IPAC2018 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOZGBD1	Towards Full Performance Operation of SwissFEL	FEL, experiment, electron, laser	24
	T. Schietinger PSI, Villigen PSI, Switzerland
	SwissFEL is the new X-ray free-electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland. It was inaugurated in December 2016 and saw its first pilot experiments at the end of 2017. We describe the commissioning steps leading to the first phase of pilot experiments and outline the plans towards reaching nominal performance levels in 2018.
	Slides MOZGBD1 [11.391 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD1
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MOZGBD2	FEL Performance Achieved at European XFEL	FEL, MMI, undulator, electron	29
	M. Scholz DESY, Hamburg, Germany
	The European XFEL has achieved first lasing by mid-2017 and first user experiments started by the end of that year. This invited talk describes the status of this facility, presenting highlights from the construction and commissioning, outlining experience from early operation, and discussing potential future developments.
	Slides MOZGBD2 [18.822 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD2
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MOZGBE5	Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA	electron, experiment, radiation, vacuum	55
	L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan CERN, Geneva, Switzerland I. Bellafont, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain S. Casalbuoni, E. Huttel KIT, Eggenstein-Leopoldshafen, Germany
	Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305. In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation. The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
	Slides MOZGBE5 [4.318 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5
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MOPMF068	Quantum Excitation due to Classical Beamstrahlung in Circular Colliders	collider, simulation, emittance, radiation	281
	M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF068
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MOPML047	Diversified Application of ILC	neutron, scattering, FEL, electron	502
	Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan T. Hayakawa QST, Tokai, Japan N. Kawamura, S. Makimura, K. Mishima, D. Nomura, K. Shimomura, S. Yamamoto, T. Yamazaki KEK, Ibaraki, Japan
	ILC will be a very powerful accelerator complex. It has not only the high power energetic electron beam but also positron and photon beams. In addition to these beams, large cryogenic plants are equipped together with various utility facilities. Some suggestions on the assumption of availability of ILC are offered from various fields. These discussions will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML047
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MOPML049	Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering	laser, scattering, electron, experiment	508
	H. Zen, T. Kii, H. Ohgaki Kyoto University, Kyoto, Japan M. Fujimoto, M. Katoh, E. Salehi UVSOR, Okazaki, Japan T. Hayakawa, T. Shizuma QST, Tokai, Japan M. Katoh Sokendai - Okazaki, Okazaki, Aichi, Japan J. Koga National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan E. Salehi AUT, Tehran, Iran
	Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 10⁶-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment. J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML049
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MOPML051	First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE	radiation, electron, experiment, proton	516
	A. Faus-Golfe LAL, Orsay, France R. Delorme, Y. Prezado IMNC, Orsay, France V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France A. Hrybok National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine
	The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML051
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MOPML058	Comparison of Water Absorbed Dose for Photons of Linac and Traceability System for Radiotherapy in China	controls, radiation, linac, electron	537
	K. Wang, S. Jin, Z. Wang, J. Zhang National Institute of Metrology, Beijing, People's Republic of China
	National Institute of Metrology (NIM) developed the standards of the absorbed dose to water for high-energy photon and electron beams, to support the PSDL and SSDL calibration capability in China. After the measurement of absorbed dose to water for 6, 10, and 25 MV photons of linac, NIM took part the BIPM. RI(I).K6 comparison with the Bureau International des Poids et Mesures (BIPM). The tissue phantom ratio (TPR_20,10) of 6MV and 10MV photons were measured by IBA CC13 chamber and Keithley 6517B with different output dose of the Linac, and also calculated by the dose ratio (D₂0⁄D₁0) with the formula in IAEA TRS-398 report. TPR_20,10 measured directly is 0.3% larger than calculated by the dose ratio D₂0⁄D₁0 . The absorbed dose to water is measured by water calorimeter with the combined standard uncertainty of 0.35%. The discrepancy of absorbed dose to water measured separately by open and sealed vessel is 0.2% at 10MV. The K6 comparison was done, the results reported as ratios of the NIM and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9917(60) at 6 MV, and 0.9941(59) at 10 MV. The quality correction factor KQ of usual used chamber was measure directly, and it is 0.3%~0.7% smaller than the data in the IAEA TRS-398 report. The typical chamber-to-chamber variations of the dose obtained with the IAEA TRS-277, TRS-398 and AAPM TG-51 were between 0.2% and 1.0% for the different photon beams. The variations of the dose obtained with IAEA TRS-398 and chambers calibrated directly by megavoltage photons were between 0.1% to 0.8%. The new standard can achieve the traceability of water absorbed dose for MV photons and will significantly reduce the uncertainty of ion chamber calibrations for Chinese radiotherapy centers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML058
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MOPML070	Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators	target, electron, simulation, site	572
	Z.H. Wang, H.B. Chen, J. Shi, H. Zha TUB, Beijing, People's Republic of China
	We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.
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MOPML072	Timing Resolution for an Optical Fibre-Based Detector in a 74 MeV Proton Therapy Beam	proton, detector, TRIUMF, timing	575
	C.A. Penner UBC & TRIUMF, Vancouver, British Columbia, Canada C. Duzenli UBC, Vancouver, B.C., Canada C.M. Hoehr, C. Lindsay TRIUMF, Vancouver, Canada S. O'Keeffe University of Limerick, Limerick, Ireland
	A Terbium activated Gadolinium Oxysulfide (Gd2O2S:Tb)-filled optical fibre sensor was developed and tested as a proton therapy beam dosimeter on a 74 MeV proton beam. Tests were carried out at the TRIUMF proton therapy centre, where a passively scattered beam is used for treatment. To create a clinically relevant spread-out Bragg peak, a modulator wheel with steps of varying thickness is employed. To determine the sensor's response in a 23 mm spread out Bragg peak, the sensor signal was sampled at depth intervals of 0.79 mm along the beam axis in a water phantom. The resulting data showed a periodic variation in the signal corresponding to the rotation of the modulator wheel and related to the depth in water of the detector. This timing resolution in the sensor response could find application in quality assurance for modulated proton beams.
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TUXGBD1	Potential and Issues for Future Accelerators and Ultimate Colliders	emittance, controls, synchrotron, laser	578
	S.J. Brooks BNL, Upton, Long Island, New York, USA
	Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.
	Slides TUXGBD1 [2.585 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD1
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TUPAF030	Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber	electron, vacuum, simulation, synchrotron	744
	G. Guillermo Cantón, F. Zimmermann CERN, Geneva, Switzerland G.H.I. Maury Cuna, E. D. Ocampo Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
	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. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.
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TUPMF008	Design, Construction, and Magnetic Field Measurements of a Helical Superconducting Undulator for the Advanced Photon Source	undulator, storage-ring, electron, experiment	1263
	M. Kasa, S.J. Bettenhausen, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A helical superconducting undulator (HSCU) was developed and installed at the Advanced Photon Source (APS). Implementation of a unique design of the helical coil former allowed for a compact turn around scheme of the conductor at the ends of the device during winding. Inherent to the coil winding design was the gradual reduction of the magnitude of the magnetic field at the ends of the device. The coil former design along with the magnetic measurement results will be described.
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TUPMF030	Operation and Performance of NSLS-II	operation, emittance, feedback, MMI	1312
