a New IR-FEL in China

FEL, undulator, cavity, electron

774

H.T. Li, Z.G. He, Q.K. Jia, Q. Luo, L. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC), whose core device is a FEL oscillator generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 μm. It will be a dedicated light source aiming at energy chemistry research, with the photo excitation, photo dissociation and photo detection experimental stations. We present the brief physical and technical design that delivers the required performance for this device and summarize the status of fabrication. Final assembly is scheduled for early in the next year with first light targeted for July 2017.

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MOPOW027

Generation of Coherent Mode-locked Radiation in a Seeded Free Electron Laser

electron, FEL, laser, simulation

777

Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We present the promise of generating mode-locked multichromatic radiations in a seeded free electron laser based on high gain harmonic generation (HGHG). 3D start-to-end simulations have been carried out and analysis & comparisons have been made to have a research on the properties of each system. In these schemes, either the electron beam density or the seed laser intensity is modulated to produce a coherent radiation pulse train that yields multiple spectral lines in FEL output. Stable peak power at gigawatt level can be generated in the undulator finally.

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MOPOW035

A Compact, Wavelength Tunable MW-THz FEL Amplifier

undulator, FEL, electron, laser

789

C.H. Chen, A.P. Lee
NSRRC, Hsinchu, Taiwan
F.H. Chao, Y.C. Chiu, Y.-C. Huang, M.H. Wu
NTHU, Hsinchu, Taiwan
G. Zhao
PKU, Beijing, People's Republic of China

We propose a compact scheme of THz free electron laser (FEL) amplifier within a 3.5 m long beam line. The amplification of a tunable THz seed laser in an FEL amplifier is driven by an rf photoinjector*. The THz seed laser is an optical parametric amplifier** pumped by a 1064-nm microchip laser and an external-cavity tunable diode laser. By varying the beam energy and undulator parameter, the radiation frequency of the THz FEL amplifier can be tunable in a broad spectral range between 1.5 and 3.0 THz. Moreover, to extract more radiation power from the electron beam within a short undulator, we employ a linearly tapered undulator in our design. The influence of the seed power on the electron-laser interaction in the undulator is studied in some detail for the FEL amplification. Our simulation results show that the radiation power of the THz FEL amplifier can achieve few MW with a 10-W seed power.
* D.T. Palmer et al., in Proceedings of Particle Acceleration Conference, Vancouver, 1997, p. 2687, (1997).
** S. Hayashi et al., SCIENTIFIC REPORTS, 4, 5045-1-6, (2014).

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TUYA01

BEPCII Performance and Beam Dynamics Studies on Luminosity

luminosity, lattice, synchrotron, synchrotron-radiation

1014

C.H. Yu, Z. Duan, S. Gu, Y.Y. Guo, X.Y. Huang, D. Ji, H.F. Ji, Y. Jiao, Zh.C. Liu, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X.H. Wang, Y. Wei, X.M. Wen, J. Wu, J. Xing, G. Xu, Y. Yue, C. Zhang, Y. Zhang
IHEP, Beijing, People's Republic of China

The upgrade of the Beijing Electron Positron Collider, BEPCII, is now in a good performance for both high energy physics and synchrotron radiation experiments. The luminosity at the design energy of 1.89 GeV reached the design value 1.0*10³³/cm²/s¹ recently. A lot of work, including accelerator physics study and technical progress, has been done for the luminosity enhancement, not only at the design energy, but all the energy region run for HEP experiments from 1.0 to 2.3 GeV. The performance of BEPCII and the process of luminosity enhancement will be described in detail.

Slides TUYA01 [5.801 MB]

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TUZA01

Soft X-ray Free Electron Laser at SINAP

FEL, undulator, laser, electron

1028

D. Wang
SINAP, Shanghai, People's Republic of China

Shanghai X-ray FEL (SXFEL) is a test facility at Shanghai Institute of Applied Physics, Chinese Academy of Sciences originally designed for studying XFEL principle and technologies. It is composed of a warm linac to provide up to 840 MeV electron beam, an undulator line with cascaded EEHG-HGHG setup and a short diagnostic beamline. The project started the construction by the end of 2014. Recently a proposal to upgrade it to an user facility at the soft x-ray regime got approved. The talk will give an overview of the test facility construction and upgrade plan.

Slides TUZA01 [9.344 MB]

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TUXB01

High Power Radiation Sources using the Steady-state Microbunching Mechanism

laser, storage-ring, FEL, focusing

1048

A. Chao, E. Granados, X. Huang, D.F. Ratner
SLAC, Menlo Park, California, USA
H.W. Luo
NTHU, Hsinchu, Taiwan

The mechanism of steady-state microbunching (SSMB) was proposed for providing high power coherent radiation using electron storage rings. The mechanism follows closely the RF bunching in conventional storage rings, except that the energy modulation of by an RF system at a microwave wavelength is replaced by a seeded laser in an undulator at an optical wavelength. No FEL mechanism, and thus no FEL energy heating, is invoked. The basic idea is firstly to make the beam microbunched so that its radiation becomes coherent, and secondly to make the microbunching a steady state so that the coherent radiation is maintained at every turn. The combination of the high repetition rate of a storage ring and the enhanced radiation power by a factor of N (the number of electrons in the microbunches within one coherence length) opens the possibility as well as challenges of very high power SSMB sources. To explore its potential reach, we apply SSMB to the infrared, deep ultraviolet and EUV regions and estimate their respective power levels using SPEAR3 as example. Several variants of the SSMB schemes are discussed. A proof-of-principle configuration without an identified testbed is also suggested.

Slides TUXB01 [1.602 MB]

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TUZB01

High Power Proton Beam Targets: Technological Evolution, Current Challenges, and the Future

target, neutron, proton, operation

1075

J. Galambos
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
This talk reviews the history of proton beam target development and the current challenges associated with the operation of high power beam targets. Beyond providing high power proton beams, accelerator facilities must also engineer robust targets to accept the load and satisfy mission needs. Recently some high power facilities are limited by target operations, rather than accelerator capabilities. The outlook for targets for future high power facilities is also considered.

Slides TUZB01 [8.971 MB]

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TUZB02

Challenge of In-vacuum and Cryogenic Undulator Technologies

undulator, vacuum, cryogenics, permanent-magnet

1080

J.C. Huang, C.-H. Chang, C.H. Chang, T.Y. Chung, C.-S. Hwang, C.K. Yang, Y.T. Yu
NSRRC, Hsinchu, Taiwan
H. Kitamura
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

An in-vacuum undulator (IVU) opens the utilization of high-brilliance X-rays in the medium energy storage rings. The development of a short-period undulator with low phase error becomes important to bring X-ray into a new unprecedented brilliant light source in an ultimate storage ring (USR). NdFeB or PrFeB cryogenic permanent magnet undulators (CPMUs) with a short period have been developed worldwide to obtain high brilliance of undulator radiation. A CPMU has high resistance against beam-induced heat load and allow to operate at a narrow gap. In a low emittance or ultimate storage ring, not only the performance of an undulator but the choice of the lattice functions is very important to obtain high bril-liance of synchrotron radiation. The optimum betatron functions and zero dispersion function shall be given for a straight section at IVU/CPMUs. In this paper, the relevant factors and design issues for IVU/CPMU will be discussed. Many technological challenges of a short-period undulator associated with beam induced-heat load, phase errors, and the deformation of in-vacuum girders will also be presented herein.

Slides TUZB02 [5.204 MB]

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TUPMB007

Research and Development of the Pulse Bump Magnet for the Injection System in CSNS/RCS

injection, neutron, high-voltage, synchrotron

1118

L. Huo, M.Y. Huang, W. Kang, Y.Q. Liu, J. Qiu, L. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The H⁻ stripping painting injection is adopted in the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS). Painting injection is realized by eight pulse bump magnets. The pulse bump magnet is the key of the performance of painting, as well as the beam loss control. The manufacture and the field measurement of the eight pulse bump magnets have been completed. In the development of the magnets, some key technical problems on fabrication of coil were solved, and the field measurement results show that the magnets fulfil the design specification.

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TUPMB010

Magnetic Center Position and Tilt Angle of Quadrupole by Vibration Wire Method

quadrupole, experiment, alignment, superconductivity

1127

L. Wu, X. Guan, X.W. Wang, S.X. Zheng
TUB, Beijing, People's Republic of China
B.C. Wang
NINT, Xi'an, People's Republic of China
G. Xialing
CIAE, Beijing, People's Republic of China

Vibrating wire method and device are described to locate the magnetic center of a Quadrupole theoretically and experimentally. With rotating 180 degrees method, it is convenience to measure the position magnetic center from mechanical center. Tilt angle can also be measured because tilt of magnetic axis will cause the difference of measured magnetic center in different harmonic driving current frequency. Errors analysis shows that tilt of Quadrupole will cause the main error and improved device is described to adjust and measure the tilt angle to fix the errors caused by tilt.

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TUPMB015

Compact Rare-Earth Permanent Magnet Material System for Industrial Electron Accelerators Irradiation Field Formation

electron, quadrupole, permanent-magnet, simulation

1139

D.S. Yurov, A.N. Ermakov, V.V. Khankin, N.V. Shvedunov, V.I. Shvedunov
M.V. Lomonosov Moscow State University (MSU), Skobeltsyn Institute of Nuclear Physics, Moscow, Russia

A compact system for industrial electron accelerators irradiation field formation is described. This system permits to get uniform distribution of electron beam current along the direction perpendicular to product movement with the width 50 - 100 cm. Its main element is a non-linear quadrupole lens, based on rare-earth permanent magnet material. This system can be used instead of an electromagnet of the conventional beam scanning systems, making much more comfortable conditions for products irradiation. Operation principles, results of calculations and test results of the system for CW 1 MeV and pulse 10 MeV electron linear accelerators are described.

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TUPMB034

Design and Manufacture of a Superconducting Solenoid for D-Line of J-PARC Muon Facility

solenoid, operation, vacuum, interface

1177

T. Semba, Y. Hagiwara, S. Kido, S. Nakajima, Y. Tanaka
Hitachi Ltd., Ibaraki-ken, Japan
N. Kawamura, Y. Makida, Y. Miyake, H. Ohhata, K. Sasaki, K. Shimomura
KEK, Ibaraki, Japan
N. Kurosawa
KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan
Y. Murata
Hitachi, Ltd., Energy and Environmental System Laboratory, Hitachi-shi, Japan
P. Strasser
High Energy Accelerator Research Organization (KEK), Institute of Materials Structure Science (IMSS), Ibaraki, Japan

A superconducting solenoid for J-PARC muon facility was newly designed and manufactured. High Energy Accelerator Research Organization (KEK) has been operating the J-PARC Muon Science Establishment (MUSE) since 2008. Among its four muon beam lines, the decay muon line (D-Line) has been extracting and providing surface muons and positive decay muons up to a momentum of 50 MeV/c for various users, utilizing a superconducting solenoid. The D-Line as well as the other J-PARC facility suffered severe damages from the earthquake on March 11, 2011. It necessitated rebuilding of the damaged superconducting solenoid. New design parameter of the solenoid is as follows: length of solenoid: 6 m, diameter of warm bore: 0.2 m, magnetic field of bore center: 3.5 T, rated current: 415 A, superconducting wire: NbTi/Cu, quench protection: quench back heaters. The six-meter-long solenoid consists of twelve pieces of 0.5-meter-long superconducting coils. The entire solenoid is forced-indirectly cooled by supercritical helium flow. This report describes the design and manufacturing process of the newly built superconducting solenoid for D-Line of J-PARC muon facility.

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TUPMB049

Development of Separator Cooling System for Helium

cryogenics, experiment, controls, vacuum

1209

W.R. Liao, S.-H. Chang, W.-S. Chiou, P.S.D. Chuang, F. Z. Hsiao, H.C. Li, T.F. Lin, H.H. Tsai
NSRRC, Hsinchu, Taiwan

A helium phase separator with a condenser is under fabrication and assembled at National Synchrotron Radiation Research Centre (NSRRC). The objective of a helium phase separator with its condenser is to separate two-phase helium flow and to re-condense vaporized gaseous helium with a cryocooler of Gifford-McMahon type. We developed a 100 litre (ltr) helium phase separator with a small heat loss as a prototype. The experimental results for the total cooling capacity of the phase separator are 0.73 W at 1.67 bara, which includes the effect of thermal conduction and thermal radiation from the environment. The helium liquefaction rate is 2 ltr/day with a 100 ltr vessel. The mechanism of heat transfer in phase separator was investigated and discussed. This paper presents the experiment of helium liquefaction process of 100 ltr separator with condenser, which was a key component of the helium phase separator.

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TUPMB050

Development of Multi-channel Line for the NSRRC Cryogenic System

cryogenics, vacuum, photon, synchrotron

1212

P.S.D. Chuang, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H.C. Li, W.R. Liao, T.F. Lin, H.H. Tsai
NSRRC, Hsinchu, Taiwan

For the past few years, the technology of X-ray photon source is getting more and more advanced, more and more countries are now striving to build the biggest synchrotron facility to meet its' need. In Taiwan, the construction of an electron accelerator with the energy of up to 3.5 GeV is constructed to fulfill the strong demands for an X-ray photon source with high brilliance and flux. Thus, to let the TPS be under stable operation, the cryogenic system is therefore very important. The refrigerant of the TPS Cryogenic System is Liquid Helium, to maintain liquid helium in its state, the temperature has to be maintained under 4.5K, however to let liquid helium turn into gas helium, only 20 W is needed. Therefore, the Multi-Channel Line is developed in our system to prevent heat from conduction in and letting liquid helium vaporize. Several mechanical parts have been designed to reduce heat loss and meet its needs, for example the Spacer. The paper presents a design methodology of long multi-channel helium cryogenic transfer lines. It describes some aspects thermo-mechanical calculation, supporting structure and contraction protection.

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TUPMB052

High Intensity Beam Test of Low Z Materials for the Upgrade of SPS-to-LHC Transfer Line Collimators and LHC Injection Absorbers

experiment, simulation, injection, proton

1218

F.L. Maciariello, O. Aberle, M.E.J. Butcher, M. Calviani, R. Folch, V. Kain, K. Karagiannis, I. Lamas Garcia, A. Lechner, F.-X. Nuiry, G.E. Steele, J.A. Uythoven
CERN, Geneva, Switzerland

In the framework of the LHC Injector Upgrade (LIU) and High-Luminosity LHC (HL-LHC) project, the collimators in the SPS-to LHC transfer lines will undergo important modifications. The changes to these collimators will allow them to cope with beam brightness and intensity levels much increased with respect to their original design parameters: nominal and ultimate LHC. The necessity for replacement of the current materials will need to be confirmed by a test in the High Radiation to Materials (HRM) facility at CERN. This test will involve low Z materials (such as Graphite and 3-D Carbon/Carbon composite), and will recreate the worst case scenario those materials could see when directly impacted by High luminosity LHC (HL-LHC) or Batch Compression Merging and Splitting (BCMS) beams. Thermo-structural simulations used for the material studies and research, the experiment preparation phase, the experiment itself, pre irradiation analysis (including ultrasound and metrology tests on the target materials), the results and their correlation with numerical simulations will be presented.

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TUPMW002

LHC Luminosity Modeling for RUNII

luminosity, emittance, scattering, proton

1403

F. Antoniou, G. Arduini, M. Hostettler, M. Lamont, S. Papadopoulou, Y. Papaphilippou, G. Papotti, M. Pojer, B. Salvachua, M. Wyszynski
CERN, Geneva, Switzerland

Funding: Research supported by the High Luminosity LHC project
After a long shut-down (LS1), LHC restarted its operation on April 2015 at a record energy of 6.5TeV, achieving soon a good luminosity performance. In this paper, a luminosity model based on the three main components of the LHC luminosity degradation (intrabeam scattering, synchrotron radiation and luminosity burn-off), is compared with data from runII. Based on the observations, other sources of luminosity degradation are discussed and the model is refined. Finally, based on the experience from runI and runII, the model is used for integrated luminosity projections for the HL-LHC beam parameters.

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TUPMW005

Characterization of the Radiation Field in the FCC-hh Detector

detector, shielding, neutron, dipole

1414

M.I. Besana, F. Cerutti, A. Ferrari, W. Riegler, V. Vlachoudis
CERN, Geneva, Switzerland

As part of the post-LHC high-energy program, a study is ongoing to design a new 100 km long hadron collider, which is expected to operate at a centre-of-mass energy of 100 TeV and to accumulate up to 30 ab−1, with a peak instantaneous luminosity that could reach 30 1034cm−2s−1. In this context, the evaluation of the radiation load on the detector is a key step for the choice of materials and technologies. In this contribution, a first detector concept will be presented. At the same time, fluence distributions, relevant for detector occupancy, and accumulated damage on materials and electronics will be shown. The effectiveness of a possible shielding configuration, intended to minimise the background in the muon chambers and tracking stations, will be presented.

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TUPMW009

Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders

emittance, simulation, synchrotron, collider

1430

X. Buffat, T. Pieloni, C. Tambasco
CERN, Geneva, Switzerland
J. Barranco, A. Florio
EPFL, Lausanne, Switzerland

The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations.

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TUPMW018

Radiation Load Optimization in the Final Focus System of FCC-hh

shielding, quadrupole, luminosity, optics

1462

R. Martin, M.I. Besana, F. Cerutti, R. Tomás
CERN, Geneva, Switzerland

With a center-of-mass energy of up to 100 TeV, FCC-hh will produce highly energetic collision debris at the Interaction Point (IP). Protecting the final focus quadrupoles from this radiation is challenging, since the required amount of shielding placed inside the magnets will reduce the free aperture, thereby limiting the β^* reach and luminosity. Hence, radiation mitigation strategies that make best use of the available aperture are required. In this paper, we study the possibility to split the first quadrupole Q1 into two quadrupoles with individual apertures, in order to distribute the radiation load more evenly and reduce the peak dose.

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TUPMW022

Modelling and Measurements of Bunch Profiles at the LHC Flat Bottom

emittance, lattice, scattering, damping

1477

S. Papadopoulou, F. Antoniou, J.E. Muller, Y. Papaphilippou, G. Trad
CERN, Geneva, Switzerland

At the LHC flat bottom the interplay between a series of effects (i.e. intrabeam scattering, longitudinal beam manipulations, non-linearities of the machine, etc) can lead to a population of the tails of the beam distributions, which may become non-Gaussian. This paper presents observations of the evolution of particle distributions in the LHC flat bottom. Novel distribution functions are employed to represent the beam profiles, and used as a guideline for generalising emittance growth rate estimations due to IBS. Finally, an attempt is made to benchmark an IBS Monte-Carlo simulation code, able to track 3D particle distributions, with the measured beam profile evolutions.

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TUPMY017

Laser Driven Dielectric Accelerator in the Non-relativistic Energy Region

laser, acceleration, electron, vacuum

1585

K. Koyama, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
S. Kurimura
NIMS, Ibaraki, Japan
H. Okamoto, S. Otsuki
The University of Tokyo, Tokyo, Japan
M. Yoshida
KEK, Ibaraki, Japan

Laser-driven dielectric accelerator (LDA) is suitable for delivering a submicron-size ultra-short electron beam, which is useful for studying basic processes of the radiation effect in a biological cell. Both the oblique incidence and the normal incidence configurations of LDA were studied. The oblique incidence configuration of LDA relaxes the synchronization condition as v_e=¥pm c L_G/¥left(¥λ+ L_G n ¥sin ¥theta ¥right) and is somewhat suitable for accelerating the non-relativistic electrons. The required energy to accelerate electrons in the oblique incidence configuration is smaller than that in the normal incidence configuration by a factor of ¥cos ¥theta, where ¥theta is the incidence angle of the laser beam. Two gratings each were made of different material structure of silica ({¥rm SiO₂}) were fabricated by the electron beam lithography. When a crystal silica was adopted, many large humps of several hundred nm size were observed in grooves of the grating. On the other hand, a glass silica had smoother grooves.

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TUPMY026

Electron Beam Generation and Injection From a Pyroelectric Crystal Array

acceleration, electron, laser, injection

1604

R.B. Yoder, Z. Kabilova, B. Saeks
Goucher College, Baltimore, Maryland, USA

Novel acceleration structures (e.g. dielectric laser accelerators [DLAs]*) powered by lasers have the potential to greatly reduce the footprint and cost of both industrial linacs and colliders. As these devices have dimensions comparable to optical wavelengths, they require injection of a sub-micron-scale electron bunch to generate high-quality output beams, which are well beyond the capability of conventional rf photocathodes. Photoexcitation and field emission from an array of nanotips, followed by further acceleration and focusing, is a promising approach to achieving the requisite small beam sizes for successful injection. Pyroelectric crystals can provide electrostatic fields of sufficient magnitude and uniformity to enable emission and acceleration. We present an initial design for a low-energy injection module using the accelerating electrostatic fields provided by pyroelectric crystals. The approach is modeled numerically and supported by direct benchtop measurements of pyroelectric fields from a 2-crystal array.
*R. J. England et al., Rev. Mod. Phys. 86, p. 1337 (2014).

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TUPMY032

Radiation from Open Ended Waveguide with a Dielectric Loading

vacuum, electron, controls, simulation

1617

S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin, V.V. Vorobev
Saint-Petersburg State University, Saint-Petersburg, Russia
S. Baturin
LETI, Saint-Petersburg, Russia
S. Baturin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).
Terahertz radiation is considered as a promising tool for a number of applications. One possible way to emit THz waves is to pass short electron bunch through a waveguide structure loaded with dielectric*. In our previous papers, we have analyzed this problem in both approximate** and rigorous*** formulation. However, we have encountered certain difficulties with calculations. In the present report, we are starting to develop another rigorous approach based on mode-matching technique and modified residue-calculus technique. We consider the radiation from the open-ended dielectrically loaded cylindrical waveguide placed inside regular cylindrical waveguide with larger radius. We present structure of reflected and transmitted modes and typical radiation patterns from the open end of larger radius waveguide.
* S. Antipov et al., Appl. Phys. Lett., vol. 100, p. 132910, 2012.
** S.N. Galyamin et al., Opt. Express, vol. 22, No. 8, p. 8902, 2014.
*** S.N. Galyamin et al., in Proc. IPAC'15, pp. 2578-2580.

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TUPMY033

Radiation of Charged Particle Flying into Chiral Isotropic Medium

polarization, vacuum, plasma, interface

1620

S.N. Galyamin, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia
A.A. Peshkov
HIJ, Jena, Germany

Funding: Work is supported by the Grant of the Russian Foundation for Basic Research (No. 15-32-20985).
In recent years, the interest to radiation of moving charged particles in media with chiral properties is connected with relatively new and prospective method for diagnostics of biological objects which uses the Cherenkov radiation ' Cherenkov luminescence imaging*. Optical activity (chirality, gyrotropy) is typical or biological matter and is caused by mirrorless structure of molecules. Contrary to such gyrotropic medium as magnetized ionospheric plasma, aforementioned media are isotropic. One distributed model describing the frequency dispersion of isotropic chiral media is Condon model. In this report, we continue the investigation performed in our previous paper** where we dealt with the field produced by uniformly moving charge in infinite chiral isotropic medium. Moreover, we perform generalization of early paper***, where the problem with half-space was considered in the specific case of slow charge motion. We present typical radiation patterns in vacuum area and corresponding ellipses of polarization which allows determination of the chiral parameter of the medium.
* Spinelli A.E. et al. // NIM A. 2011. V. 648. P. S310.
** Galyamin S.N. et al. // Phys. Rev. E. 2013. V. 88. P. 013206.
*** Engheta N., Mickelson A.R. // IEEE Trans. AP. 1982. V. 30. P. 1213.

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TUPMY034

On Bunch Diagnostics with use of Surface Waves Generated on Planar Wire Grid

vacuum, electronics, diagnostics, electromagnetic-fields

1623

V.V. Vorobev, S.N. Galyamin, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

Funding: Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).
Periodic structures can be used for non-destructive diagnostics of charged particle bunches*. We consider structures which consist of thin conducting parallel wires. It is assumed that the structure period is much less than the typical wavelength under consideration. Therefore the influence of the structure on the electromagnetic field can be described with help of the averaged boundary conditions**. We consider radiation of bunches which move along the grid but transversely to wires. Unlike previous works the bunch is assumed to have essential transversal dimensions along with definite longitudinal charge distribution. In particular we analyze the effect of reflection of the surface wave from the structure edge. For all considered situations, analytical and numerical results demonstrate that analysis of the surface waves allows estimating the size and the shape of the bunch.
* A.V. Tyukhtin et al., Phys. Rev. ST AB 17, 122802 (2014); A.V. Tyukhtin et al., Phys. Rev. E 91, 063202 (2015).
** M.I. Kontorovich et al., Electrodynamics of Grid Structures (Moscow, 1987).

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TUPMY035

Short-wavelength Radiation of a Small Charged Bunch in Presence of a Dielectric Prism

target, optics, polarization, vacuum

1626

A.V. Tyukhtin, S.N. Galyamin
Saint-Petersburg State University, Saint-Petersburg, Russia
E.S. Belonogaya
LETI, Saint-Petersburg, Russia

Funding: Work is supported by the Grant from Russian Foundation for Basic Research (No. 15-02-03913).
Investigation of radiation of a charged particle bunch in the presence of a large (compared with wavelengths under consideration) dielectric object can be performed using certain approximate methods. We develop here the method based on the known Stratton-Chu formulae which allows calculating the field everywhere outside the object including the Fresnel and Fraunhofer areas, as well as neighborhoods of focal points*. The main problem considered here consists in investigation of radiation of a small bunch moving along boundary of a dielectric prism or in channel inside a prism. Approximate analytical solutions of the problem are obtained and typical numerical results are given.
*S.N. Galyamin and A.V. Tyukhtin, Phys. Rev. Lett. 113, 064802, 2014.

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TUPOR003

CSR-Driven Longitudinal Single Bunch Instability with Negative Momentum Compaction Factor

synchrotron, shielding, damping, electron

1651

P. Kuske
HZB, Berlin, Germany

Acceptable agreement is found between experimental results obtained at the Metrology Light Source (MLS) operated with negative momentum compaction factor, α, and theoretical estimates of the CSR-driven threshold currents. Theoretical instability thresholds are estimated by numerically solving the Vlasov-Fokker-Planck equation and/or by multi particle tracking and taking into account the shielded CSR-interaction. Some of the issues with the calculations, the determination of the theoretical thresholds as well as the derivation of a general scaling law will be presented

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TUPOR006

Systematic Studies of Short Bunch-Length Bursting at ANKA

synchrotron, shielding, synchrotron-radiation, electron

1662

M. Brosi, E. Blomley, E. Bründermann, N. Hiller, B. Kehrer, A.-S. Müller, M. Schedler, M. Schuh, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

Funding: Supported by the German Federal Ministry of Education and Research (05K13VKA), the Helmholtz Association (VH-NG-320) and by the Helmholtz International Research School for Teratronics (HIRST).
At ANKA, the Karlsruhe synchrotron radiation source, the so called short bunch-length operation mode allows the reduction of the bunch length down to a few picoseconds. The micro-bunching instability resulting from the high degree of longitudinal compression leads to fluctuations in the emitted intensity in the THz regime, referred to as bursting. For extremely compressed bunches at ANKA bursting also occurs, in a certain current range, below the main bursting threshold. This contribution shows measurements of this short bunch-length bursting and makes first comparisons with theory.

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TUPOR012

THz Coherent Synchrotron Radiation from Ultra-low Alpha Operating Mode at Diamond Light Source

simulation, storage-ring, impedance, electron

1682

T. Chanwattana, M. Atay, R. Bartolini
JAI, Oxford, United Kingdom
R. Bartolini, G. Cinque, M. Frogley, E. Koukovini-Platia, I.P.S. Martin
DLS, Oxfordshire, United Kingdom

Diamond Light Source is regularly operated in low-alpha mode to provide THz coherent synchrotron radiation (CSR) and short X-ray pulses for users. In order to maintain the wide frequency range of the coherent radiation whilst improving the signal to noise ratio, an ultra-low alpha mode has been considered to shorten the bunch length even further. In order to study this mode, the analysis of single bunch dynamics resulting from a variety of wakefield sources has been investigated using a single bunch multiparticle tracking code. These results are compared with measurements recorded using a Fourier transform infrared (FTIR) interferometer on the MIRIAM beam-line at Diamond.

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TUPOR020

Combination of Density and Energy Modulation in Microbunching Analysis

electron, collective-effects, synchrotron-radiation, synchrotron

1703

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
R. Li
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Microbunching instability (MBI) has been one of the most challenging issues in the transport of high-brightness electron beams for modern recirculating or energy recovery linac machines. Recently we have developed and implemented a Vlasov solver* to calculate microbunching gain for an arbitrary beamline lattice design, based on the extension of early theoretical formulation** for the microbunching amplification from an initial density perturbation to the final density modulation. For more thorough analyses, in addition to the case of (initial) density to (final) density amplification, we in this paper extend the previous formulation to more general cases, including energy-to-density, density-to-energy and energy-to-energy amplifications for a recirculation machine. Such semi-analytical formulae are then incorporated into our Vlasov solver, and reasonable agreement is obtained when the semi-analytical results are benchmarked with particle tracking simulation using ELEGANT***.
* C.Y. Tsai et al, FEL'15
** S. Heifets et al, PRSTAB 5, 064401 (2002), Z. Huang and K. Kim, PRSTAB 5, 074401 (2002), M. Vneturini, PRSTAB 10, 104401 (2007)
*** M. Borland, APS LS-287, 2000

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TUPOR031

Trapped Ion Effects and Mitigation During High Current Operation in the Cornell DC Photoinjector

ion, experiment, linac, vacuum

1735

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

Funding: U.S. Department of Energy (Grant No. DE-SC0012493), National Science Foundation (Award No. NSF-DMR 0807731)
The Cornell high intensity photoinjector reaches a new regime of linac beam parameters where high continuous-wave electron beam currents lead to ion trapping. Above 10 mA, we have observed beam trips that limit stable machine operation to approximately 10^-15 minutes. By applying known ion clearing methods, the machine lifetime increases to at least 24 hours of continuous operation, suggesting that trapped ions are the most likely cause of the trips. In this paper we share some of our observations ion trapping in the photoinjector, as well as experimental tests of three common ion mitigation methods: clearing electrodes, beam shaking and bunch gaps.

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TUPOW008

Generation of Short Bunch Electron Beam from Compact Accelerator for Terahertz Radiation

laser, electron, injection, detector

1757

S. Suphakul, T. Kii, K. Masuda, K. Morita, H. Ohgaki, K. Torgasin, H. Zen
Kyoto University, Kyoto, Japan

We are developing a new compact accelerator system to generate a high power terahertz (THz) radiation at the Institute of Advanced Energy, Kyoto University. THz radiations are produced by injecting ultra-short and intense electron pulses to a short plannar undulator. The bunch compression characteristic by the newly installed chicane was investigated by observation of a coherent part of an optical transition radiation (OTR). As the result, the chicane can compress the electron bunch at the laser injection phase from 10 to 40 degree. The beam energy and relative rms energy spread were also measured and the results were 4.6 MeV and 1.3 %, respectively.

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TUPOW009

Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University

undulator, electron, bunching, injection

1760

S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.

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TUPOW010

Production of Ultra-short Electron Pulse and Observation of Coherent Transition Radiation at t-ACTS, Tohoku University

electron, bunching, detector, injection

1763

T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

A test-Accelerator as Coherent Terahertz Source (t-ACTS) project has been under development at Research Center for Electron Photon Science, Tohoku University. In order to generate a coherent radiation in terahertz (THz) region, it is necessary to produce sub-picosecond electron pulses. Velocity bunching scheme is employed for the short electron pulse production in t-ACTS. We experimentally confirmed the production of short electron pulse under 500 fs by measuring the bunch length using a streak camera. Coherent transition radiation in THz region was produced by which the short electron pulses pass through a vacuum-metal interface. Several radiation properties including　spatial distribution, polarization and spectrum were measured and compared with theoretical calculations. The details of the beam experiment at t-ACTS are described.