	G.M. Wang BNL, Upton, Long Island, New York, USA
	NSLS-II facility hosts 23 operating beamlines with 2 more under commissioning. The radiation sources varies, including damping wiggler, IVU, EPU, 3PW, and bending magnets. Over the past year, the storage ring performance continuously improved, including frequency feedback and photon local feedback. Machine reliability reached 96.9% for 4500 hrs operation with beam current upto 350 mA. Beam orbit short and long term stability has been significantly improved. Operation beam emittance were optimized with beamlines.
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TUPMF035	First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring	feedback, experiment, lattice, operation	1323
	X. Yang, V.V. Smaluk, Y. Tian, L. Yu BNL, Upton, Long Island, New York, USA
	To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF035
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TUPMF048	On-Axis Beam Accumulation Based on a Triple-Frequency RF System for Diffraction-Limited Storage Rings	cavity, injection, simulation, accumulation	1359
	S.C. Jiang, Z. Duan, G. Xu IHEP, Beijing, People's Republic of China
	Since the multi-bend achromats have been applied to lattice design in the future light source to achieve ultralow emittance, strong sextupoles and concomitant nonlinearities restrict its performance to a certain extent. The empirical understanding is the exclusion of conventional off-axis injection scheme on these light sources. In this paper, we will present a new on-axis beam accumulation scheme, which is based on the triple-frequency RF system. By means of delicate superposition of RF voltage with fundamental and two other harmonic frequencies, a commodious and steady main bucket is able to be formed. The electron bunch from the injector will be kicked into the main bucket on-axis with a reasonable time offset to the circular bunch, and this process may make the minimal disturbance to the experiment users while operating on the top-up mode. The application of this scheme to the High Energy Photon Source (HEPS) will be discussed in the paper, corresponding simulation results are also presented.
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TUPMF049	Evolution of the Lattice Design for the High Energy Photon Source	lattice, emittance, storage-ring, injection	1363
	G. Xu, S.Y. Chen, Y. Jiao, J.L. Li, Y.M. Peng, Q. Qin, J.Q. Wang, C.H. Yu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a high-energy, ultralow-emittance, kilometer-scale storage ring light source to be built in China. The HEPS lattice design has been started since 2008. In this paper we will review the evolution of the HEPS lattice design over the past ten years, focusing mainly on the linear optics design and nonlinear optimization.
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TUPMF050	DA Optimization Experiences in the Heps Lattice Design	lattice, sextupole, emittance, storage-ring	1367
	Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	In the past decade, the so-called diffraction-limited storage ring (DLSR) light sources were proposed, promising much better radiation performance than available in the existing third generation light sources. Regarding the very strong focusing and chromatic sextupoles that required for reaching an ultralow emittance, to optimize the nonlinear dynamics and achieve an adequate dynamic aperture is an important topic in a DLSR design. In this paper we will present some tips distilled from the DA optimization experience of the High Energy Photon Source over the past ten years, hoping it could provide some aids to other ultralow-emittance designs.
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TUPMF055	Phase Matching Application in Hard X-Ray Region of HEPS	undulator, brilliance, radiation, electron	1386
	X.Y. Li, Z. Duan, Y. Jiao, S.K. Tian IHEP, Beijing, People's Republic of China
	For the 6 meters long straight-section of HEPS, a double collinear double-cryogenic permanent magnet undulator(CPMU) structure is designed for high energy photon users to achieve higher brightness. Angular profiles of radiation produced by the double undulator configuration has been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread is taken into account.
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TUPMF056	Brightness Dependence Investigation and Optimizaiton for the Heps	brightness, lattice, emittance, undulator	1390
	Y. Jiao, M. Li, X.Y. Li IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. To maximize the photon spectral brightness, one of the most important performance parameters of the light source, we investigated the dependence of brightness on different parameters, such as the natural emittance, coupling, beta functions of the undulator section, and length of the undulator section. Based on this study, we optimized the HEPS lattice by using brightness as an optimizing objective.
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TUPMF060	Design of Bunch Lengthening System in Electron Linac	linac, booster, lattice, bunching	1401
	C. Meng, Y. Jiao, J.L. Li, S. Pei, Y.M. Peng, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a linac and a full energy booster. To increase the threshold of TMCI in the booster, the HEPS linac design has been evolved with several iterations. The important middle-version design is a 300 MeV linac with rms bunch length larger than 20 ps. One bunch lengthening system is proposed and discussed in this paper.
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TUPMF065	The Role of Electron-Phonon Scattering in Transverse Momentum Conservation in PbTe(111) Photocathodes	electron, experiment, scattering, cathode	1414
	J. K. Nangoi, T.A. Arias Cornell University, Ithaca, New York, USA S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA W.A. Schroeder UIC, Chicago, Illinois, USA
	Funding: The U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams. The state of the art in creating high quality electron beams for particle accelerator applications and next generation ultrafast electron diffraction and microscopy involves laser-generated photoemission. A high quality beam requires that electrons emerge from the surface with low mean transverse energy (MTE). Recent density-functional theory calculations by T. Li and W. A. S. [arXiv:1704.00194v1 [physics.acc-ph] (2017)] suggest that PbTe(111) will produce low-MTE photoelectrons due to the low effective electron mass associated with its electronic band structure. Based on this, we measured the distribution of photoelectrons from PbTe(111) and found the MTE to be about 20x larger than expected. To explain the apparent lack of transverse momentum conservation, we carried out many-body photoemission calculations including electron-phonon scattering. Our results are in far better agreement with the experiment, underscoring the importance of electron-phonon scattering in photoemission from PbTe(111), and suggest that cooling could mitigate the phonon effects on the MTE for this material.
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TUPMF076	Temporal X-ray Reconstruction Using Temporal and Spectral Measurements	electron, simulation, FEL, laser	1440
	F. Christie, J. Rönsch-Schulenburg, M. Vogt DESY, Hamburg, Germany Y. Ding, Z. Huang, J. Krzywinski, A.A. Lutman, T.J. Maxwell, D.F. Ratner SLAC, Menlo Park, California, USA V. A. Jhalani CALTECH, Pasadena, California, USA
	Transverse deflecting structures (TDS) are widely used in accelerator physics to measure the longitudinal density of particle bunches. When used in combination with a dispersive section, the whole longitudinal phase space density can be imaged. At the Linac Coherent Light Source (LCLS), the installation of such a device downstream of the undulators enables the reconstruction of the X-ray temporal intensity profile by comparing longitudinal phase space distributions with lasing on and lasing off. However, the resolution of this TDS is limited to around 1 fs rms (root mean square), and therefore, in most cases, it is not possible to resolve single self-amplified spontaneous emission (SASE) spikes within one photon pulse. By combining the intensity spectrum from a high resolution photon spectrometer* and the temporal structure from the TDS, the overall resolution is enhanced, thus allowing the observation of temporal, single SASE spikes. The combined data from the spectrometer and the TDS is analyzed using an iterative algorithm to obtain the actual intensity profile. In this paper, we present the reconstruction algorithm as well as analyzed data obtained from simulations which shows the reliability of this method. Real data will be published at a later stage. Y. Ding et al., Phys. Rev. ST AB, 14, 120701, 2011. *D. Zhu et al., Appl. Phys. Lett., 101, 034103, 2012.
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TUPMF085	Status of the sFLASH Experiment	FEL, electron, laser, experiment	1471
	C. Lechner, R.W. Aßmann, J. Bödewadt, V. Grattoni, I. Hartl, T. Laarmann, M.M. Mohammad Kazemi, A. Przystawik DESY, Hamburg, Germany A. Azima, H.B. Biss, M. Drescher, W. Hillert, L.L. Lazzarino, V. Miltchev, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Khan, T. Plath DELTA, Dortmund, Germany
	Funding: This work is supported by the Federal Ministry of Education and Research of Germany within FSP-302 under FKZ 05K13GU4, 05K13PE3, and 05K16PEA. The sFLASH experiment at the free-electron laser (FEL) FLASH1 is a setup for the investigation of external FEL seeding. Since 2015, the seeding scheme high-gain harmonic generation (HGHG) is being studied. At the end of the seeded FEL, an RF deflector enables time-resolved analysis of the seeded electron bunches while the photon pulses can be characterized using the technique of THz streaking. In this contribution, we present the current configuration of the experiment and give an overview of recent experimental results.
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TUPML025	Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te	cathode, electron, polarization, vacuum	1589
	J. Bae, L. Cultrera, P. Digiacomo Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA I.V. Bazarov Cornell University, Ithaca, New York, USA
	Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111. High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.
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TUPML026	Multi-photon Photoemission and Ultrafast Electron Heating in Cu Photocathodes at Threshold	electron, cathode, laser, radiation	1593
	J. Bae, L. Cultrera Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA I.V. Bazarov, J.M. Maxson Cornell University, Ithaca, New York, USA S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA P. Musumeci, X.L. Shen UCLA, Los Angeles, California, USA
	Funding: U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams. Operating photocathodes near the photoemission threshold holds the promise of yielding small intrinsic emittance, at the cost of significantly reduced quantum efficiency. In modern femtosecond photoemission electron sources, this requires a very high intensity (10s of GW/cm²) to extract a useful quantity of electrons. At this intensity, the electron occupation function is far from equilibrium and evolves rapidly on sub-ps timescales. Thus, ultrafast laser heating and multiphoton photoemission effects may play a significant role in emission, thereby increasing the minimum achievable emittance. In this work, we use a Boltzmann equation approach to calculate the non-equilibrium occupation function evolution in time for a copper photocathode, yielding a prediction of quantum efficiency and mean transverse energy as a function of input intensity.
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TUPML027	Barium Tin Oxide Ordered Photocathodes: First Measurements and Future Perspectives	electron, cathode, laser, emittance	1597
	A. Galdi, E. B. Lochocki, H. Paik, C.T. Parzyck, D. G. Schlom, K.M. Shen Cornell University, Ithaca, New York, USA G. Adhikari, W.A. Schroeder UIC, Chicago, Illinois, USA I.V. Bazarov, L. Cultrera, W. H. Li, J.M. Maxson, C. M. Pierce Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams. Single crystalline photocathodes with small electron effective mass are supposed to enable ultra-low emittance beams, by taking advantage of the conservation of transverse (crystal) momentum. We present a preliminary study on photoemission from epitaxial films of La-doped BaSnO₃ with (100) orientation. We demonstrate here the possibility of generating and characterizing electron beams by exciting photoelectrons solely from the conduction band. We report quantum efficiency and mean transverse energy meaurements as a function of photon energy from the bare and Cs-activated La-doped BaSnO₃ surface.
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TUPML061	Study of Mean Transverse Energy of (N)UNCD with Tunable Laser Source	solenoid, cathode, electron, laser	1677
	G. Chen IIT, Chicago, Illinois, USA G. Adhikari, W.A. Schroeder UIC, Chicago, Illinois, USA S.P. Antipov, C.-J. Jing, K. Kovi Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Baryshev ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: NSF grant No. NSF-1739150, DOE SBIR program grant No. DE-SC0013145, NSF grant No. PHYS-1535279, DOE Contract No. DE-AC02-06CH11357. There is a strong motivation to develop and understand novel materials with the potential to be utilized as photocathodes, as these could have desirable photoemission properties for research and industrial applications. Nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) photocathodes have potential to become a material of choice for photocathode applications. (N)UNCD has high quantum efficiency when processed in hydrogen plasma, low surface roughness, and high electron conductivity through the bulk*. The mean transverse energy (MTE) was calculated for (N)UNCD thin films using the double-solenoid scan method. (N)UNCD thin film with thickness of 160nm was deposited on highly-doped silicon substrate. Studies of the MTE of a (N)UNCD sample were done using a tunable laser source with photon energies of 3.56 eV to 5.26 eV. These results are presented. K.J. Pérez Quintero et al., Appl. Phys. Lett. 105, 123103 (2014). ** S. Bhattacharyya et al., Appl. Phys. Lett. 79, 1441 (2001)
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WEXGBE2	Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings	emittance, wiggler, lattice, electron	1751
	F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.
	Slides WEXGBE2 [4.543 MB]
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WEYGBD3	The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source	factory, electron, neutron, positron	1780
	M.W. Krasny LPNHE, Paris, France R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann CERN, Geneva, Switzerland P.S. Antsifarov Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia A. Apyan ANSL, Yerevan, Armenia E.G. Bessonov LPI, Moscow, Russia J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland D. Budker Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer LAL, Orsay, France F. Castelli Università degli Studi di Milano, Milano, Italy C. Curatolo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy K. Kroeger FSU Jena, Jena, Germany V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy V.P. Shevelko LPI RAS, Moscow, Russia T. Stöhlker HIJ, Jena, Germany G. Weber IOQ, Jena, Germany Y.K. Wu FEL/Duke University, Durham, North Carolina, USA M.S. Zolotorev LBNL, Berkeley, California, USA
	This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 10¹⁷ photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.
	Slides WEYGBD3 [7.531 MB]
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WEPAF005	A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring	radiation, operation, shielding, detector	1815
	J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.
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WEPAF006	Fast Photodetector Bunch Duration Monitor for the Advanced Photon Source Particle Accumulator Ring	detector, laser, synchrotron, linac	1819
	J.C. Dooling, J.R. Calvey, K.C. Harkay, B.X. Yang, C. Yao ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A fast photodetector is used to monitor the bunch duration in the Advanced Photon Source (APS) Particle Accumulator Ring (PAR). The Bunch Duration Monitor (BDM) diagnostic provides an accurate measure of the PAR bunch length. PAR BDM data show good agreement with streak camera measurements. The BDM is based on the metal-semiconductor-metal (MSM) photodetector Hamamatsu G4176-03 MSM with specified rise and fall times of 30 ps. The BDM has sufficient frequency response to resolve the PAR bunch near extraction where, under low-charge conditions, minimum rms pulse durations of 200-300 ps are observed. Beam from the PAR is injected into the Booster; for efficient capture, injected rms bunch duration from the PAR must be less than 600 ps. The MSM detector exhibits a ringing response to fast input signals. To overcome this, the BDM output is de-convolved with the impulse response function of the detector-amplifier circuit. Turn-by-turn bunch duration data is presented versus charge and time in the PAR cycle. Charge calibration is used to determine fit parameters for bunch duration measurements in peak-detection mode. Observations relevant to APS Upgrade high-charge studies are presented.
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WEPAF012	Improvements of NSLS-II X-ray Diagnostic Beamlines	emittance, storage-ring, vacuum, radiation	1837
	W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.
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WEPAF034	A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC	electron, luminosity, gun, hadron	1891
	H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness CERN, Geneva, Switzerland A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom P. Forck, S. Udrea GSI, Darmstadt, Germany P. Smakulski WRUT, Wroclaw, Poland
	Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1. The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given.
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WEPAF074	Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation	radiation, detector, electron, plasma	2005