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TUPOW018

Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

electron, experiment, space-charge, gun

1782

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

High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.

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TUPOW026

Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory

undulator, electron, linac, emittance

1803

N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand

Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand.
Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.

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TUPOW038

Measurement and Control of Beam Losses Under High Average-current Operation of the Compact ERL at KEK

operation, beam-losses, recirculation, optics

1839

S. Sakanaka, K. Haga, Y. Honda, H. Matsumura, T. Miyajima, T. Nogami, T. Obina, H. Sagehashi, M. Shimada, M. Yamamoto
KEK, Ibaraki, Japan

The compact ERL (cERL)* is a superconducting accelerator aimed at demonstrating excellent ERL technologies for the future light source. The cERL comprises a 5 MeV injector, a main linac, and a recirculation loop. In the cERL, production and transportation of low-emittance and high average-current beams (tentative goals: 1 mm-mrad and 10 mA) is primarily important. At this moment (in December 2015), beam currents of up to 80 uA (CW) have successfully been transported through the recirculation loop at a beam energy of 20 MeV. Before such high-current operations, we carefully tuned up the machine so that beam losses became very small. The beam losses were watched using fast beam-loss detectors and radiation monitors while absolute losses were estimated from measured radiation levels on the roof of the shield. After careful beam-optics corrections and elimination of beam halos / tails at low-energy section, we achieved the beam losses of at most a few nA level at several locations along the loop, and those below 1 nA elsewhere in the loop. We will report these results together with the result of higher-current operation which is planned early in 2016.
* S. Sakanaka et al., IPAC'15, TUBC1; T. Obina et al., to be presented at IPAC'16.

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TUPOW040

UH-FLUX: Compact, Energy Efficient Superconducting Asymmetric Energy Recovery LINAC for Ultra-high Fluxes of X-ray and THz Radiation

cavity, HOM, electron, coupling

1847

I.V. Konoplev, A. Seryi
JAI, Oxford, United Kingdom
R. Ainsworth
Fermilab, Batavia, Illinois, USA
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Funding: This work was supported (in part) by The Leverhulme Trust through the International Network Grant IN-2015-012.
The conventional ERLs have limited peak beam current because increasing the beam charge and repetition rate leads to appearance of the beam break-up instabilities. At this stage the highest current, from the SRF ERL, is around 300 mA. A single turn (the beam will be transported through the accelerating section, interaction point and deceleration section of the AERL only once) Asymmetric Energy Recovery LINAC (AERL) is proposed. The RF cells in different sections of the cavity are tuned in such a way that only operating mode is uniform inside all of the cells. The AERL will drive the electron beams with typical energies of 10 - 30 MeV and peak currents above 1 A, enabling the generation of high flux UV/X-rays and high power coherent THz radiation. We aim to build a copper prototype of the RF cavity for a compact AERL to study its EM properties. The final goal is to build AERL based on the superconducting RF cavity. Preliminary design for AERL's cavity has been developed and will be presented. The results of numerical and analytical models and the next steps toward the AERL operation will also be discussed.

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TUPOW044

Experimental Investigation of THz Smith-Purcell Radiation From Composite Corrugated Capillary

simulation, detector, electron, vacuum

1861

K. Lekomtsev, A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A. Ponomarenko, A.A. Tishchenko
MEPhI, Moscow, Russia

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
Terahertz part of electromagnetic spectrum has a variety of potential applications ranging from fundamental to security applications. Further advances in development of a linac based, tunable, and narrow band coherent source of THz radiation are very important. Mechanisms of Cherenkov radiation and Smith-Purcell radiation (SPR) [*] may be used for generation of THz radiation via coherent emission [**, ***]. In this report we will present experimental investigations of the SPR generated from the corrugated capillary with a reflector, using the femtosecond multi-bunch electron beam of LUCX accelerator at KEK, Japan [****]. LUCX is capable to generate a train of 4 bunches each with 200 femtosecond (60 micrometer) duration and 200 micrometer transverse size. We will discuss the composite design of the capillary, measurements of the SPR angular distributions and the comparison of these measurements with PIC simulations. In addition, we will discuss SPR spectral characteristics; bunch energy modulation, introduced by the corrugated capillary; and the way in which the bunch spacing changes the spectrum and angular distributions of SPR.
*K.Lekomtsev et al., NIMB 355 (2015) 164
**A. M. Cook et al., PRL 103, (2009) 095003.
***S. E. Korbly et al., PRL 94, (2005) 054803.
****A. Aryshev, arXiv:1507.03302 [physics.acc-ph]

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TUPOW045

Pre-bunched Electron Beam Emittance Simulation and Measurement

electron, simulation, emittance, gun

1864

Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.

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TUPOW047

Generation of a Coherent Cherenkov Radiation by using Electron Bunch Tilting

electron, target, gun, experiment

1870

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
M. Nishida, M. Washio
Waseda University, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

We have been developing a compact accelerator based a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.

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TUPOW053

Measurement of Terahertz Generation in a Metallic, Corrugated Beam Pipe

electron, experiment, dipole, laser

1889

K.L.F. Bane
SLAC, Menlo Park, California, USA
S.P. Antipov
ANL, Argonne, Illinois, USA
M.G. Fedurin, K. Kusche, C. Swinson
BNL, Upton, Long Island, New York, USA
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

Funding: Work supported by the Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-76SF00515
A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations*. We present results of a measurement of such an arrangement at BNL's Advanced Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 um. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam–-compared to the wavelength of the radiation–-to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. Our experimental set-up was simple and not optimized for the efficient collection of the radiation by e.g. the use of tapered horns. As such it can be considered a proof-of-principle experiment.
* K. Bane and G. Stupakov, NIM A677 (2012) 67-73.

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TUPOW054

Characterization of a Sub-THz Radiation Source Based on a 3 MeV Electron Beam and Future Plans

electron, experiment, quadrupole, laser

1892

A.V. Smirnov, R.B. Agustsson, T.J. Campese, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, California, USA
W. Berg, J.C. Dooling, L. Erwin, R.R. Lindberg, S.J. Pasky, N. Sereno, Y.-E. Sun, A. Zholents
ANL, Argonne, Ilinois, USA
Y. Kim
KAERI, Jeongeup-si, Republic of Korea

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC-FOA-0007702)
Design features and some past experimental results are presented for a sub-THz wave source employing the Advanced Photon Source's RF thermionic electron gun. The setup includes a compact alpha-magnet, four quadrupoles, a novel radiator, a THz transport line, and THz diagnostics. The radiator is composed of a dielectric-free, planar, over-sized structure with gratings. The gratings are integrated into a combined horn antenna and ~90° permanent bending magnet. The magnetic lattice enables operation in different modes, including conversion to a flat beam for efficient interaction with the radiating structure. The experiment described demonstrated the generation of narrow bandwidth THz radiation from a compact, laser and undulator-free, table-top system. This concept could be scaled to create a THz-sub-THz source capable of operating in long-pulse, multi-bunch, and CW modes. Additionally, the system can be used to remove unwanted time-dependent energy variations in longitudinally compressed electron bunches or for various time-dependent beam diagnostics. Plans for future experiments and upgrades are also discussed.

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TUPOY003

Novel Approach to Utilize Proton Beams from High Power Laser Accelerators for Therapy

laser, proton, acceleration, target

1905

U. Masood, M. Baumann, W. Enghardt, L. Karsch, J. Pawelke, S. Schürer
OncoRay, Dresden, Germany
M. Baumann
German Cancer Research Center (DKFZ), Heidelberg, Germany
M. Baumann
German Cancer Consortium (DKTK), Dresden, Germany
T.E. Cowan, U. Schramm
Technische Universität Dresden, Dresden, Germany
T.E. Cowan, W. Enghardt, T. Herrmannsdoerfer, J. Pawelke, U. Schramm
HZDR, Dresden, Germany
K.M. Hofmann, J.J. Wilkens
Technische Universität München, Klinikum rechts der Isar & Physics Department, Munich, Germany
F. Kroll
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

Funding: Supported by German BMBF, nos. 03Z1N511 and 03Z1O511 & DFG cluster of excellence MAP.
Protons provide superior radiotherapy benefits to patients, but immense size and cost of the system limits it to only few centers worldwide. Proton acceleration on μm scale via high intensity laser is promising to reduce size and costs of proton therapy, but associated beamlines are still big and massive. Also, in contrast to conventionally accelerated quasi-continuous mono-energetic pencil beams, laser-driven beams have distinct beam properties, i.e. ultra-intense pico-sec bunches with large energy spread and large divergences, and with low repetition rate. With new lasers with petawatt power, protons with therapy related energies could be achieved, however, the beam properties make it challenging to adapt them directly for medical applications. We will present our compact beamline solution including energy selection and divergence control, and a new beam scanning and dose delivery system with specialized 3D treatment planning system for laser-driven proton beams. The beamline is based on high field iron-less pulsed magnets and about three times smaller than the conventional systems*, and can provide high quality clinical treatment plans**.
* U. Masood et al, Applied Phys B, 117(1):41-52, 2014
** K.M. Hofmann et al, Medical Physics, 42(9):5120-5129, 2015

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TUPOY008

Design of a Radiotherapy Machine using the 6 MeV C-Band Standing-Wave Accelerator

linac, electron, vacuum, controls

1921

H. Lim, D.H. Jeong, M.W. Lee, M.J. Lee, S.W. Shin, J. Yi
Dongnam Institute of Radiological and Medical Sciences, Busan, Republic of Korea

The majority of the radiotherapy are performed with linacs producing a uniformly intense electron-beam or X-ray beam of different energies. The linacs have the strong attraction of compactness, efficiency, reliability, moderate cost, and well-known technology. We developed and constructed the 6 MeV C-band linac which consists of a thermionic electron gun, a standing-wave accelerating column with the length of 450 mm, a 2.5 MW magnetron, a beam transport system, a beam collimation and monitoring system, and auxiliary systems of vacuum system, water cooling system etc. For the medical application, the gantry system is required to be rotated around the patient and to deliver the beam to the tumor from the linac. We design the gantry mounting our developed C-band linac isocentrically. In addition, the beam bending system and beam collimation are discussed to optimize the gantry space and to improve the beam performance. In this paper, we describe the designed radiotherapy machine including the gantry, a treatment couch and a control console, and present the study results.

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TUPOY010

6/9 MeV S-band Standing Wave Accelerating Structure for Container X-ray Inspection System at RTX

electron, cavity, linac, gun

1924

P. Buaphad, H.D. Park, S. Song, S.Y. Yoo
RTX, Daejeon, Republic of Korea
H.K. Cha, S.S. Cha, J.H. Ha, Y. Kim, B.C. Lee
KAERI, Daejon, Republic of Korea

Recently, there is a need of X-ray inspection system around the world to combat terrorism, drug and weapons smuggling, illegal immigration, and trade fraud. A compact standing wave (SW) linear accelerator (linac) for container X-ray inspection system has been produced at Radiation Technology eXcellence (RTX) to meet this growing need. The RF accelerating structure uses standing wave side-coupled structure fed by a 5 MW e2v magnetron with frequency of 2856 MHz. The electrons are accelerated from DC gun with energy of 25 keV to the final energy of 6 or 9 MeV at the X-ray target and generate X-ray with the dose rate of 8 Gy/min at 1 m after X-ray target. In this paper, we describe the design and optimization of side-coupled RF structure operating at π/2 mode. The beam dynamic of particle along the RF structure is also included in this paper by using ASTRA code.

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TUPOY018

FLUKA Simulations for Radiation Protection at 3 Different Facilities

neutron, proton, ion, photon

1940

R. Rata, S.C. Lee
IIAA, Huddersfield, United Kingdom
R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom

FLUKA Monte Carlo Code is a transport code widely used in radiation protection studies. The code was developed in 1962 by Johannes Ranft and the name stands for FLUktuierende Kaskade (Fluctuating Cascade). The code was developede for high-energy physics and it can track 60 different particles from 1keV to thousands of TeV. It can be applied to accelerator design, shielding design, dosimetry, space radiation and hadron therapy. For particle therapy, FLUKA uses various physical models, all implemented in the PEANUT (Pre-Equilibrium Approach to Nuclear Thermalization) framework. The investigation was made for three different facilities : the Clatterbridge Cancer Centre, the Christie Hospital and the OpenMeD facility at CERN. We calculated the secondary dose distributed to the patient, in case of Clatterbridge Cancer Centre, and to the workers in case of the Christie Hospital and OpenMeD, and to investigate whether the shielding methods meet the existing radiation protection requirements and that the doses to the staff are kept As Low As Reasonably Achievable (ALARA).

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TUPOY036

Diffusion and Thermal Stability of Implanted Hydrogen in ZnO Nanorods

proton, resonance, lattice, ion

1982

J.K. Park, Y.-S. Cho, H.-J. Kwon, K.T. Seol, S.P. Yun
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC operation fund of KAERI by Ministry of Science ICT and Future Planning of Korean Government.
The 20-MeV proton-beams with a fluence of 10¹² cm^-2 were irradiated on ZnO nanorods. The effects of proton-beam irradiation on ZnO nanorods are investigated by using ¹H nuclear magnetic resonance (NMR) spectroscopy. After irradiation, new and modified NMR resonance lines are observed in ¹H NMR spectra. The diffusion and thermal stability of each proton species are investigated from the lab- and rotating-frame spin-lattice relaxation data depending on temperature. Understanding the properties of thermally stable hydrogen species created by the beam irradiation may promise many possible applications, since the hydrogen stable up to high temperature only meets the device working conditions.

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TUPOY039

Studies on Electron Linear Accelerator System for Polymer Research

electron, linac, coupling, plasma

1985

E. Kongmon
IST, Chiang Mai, Thailand
N. Kangrang
Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand
S. Rimjaem, J. Saisut, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand
P. Wichaisirimongkol
Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand

This research focuses on modification of an elec-tron linear accelerator system for irradiation of natural rubber latex and polymeric materials at the Plasma and Beam Physics Research Facility, Chiang Mai Universi-ty, Thailand. This is in order to study the change of material properties due to electron beam irradiation. The main accelerator system consists of a DC thermi-onic electron gun and a short standing-wave linac. This system will be able to produce electron beams with variable energy in the range of 0.5 to 4 MeV. The linac macro pulse frequency is adjustable within the range of 20 to 1000 Hz. The macro pulse duration is 4 μs. The electron pulse current can be varied from 10 to 100 mA. This lead to the electron dose of about 0.44 to 4.4 Gy-m2/min. In this paper, overview of the accelera-tor and the irradiation system is presented. Results of low-level RF measurements of the accelerating struc-ture are also reported and discussed.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Faculty of science, Chiang Mai University.

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TUPOY047

Development of a Non-destructive Inspection System for Industrial and Societal Infrastructures with 950 keV/3.95 MeV Portable X-band Linac-based X-ray

linac, experiment, site, distributed

2011

R. Yano
The University of Tokyo, Tokyo, Japan
J. Kusano
Accuthera Inc., Kawasaki, Kanagawa, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Advanced maintenance for aging industrial and societal infrastructures such as chemical plant and bridge are strongly needed recently. For the purpose, we are developing, applying and upgrading the 950 keV/3.95 MeV X-band linac X-ray sources for the on-site inspection. Less than 1 MeV accelerators are available for on-site inspection and less than 3.95 MeV accelerators are allowable for only bridge on-site inspection. These systems can visualize in seconds inner states of infrastructures, such as crack of concrete, iron-reinforced rod/wire and other imperfections. By using the 950 keV system, we conducted the first inspection of the real bridge and evaluated degradation of pre-stressed concrete wires. We also demonstrated first on-site use of the 3.95 MeV system in Japan in 2015. We are also performing structural analysis to evaluate the degradation of strength. For more precise evaluation, we are going to carry out a partial angle CT to reconstruct a two-dimensional inner structure. We are going to present the results and strategy of degradation evaluation of the industrial and societal infrastructures by the 950 keV / 3.95 MeV X-ray sources.