	T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni CERN, Geneva, Switzerland L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Bergamaschi, P. Karataev Royal Holloway, University of London, Surrey, United Kingdom V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn TPU, Tomsk, Russia L. Bobb DLS, Oxfordshire, United Kingdom K. Lekomtsev JAI, Egham, Surrey, United Kingdom
	Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.
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WEPAK009	Applications of the Interferometric Beam Size Monitor at BESSY II	storage-ring, diagnostics, operation, electron	2103
	M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz HZB, Berlin, Germany
	For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented. * A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001
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WEPAL005	Beam Size Measurement and PSF Evaluate of KB Mirror Monitor at SSRF	SRF, storage-ring, optics, electron	2151
	D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue IHEP, Beijing, People's Republic of China
	Funding: Work supported by National Nature Science Foundation of China(11605213) A Kirkpatrick Baez mirror imaging system was designed and installed to measure the transverse beam size and emittance of SSRF storage ring. Two crossed cylindrical mirrors are used to image the dipole source point in the horizontal and vertical direction. Both mirrors could be moved in and out in order to interchangeable with an original X-ray pinhole system. Hard X-ray with peak energy of 20.5 keV was focused at the X-ray scintillator camera. Aberration and point spread function which would cause image blur were evaluated. System commissioning and optimization have been done. PSF measurement was acquired using beam based calibration scheme by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes.
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WEPAL027	Filling Pattern Measurements Using Dead-Time Corrected Single Photon Counting	synchrotron, storage-ring, radiation, data-analysis	2219
	B. Kehrer, E. Blomley, M. Brosi, E. Bründermann, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	Time-correlated single photon counting (TCSPC) is a versatile tool for various accelerator diagnostics aspects. Amongst others it allows a precise determination of the filling pattern. At the visible light diagnostics port at the Karlsruhe Research Accelerator (KARA), the KIT storage ring, a Single-Photon Avalanche Diode (SPAD) in combination with a histogramming device (PicoHarp) is used. To compensate for possible dead-time effects, a correction scheme was developed and tested successfully. The compensation increases the dynamic range in which accurate measurements are possible and avoids distortion of the measured filling pattern. This contribution presents the experimental setup, as well as a series of benchmark measurements.
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WEPAL057	Methods to Detect Error Sources and Their Application at the TPS	kicker, storage-ring, cavity, injection	2305
	C.H. Huang, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu NSRRC, Hsinchu, Taiwan
	For a low-emittance photon light source, beam stability is a very important property to attain a high-quality photon beam. While it is hard to avoid beam perturbations in a storage ring, it is more important to quickly find the source locations and to remove or eliminate the sources as soon as possible. In this report, we develop a method to identify the locations of multiple sources. For a source with a particular frequency, the relative phase between sources can also be obtained. This method has been a useful tool during TPS operation and its methodology and practical applications are described in this report.
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WEPAL062	Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS	synchrotron, lattice, operation, emittance	2316
	C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements. * L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15. ** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.
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WEPMF057	PETRA III Vacuum System - Experiences from the First Decade of Operation	vacuum, operation, radiation, experiment	2499
	L. Lilje, R. Bospflug, N. Plambeck DESY, Hamburg, Germany
	In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.
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WEPML025	Advantages and Challenges of Nb3Sn Superconducting Undulators	undulator, site, experiment, operation	2734
	A.V. Zlobin, E.Z. Barzi, D. Turrioni Fermilab, Batavia, Illinois, USA Y. Ivanyushenkov, I. Kesgin ANL, Argonne, Illinois, USA
	Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.
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WEPML057	First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB	vacuum, MMI, operation, positron	2826
	K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui KEK, Ibaraki, Japan
	To satisfy the requirements of high beam quality for positron injection into the SuperKEKB main ring, a new damping ring (DR) is constructed in an upgraded injector system. The DR is a racetrack-shaped storage ring with a circumference of 135.5 m, in which the 1.1 GeV positron beam is stored for 40 ms to damp the emittance. The maximum stored beam current is 70.8 mA. Required beam lifetime due to residual gas scattering is longer than 1000 s and the average pressure should be lower than 10^-5 Pa. Non-evaporable getter (NEG) pumps are mainly used, and the average effective pumping speed for CO is expected to be 0.013 m3s⁻¹m-1 immediately after NEG activation. The beam pipes are made of aluminum alloy, and have antechambers to deal with synchrotron radiation (critical energy 0.8-0.9 keV, total power 7.2 kW) in arc sections, which are effective in reducing the electron cloud and the impedance of the beam pipes. As additional countermeasures against the electron cloud effect, TiN coating and grooved surfacing are also adopted. The commissioning of the DR will commence at the beginning of 2018. The status of the vacuum system of the DR during the first commissioning will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML057
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WEPML075	Test of Magnet Girder Prototypes for HEPS-TF	alignment, coupling, HOM, site	2863
	H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu IHEP, Beijing, People's Republic of China H.Y. Zhu Institute of High Energy Physics (IHEP), People's Republic of China
	Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML075
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THYGBE4	Early Phase 2 Results of LumiBelle2 for the SuperKEKB Electron Ring	luminosity, background, simulation, electron	2934
	S. Di Carlo, P. Bambade, D. Jehanno, V. Kubytskyi, C.G. Pang, Y. Peinaud, C. Rimbault LAL, Orsay, France
	We report on the early SuperKEKB Phase 2 operations of the fast luminosity monitor (LumiBelle2 project). Fast luminosity monitoring is required by the dithering feedback system, which is used to stabilize the beam in the presence of horizontal vibrations. In this report, we focus on the operations related to the electron side of LumiBelle2. Diamond sensors are located 30 meters downstream of the IP, just above, beside, and below the electron beam pipe. During early Phase 2, the sensors are used to measure the background, arising from beam-gas scattering. We present the hardware design, the detection algorithm, and the analysis of the background measurements taken up-to-date. The results are then compared with a detailed simulation of the background, in order to well understand the physical processes involved. The simulation is performed using SAD for generation and tracking purposes, while Geant4 is used to calculate the energy deposition in the diamond sensors.
	Slides THYGBE4 [3.091 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBE4
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THPAF026	Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA	electron, simulation, vacuum, site	3011
	S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF026
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THPAL058	Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber	vacuum, ECR, experiment, radiation	3778
	C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang NSRRC, Hsinchu, Taiwan
	Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL058
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THPMF005	Evaluating the Impact of Diamond-II Possible Lattices on Beamlines	lattice, radiation, synchrotron, emittance	4033
	M. Apollonio, L. Alianelli, F. Bakkali Taheri, R. Bartolini, A.J. Dent DLS, Oxfordshire, United Kingdom R. Bartolini, J. Li JAI, Oxford, United Kingdom
	At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF005
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THPMF011	Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates	optics, laser, storage-ring, experiment	4057
	S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA L. Assoufid, W.C. Grizolli, J. Qian, X. Shi ANL, Argonne, Illinois, USA
	Funding: DOE SBIR The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF011
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THPMF056	Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source	laser, cavity, electron, gun	4192