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WEXA01

The ESRF Low-emittance Upgrade

lattice, emittance, dipole, vacuum

2023

P. Raimondi
ESRF, Grenoble, France

This talk focuses on novel aspects of the lattice design, describes the technical solutions that have been found for meeting the design goals (including the use of permanent magnet dipoles), outlines the main challenges that will be faced in commissioning and operating the new lattice in a very demanding parameter regime, and discusses how it is hoped to maximize eventual benefits for users while minimizing disruption during the upgrade process.

Slides WEXA01 [23.005 MB]

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WEOAA03

Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III

undulator, experiment, synchrotron, synchrotron-radiation

2036

M. Hosaka
Nagoya University, Nagoya, Japan
M. Katoh, N.S. Mirian
UVSOR, Okazaki, Japan
T. Konomi, N. Yamamoto
KEK, Ibaraki, Japan
K. Kuroda
ISSP, Kashiwa-shi, Japan
K. Miyamoto, S. Sasaki
HSRC, Higashi-Hiroshima, Japan

A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY** and UVSOR-III***. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation.
* S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008)
** J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013)
*** e.g. S. Sasaki et al., presented in SRI2015 (2015)

Slides WEOAA03 [11.023 MB]

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WEOCA03

Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC and FCC-hh

photon, optics, simulation, electron

2073

G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber.

Slides WEOCA03 [0.329 MB]

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WEIB01

Collaboration with Industry in Korea for Medical Accelerators

cyclotron, proton, medical-accelerators, ion

2105

S.H. Nam
KIRAMS/KHIMA, Seoul, Republic of Korea

Activities related to medical accelerator development in Korea have been very active recently. Industrial collaboration in this respect has also been highly active. The current main medical accelerator project in Korea is the Korean Heavy Ion Medical Accelerator (KHIMA) project, which is an heavy ion therapy facility mainly with carbon ions. The collaboration covers wide technical areas such as RF structures, magnets, vacuum components, diagnostics, etc. In this talk, such industrial collaboration aspects in Korea will be presented and further collaboration areas will be proposed.

Slides WEIB01 [5.766 MB]

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WEPMB013

Long Term Cavity Performance in Compact-ERL Injector Cryomodule

cavity, cryomodule, operation, electron

2145

E. Kako, T. Konomi, T. Miura, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

Degradation of cavity performance due to heavy field emission was observed in three 2-cell cavities after beam operation at 5 MeV for 2 years.

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WEPMB017

High Gradient Cavity Performance in STF-2 Cryomodule for the ILC at KEK

cavity, cryomodule, HOM, accelerating-gradient

2158

Y. Yamamoto, T. Honma, E. Kako, Y. Kojima, T. Matsumoto, H. Nakai, T. Shishido
KEK, Ibaraki, Japan

The high power test for STF-2 cryomodule has completed successfully in 2015. Before cooldown of cryomodule, at first, the input coupler conditioning at room temperature is done with detuned cavities. After cooldown, the cavity conditioning, which is the main part in the performance test, is done by monitoring the radiation level measured at three locations around the cryomodule, and the heating and RF output at two HOM (Higher Order Mode) couplers. Consequently, it became clear the average accelerating gradient is 30 MV/m for STF-2 cryomodule (39 MV/m at max. and 15 MV/m at min.), and the second cavity string with four cavities had the significant performance degradation by heavy field emission due to the additional clean room work in the STF tunnel. As the following next steps, there are the LFD (Lorenz Force Detuning) measurement, LFD compensation by piezo, and long run for check of stable operation at high gradient. In the long run around 32 MV/m, each cavity without degradation showed the stable operation with the successful LFD compensation by piezo and RF feedback system. In this paper, the detailed test result will be presented.

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WEPMB024

Study on Nondestructive Inspections for Super-conducting Cavity

cavity, cryogenics, survey, interface

2174

H. Tongu, H. Hokonohara, Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, M. Sawamura
JAEA, Ibaraki-ken, Japan
H. Hayano, T. Kubo, T. Saeki, Y. Yamamoto
KEK, Ibaraki, Japan

Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been studying nondestructive inspections for super-conducting spoke cavities. The temperature mapping (T-map) and X-ray mapping (X-map) are powerful inspection methods to locate a hot spot during the vertical RF tests. There would be a defect under the hot spot and the defect may be the cause of a quench. Our XT-map system (a combined system of T-map and X-map) has a high resolution in space. Because the huge amount of sensor signals are multiplexed at a hi-speed scanning rate in the vicinity of the sensors, the small number of signal lines makes the installation process easy and reduces the system complexity. Our XT-map got useful results on finding a defect in vertical RF tests of International Linear collider super-conducting cavity. The XT-map system is useful as low cost nondestructive inspections for superconducting spoke cavity. The study will be reported. progresses will be reported.

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WEPMB039

Operation Techniques for HWR1 Cryomodule

PLC, EPICS, controls, cryomodule

2205

H. Kim, J.W. Choi, Y.W. Jo, W.K. Kim, Y. Kim, M. Lee
IBS, Daejeon, Republic of Korea

Control systems such as PLC and EPICS are developed for a half-wave resonator (HWR) cryomodule. PLC rack is fabricated for the HWR1 cryomodule. The PLC controls pumps, heaters and valves. The PLC communicates with temperature monitors through Ethernet. HMI of PLC and EPICS controls and monitors pumps, heaters, valves and temperature sensors through switching hub. The PLC HMI is developed and EPICS is also developed. The CSS of EPICS consists of control, monitor, parameter set-up, alarm and data browser screen.

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WEPMB050

RF Test of ESS Superconducting Spoke Cavities at Uppsala University

cavity, resonance, pick-up, controls

2227

H. Li, A.K. Bhattacharyya, V.A. Goryashko, L. Hermansson, R.J.M.Y. Ruber, R. Santiago Kern
Uppsala University, Uppsala, Sweden
N. Gandolfo, G. Olry
IPN, Orsay, France

The European Spallation Source (ESS) is an accelerator-driven neutron spallation source built in Sweden. It will deliver the first protons to a rotating tungsten target by 2019 and will reach the full 5 MW average beam power in the following years. The superconducting Spoke cavities are considered compact structures at low frequencies and having an excellent RF performance in both low and medium velocity regimes, therefore ESS will include a total of 26 double-spoke cavities. The testing of the double-spoke prototype cavity at high power has been conceded to Uppsala University, Sweden, where the Facility for Research Instrumentation and Accelerator development (FREIA) has been equipped with superconducting cavity test facility. A bare spoke cavity has been tested at the FREIA Laboratory with a self-exited loop at low power level to confirm its vertical test performance at IPNO. Similar test results as IPNO's previous test were obtained with FREIA system. In this paper we present the methods and preliminary study results of the cavity performance.

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WEPMR046

Thermal Analysis of the Injection Beam Dump at J-PARC RCS

injection, proton, shielding, synchrotron

2380

J. Kamiya, M. Kinsho, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

In the J-PARC accelerator facility, 400 MeV H⁻ ions are injected from linac to rapid cycling synchrotron (RCS). A thin graphite foil with the thickness of about 300 ug/cm² is located at the injection point to strip two electrons from H⁻ ion and convert it to proton. The charge stripping efficiency is usually more than 99.7 %. In other words, less than 0.3 % H⁻ ions are not accurately exchanged to protons. Most of those remaining H⁻ ions or H⁰ atoms (stripped only one electron from H⁻ ion) are eventually converted to protons by second and third graphite foils and transported to the beam dump. This beam dump consists of an iron block with the size of 0.3×0.3×0.4 m3 for beam stop and the iron block with the size of 3×3×2.5 m3 and concrete with the size of 6×6×6 m3 around the iron block for the radiation shielding. The radiation shielding was designed to endure the 4 kW proton beam to the beam dump. In this presentation, we show the thermal analysis of the beam dump and compare it to the real operation.

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WEPMR055

openSE: a Systems Engineering Framework Particularly Suited to Particle Accelerator Studies and Development Projects

project-management, framework, operation, electronics

2398

P. Bonnal, B. Feral, K. Kershaw, B. Nicquevert
CERN, Geneva, Switzerland
M. Baudin
ENS, Paris, France
L. Lari
ESS, Lund, Sweden
J. Le Cardinal
École Centrale/Supélec, Chatenay Malabry, France

Particle accelerator projects share many characteristics with industrial projects. However, experience has shown that best practice of industrial project management is not always well suited to particle accelerator projects. Major differences include the number and complexity of technologies involved, the importance of collaborative work, development phases that can last more than a decade, and the importance of telerobotics and remote handling to address future preventive and corrective maintenance requirements due to induced radioactivity, to cite just a few. The openSE framework was developed as part of the PURESAFE ITN project funded by the European Commission; it is a systems engineering and project management framework specifically designed for scientific facilities' systems and equipment studies and development projects. Best practices in project management, in systems and requirements engineering, in telerobotics and remote handling and in radiation safety management were used as sources of inspiration, together with analysis of current practices surveyed at CERN, GSI and ESS.

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WEPMR056

Septum Magnet using a Superconducting Shield

septum, shielding, extraction, dipole

2402

D. Barna
University of Tokyo, Tokyo, Japan
F. Burkart
CERN, Geneva, Switzerland

A field-free region can be created within a dipole magnet using a superconducting shield, which maintains persistent eddy currents induced during the ramp-up of the magnet. We will study the possibility to realize a high-field superconducting septum magnet using this principle. Properties of different configurations will be presented, and compared to the requirements of the FCC dump system.

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WEPMW010

Effect of Beamstrahlung on Bunch Length and Emittance in Future Circular e⁺e⁻ Colliders

photon, collider, emittance, synchrotron

2438

M.A. Valdivia García, F. Zimmermann
CERN, Geneva, Switzerland

In future circular e⁺e⁻ colliders, beamstrahlung may limit the beam lifetime at high energies, and increase the energy spread and bunch length at low energies. If the dispersion or slop of the dispersion is not zero at the collision point, beamstrahlung will also affect the transverse emittance. In this paper, we first examine the beamstrahlung properties, and show that for the proposed FCC-ee, the radiation is fairly well modelled by the classical formulae describing synchrotron radiation in bending magnets. We then derive a set of equations describing the equilibrium beam parameters in the presence of a nonzero dispersion at the collision point. An example case from FCC-ee will serve as an illustration.

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WEPMW025

Optimizing the Design of Linear Non-scaling Fixed Field Alternating Gradient Arcs for the Electron Rings of eRHIC

synchrotron, synchrotron-radiation, lattice, electron

2475

J.S. Berg
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
I describe a process for producing optimal linear non-scaling fixed field alternating gradient (FFAG) arc designs for the electron rings of eRHIC, an electron-ion collider in the RHIC tunnel at Brookhaven National Laboratory. The electrons are accelerated in two FFAG rings (low and high energy), which in addition to the arcs optimized here, contain straight sections, splitter/combiner sections, and a linac shared between the rings. The optimization process I use has two layers, an inner one meeting constraints and an outer optimization that minimizes a target function. The target function is an approximation to the FFAG arc cost, for which I give the function used and the basis for that choice. While reducing synchrotron radiation is important, I show that optimizing for synchrotron radiation alone leads to significant cost an performance penalties for the rest of the machine design for very little reduction in synchrotron radiation. I describe important constraints on the design, in particular minimum drift lengths, maximum and minimum tunes, and clearance from the beam to the beam pipe. Finally, I present possible eRHIC FFAG parameters resulting from this optimization.

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WEPMW032

Radiation-induced Effects on LHC Collimator Materials under Extreme Beam Conditions

ion, proton, neutron, heavy-ion

2502

E. Quaranta, A. Bertarelli, F. Carra, P.D. Hermes, S. Redaelli, A. Rossi
CERN, Geneva, Switzerland
K. Bunk
Goethe Universität Frankfurt, Frankfurt am Main, Germany
F. Carra
Politecnico di Torino, Torino, Italy
J. Guardia Valenzuela
Universidad de Zaragoza, Zaragoza, Spain
P.D. Hermes
Westfaelische Wilhelms-Universität Muenster, Muenster, Germany
C.L. Hubert, M. Tomut
GSI, Darmstadt, Germany
P. Nocera
Università di Roma I La Sapienza, Roma, Italy
C. Porth
TU Darmstadt, Darmstadt, Germany
N. Simos
BNL, Upton, Long Island, New York, USA

Over the last years, several samples of present and novel LHC collimator materials were irradiated under various beam conditions (using protons, fast neutrons, light and heavy ions at different energies and fluences) in different facilities around the world. This was achieved through an international collaboration including many companies and laboratories over the world. The main goal of the beam tests and the post-irradiation campaign is the definition of a threshold for radiation damage above which LHC collimators need to be replaced. In this paper, highlights of the measurements performed will be presented. First conclusions from the available data are also discussed.

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WEPMY015

Numerical Studies on Tunable Coherent Radiations with a Laser-Plasma Accelerator

electron, plasma, laser, acceleration

2579

J. Kim, M. Kim, I.H. Nam, H. Suk
GIST, Gwangju, Republic of Korea
M.S. Hur
UNIST, Ulsan, Republic of Korea

Generation of tunable coherent radiation is numerically investigated via the two-dimensional particle-in-cell (2D-PIC) code developed by UNIST* and SIMPLEX developed by Spring-8. The electron beams can be produced by the laser-driven wakefield acceleration technique. The electron beam energy can be easily adjusted between 450 MeV and 800 MeV with a tapered density plasma on the order of 1×10¹⁸ cm^-3 while the driving laser power is fixed, and the high-energy electron beams can be sent through the undulator arrays for the coherent light emission. The energy-controllable electron bunches can provide an opportunity to control the radiation wave-length with the fixed gap undulators. For the tapered density profile, a capillary cell with two gas inlets can be used. In this paper, we show some simulation and numerical research results regarding these issues, which reveal the possibility for a tunable light source in the soft X-ray regime.
* M. S. Hur, H. Suk, Phys. Plasmas 18 033102 (2011).

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WEPOR018

Position Monitoring System for HL-LHC Crab Cavities

cavity, monitoring, vacuum, alignment

2704

M. Sosin, T. Dijoud, H. Mainaud Durand
CERN, Geneva, Switzerland
V. Rude
ESGT-CNAM, Le Mans, France

The high luminosity upgrade for the LHC at CERN (HL-LHC project) will extend the discovery potential of the LHC by a factor 10. It relies on key innovative technologies like superconducting cavities for beam rotation, named 'crab cavities'. Two crab cavities will be hosted in a superconducting cryostat working at a cold (<3 K). The position of each cavity will be monitored during the cool-down and the operation in order to comply with the tight alignment tolerances: the misalignment of a cavity axis w.r.t. the other will have to be lower than 0.5 mm and each cavity roll w.r.t. the cryostat axis will have to be lower than 1 mrad. Moreover, the monitoring system will have to be radiation hard (up to 10 MGy) and maintenance free. We propose a solution based on the Frequency Scanning Interferometry to provide the position monitoring of the crab cavities. This paper describes the design and study of such a solution, including the engineering approach, the issues encountered and the lessons learnt.

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WEPOR019

Development of CVD Diamond Detector for Beam Conditioning Monitor at the SuperKEKB Linac

detector, target, electron, linac

2707

S. Kazama, T. Kamitani
KEK, Ibaraki, Japan
P. Bambade, V. Kubytskyi
LAL, Orsay, France

Positron beams in SuperKEKB will be produced from electromagnetic showers originating from the interaction between primary electron beams and a tungsten target. Since the emittance of primary beams is very small, the target is easy to be destroyed if focused beams are irradiated. In the SuperKEKB LINAC, a plate called spoiler is placed in the upstream of the target to enlarge the beam spot size. If the beam control is in a correct way, radioactive rays will be observed near both the spoiler and the target. However, if the beam control is not successful and primary beams are irradiated directly on the target, significant radiations are observed only near the target. If such a behavior is observed, primary beams must be stopped to protect the target. Since the number of electrons in a bunch is quite large(~10nC), the radiation dose is expected to be very high. Therefore, the radiation detector is required to have a high radiation-tolerance over a long period of time. Diamond has a high radiation tolerance due to its strong covalent bond, and we are now developing radiation detectors using diamond crystals. In this talk, current status including beam test measurements will be shown.