	I. Drebot, A. Bacci, F. Broggi, S. Cialdi, C. Curatolo, D. Giannotti, D. Giove, A.R. Rossi, L. Serafini, M. Statera, V. Torri Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Bosotti, P. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy R. Calandrino, A. Delvecchio HSP, Milan, Italy P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi INFN-Ferrara, Ferrara, Italy A. Esposito, L. Faillace, A. Gallo, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy G. Galzerano, E. Puppin, A. Tagliaferri Politecnico/Milano, Milano, Italy G. Mettivier, P. Russo UniNa, Napoli, Italy V. Petrillo, F. Prelz, M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy M. Placidi, G. Turchetti Bologna University, Bologna, Italy A. Sarno INFN-Napoli, Napoli, Italy
	We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF056
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THPMF057	Multi Colour X-Gamma Ray Inverse Compton Back-Scattering Source	laser, electron, radiation, cavity	4196
	I. Drebot, S. Cialdi, D. Giannotti, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy R. Calandrino HSP, Milan, Italy P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi INFN-Ferrara, Ferrara, Italy G. Galzerano Politecnico/Milano, Milano, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy
	We present a simple and new scheme for producing multi colour Thomson/Compton radiation with the possibility of controlling separately their polarization, based on the interaction of one single electron beam with two and more laser pulses that can come from the same laser setup or from two different lasers system and that collide with the electrons at different angle inside one optical cavity. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF057
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THPMF067	Design and Tests of Switchable Period Length Superconducting Undulator Coils	undulator, insertion-device, insertion, synchrotron	4226
	T. Holubek, S. Casalbuoni, S. Gerstl, N. Glamann, A.W. Grau, C.A.J. Meuter, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany
	Several photon beamlines in different synchrotron make use of undulators with switchable period length, which offer a larger tunability of the emitted photons energy. Superconducting technology allows switching the period length by changing the sign of the current in separately powered subset of windings. We present here the design and tests performed in liquid helium of switchable period length superconducting undulator coils performing period doubling from 17 mm to 34 mm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF067
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THPMF076	New Simulation Programs for Partially Stripped Ions - Laser Light Collisions	laser, electron, factory, FEL	4249
	C. Curatolo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy M.W. Krasny LPNHE, Paris, France W. Placzek Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
	We present for the first time two new indipendent Monte Carlo codes for simulating the collisions of Partially Stripped Ions with Laser light. Such collisions if realised at LHC could drive a high intensity gamma source and are the back-bone of the recent Gamma Factory proposal. The implementation aspects will be discussed and the simulation results will be compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF076
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THPMF081	Intrinsic Emittance of Single Crystal Cathodes	electron, cathode, acceleration, emittance	4263
	S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA G. Adhikari, W.A. Schroeder UIC, Chicago, Illinois, USA
	The transverse momentum of electrons is conserved during photoemission from atomically ordered surfaces of single crystal materials. Photocathodes used in all photoinjectors today have disordered surfaces and do not exploit this phenomenon. Recently, using this conservation of transverse momentum, significant reduction in intrinsic emittance was demonstrated from the (111) surface of silver. Here, we present measurements of transverse momentum distributions of electrons photoemitted from the ordered surfaces of Ag and Cu single crystals at several photon energies. These measurements will help in understanding the photoemission process and show how band-structure and the conservation of transverse momentum can be used to obtain further reduction in intrinsic emittance from photocathodes. Karkare et al., Phys. Rev. Lett. 118, 164802 (2017)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF081
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THPMK004	Pulse-Picking by Resonant Excitation (PPRE) for Timing Users at the MAX IV 3 GeV Storage Ring	emittance, simulation, storage-ring, cavity	4300
	T. Olsson, Å. Andersson, D.K. Olsson MAX IV Laboratory, Lund University, Lund, Sweden
	At synchrotron light storage rings there is demand for serving both high-brilliance and timing users simultaneously. At many rings this is commonly achieved by operating fill patterns with gaps of sufficient length, but this is not favorable for rings that operate with passive harmonic cavities to damp instabilities and increase Touschek lifetime by lengthening the bunches. For such rings, gaps in the fill pattern could severely reduce the achievable bunch lengths. For the MAX IV 3 GeV storage ring, sufficient bunch lengthening is also essential for conserving the ultralow emittance and reducing heat load on vacuum components at high current. It is therefore of interest to study methods to serve timing users while operating without gap in the fill pattern. Once such method is PPRE, where the transverse emittance of one bunch in the bunch train is increased by an incoherent betatron excitation. This paper presents simulations for the MAX IV 3 GeV storage ring and discusses the machine requirements as well as the achievable performance for timing users.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK004
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THPMK007	Surface Acoustic Wave Enhancement of Photocathodes	simulation, electron, cathode, laser	4304
	R.P. Johnson Muons, Inc, Illinois, USA A. Afanasev, B. Dong, M. E. Zaghloul GWU, Washington, USA
	Funding: Work supported by DOE HEP STTR Grant DE-SC0017831 Numerical simulations and fabrication techniques are being used to investigate the use of surface acoustic waves to suppress electron-hole recombination on the surface of GaAs photocathodes in order to increase the quantum efficiency for polarized and unpolarized electron beam generation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK007
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THPMK013	A Wiggler Magnet Design for the TPS	emittance, wiggler, electron, undulator	4317
	J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK013
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THPMK019	Generation of Tunable Femtosecond X-Rays from High-Period-Number Resonant Transition Radiation Emitters	radiation, electron, linac, bunching	4339
	P. Wang, K.C. Leou NTHU, Hsinchu, Taiwan M.C. Chou, J.-Y. Hwang, W.K. Lau, A.P. Lee NSRRC, Hsinchu, Taiwan C.T. Lee ITRC, Hsinchu, Taiwan
	Funding: Work supported by the Ministry of Science and Technology, ROC (Taiwan). Femtosecond resonant transition radiation (RTR) in x-ray region can be generated from alternatively stacked multilayer structures when they are driven by relativistic ultrashort electron beams. These structures can be fabricated by coating layer pairs of high and low density materials. By increasing the number of these layer pairs, narrow-band x-ray can be generated. In this report, we present our efforts on the development of a 12 keV femtosecond narrow-band x-ray source by driving high-period-number RTR emitters with the NSRRC photoinjector linac system. Radiation wavelength is tunable by varying the incident angle of the beam. A few tens MeV, ultrashort beam has been available from the photoinjector system via velocity bunching in the rf linac. A 100-period (200 layers) Mo/Si multi-layer emitters with thin substrate have been fabricated. For a 100 pC drive beam, the expected photon yield from such emitter is about 4x104.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK019
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THPMK020	Beam-Based Alignment Procedures for Small Gap in-Vacuum Undulators at the Taiwan Photon Source	alignment, undulator, MMI, electron	4342
	Y.-C. Liu, J.C. Huang, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We have developed a beam-based alignment procedure for small gap IVUs (In-vacuum undulators) at TPS, which allow us to measure the field center and mechanical canter of IVUs with 0.1 mm accuracy. The measurement method and results are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK020
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THPMK042	Two and Multiple Bunches at LCLS	laser, undulator, diagnostics, FEL	4378
	F.-J. Decker, K.L.F. Bane, R.N. Coffee, W.S. Colocho, S. Gilevich, S.H. Glenzer, A.A. Lutman, A. Miahnahri, D.F. Ratner, J.C. Sheppard, S. Vetter SLAC, Menlo Park, California, USA