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WEPOR021

Residual Radiation Monitoring by Beam Loss Monitors at the J-PARC Main Ring

detector, extraction, proton, quadrupole

2715

T. Toyama, K. Satou
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
H. Kuboki, H. Nakamura, B. Yee-Rendón
KEK, Tokai, Ibaraki, Japan
M.J. Shirakata
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

At J-PARC (the Japan Proton Accelerator Research Complex), high intensity proton accelerator, controlling and localizing beam losses and residual radiations are key issue, because the residual radiation limits maintenance work in efficiency and working hours, and then limits machine availability. We are accumulating continuous measurement data of residual radiation after beam stop using beam loss monitors in the Main Ring (MR). The wire cylinder gaseous radiation detectors are used in a proportional counting region. The heads are DC-connected and have a gain as large as 30000 with a bias of -2 kV. We switch the DAQ trigger from "Beam Trigger" to "No Beam Trigger", change the ADC sampling rate to 16 ms, and raise the gain by changing the bias voltage from -1.6 kV to -2.0 kV with a few exceptions when the accelerator operation ends. The offsets are measured with zero bias voltage. Identification of radionuclides has been performed with time decay analysis, with assistance of energy spectrum measurements with the Gamma Ray Spectrometer, Kromek GR1-Spectro.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR021

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WEPOR022

Residual Radiation Measurements at J-PARC MR Using the ASTROCAM 7000HS Newly Developed Radioactive Substance Visualization Camera

scattering, controls, electron, site

2719

N. Ikeda, T. Sugano
MHI-MS, Kobe, Japan
K. Genba, M. Komeda, Y. Kuroda, D.M. Matsuura
MHI, Komaki-si, Japan
A. Harayama, T. Takahashi, S. Watanabe
ISAS/JAXA, Kanazawa, Japan
H. Nakamura, K. Niki, C. Ohmori, M.J. Shirakata
KEK, Ibaraki, Japan
S. Takeda
OIST, Onna-son, Okinawa, Japan

Mitsubishi Heavy Industries, Ltd. (MHI) released the ASTROCAM 7000HS, a radioactive substance visualization camera. The ASTROCAM 7000HS incorporates the technologies for the gamma-ray detector used for the ASTRO-H satellite, which MHI has been developing under entrustment from and together with scientists at the Institute of Space and Astronautical Science (ISAS) at the Japan Aerospace Exploration Agency (JAXA), and the design was modified for use on land to commercialize the product. MHI and Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS) performed on-site residual radiation measurements at the 50 GeV Main Ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC) under collaboration with the High Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Agency (JAEA) and succeeded visualization of radiation hot spots of the accelerator components. The outline of the ASTROCAM 7000HS, the measurement principle and the first measurement results at the J-PARC MR are described.

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WEPOR023

Radiation Shielding Considerations for CEPC-SPPC

shielding, synchrotron-radiation, synchrotron, monitoring

2722

Z.J. Ma, Y.D. Ding, N. Li, Q.B. Wang, M.Y. Yan, Q.J. Zhang
IHEP, Beijing, People's Republic of China

A planned project CEPC-SPPC is under-researched by IHEP, CAS, China. Due to its big circumference and high energy, the radiation shielding issues should be treated more serious than ever whether for the machine itself or the worker and the public. In this paper, we briefly introduce the configurations and parameters of the machine, the tools and principle used in the radiation shielding design, and discuss the preliminary result for the shielding of main tunnel and the synchrotron radia-tion. Some radiation protection issues are listed to be resolved next. All the aspects presented should be dis-cussed and verified, any other unmentioned radiation protection problems will be excavated in the future.
CEPC: Circular Electron-Positron Collider
SPPC: Super Proton-Proton Collider
IHEP: Institute of High Energy Physics
CAS: Chinese Academy of Sciences

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WEPOR029

Concept of a Fire and Gas Safety System for Accelerators

interface, operation, detector, cryogenics

2729

M. Dole, S. Grau, D. Raffourt
CERN, Geneva, Switzerland

Today CERN's facilities are equipped with automatic smoke and gas detection systems. Upon smoke or gas leak detection, local safety actions are automatically performed and alarms indicating the location and type of danger are transmitted to the CERN Fire Brigade. The firefighters then size their intervention based on the information received. The increasing complexity, size and quantity of CERN installations drives safety systems to evolve in the direction of simplicity. Intuitive interfaces are required to cope with high turnover of firefighters, and the inherent multinational environment. Global overview of alarms and safety actions statuses are needed by firefighters to decide on the best strategy for intervention. In some emergency situations, it might be necessary to manually trigger remote actions. CERN is studying a new concept, inspired by French standards, where the detection and protection layers are separated and act independently, but provide a common interface. This paper presents an application of this concept for the SPS* accelerator. Detection, fire-compartment and evacuation zones are presented, as well as the architecture of the detection and protection layers.
*SPS: Super Proton Synchrotron

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WEPOR030

Gas Filled RF Resonator Hadron Beam Monitor for Intense Neutrino Beam Experiments

electron, plasma, cavity, experiment

2733

K. Yonehara, A.V. Tollestrup, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
R.J. Abrams, R.P. Johnson, G.M. Kazakevich
Muons, Inc, Illinois, USA
H.M. Dinkel
University of Missouri, Columbia, Columbia, Missouri, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE HEP STTR Grant DE-SC0013795.
MW-class beam facilities are being considered all over the world to produce an intense neutrino beam for fundamental particle physics experiments. A radiation-robust beam monitor system is required to diagnose the primary and secondary beam qualities in high-radiation environments. We have proposed a novel gas-filled RF-resonator hadron beam monitor in which charged particles passing through the resonator produce ionized plasma that changes the permittivity of the gas. The sensitivity of the monitor has been evaluated in numerical simulation. A signal manipulation algorithm has been designed. A prototype system will be constructed and tested by using a proton beam at the MuCool Test Area at Fermilab.

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WEPOR031

Field Emission Radiation Characterization of LCLS-II Cavities

cavity, cryomodule, detector, linac

2736

M. Santana-Leitner, C. Adolphsen, L. Ge, Z. Li, T.O. Raubenheimer, M.C. Ross
SLAC, Menlo Park, California, USA
S. Aderhold, A. Grassellino, O.S. Melnychuk, R.V. Pilipenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
LCLS-II XFEL facility at the SLAC National Accelerator Laboratory will accelerate CW beams of up to 300 uA to 4 GeV using superconducting radio frequency cavities. Before installation, fully assembled cryomodules will be tested at Fermilab and Jefferson Lab. Besides the basic measurements of cavity gradients and cryogenic heat loads, radiation and dark current levels will be recorded. The latter parameters need to be limited to ensure the safety of the machine and the lifetime of radio-sensitive components installed near the cavities. In this paper we describe the simulation studies being done in preparation of tests, where expected radiation measurements in the different detectors are correlated with field emission and with dark currents in Faraday cups at each end of the cryomodule. This work includes simulations using a detailed model of the cryomodules and detectors, where field emission data generated with Track3P is parsed to the FLUKA radiation transport code.

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WEPOR057

A Mass Spectrometer for Measuring a High Current Ion Beam With a Big Range of the Charge-to-Mass Ratio

ion, detector, induction, ion-source

2799

Z. Bowen, S. An
PLAI, Nanjing, People's Republic of China
L. Zhang
Chang'an University, Chang'an, People's Republic of China

In order to analyze a high-current mixed-ion beam's physical properties with a current of 100 mA and a charge-to-mass ratio range from 1:1 to 1:48, a mass spectrometer has been developed to measure the beam's current, profile and ratio of the different ions by Nanjing University and Andesun Technology Inc. The main part of the mass spectrometer is a mass analyzer, which is used to measure the different ion's beam current at the same time. This paper introduces the design of the mass analyzer.

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WEPOR059

Calculation for the Radiation Dose in Storage Ring Hall based on Monte Carlo Method

storage-ring, electron, neutron, vacuum

2805

S. Huang, T.L. He, S.C. Zhang, T. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Radiation dose assessment in synchrotron radiation facility is challenging due to the complexity and uncertainties of radiation source terms induced by high energy particle accelerator. Hefei light source (HLS) is the first dedicated synchrotron radiation light source in China. Radiation dose assessment for users at HLS Beam lines is highly concerned. This study presents the method calculating the radiation dose in storage ring hall under normal operation state, the simplified Monte Carlo calculation model was introduced in detail. We obtained the results of radiation dose distribution in HLS storage ring hall with using MCNP, which are in the same order of magnitude with the experimental results. It indicates that the method can be used to calculate the radiation dose level in storage ring hall, and it has certain guiding significance for the radiation protection.

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WEPOW005

Updates on Lattice Modeling and Tuning for the ESRF-EBS Lattice.

lattice, injection, dipole, quadrupole

2818

S.M. Liuzzo, N. Carmignani, J. Chavanne, L. Farvacque, G. Le Bec, B. Nash, P. Raimondi, R. Versteegen, S.M. White
ESRF, Grenoble, France

The ESRF-EBS lattice model is updated to include the effect of magnetic lengths in dipoles, quadrupoles, sextupoles and combined function magnets. The effect of this modification and the updates to the injection cell are considered with particular focus on injection efficiency and Touschek lifetime. The solutions to introduce new sources of radiation suitable for the existing bending magnet radiation beamlines are also presented.

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WEPOW008

Specific Operation Modes at the Metrology Light Source

operation, electron, emittance, cavity

2829

J. Feikes, P. Goslawski, J. Li, M. Ries, M. Ruprecht, G. Wüstefeld
HZB, Berlin, Germany
A. Hoehl
PTB, Berlin, Germany

The high flexibility of the Metrology Light Source (MLS) allows application of various nonstandard user modes adapted to the specific needs of their users. We report on some of them including a mode for division of the revolution frequency for the user signal and a mode with an adjustable photon pulse delay on the few ps scale.

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WEPOW009

The Bessy Vsr Project for Short X-Ray Pulse Production

operation, optics, storage-ring, SRF

2833

A. Jankowiak, W. Anders, T. Atkinson, H. Ehmler, A. Föhlisch, P. Goslawski, K. Holldack, J. Knobloch, P. Kuske, D. Malyutin, A.N. Matveenko, R. Müller, A. Neumann, K. Ott, M. Ries, M. Ruprecht, A. Schälicke, A.V. Vélez, G. Wüstefeld
HZB, Berlin, Germany
A. Burrill
SLAC, Menlo Park, California, USA

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association
HZB has started the innovative project, BESSY VSR, to upgrade the 1.7 GeV synchrotron radiation source BESSY II. Its goal is to provide both 1.7 ps and 15 ps long, intense X-ray pulses simultaneously at all beam lines. These pulses are generated by enhanced longitudinal bunch focusing using superconducting 5-cell cavities operating at 1.5 GHz and 1.75 GHz. The resulting beating of the voltages creates alternating long and short buckets that can be custom filled. As a first major step, prototype superconducting cavities, initially only cooled to 4.4 K and thus operating at reduced voltage, will be installed into the BESSY II storage ring. Physical and technical aspects of this proposal where recently studied* and the results and project status are presented.
* A. Jankowiak, J. Knobloch for the BESSY VSR team, Technical Design Study BESSY VSR, doi:10.5442/R0001, Helmholtz-Zentrum Berlin (Germany), June 2015.

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WEPOW010

Beam Lifetime Optimization by Adjusting the Sextupoles at the MLS and BESSY

sextupole, emittance, storage-ring, operation

2837

J. Li, J. Feikes, P. Goslawski, M. Ries, M. Ruprecht, T. Tydecks
HZB, Berlin, Germany

The Metrology Light Source (MLS) is a dedicated elec-tron storage ring for metrology applications with three families of sextupoles. The existing setting of the three independently powered sextupole families respective to lifetime were roughly determined by scanning their strengths against each other. As a flexible machine the sextupole families of the MLS can be regrouped into new families, which increase the complexity of the scan pro-cedure. Consequently the former strategy would be too time-consuming for refined global scan and it has to be complemented with physical constraints. Therefore a scheme has been developed to keep the chromaticity in a reasonable range during the scan and to reduce the degree of freedom, which is even more important at BESSY II with increasing number of independent sextupole cir-cuits. This paper presents the principle of sextupole scan and the experimental results at the MLS and preliminary test at BESSY II.

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WEPOW013

Coherent Harmonic Generation in the Presence of Synchronized RF Phase Modulation at DELTA

electron, resonance, synchrotron, laser

2847

M.A. Jebramcik, F.H. Bahnsen, M. Bolsinger, S. Hilbrich, M. Höner, S. Khan, C. Mai, A. Meyer auf der Heide, R. Molo, G. Shayeganrad, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF (05K13PEC), DFG (INST 212/236-1) and the Stiftung Mercator (Pr-2014-0047).
At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort coherent pulses in the VUV and THz regime are generated via coherent harmonic generation (CHG). The intensity of the light depends strongly on the quality of the laser-electron interaction and therefore on the energy spread and density of the electron bunches. In 2014, a significant increase of the CHG intensity was observed by phase-modulating the RF cavity voltage, which is routinely used to prolong the beam lifetime. RF phase modulation can generate multiple stable regimes (islands) in longitudinal phase space when run near an integer multiple of the synchrotron frequency resulting in a modulation of the electron density and energy spread. A numerical simulation supporting the experimental observations is presented.

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WEPOW014

Spectral Studies of Ultrashort and Coherent Radiation Pulses at the DELTA Storage Ring

laser, electron, undulator, bunching

2851

S. Khan, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M.A. Jebramcik, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, G. Shayeganrad, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF (05K13PEC, 05K13PE3), the DFG (INST 212/236-1 FUGG), the Stiftung Mercator (Pr-2014-0047) and the state of NRW.
At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort and coherent radiation pulses in the VUV and THz regime are routinely generated by the interaction of electron bunches with 45-fs laser pulses. A laser-induced modulation of the electron energy is converted into a density modulation (microbunching) by a magnetic chicane, giving rise to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). As a first step towards active control of the shape and spectrum of CHG pulses, spectral studies were performed under variation of the chicane strength and the laser properties. The spectral phase of the laser pulses was controlled by tuning the compressor of the laser amplifier and was monitored using FROG (frequency-resolved optical gating). In this paper, monochromator scans as well as single-shot spectrograms of the CHG radiation are presented and compared to simulations of the laser-electron interaction and microbunching process. In addition, other results from the short-pulse facility as well as a future upgrade employing the echo-enabled harmonic generation (EEHG) scheme will be outlined.

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WEPOW015

Influence of Filling Pattern Structure on Synchrotron Radiation Spectrum at ANKA

synchrotron, synchrotron-radiation, storage-ring, detector

2855

J.L. Steinmann, E. Blomley, M. Brosi, E. Bründermann, C.M. Caselle, N. Hiller, B. Kehrer, A.-S. Müller, M. Schedler, M. Schuh, M. Schwarz, P. Schönfeldt, M. Siegel
KIT, Karlsruhe, Germany

Funding: This work is supported by the Helmholtz International School for Teratronics (HIRST)
We present the effects of the filling pattern structure in multi-bunch mode on the beam spectrum. This effects can be seen by all detectors whose resolution is better than the RF frequency, ranging from stripline and Schottky measurements to high resolution synchrotron radiation measurements. Our heterodyne measurements of the emitted coherent synchrotron radiation at 270 GHz reveal discrete frequency harmonics around the 100 000th revolution harmonic of ANKA, the synchrotron radiation facility in Karlsruhe, Germany. Significant effects of bunch spacing, gaps between bunch trains and variations in individual bunch currents on the emitted CSR spectrum are described by theory and supported by observations.