	The LCLS X-Ray FEL at SLAC typically delivers one bunch at the time. Different schemes of two pulses have been developed: Two bucket, Twin bunch, split undulator, and fresh slice. Here we discuss a four bunch or even eight bunch setup, where the separation between the individual bunches is two RF buckets: 0.7 ns.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK042
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THPMK045	Generation of High Power, High Intensity, Ultra Short X-Ray FEL Pulses	electron, laser, free-electron-laser, emittance	4384
	M.W. Guetg, Y. Ding, Z. Huang, A.A. Lutman SLAC, Menlo Park, California, USA
	X-ray Free Electron Lasers combine high pulse power, short pulse length, narrow bandwidth and a high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key XFEL applications including single molecule imaging and novel nonlinear X-ray methods. We will present experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit, while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw, and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK045
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THPMK053	Simulation for LCLS-II Hard X-ray Self Seeding Scheme	undulator, FEL, simulation, electron	4406
	C. Yang, Y. Feng, J. Krzywinski, T.O. Raubenheimer, C.-Y. Tsai, J. Wu, M. Yoon, G. Zhou SLAC, Menlo Park, California, USA H.X. Deng SINAP, Shanghai, People's Republic of China D.H. He USTC/NSRL, Hefei, Anhui, People's Republic of China Y. Hong, B. Yang University of Texas at Arlington, Arlington, USA X.F. Wang CIAE, Beijing, People's Republic of China M. Yoon POSTECH, Pohang, Kyungbuk, Republic of Korea G. Zhou IHEP, Beijing, People's Republic of China
	Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Oﬃce of Science Early Career Research Program grant FWP-2013-SLAC-100164. Typical SASE FELs have poor temporal coherence because of starting from shot noise. Self-seeding scheme is an approach to improve the longitudinal coherence. The single crystal monochromator self-seeding has been in successful operation in LCLS. For the high repetition rate LCLS-II machine, for damage consideration, it was initially proposed to have a two-stage self-seeding scheme, yet we have found the two-stage self-seeding scheme has no advantage over one-stage self-seeding scheme. In this paper, we investigate the optimal self-seeding conﬁguration of LCLS-II for different photon energies, and present a comparison between one-stage and two-stage self-seeding scheme of LCLS-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK053
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THPMK073	Multi FEL Lines with Compact Undulator Layout	undulator, FEL, electron, laser	4470
	D. Wang SINAP, Shanghai, People's Republic of China
	Today the high repetition rate X-ray Free Electron Lasers based on superconducting radiofrequency technologies have come to their age. Such kind of facilities are able to serve many FEL photon beamlines simultaneously with each of which have large flexibilities in selecting wavelength, intensity, polarization, coherence and other properties through independent tuning of the undulator magnets. In reality the space needed to accommodate many undulator lines could be a limiting factor of user capacity, especially for the high rep rate XFELs that tend to utilize the underground tunnel to host long superconducting accelerator machines. In this paper we present a concept of compact undulator layout for more FEL lines in the precious tunnel spaces or similar environment. Shanghai Coherent Light Facility(SCLF) is a high repe-tition rate X-ray Free Electron Lasers installed in under-ground tunnels with an overall length of more than 3 km. The concept described in this paper could be applied to the SCLF or similar FEL facilities. The design and R&D progress will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK073
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THPMK077	The Preliminary Experiment Studies for Soft X-Ray Self-Seeding System Design of SCLF Facility	FEL, experiment, simulation, electron	4481
	K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	The preliminary experiment studies for soft x-ray self-seeding system design of SCLF facility have been pre-sented in this paper. Some practical problems and pre-engineering design have been studied for the experimental prepare of soft x-ray self-seeding for the future SCLF facility. The monochromator system designs in this paper include optical structure, optical parameters and mechanical design. The designed optical system has an optical resolution of 1/10000 at the photon energy of 700-1300eV based on the optical simulation. To make the system satisfy the experimental requirements, mechanical install requirements and install precisions are also analysed. Considering the actual varies errors, the errors analyses such as the surface errors of the optical mirror and the machining errors of the VLS grating are also carried out. In conclusion, preliminary experimental studies including system design and varies engineering requirements are introduced to make sure that the presented design is reliable for final soft x-ray self-seeding experiment of SCLF facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK077
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THPMK146	Enhancement of Laser-Compton X-ray by Crab Crossing	laser, electron, luminosity, scattering	4645
	Y. Koshiba, R. Morita, S. Ota, M. Washio Waseda University, Tokyo, Japan T. Higashiguchi Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	Funding: This work is supported by JSPS Research Fellowships for Young Scientists (17J04371). We are going to apply crab crossing of electrons and laser photons for the enhancement of laser-Compton X-ray flux. Crab crossing will enable quasi-head-on collision and increase the luminosity. Therefore, it could be combined with an optical enhancement cavity without the interference of beams and cavity mirrors, leading to the generation of intense X-ray pulses. Calculation show more than fourfold luminosity will be achievable in our system, and could be larger depending on beam parameters. Although crab crossing in laser-Compton scattering has been already proposed, it has not been demonstrated yet anywhere. This will be the proof-of-principle study of the crab crossing laser-Compton scattering. In this conference, we will report our laser system based on thin-disk technology, and results of crab crossing laser-Compton scattering. Variola Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK146
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THPMK148	Design Study on Linac-bsed Laser-cmpton Scattering X-Ray Source	cavity, laser, electron, linac	4651
	K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M.K. Fukuda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan Y. Koshiba RISE, Tokyo, Japan M. Washio Waseda University, Tokyo, Japan
	We have been developing a laser-Compton scattering X-ray source using multi-bunch linac and optical enhancement cavity. This combination have a possibility to realize a high brightness compact X-ray source. A key issue of the system is around interaction point. Compatibility of electron focusing, optical cavity and X-ray path is difficult in the current setup. Thus we propose to use rf transverse deflecting cavity for crab crossing of laser and electron. In this conference, design study of the whole laser-Compton X-ray source consist of electron linac and optical enhancement cavity will be reported. The system configuration, resulting flux and brightness, and its applications will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK148
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THPML034	Baseline Lattice for the Upgrade of SOLEIL	emittance, lattice, injection, storage-ring	4726
	A. Loulergue, P. Alexandre, P. Brunelle, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka, K.T. Tavakoli, M.-A. Tordeux, A. Vivoli SOLEIL, Gif-sur-Yvette, France L. Hoummi Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Previous MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV.
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THPML070	Point Spread Function Study of Quasi-Monochromatic X-Ray Pinhole Camera at SSRF	simulation, SRF, experiment, synchrotron	4803
	B. Gao, H.J. Chen SINAP, Shanghai, People's Republic of China J. Chen, Y.B. Leng SSRF, Shanghai, People's Republic of China
	Since 2009 an X-ray pinhole camera that has been used to present the transverse beam size and emittance on diagnostic beam line of the storage ring at SSRF. The real beam size is a function of the image size of the CCD camera and point spread function (PSF) of the system. The performance of the measurement of the transverse electron beam size is given by the width of the PSF of X-ray pinhole camera. The contributions to the PSF width are the PSF of pinhole itself due to diffraction, and the PSF of the screen and camera. An X-ray monochromatic system has been established to measure the PSF accurately, and decrease the variation in the beam size between the theoretical values and the measured ones at SSRF. In this article, both calculated and measured PSF of quasi-monochromatic X-ray pinhole camera will be presented in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML070
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Paper

Title

Other Keywords

Page

MOZGBD1

Towards Full Performance Operation of SwissFEL

FEL, experiment, electron, laser

24

T. Schietinger
PSI, Villigen PSI, Switzerland

SwissFEL is the new X-ray free-electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland. It was inaugurated in December 2016 and saw its first pilot experiments at the end of 2017. We describe the commissioning steps leading to the first phase of pilot experiments and outline the plans towards reaching nominal performance levels in 2018.

Slides MOZGBD1 [11.391 MB]

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MOZGBD2

FEL Performance Achieved at European XFEL

FEL, MMI, undulator, electron

29

M. Scholz
DESY, Hamburg, Germany

The European XFEL has achieved first lasing by mid-2017 and first user experiments started by the end of that year. This invited talk describes the status of this facility, presenting highlights from the construction and commissioning, outlining experience from early operation, and discussing potential future developments.

Slides MOZGBD2 [18.822 MB]

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MOZGBE5

Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA

electron, experiment, radiation, vacuum

55

L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan
CERN, Geneva, Switzerland
I. Bellafont, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
S. Casalbuoni, E. Huttel
KIT, Eggenstein-Leopoldshafen, Germany

Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.

Slides MOZGBE5 [4.318 MB]

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MOPMF068

Quantum Excitation due to Classical Beamstrahlung in Circular Colliders

collider, simulation, emittance, radiation

281

M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann
CERN, Geneva, Switzerland

In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.

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MOPML047

Diversified Application of ILC

neutron, scattering, FEL, electron

502

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
T. Hayakawa
QST, Tokai, Japan
N. Kawamura, S. Makimura, K. Mishima, D. Nomura, K. Shimomura, S. Yamamoto, T. Yamazaki
KEK, Ibaraki, Japan

ILC will be a very powerful accelerator complex. It has not only the high power energetic electron beam but also positron and photon beams. In addition to these beams, large cryogenic plants are equipped together with various utility facilities. Some suggestions on the assumption of availability of ILC are offered from various fields. These discussions will be reported.

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MOPML049

Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering

laser, scattering, electron, experiment

508

H. Zen, T. Kii, H. Ohgaki
Kyoto University, Kyoto, Japan
M. Fujimoto, M. Katoh, E. Salehi
UVSOR, Okazaki, Japan
T. Hayakawa, T. Shizuma
QST, Tokai, Japan
M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan
J. Koga
National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan
E. Salehi
AUT, Tehran, Iran

Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes*. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 10⁶-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment.
*J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).

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MOPML051

First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE

radiation, electron, experiment, proton

516

A. Faus-Golfe
LAL, Orsay, France
R. Delorme, Y. Prezado
IMNC, Orsay, France
V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle
Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France
A. Hrybok
National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine

The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.

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MOPML058

Comparison of Water Absorbed Dose for Photons of Linac and Traceability System for Radiotherapy in China

controls, radiation, linac, electron

537

K. Wang, S. Jin, Z. Wang, J. Zhang
National Institute of Metrology, Beijing, People's Republic of China

National Institute of Metrology (NIM) developed the standards of the absorbed dose to water for high-energy photon and electron beams, to support the PSDL and SSDL calibration capability in China. After the measurement of absorbed dose to water for 6, 10, and 25 MV photons of linac, NIM took part the BIPM. RI(I).K6 comparison with the Bureau International des Poids et Mesures (BIPM). The tissue phantom ratio (TPR_20,10) of 6MV and 10MV photons were measured by IBA CC13 chamber and Keithley 6517B with different output dose of the Linac, and also calculated by the dose ratio (D₂0⁄D₁0) with the formula in IAEA TRS-398 report. TPR_20,10 measured directly is 0.3% larger than calculated by the dose ratio D₂0⁄D₁0 . The absorbed dose to water is measured by water calorimeter with the combined standard uncertainty of 0.35%. The discrepancy of absorbed dose to water measured separately by open and sealed vessel is 0.2% at 10MV. The K6 comparison was done, the results reported as ratios of the NIM and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9917(60) at 6 MV, and 0.9941(59) at 10 MV. The quality correction factor KQ of usual used chamber was measure directly, and it is 0.3%~0.7% smaller than the data in the IAEA TRS-398 report. The typical chamber-to-chamber variations of the dose obtained with the IAEA TRS-277, TRS-398 and AAPM TG-51 were between 0.2% and 1.0% for the different photon beams. The variations of the dose obtained with IAEA TRS-398 and chambers calibrated directly by megavoltage photons were between 0.1% to 0.8%. The new standard can achieve the traceability of water absorbed dose for MV photons and will significantly reduce the uncertainty of ion chamber calibrations for Chinese radiotherapy centers.

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MOPML070

Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators

target, electron, simulation, site

572

Z.H. Wang, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.

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MOPML072

Timing Resolution for an Optical Fibre-Based Detector in a 74 MeV Proton Therapy Beam

proton, detector, TRIUMF, timing

575

C.A. Penner
UBC & TRIUMF, Vancouver, British Columbia, Canada
C. Duzenli
UBC, Vancouver, B.C., Canada
C.M. Hoehr, C. Lindsay
TRIUMF, Vancouver, Canada
S. O'Keeffe
University of Limerick, Limerick, Ireland

A Terbium activated Gadolinium Oxysulfide (Gd2O2S:Tb)-filled optical fibre sensor was developed and tested as a proton therapy beam dosimeter on a 74 MeV proton beam. Tests were carried out at the TRIUMF proton therapy centre, where a passively scattered beam is used for treatment. To create a clinically relevant spread-out Bragg peak, a modulator wheel with steps of varying thickness is employed. To determine the sensor's response in a 23 mm spread out Bragg peak, the sensor signal was sampled at depth intervals of 0.79 mm along the beam axis in a water phantom. The resulting data showed a periodic variation in the signal corresponding to the rotation of the modulator wheel and related to the depth in water of the detector. This timing resolution in the sensor response could find application in quality assurance for modulated proton beams.

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TUXGBD1

Potential and Issues for Future Accelerators and Ultimate Colliders

emittance, controls, synchrotron, laser

578

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

Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.

Slides TUXGBD1 [2.585 MB]

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TUPAF030

Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber

electron, vacuum, simulation, synchrotron

744

G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
G.H.I. Maury Cuna, E. D. Ocampo
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico

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. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.

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TUPMF008

Design, Construction, and Magnetic Field Measurements of a Helical Superconducting Undulator for the Advanced Photon Source

undulator, storage-ring, electron, experiment

1263

M. Kasa, S.J. Bettenhausen, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator (HSCU) was developed and installed at the Advanced Photon Source (APS). Implementation of a unique design of the helical coil former allowed for a compact turn around scheme of the conductor at the ends of the device during winding. Inherent to the coil winding design was the gradual reduction of the magnitude of the magnetic field at the ends of the device. The coil former design along with the magnetic measurement results will be described.

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TUPMF030

Operation and Performance of NSLS-II

operation, emittance, feedback, MMI

1312

G.M. Wang
BNL, Upton, Long Island, New York, USA

NSLS-II facility hosts 23 operating beamlines with 2 more under commissioning. The radiation sources varies, including damping wiggler, IVU, EPU, 3PW, and bending magnets. Over the past year, the storage ring performance continuously improved, including frequency feedback and photon local feedback. Machine reliability reached 96.9% for 4500 hrs operation with beam current upto 350 mA. Beam orbit short and long term stability has been significantly improved. Operation beam emittance were optimized with beamlines.

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TUPMF035

First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring

feedback, experiment, lattice, operation

1323

X. Yang, V.V. Smaluk, Y. Tian, L. Yu
BNL, Upton, Long Island, New York, USA

To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.

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TUPMF048

On-Axis Beam Accumulation Based on a Triple-Frequency RF System for Diffraction-Limited Storage Rings

cavity, injection, simulation, accumulation

1359

S.C. Jiang, Z. Duan, G. Xu
IHEP, Beijing, People's Republic of China

Since the multi-bend achromats have been applied to lattice design in the future light source to achieve ultralow emittance, strong sextupoles and concomitant nonlinearities restrict its performance to a certain extent. The empirical understanding is the exclusion of conventional off-axis injection scheme on these light sources. In this paper, we will present a new on-axis beam accumulation scheme, which is based on the triple-frequency RF system. By means of delicate superposition of RF voltage with fundamental and two other harmonic frequencies, a commodious and steady main bucket is able to be formed. The electron bunch from the injector will be kicked into the main bucket on-axis with a reasonable time offset to the circular bunch, and this process may make the minimal disturbance to the experiment users while operating on the top-up mode. The application of this scheme to the High Energy Photon Source (HEPS) will be discussed in the paper, corresponding simulation results are also presented.