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WEPOW019

SPring-8 Upgrade Project

undulator, emittance, operation, laser

2867

H. Tanaka, T. Ishikawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Goto, S. Takano, T. Watanabe, M. Yabashi
JASRI/SPring-8, Hyogo, Japan

Plans are underway for the upgrade of the SPring-8 facility, targeting completion in the early 2020's. Sustainability is a key guiding principle for the fourth-generation X-ray source - a beam emittance of around 100 pm.rad is pursued simultaneously with substantial energy-saving. The three key features of the design are (i) to replace the main dipole electric magnets with permanent magnets, (ii) to reduce the electron beam energy from 8 to 6 GeV, and (iii) to use the SACLA linac as an injector. Lowering the beam energy leads to reduction of (a) beam emittance, (b) magnetic fields, (c) the lengths of ID straight sections to maintain larger spaces for the magnets, and (d) the RF power consumption. Timeshare use of the SACLA linac enables beam injection to the upgraded ring with a low-emittance and short-pulsed beam as well as a reduction of injector power consumption by stopping the present injector consisting of a 1-GeV linac and a booster synchrotron. The outline of the upgrade plan will be reported with the current status of R&D started in 2015.

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WEPOW023

Present Status of Accelerators in Aichi Synchrotron Radiation Center

synchrotron, storage-ring, synchrotron-radiation, injection

2877

Y. Takashima, M. Hosaka, A. Mano
Nagoya University, Nagoya, Japan
Y. Hori, N. Yamamoto
KEK, Ibaraki, Japan
M. Katoh
UVSOR, Okazaki, Japan
S. Koda
SAGA, Tosu, Japan
S. Sasaki
JASRI/SPring-8, Hyogo, Japan
T. Takano
Hitachi Ltd., Ibaraki-ken, Japan

Aichi Synchrotron Radiation Center is the newest synchrotron radiation facility in Japan. The construction was started in 2010 and the facility was opened for public use on March 26, 2013. The circumference of the storage ring is 72 m with the electron energy of 1.2 GeV, the beam current of 300 mA and the natural emittance of about 53 nmrad. The beam is injected from a booster synchrotron with the energy of 1.2 GeV as full energy injection and the top-up operation has been carried out routinely with stored current of 300 mA since opened for public use. We have tested a pulsed multi-pole magnet for improving the deviation of the orbit of stored beam during the top-up beam injection. The storage ring consists of four triple bend cells. Eight of the twelve bending magnets are normal conducting ones. Four of them are 5 T superconducting magnets(superbend) of which bending angle is 12 degrees. The superbends are running without any trouble with refrigerator maintenance once per year. The accelerators have been operated about 1400 hours stable in a year. Eight of the synchrotron radiation beamlines have been operational for public use and other two beamlines are under construction.

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WEPOW029

Solaris Storage Ring Commissioning

storage-ring, vacuum, optics, closed-orbit

2895

A.I. Wawrzyniak, P.B. Borowiec, L.J. Dudek, K. Karaś, A.M. Marendziak, K. Wawrzyniak, J. Wikłacz, M. Zając
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
C.J. Bocchetta, M. Boruchowski, P. Bulira, P.P. Goryl, A. Kisiel, W.T. Kitka, M.P. Kopec, P. Król, M.J. Stankiewicz, J.J. Wiechecki, L. Żytniak
Solaris, Kraków, Poland
R. Nietubyć
NCBJ, Świerk/Otwock, Poland

Funding: Work supported by the European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09
The Solaris storage ring represents a new class of light source that utilizes the innovative concept of a solid iron block containing all the Double Bend Achromat (DBA) magnets. The use of small magnet gaps brings the benefit of high fields but requires vacuum chambers of high me-chanical accuracy and distributed pumping. Due to very tight mechanical tolerances of the magnet blocks and of the vacuum vessels, the installation of the Solaris storage ring was a challenging task. In this paper the commission-ing results and the performance of this novel machine will be discussed.

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WEPOW034

Emittance Diagnostics at the Max Iv 3 Gev Storage Ring

dipole, emittance, electron, diagnostics

2908

J. Breunlin, Å. Andersson
MAX IV Laboratory, Lund University, Lund, Sweden

With the MAX IV project in Lund, Sweden an ultralow emittance storage ring light source is going into user operation in 2016. Due to its multibend achromat lattice design the 3 GeV storage ring reaches a horizontal emittance lower than 330 pm rad. Emittance diagnostic will involve two diagnostic beamlines to image the electron beam with infrared and ultraviolet synchrotron radiation from bending dipoles. Placed in locations of different optic functions the beamlines will provide experimental access to both horizontal and vertical emittance and to beam energy spread. Since bunch lengthening with harmonic cavities is essential for machine performance, time resolved measurements with synchrotron radiation for individual longitudinal bunch distributions are of special interest as well.

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WEPOW039

Preliminary Beam Loss Study of TPS during Beam Commissioning

injection, photon, scattering, EPICS

2926

C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Liao, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Taiwan photon source (TPS) is a 3rd generation and 3 GeV synchrotron light source in NSRRC. Several types of beam loss monitors (BLMs) such as RadFETs and PIN-diode BLMs are installed in the storage ring to understand the beam loss distribution and mechanism during the injection, decay mode, top-up operation and beam trip. Several RadFETs are also installed around the inserting devices to study the beam loss near the linear scalar. The preliminary beam loss study using RadFETs are PIN-diode BLMs in the storage will be summarized in this report.

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WEPOW042

Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function

undulator, electron, brilliance, photon

2933

H.W. Luo, C.H. Lee
NTHU, Hsinchu, Taiwan
T.Y. Chung, C.-S. Hwang
NSRRC, Hsinchu, Taiwan

Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.

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WEPOW043

Accelerator Based Light Source Projects of Turkey

FEL, electron, undulator, linac

2936

A.A. Aksoy, Ö. Karslı, C. Kaya
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
B. Ketenoğlu, O. Yavaş
Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey
Z. Nergiz
Nigde University, Nigde, Turkey

Three light source project is ongoing in Turkey within the frame of Turkish Accelerator Center (TAC) Project which has been supported by Ministry of Development since 2006. As a first facility of TAC, 3-250 μ mm IR-FEL facility (TARLA) based on superconducting accelerator with an energy of maximum 40 MeV is under construction at Institute of Accelerator Technologies of Ankara University. In addition to TARLA, Conceptual/Technical Design Report of a third generation synchrotron radiation facility based on 3 GeV, and a fourth generation FEL facility based 1-6 GeV is being prepared for the next steps of TAC. Therewithal a proton accelerator facility with up 2 GeV and an electron-positron collider as a super charm factory are proposed within the frame of TAC project. In this presentation, current status of TARLA project and main goals, road map of Turkish Light Sources will be explained.

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WEPOW046

Status of the Front Ends Project at MAXIV

storage-ring, vacuum, insertion, insertion-device

2947

A. Bartalesi, Y. Cerenius
MAX IV Laboratory, Lund University, Lund, Sweden
S. Forcat Oller
SLAC, Menlo Park, California, USA

The MAX IV laboratory is a Swedish national laboratory for synchrotron radiation hosted by the Lund University. It will operate two storage rings to produce synchrotron light of very high intensity and quality over a broad wavelength range. A linear accelerator will feed these storage rings in topping up mode as well as serve as an electron source for a short pulse facility built on its extension. The storage rings have different sizes and operates at different energies: the MAX IV 1.5 GeV ring has 12 straight sections optimized for soft x-rays; while the MAX IV 3.0 GeV ring, has 20 straight sections, optimized for harder x-rays. In the initial stage of the project, five beamlines are foreseen to operate on the 3 GeV storage ring and an additional five on the 1.5 GeV ring. Each beamline requires a front end to interface the different characteristics in terms of vacuum level, heat loads, radiation safety, beam size and position, with respect to the storage ring. This paper describes the status of the different Front Ends project at MAXIV.

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WEPOW059

The NSLS-II Top Off Safety System

operation, injection, storage-ring, controls

2985

R.P. Fliller, D. Bergman, A. Caracappa, L. Doom, G. Ganetis, Y. Hu, Y. Li, W. Louie, D. Padrazo, O. Singh, J. Tagger, G.M. Wang, Z. Xia
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Top Off operation is the desired mode of operation for 3rd generation light sources to ensure beam current stability for user experiments. However, top off operation introduces the hazard of injecting electrons into the front ends with the beamline shutters open. This hazard can be mitigated with the appropriate safety system. This past year, the NSLS-II has transitioned from decay mode to top off operation with the introduction of the Top Off Safety System (TOSS). Top Off was initially demonstrated September 22, 2015 and become standard mode of operating. In this paper we discuss the top off safety system, operation with the system, and future directions.

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WEPOY004

Integrated Green Function for Charged Particle moving along Bending Orbit

synchrotron, synchrotron-radiation, simulation, collider

2997

K. Ohmi, S. Chen
KEK, Ibaraki, Japan
H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ³/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σ_x/n_x× σ_y/n_y× σ_z/n_z (n_xyz ∼ 10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space.

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WEPOY016

Use of Nonuniform Magnets for Emittance Reduction

emittance, lattice, dipole, simulation

3014

E.B. Levichev, G.N. Baranov, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia

We study a theoretical minimum emittance (TME) for a non-uniform bending magnet including a three-step bend (sandwich magnet), a dipole with linear ramp of the bend-ing radius and the same but with a central segment of constant field. We derive expression for the minimum emittance and expand it into a power series with respect to the bending angle. A zero-order term naturally gives the uniform magnet TME while higher-order terms are responsible for the emittance reduction. Theoretical re-sults are verified by numerical simulation.

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WEPOY021

Nonlinear Phase Distortion in a Ti:Sapphire Optical Amplifier for Optical Stochastic Cooling

undulator, laser, kicker, pick-up

3024

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Optical Stochastic Cooling (OSC) has been considered for future high-luminosity colliders as it offers much faster cooling time in comparison to the micro-wave stochastic cooling. The OSC technique relies on collecting and amplifying a broadband optical signal from a pickup undulator and feeding the amplified signal back to the beam. It creates a corrective kick in a kicker undulator. Owing to its superb gain qualities and broadband amplification features, Titanium:Sapphire medium has been considered as a gain medium for the optical amplifier (OA) needed in the OSC*. A limiting factor for any OA used in OSC is the possibility of nonlinear phase distortions. In this paper we experimentally measure phase distortions by inserting a single-pass OA into one leg of a Mach-Zehnder interferometer. The measurement results are used to estimate the reduction of the corrective kick a particle would receive due to these phase distortions in the kicker undulator.
* A. Zholents, and M. Zolotorev. Proc. PAC'97, 1805 (1998).

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WEPOY022

Light Optics for Optical Stochastic Cooling

undulator, kicker, electron, pick-up

3028

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.
* V. Lebedev, et al., Proc. COOL'15 (in press, 2015).

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WEPOY026

Simulation and Measurement of the Beam Breakup Instability in a W-band Corrugated Structure

wakefield, dipole, electron, simulation

3044

D. Wang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA

The corrugated wakefield structure has wide application in electron beam energy manipulation and high frequency RF radiation generation. The transverse wakefield which cause beam breakup (BBU) instability is excited when the drive beam is not perfectly centered through the structure. Here we report on the numerical and experimental investigation of the BBU effect in a W-band corrugated structure, for both cases of short range wakefield and long range wakefield. In the numerical part we develop a point to point (P2P) code that allows rapid and efficiency simulations of the beam dynamics effect by wakefield, which is based on the the particle-wake function coupled dynamics equation of motion. And the experimental measurements of BBU effect are found to be in good agreement with the simulations.

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WEPOY035

Free Electron Laser Simulation Tool Based on FDTD/PIC in the Lorentz Boosted Frame

FEL, simulation, undulator, electron

3061

A. Yahaghi, A. Fallahi, F.X. Kärtner
CFEL, Hamburg, Germany
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA

Funding: Alexander von Humboldt-Foundation European Research Council(ERC)
Free Electron Lasers (FELs) are promising sources capable of generating electromagnetic waves in the whole spectrum. Therefore, it is crucial and additionally very useful to develop sophisticated though complete simulation tools. This goal is mainly motivated by our research focus on the development of compact X-ray sources based on radiation in optical undulators. The currently existing softwares are usually written to tackle special cases with particular approximations, such as 1D FEL theory, steady state, slow wave and forward wave approximation, wiggler-averaged electron motion and slices approximation. Many of the above approximations are hardly valid when sub-femtosecond bunches interact with intense optical lasers. The presented software aims the analysis of the FEL interaction without considering any of the above approximations. The developed tool apparently suffers from long computation times but offers a more accurate picture on the radiation process. In order to overcome the problem of multidimensionality, we exploit Lorentz boosted coordinate system and implement Finite Difference Time Domain (FDTD) method combined with Particle in Cell (PIC) simulation in this frame.

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WEPOY037

Optimization of THz Radiation Pulses at FLUTE

electron, simulation, gun, linac

3067

M. Yan, A.-S. Müller, M.J. Nasse, M. Schuh, M. Schwarz
KIT, Karlsruhe, Germany

The accelerator test facility FLUTE (Ferninfrarot Linac Und Test Experiment) will allow research and development in electron accelerator technology as well as photon science. Electron bunches of durations in the femtosecond range will be provided to generate intense THz radiation. Start-to-end simulation of the accelerator has been performed with the bunch length as the optimization objective. Based on the resulting charge distribution the expected THz field properties can be calculated. In this paper we combine the two tools and present first results.

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WEPOY046

Beam Delivery Simulation: BDSIM - Automatic Geant4 Models of Accelerators

simulation, collider, background, detector

3098

L.J. Nevay, S.T. Boogert, L.C. Deacon, S.M. Gibson, R. Kwee-Hinzmann, W. Shields, J. Snuverink
JAI, Egham, Surrey, United Kingdom
H. Garcia
CERN, Geneva, Switzerland

Beam Delivery Simulation (BDSIM) is a program that uses a suite of high energy physics software including Geant4, CLHEP & ROOT, that seamlessly tracks particles through accelerators and detectors utilising the full range of particles and physics processes from Geant4. BDSIM has been used to simulate linear colliders such as the International Linear Collider (ILC) and more recently, circular colliders such as the Large Hadron Collider (LHC). The latest developments including improved geometry modelling; external geometry support; process biasing; and a new event display are presented. A significantly revised and improved accompanying tool chain is presented comprising of a series of Python utilities that allow efficient and automatic preparation of models. Furthermore, a library for both ROOT and Python that provides powerful analysis and event viewing after simulation is demonstrated.

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WEPOY060

YACS - Progression Towards Isoparametric 2.5D Finite Elements

cavity, software, synchrotron-radiation, experiment

3135

B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB.
YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. Prior studies and benchmarks, comparing YACS to well known commercial 3D and 2D applications, already demonstrated its capabilities of performing fast optimizations of geometries, due to its minimal computational overhead. However, because of the first order elements and basis functions used for approximation of the domain and field, this solving speed advantage vastly diminishes when targeting higher accuracies. In order to circumvent these issues, YACS was upgraded to support arbitrary order basis functions and curved meshes, leading to, but not limited to, isoparametric finite elements. This led to distinct performance and convergence improvements, especially when considering curved geometries, ideally representable by a polynomial mapping, e.g. when choosing a cavity geometry parametrization based on splines.

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THOBB01

PAL-XFEL Linac RF System

klystron, linac, network, vacuum

3192

H.-S. Lee, H. Heo, J. Hu, H.-S. Kang, K.W. Kim, K.H. Kim, S.H. Kim, I.S. Ko, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
H. Matsumoto
KEK, Tokai, Ibaraki, Japan

The PAL-XFEL hard X-ray linac has a 716 m long gallery and tunnel for 10 GeV. Forty nine modulators are necessary in the hard X-ray gallery for an X-band linearizer, an S-band RF gun, two S-band deflectors and 45 S-band klystrons for accelerating structures. They have been installed completely from March 15, 2015 to December 30, 2015 after completing the building construction. There are 51 modulators, 178 accelerators structures, 42 SLEDs in the hard X-ray linac and the soft X-ray linac. The RF conditioning of the klystrons, SLEDs and accelerating structures were stated from November 24, 2015. We describe the PAL-XFEL system and the current status of the linac RF system.

Slides THOBB01 [22.023 MB]

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THPMB027

Beam Transport Line of the LPA-FEL Facility Based on Transverse Gradient Undulator

FEL, undulator, beam-transport, laser

3287

T. Liu, B. Liu, D. Wang, T. Zhang
SINAP, Shanghai, People's Republic of China
Z. Huang
SLAC, Menlo Park, California, USA
J.S. Liu
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China

Free electron lasers (FELs) based on Laser Plasma Accelerators (LPAs) present a main research direction for achieving next generation compact advanced light sources. There are several major challenges of the LPA beam to generate high-brilliance FEL radiation including the large initial angular divergence and the large energy spread. Based on the LPA facility in SIOM that has successfully obtained quasi-monochromatic beam with the central energy of hundreds of MeV, a specific design of a beam transport line is proposed to realize FEL gain using Transverse Gradient Undulator to compensate the relatively large beam energy spread. This beamline uses a single dipole, several strong focusing quadrupoles and correcting sextupoles to match proper beta functions and linear dispersion from the LPA beam to FEL radiation. The corresponding experimental facility of LPA-FEL in SIOM has been set up and will perform first tests to generate FEL radiation.

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THPMB050

The Commmissioning of Phase-I Insertion Devices in TPS

storage-ring, coupling, lattice, undulator

3360

M.-S. Chiu, C.H. Chang, C.H. Chen, J. Chen, J.Y. Chen, Y.-S. Cheng, P.C. Chiu, P.J. Chou, T.Y. Chung, S. Fann, K.H. Hu, C.H. Huang, J.C. Huang, C.-S. Hwang, C.-C. Kuo, T.Y. Lee, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng, C.Y. Wu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center, next to the Taiwan Light source (1.5 GeV). On March 26, 2015, the TPS storage ring with two 5-cell PETRA cavities has successfully operated in 100 mA in top-up mode without the installation of insertion devices (IDs). To reach the design goal of 500 mA, the machine was shut down for 5 months to replace PETRA cavitites with superconducting RF (SRF) cavities and to install 10 IDs: 7 in-vacuum undulators (IU) and 3 elliptically polarized undulators (EPU). The commissioning of TPS storage ring with SRF cavities and IDs began in Sep. 2015. In this paper, we present our results and proceedures of ID commissioning.

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THPMB051

Development of Intelligent Alarm Message System at TPS

status, vacuum, operation, SRF

3363

C.C. Liang, C.H. Chang, C.H. Chen, J. Chen, J.Y. Chen, Y.-S. Cheng, M.-S. Chiu, S. Fann, C.S. Huang, C.-C. Kuo, T.Y. Lee, Y.C. Lin, Y.-C. Liu, H.-J. Tsai, F.H. Tseng, I.C. Yang, T.-C. Yu
NSRRC, Hsinchu, Taiwan

The traditional alarm systems usually set up/low limit for various signals. When the acquired values exceed the limits, the alarm system would be activated. The proposed system in this article can focus on various possible events with many kinds of signals for response judgments. During alarm calling period, data can also be announced and recorded. The system can also monitor various events according to different time shifts. Integrating LabVIEW, mobile phone, AT-command and Bluetooth communication, the system can handle factory broadcast, sending E-mail and SMS message. The above sound and words messages can be set directly at the home-made software interface. The new intelligent alarm system can eliminate the procedure made by man with the added event recording, system stability improvement and debugging function in wider application fields.

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THPMR045

CLIC Beam Delivery System Rebaselining and Long L* Lattice Optimization

luminosity, lattice, sextupole, synchrotron-radiation

3500

F. Plassard, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
P. Bambade
LAL, Orsay, France

This paper summarizes the re-optimization study made on the CLIC Beam Delivery System (BDS) in the framework of the rebaselining for beam collisions at 380 GeV for the initial energy stage. It describes the optimization process applied for the beam parameters as well as for the Final Focus system (FFS) lattice design with respect to the energy upgrade transition to 3 TeV. Both initial and final energy stages were optimized for a short (nominal) and a long L* (6 meters). The long L* option allows the last quadrupole (QD0) to be be located outward of the detector solenoid field influence. FFS optics designs based on the Local chromaticity correction and performance comparisons for both L* options are shown.

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THPMY001

Design and R&D for the SPring-8 Upgrade Storage Ring Vacuum System

vacuum, photon, storage-ring, laser

3651

M. Oishi, T. Bizen, H. Ohkuma, M. Shoji, S. Takahashi, K. Tamura, Y. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

Conceptual design report for the SPring-8 upgrade project (SPring-8-II) was published in November of 2014. Vacuum system for the targeted storage ring should handle some fateful boundary conditions, such as miniaturization of vacuum chamber and increase in number of photon absorbers resulting from the multi-bend achromat configuration. Furthermore, reuse of the existing tunnel brings the severe packing factor issue of vacuum components and the time constraints issue of one-year blackout. Considering the above circumstances, a concept of 12-m long vacuum chamber with welded integral structure was proposed to omit in-situ baking. The 12-m long chamber will be evacuated to ultra-high vacuum by ex-situ baking followed by NEG activation, and moved to the tunnel with special thin gate valves at both ends. Recently, the chamber material has been changed from aluminum alloy to stainless steel (SS) from the viewpoints of elimination of aluminum-SS transition space, beam vibration suppression, and superior outgassing property. Trial production of SS chamber is proceeding to establish appropriate manufacturing processes, while focusing on the accuracy of dimension and magnetic permeability.

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THPMY011

Chamber Upgrade for EPU48 in TPS

vacuum, storage-ring, synchrotron, synchrotron-radiation

3676

I.C. Sheng, C.K. Chan, C.-C. Chang, C.M. Cheng, Y.T. Cheng, J. -Y. Chuang, Y.M. Hsiao, Y.T. Huang, C. Shueh, L.H. Wu, I.C. Yang
NSRRC, Hsinchu, Taiwan

Due to high total power and power density in Taiwan Photon Source (TPS) of EPU48 (Elliptical Polarized Undulator) in double minimum sector, we fabricate a new Aluminum vacuum chamber to increase sufficient room for synchrotron radiation to pass through without damage the storage ring chamber. A new method of in-site replacement of bending chamber is also presented, the result of this replacement procedure shows that it is very cost-effective as well as good UHV vacuum quality.

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THPMY022

Design of the Beam Dump for Low Flux Beamline in KOMAC

proton, radioactivity, linac, operation

3702

C.R. Kim, Y.-S. Cho, H.S. Kim, H.-J. Kwon
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning)
A linac in KOMAC (Korea Multi-Purpose Accelerator Complex) is providing users with 100-MeV proton beam for various applications. A new target room (TR102) for low dose of radiation beam will be constructed in 2016. The beam dump is an important part of this beam line and must be designed to stop 100 MeV beams with a maximum power of 10 kW. Incepting the waste of beam increases the temperature of the beam dump, which can make a structural problem. Therefore, the material of it should be robust under the high temperature and the radioactive circumstance. To ensure safety, thermo-mechanical analyses have been performed for a few materials using a finite element code. The beam dump will be fabricated based on the analysis results.

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THPMY024

Upgrade of a UHV Furnace for 1700 C Heat Treatment and Processing of Niobium Samples

vacuum, niobium, power-supply, radio-frequency

3709

J. Conrad, L. Alff, R. Grewe, T. Kürzeder, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany
S.T. Sievers
MIT, Marburg, Germany

Funding: Supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05H15RDRBA
In 2005 a high temperature vacuum furnace was put into operation at the Institute for Nuclear Physics at the Technische Universität Darmstadt. It has been designed for firing pure Niobium at temperatures of up to 1870 C. Until now several Nb cavities have been heat treated at 850 C with a proven record of success. The current focus of research in improving the superconductive characteristics of accelerator cavities is on new materials such as Nb3Sn or NbN or on the doping of Nb surfaces with nitrogen, so called N2-Doping. The surface preparations generally take place at temperatures of not more than 1000 C. To study phenomena that occur at higher temperatures, like the formation of delta-phase NbN at 1300 to 1700 C, it is planned to refurbish the UHV furnace and use it for corresponding studies. We will report on the design of a new annealing pot and a sample holder and give a review on our first experiences with the upgraded furnace.

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THPMY030

How to Manage a Large Scale Beam Line Consolidation in a Highly Activated Area?

operation, controls, target, vacuum

3721

S. Evrard, J.L. Grenard, E. Harrouch, A. Herve, A. Pardons, Y. Pira, Y.D.R. Seraphin, C. Theis, H. Vincke
CERN, Geneva, Switzerland

The TDC2/TCC2 consolidation is a good example showing how the complexity of interventions in high radiation areas has increased over the last five years. Due to its duration, its dispersion, the diversity of the teams involved, the fixed deadlines, the risks and external constraints, this worksite prefigures large scale-interventions in the LHC during long shutdown 2 (LS2) and even more LS3. The paper describes the three main project phases: preparation, execution (including monitoring and control) and closure emphasizing the indispensable steps in each stage. It also explains why integrating scope, schedule and dose into a single baseline is of prime importance and shows how to manage and monitor the radiation safety performance of the various interventions throughout the execution phase. Eventually, some recommendations are formulated in order to better accommodate the design of high radiation areas to their operation and maintenance constraints.

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THPMY034

Power Saving Status at NSRRC

controls, synchrotron, synchrotron-radiation, operation

3734

J.-C. Chang, W.S. Chan, Y.C. Chang, C.S. Chen, Y.F. Chiu, Y.-C. Chung, K.C. Kuo, M.T. Lee, Y.-C. Lin, C.Y. Liu, Y.-H. Liu, Z.-D. Tsai, T.-S. Ueng, J.P. Wang
NSRRC, Hsinchu, Taiwan

National Synchrotron Radiation Research Center (NSRRC), Taiwan currently operates two synchrotrons, the Taiwan Light Source (TLS) and Taiwan Photon Source (TPS). The former one has been operated for more than 22 years, while the latter is in commissioning phase. We target of the beam current on 500 mA. Thus, the power consumption increases higher than ever. Currently, the contract power capacities of the TLS and TPS with the Taiwan Power Company (TPC) are 5.5MW and 7.5MW, respectively. The ultimate power consumption of the TPS is estimated about 12.5MW. To cope with increasing power requirement, we have conducting several power saving schemes for years. This paper presents our latest power schemes, which include installation of power saving fan for the cooling tower, adjustment of supply air temperature according to the atmosphere enthalpy, replacement of old air conditioning unit (AHU), power consumption control by the operation of chillers, and power factor improvement.

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THPOR004

Magnetic Measurement for Superconducting-Quadrupole-Magnets of Final-Focus System for SuperKEKB

quadrupole, sextupole, luminosity, octupole

3771

Y. Arimoto, M. Iwasaki, N. Ohuchi, K. Tsuchiya, X. Wang, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan

SuperKEKB is an upgrade project of KEKB to increase its luminosity to 8 x 10³⁵ cm^-2 s^-1 based on the nano-beam scheme. In SuperKEKB, one of a key element is a final-focus system; it reduces e⁻/e⁺ beam size to 50 nm in vertical and 10 μm in horizontal direction at an interaction point (IP). The system consists of eight superconducting quadrupole magnets and four quadrupoles are aligned on the each beam line. The quadrupole, QC1P(QC1E), which is located at the closest position to the IP on the e⁺(e⁻) beam line, generates a field gradient of about 70 T/m. An inner diameter of coil and a magnetic length for QC1P(QC1E) are 25(33) mm and 334(373) mm, respectively. The production of all quadrupole magnets are completed. To confirm their field qualities, we performed magnetic measurement for each magnet in advance to be integrated into cryostats on the beam lines. In the measurement, the quadrupoles were cooled down to 4.2 K in a test vertical cryostat and field harmonic components were measured with harmonic coils. The magnitude of error multipole components for all magnets met requirements from beam optics design. In this paper we describe the measurement results.

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THPOR005

Tunnel Level Variation in the SuperKEKB Interaction Region

alignment, luminosity, operation, feedback

3774

M. Masuzawa, T. Adachi, T. Kawamoto
KEK, Ibaraki, Japan

SuperKEKB is an electron-positron collider, which aims to achieve a peak luminosity 40 times higher than that of KEKB. The vertical beam sizes of both rings are squeezed down to 50 - 60 nm at the interaction point (IP), which accounts for a factor of 20 in the luminosity increase, and the beam currents are doubled from those of KEKB. Tunnel motion can be critical for realizing the collisions of such small beams. A Hydrostatic Leveling System (HLS), which consists of 18 sensors, was installed on both sides of the IP to monitor tunnel level variations continuously. Effects of heavy rain and installation of the radiation shield blocks on the tunnel floor level are clearly seen. The HLS data during construction and SuperKEKB commissioning are reported.

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THPOR014

MDI Design in CEPC Partial Double Ring

detector, solenoid, scattering, synchrotron

3802

S. Bai, J. Gao, Y. Wang, Q.L. Xiu, W.C. Yao, Y. Yue
IHEP, Beijing, People's Republic of China

With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2 s^-1) is becoming more popular in the accelerator world. The CEPC project in China is one of them. Machine Detector Interface (MDI) is the key research area in electron-positron colliders, especially in CEPC, it is one of the criteria to measure the accelerator and detector design performance. Detector background, collimator and solenoid compensation are the most critical physics problem. Beamstrahlung is the problem which is never gotten into before in the existed electron positron collider of world history. Every kinds of background are bad for detector, and solenoid can make damage to accelerator beam. We will use a Monte Carlo simulation method to calculate and analysis the CEPC detector background and the harm it makes to detector. Anti-solenoid are designed to compensate the strong detector solenoid field of several tesla.

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THPOR022

Design of Beam Optics for the FCC-ee Collider Ring

optics, sextupole, quadrupole, synchrotron

3821

K. Oide, K. Ohmi, D. Zhou
KEK, Ibaraki, Japan
M. Aiba
PSI, Villigen PSI, Switzerland
S. Aumon, M. Benedikt, H. Burkhardt, A. Doblhammer, B. Härer, B.J. Holzer, J.M. Jowett, M. Koratzinos, L.E. Medina Medrano, Y. Papaphilippou, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland
A.P. Blondel
DPNC, Genève, Switzerland
A.V. Bogomyagkov, I. Koop, E.B. Levichev, P.A. Piminov, D.N. Shatilov, D.B. Shwartz, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia
M. Boscolo
INFN/LNF, Frascati (Roma), Italy
Y. Cai, M.K. Sullivan, U. Wienands
SLAC, Menlo Park, California, USA

A design of beam optics will be presented for the FCC-ee double-ring collider. The main characteristics are 45 to 175 GeV beam energy, 100 km circumference with two IPs/ring, 30 mrad crossing angle at the IP, crab-waist scheme with local chromaticity correction system, and "tapering" of the magnets along with the local beam energy. An asymmetric layout near the interaction region suppresses the critical energy of synchrotron radiation toward the detector at the IP less than 100 keV, while keeping the geometry as close as to the FCC-hh beam line. A sufficient transverse/longitudinal dynamic aperture is obtained to assure the lifetime with beamstrahlung and top-up injection. The synchrotron radiation in all magnets, the IP solenoid and its compensation, nonlinearity of the final quadrupoles are taken into account.

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THPOR036

Updates on the Sliding Contact Cooling ILC Positron Source Target Development

target, vacuum, positron, undulator

3865

W. Liu, D.S. Doran, R.A. Erck, G.R. Fenske, W. Gai, V.J. Guarino
ANL, Argonne, Illinois, USA

The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnetic torque coupler to drive the solid spinning wheel target. The energy deposited from positron production process is taken away via cooling pads sliding against the spinning wheel. A full size test wheel has been built and some initial tests have been done with promising outcomes. Results of these tests are presented in this paper along with a plan for developing a prototype.

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THPOR042

New Quantity Describing the Pulse Shape Dependence of the High Gradient Limit in Single Cell Standing-Wave Accelerating Structures

operation, vacuum, data-analysis, experiment

3878

J. Shi, H.B. Chen, X.W. Wu
TUB, Beijing, People's Republic of China
V.A. Dolgashev
SLAC, Menlo Park, California, USA
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
Y. Higashi
KEK, Ibaraki, Japan
B. Spataro
INFN/LNF, Frascati (Roma), Italy

A new quantity has been developed to study the relationship among the breakdown rate, the pulse width and the gradient. Difference pulse shapes can be treated by introducing a Green's function. This paper describes the quantity and the results while it is applied to the data of many high-power test runs of different single-cell standing wave accelerating structures. A remarkably similar relationship between the new quantity and breakdown rate is observed from all of the test results.

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THPOW007

Cs2Te Photocathode Response Time Measurements and Femtosecond Comb Electron Beam Generation as a Milestone Towards Pre-Bunched Thz Fel Realization

electron, laser, gun, FEL

3941

A. Aryshev, Y. Honda, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan and JSPS KAKENHI: 23226020 and 24654076
Currently there is a rapidly growing demand to increase the brightness of electron beams generated by conventional RF guns as well as to decrease the cost of the injector accelerator system for many research facilities worldwide. To address this demand we investigate one of the most important parameter of the high Q.E. conventional semiconductor Cs2Te photocathode, its response time. It sets the principle limitation for generated bunch length and hence maximum achievable beam brightness of electron diffraction and pre-bunched THz FEL facility's injectors. The experimental investigation was done at KEK: LUCX facility. The Cs2Te photocathode response time better than 250 fs was demonstrated. The generation of 4 micro-bunch comb electron beam with variable time separation as a crucial technology for pre-bunched THz FEL realization was achieved.

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THPOW036

Evaluation of Immutability against Radiation-induced Demagnetization for a Hybrid Wiggler with NdFeB Magnets at the Canadian Light Source

wiggler, electron, injection, operation

4022

C.K. Baribeau, D. Bertwistle, L.O. Dallin, J.M. Vogt, W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada

The BioXAS beamline at Canadian Light Source installed a hybrid wiggler in 2013. Quantitative studies building on the experience of other facilities suggest the wiggler's NdFeB magnets are at risk of demagnetization due to radiation induced by the synchrotron's 2.9 GeV electrons. We use a phenomenological model to convert simulated peak demagnetizing fields into a radiation dose corresponding to a chosen %-demagnetization, and compare against an estimated dose per year due to injected beam. We find that injecting with the wiggler closed will cause 1% demagnetization in sections of its magnet blocks within 2 years of operation, assuming a worst case scenario. The wiggler has thus far been forced open for injections, but this will cease to be an option when CLS moves to top-up operation. In a related test, qualitative measurements of radiation during injections with the wiggler closed were taken by covering its magnets in Polaroid film. We find that radiation drops significantly when the injection efficiency is well-tuned. Our results suggest the wiggler will not receive damaging levels of radiation at closed gap so long as the injection system remains optimized.

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THPOW042

Start-to-End Simulation on Terahertz Superradiation of Ultrashort Electron Bunch in an Undulator

undulator, simulation, electron, laser

4041

X.L. Su, Y.-C. Du, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan, Z. Zhang
TUB, Beijing, People's Republic of China

The narrowband, intense and frequency-tunable THz radiation can be generated by letting an ultrashort electron bunch pass through an undulator. Start-to-end simulation of terahertz radiation from electron bunch in an undulator is studied in this paper. GPT code is used to track particle distribution from the photocathode RF gun to the entrance of the undulator and Genesis 1.3 is applied to simulate the radiation. The simulation results agree well with theoretical predictions.

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THPOW045

Development of PAL-XFEL Undulator System

undulator, FEL, laser, electron

4044

D.E. Kim, Y.-G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented.

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THPOW048

Optimization of a Multipole Wiggler for Tps

photon, wiggler, electron, permanent-magnet

4050

J.C. Jan, C.-H. Chang, T.Y. Chung, J.C. Huang, C.-S. Hwang, C.Y. Kuo
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a synchrotron radia-tion facility with electron energy 3 GeV that was commissioned in 2015. Taiwan Light Source (TLS) with electron energy 1.5 GeV concurrently provides user time. Three beam lines of TLS supply photons of energy 6-18 keV for user experiments; these beam lines are served with an in-achromatic superconduct-ing wiggler (IASW, 3.1 T). This superconducting inser-tion device has the disadvantages of complicated maintenance and operation. A traditional multipole wiggler (MPW) magnet of hybrid type is hence planned to be installed in TPS to cover the range of photon energy of IASW for user experiments. For the design of the magnetic circuit, the side block and the extreme block are arranged surrounding a Permendur Vanadium cobalt steel pole that enhances the field strength and good field region of a MPW magnet. The dynamic integral field and the demagnetizing field of MPW magnet were estimated. The optimization of the pole dimensions and photon characteristics were simu-lated and are discussed in this work.

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THPOW049

Status of Insertion Devices at Taiwan Photon Source

undulator, vacuum, photon, polarization

4054

T.Y. Chung, C.-H. Chang, C.H. Chang, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.-C. Kuo, Y.-C. Liu, F.H. Tseng, C.K. Yang
NSRRC, Hsinchu, Taiwan

The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region.

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THPOW051

Design and Construction of Compact Electromagnetic Undulator for THz Radiation Production

undulator, electron, linac, insertion-device

4060

C. Thongbai, N. Chaisueb, S. Rimjaem, J. Saisut, K. Thaijai-un
Chiang Mai University, Chiang Mai, Thailand
N. Kangrang
Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand
P. Wichaisirimongkol
Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand

Funding: Chiang Mai University Research Fellowship Program
The goal of this research is to design and construct a compact electromagnetic undulator. This insertion device will be installed at the PBP-CMU-LINAC system of Chiang Mai University (CMU), Thailand, to produce THz radiation. The undulator magnet is designed by using 2D POISSON and 3D RADIA computer code to optimize the magnet dimensions. The width of iron pole (W) should be 12 mm. The length of iron pole (L) should be about 80 mm long and the thickness of return yoke (d) should be more than 10 mm. The magnet design, the in-house con-struction of the magnet, and the measurement results will be presented.

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THPOW052

Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory

electron, undulator, vacuum, synchrotron

4063

M. Musardo, P.L. Cappadoro, O.V. Chubar, T.M. Corwin, H.C. Fernandes, D.A. Harder, D.A. Hidas, C.A. Kitegi, B.N. Kosciuk, W. Licciardi, J. Rank, C. Rhein, T. Tanabe
BNL, Upton, New York, USA

National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory.

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THPOW056

Fiber Laser Development for Dielectric Laser-driven Accelerator and Electron Beam Source

laser, electron, target, acceleration

4070

H. Okamoto, S. Otsuki
The University of Tokyo, Tokyo, Japan
K. Koyama, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
D. Satoh, T. Shibuya
TIT, Tokyo, Japan
M. Yoshida
KEK, Ibaraki, Japan

Our group is aiming for developing a table-top electronμbeam source, whose beam size is micro-meter order so that we can irradiate just the nuclei of cells (1μm) and observe the behavior in real time. This beam source will be realized by dielectric laser-driven accelerators(DLAs), which is expected to produce acceleration gradients of ~GV/m. To drive these accelerators, ultra-short pulse laser has to be incident to the structure*. We chose Ytterbium (Yb) fiber laser for generating and amplifying ultra-short laser pulse, which has high quantum efficiency and can easily pumped by LD, and is proper to produce ultra-short pulses because of its wide-band oscillation. We succeeded in getting ultra-short pulse (central wavelength: {1030} nm, average output: 10 W, pulse duration: ~10 ps, reputation rate: 84 MHz) from Yb fiber laser system. Also in order to make electron bunch by photo cathode, we then converted the obtained IR laser to UV of 258 nm (4ω) using BBO and LBO crystals. We are planning to amplify the pulses by Yb:YAG in future, which has its amplification band in {1030} nm.
* K. Koyama el al., "Design Of Photonic Crystal Accelerator For Radiation Biology," IPAC'12 Proceedings (2014)

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THPOY002

The New External Beamline for Detector Tests at ELSA

simulation, quadrupole, electron, detector

4088

N. Heurich, F. Frommberger, P. Hänisch, W. Hillert
ELSA, Bonn, Germany

At the electron accelerator ELSA, a new external beam line has been constructed whose task is to provide a primary electron beam for detector tests. Using a slow resonance extraction method, it is possible to extract a quasi continuous electron beam with a maximum energy of 3.2 GeV to the test area. An external beam current of 100 pA to 1 fA can be realized. A further reduction of the beam current is envisaged as well. The beam width can be changed in both transverse directions from 1 mm to 8 mm. To dump and simultaneously measure the current of the electron beam behind the detector components a Faraday cup consisting of depleted uanium is used. The residual radiation leaving the cup is absorbed in a concrete casing. The radiation protection concept for the entire area of the new beamline was designed with the help of the Monte Carlo simulation program Fluka. In addition to the concrete casing, radiation protection walls were built to allow a safe working environment in the neighboring control room.

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THPOY023

Upgrade of NSLS-II Active Interlock System

storage-ring, operation, synchrotron, synchrotron-radiation

4140

S. Seletskiy, J. Choi, K. Ha, R.M. Smith
BNL, Upton, Long Island, New York, USA

The NSLS-II Storage Ring is protected from possible damage from synchrotron radiation by a dedicated active interlock system (AIS). The AIS monitors electron beam position and angle and triggers beam drop if beam orbit exceeds the boundaries of pre-calculated active interlock envelope. The one year worth of the AIS operation showed that there is a number of erroneous machine trips associated with the AIS. In this paper we describe an upgrade of the AIS that allowed us to get rid of the Storage Ring faults and improved the overall NSLS-II reliability.

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THPOY034

Simulations of the Beam Loss Distribution at J-PARC Main Ring

proton, simulation, scattering, operation

4175

B. Yee-Rendón, H. Kuboki, Y. Sato, K. Satou, M.J. Shirakata, T. Toyama
KEK, Ibaraki, Japan
H. Harada
JAEA/J-PARC, Tokai-mura, Japan

The Japan Proton Accelerator Research Complex (J-PARC) is integrated by a set of high intensity proton accelerators. At this operation level, the monitoring and control of the beam losses and residual radiation are priority for its safe performance and maintenance. At Main Ring (MR), a discrepancy appears between the beam loss signal detected by the monitors and the residual dose measured. To understand this difference and the mechanism that produces these losses, a beam simulation study is implemented using the Strategic Accelerator Design (SAD) and Geometry and Tracking (Geant4) code. The first stage of the survey uses SAD to obtain the location of the losses around the lattice per turn. Then, Geant4 produces the secondary showers in the elements. Finally, we make the extrapolation with the residual radiation and compare with the measurements. The description and results of this work are presented in this paper.

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THPOY041

CERN Beam Interlock Redundant Dump Trigger Module Performance during LHC Run 2

operation, dumping, extraction, collider

4189

D.O. Calcoen, S. Gabourin, A.P. Siemko
CERN, Geneva, Switzerland

During the Long Shutdown 1 an additional link between the Beam Interlocks System and the LHC Beam Dumping System was installed. This third channel is a direct access from the BIS to the asynchronous dump triggering lines. This paper describes the experience collected for the first 10 months of operation and the improvements proposed for a future upgrade of the module.
IPAC 2014 THPRI021

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THPOY042

Evolution and Perspectives of Second Generation Magnet Interlock Systems at CERN

PLC, operation, interlocks, dipole

4192

I. Romera, Y. Bastian, G. Csendes, P. Dahlen, R. Mompo, C. Von Siebenthal, M. Zerlauth
CERN, Geneva, Switzerland

The CERN accelerator complex relies on thousands of superconducting and normal conducting magnets to guide the particle beams on their trajectories throughout the accelerator chain. In order to protect magnet and powering equipment from damage, complex magnet interlock systems are deployed and operated in the LHC and its injectors. Despite a very good track record during the first 10 years of operation, important consolidation activities are ongoing and planned to further increase the dependability of the injector chain and enhance the sys-tem functionality where required. This paper reviews the performance of the various magnet interlock systems at CERN during the past years of operation and presents the ongoing renovation projects carried out in the LHC in-jector complex to achieve the high level of dependability and maintainability required for long term operation. Finally, some design aspects of the existing LHC magnet interlocks will be discussed and possibilities to further enhance the dependability and functionality of the mag-net powering system will be presented in view of the High Luminosity LHC.

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THPOY047

Comprehensive Approach to Synchrotron Radiation Protection of NSLS-II

synchrotron, synchrotron-radiation, electron, undulator

4211

S. Seletskiy, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

To protect the NSLS-II Storage Ring components from possible damage from synchrotron radiation produced by insertion devices (IDs) and bending magnets (BMs) the Active Interlock System (AIS) keeps electron beam within the AI safe envelope (AIE) in the transverse phase space. The NSLS-II beamlines (BLs) and frontends (FEs) are designed under assumption that above certain safe beam current the ID synchrotron radiation (IDSR) fan is produced by the interlocked e-beam. In this paper we describe a new approach to defining the AIS parameters and settings, which significantly simplifies the process of the FE and BL design.

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THPOY049

Helical Undulator as a Source of Spectromicroscopy Beamline of ILSF

polarization, undulator, electron, photon

4217

S. Amiri, A. Gholampour, M. Jafarzadeh, M. Lamehi, J. Rahighi
ILSF, Tehran, Iran
M. Lamehi, J. Rahighi
IPM, Tehran, Iran

Regarding user requirements of spectromicroscopy beamline such as high flux, small spot size, linear and circular polarization light, a helical undulator have been chosen as a source for this beamline. Radiation properties of the source e.g. flux, flux density, brilliance, size and divergence of the photon beam, power, power density, angular distribution of power and flux on the axis of the undulator have been considered by theoretical formula and using SPECTRA code. At the circular polarization, the first harmonic covers the energies in the 100-1300 eV range and for the linear polarization energy ranges, 100-1000 eV and 1000-1500 eV, are provided by the first and third harmonics respectively. In the case of circular and linear polarization mode, maximum flux in the central cone for maximum undulator strength are 4.5 × 10¹⁶ (ph/s) at kX=ky=3.6 and 2.4 × 10¹⁶ (ph/s) at K=5.
* James A. Clarke, "The science and technology of undulators and wigglers", 2004.
** H. Onuki, P. Elleaume, "WIGGLERS UNDULATORs and their APLICATIONS", 2003.

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THPOY050

Time Response of a Gridded X-ray Beam Ionization Chamber

ion, electron, experiment, photon

4220

Y.H. Xu, Z.H. Sun
DongHua University, Songjiang, People's Republic of China
D.V. Campen, W.J. Corbett
SLAC, Menlo Park, California, USA
C.L. Li
East China University of Science and Technology, Shanghai, People's Republic of China
W.J. Zhang
University of Saskatchewan, Saskatoon, Canada

Recently, Quick-Scanning Extended X-ray Absorption Spectroscopy (QEXAS) has become an important tool for in-situ characterization of materials and measurement of associated electronic structure. In this case the time response of the ionization chamber affects the measurement resolution and therefore overall performance of the QEXAS system. Common parallel-plate ionization chambers have a step-response rise time of about 0.1 sec, which does not meet the requirements of QEXAS. To speed up the response, we constructed a gridded ionization chamber with variable bias voltage and optional background gas (N2 or He, respectively). To characterize the system we used a high-frequency beam chopper upstream of the ionization chamber and a high-speed, low-noise preamplifier to measure the step response of the chamber as a function of bias voltage and background gas conditions.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY050

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