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TUPMF049

Evolution of the Lattice Design for the High Energy Photon Source

lattice, emittance, storage-ring, injection

1363

G. Xu, S.Y. Chen, Y. Jiao, J.L. Li, Y.M. Peng, Q. Qin, J.Q. Wang, C.H. Yu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a high-energy, ultralow-emittance, kilometer-scale storage ring light source to be built in China. The HEPS lattice design has been started since 2008. In this paper we will review the evolution of the HEPS lattice design over the past ten years, focusing mainly on the linear optics design and nonlinear optimization.

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TUPMF050

DA Optimization Experiences in the Heps Lattice Design

lattice, sextupole, emittance, storage-ring

1367

Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

In the past decade, the so-called diffraction-limited storage ring (DLSR) light sources were proposed, promising much better radiation performance than available in the existing third generation light sources. Regarding the very strong focusing and chromatic sextupoles that required for reaching an ultralow emittance, to optimize the nonlinear dynamics and achieve an adequate dynamic aperture is an important topic in a DLSR design. In this paper we will present some tips distilled from the DA optimization experience of the High Energy Photon Source over the past ten years, hoping it could provide some aids to other ultralow-emittance designs.

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TUPMF055

Phase Matching Application in Hard X-Ray Region of HEPS

undulator, brilliance, radiation, electron

1386

X.Y. Li, Z. Duan, Y. Jiao, S.K. Tian
IHEP, Beijing, People's Republic of China

For the 6 meters long straight-section of HEPS, a double collinear double-cryogenic permanent magnet undulator(CPMU) structure is designed for high energy photon users to achieve higher brightness. Angular profiles of radiation produced by the double undulator configuration has been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread is taken into account.

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TUPMF056

Brightness Dependence Investigation and Optimizaiton for the Heps

brightness, lattice, emittance, undulator

1390

Y. Jiao, M. Li, X.Y. Li
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. To maximize the photon spectral brightness, one of the most important performance parameters of the light source, we investigated the dependence of brightness on different parameters, such as the natural emittance, coupling, beta functions of the undulator section, and length of the undulator section. Based on this study, we optimized the HEPS lattice by using brightness as an optimizing objective.

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TUPMF060

Design of Bunch Lengthening System in Electron Linac

linac, booster, lattice, bunching

1401

C. Meng, Y. Jiao, J.L. Li, S. Pei, Y.M. Peng, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a linac and a full energy booster. To increase the threshold of TMCI in the booster, the HEPS linac design has been evolved with several iterations. The important middle-version design is a 300 MeV linac with rms bunch length larger than 20 ps. One bunch lengthening system is proposed and discussed in this paper.

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TUPMF065

The Role of Electron-Phonon Scattering in Transverse Momentum Conservation in PbTe(111) Photocathodes

electron, experiment, scattering, cathode

1414

J. K. Nangoi, T.A. Arias
Cornell University, Ithaca, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA
W.A. Schroeder
UIC, Chicago, Illinois, USA

Funding: The U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
The state of the art in creating high quality electron beams for particle accelerator applications and next generation ultrafast electron diffraction and microscopy involves laser-generated photoemission. A high quality beam requires that electrons emerge from the surface with low mean transverse energy (MTE). Recent density-functional theory calculations by T. Li and W. A. S. [arXiv:1704.00194v1 [physics.acc-ph] (2017)] suggest that PbTe(111) will produce low-MTE photoelectrons due to the low effective electron mass associated with its electronic band structure. Based on this, we measured the distribution of photoelectrons from PbTe(111) and found the MTE to be about 20x larger than expected. To explain the apparent lack of transverse momentum conservation, we carried out many-body photoemission calculations including electron-phonon scattering. Our results are in far better agreement with the experiment, underscoring the importance of electron-phonon scattering in photoemission from PbTe(111), and suggest that cooling could mitigate the phonon effects on the MTE for this material.

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TUPMF076

Temporal X-ray Reconstruction Using Temporal and Spectral Measurements

electron, simulation, FEL, laser

1440

F. Christie, J. Rönsch-Schulenburg, M. Vogt
DESY, Hamburg, Germany
Y. Ding, Z. Huang, J. Krzywinski, A.A. Lutman, T.J. Maxwell, D.F. Ratner
SLAC, Menlo Park, California, USA
V. A. Jhalani
CALTECH, Pasadena, California, USA

Transverse deflecting structures (TDS) are widely used in accelerator physics to measure the longitudinal density of particle bunches. When used in combination with a dispersive section, the whole longitudinal phase space density can be imaged. At the Linac Coherent Light Source (LCLS), the installation of such a device downstream of the undulators enables the reconstruction of the X-ray temporal intensity profile by comparing longitudinal phase space distributions with lasing on and lasing off*. However, the resolution of this TDS is limited to around 1 fs rms (root mean square), and therefore, in most cases, it is not possible to resolve single self-amplified spontaneous emission (SASE) spikes within one photon pulse. By combining the intensity spectrum from a high resolution photon spectrometer** and the temporal structure from the TDS, the overall resolution is enhanced, thus allowing the observation of temporal, single SASE spikes. The combined data from the spectrometer and the TDS is analyzed using an iterative algorithm to obtain the actual intensity profile. In this paper, we present the reconstruction algorithm as well as analyzed data obtained from simulations which shows the reliability of this method. Real data will be published at a later stage.
*Y. Ding et al., Phys. Rev. ST AB, 14, 120701, 2011.
**D. Zhu et al., Appl. Phys. Lett., 101, 034103, 2012.

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TUPMF085

Status of the sFLASH Experiment

FEL, electron, laser, experiment

1471

C. Lechner, R.W. Aßmann, J. Bödewadt, V. Grattoni, I. Hartl, T. Laarmann, M.M. Mohammad Kazemi, A. Przystawik
DESY, Hamburg, Germany
A. Azima, H.B. Biss, M. Drescher, W. Hillert, L.L. Lazzarino, V. Miltchev, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan, T. Plath
DELTA, Dortmund, Germany

Funding: This work is supported by the Federal Ministry of Education and Research of Germany within FSP-302 under FKZ 05K13GU4, 05K13PE3, and 05K16PEA.
The sFLASH experiment at the free-electron laser (FEL) FLASH1 is a setup for the investigation of external FEL seeding. Since 2015, the seeding scheme high-gain harmonic generation (HGHG) is being studied. At the end of the seeded FEL, an RF deflector enables time-resolved analysis of the seeded electron bunches while the photon pulses can be characterized using the technique of THz streaking. In this contribution, we present the current configuration of the experiment and give an overview of recent experimental results.

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TUPML025

Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te

cathode, electron, polarization, vacuum

1589

J. Bae, L. Cultrera, P. Digiacomo
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I.V. Bazarov
Cornell University, Ithaca, New York, USA

Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111.
High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.

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TUPML026

Multi-photon Photoemission and Ultrafast Electron Heating in Cu Photocathodes at Threshold

electron, cathode, laser, radiation

1593

J. Bae, L. Cultrera
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I.V. Bazarov, J.M. Maxson
Cornell University, Ithaca, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA
P. Musumeci, X.L. Shen
UCLA, Los Angeles, California, USA

Funding: U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
Operating photocathodes near the photoemission threshold holds the promise of yielding small intrinsic emittance, at the cost of significantly reduced quantum efficiency. In modern femtosecond photoemission electron sources, this requires a very high intensity (10s of GW/cm²) to extract a useful quantity of electrons. At this intensity, the electron occupation function is far from equilibrium and evolves rapidly on sub-ps timescales. Thus, ultrafast laser heating and multiphoton photoemission effects may play a significant role in emission, thereby increasing the minimum achievable emittance. In this work, we use a Boltzmann equation approach to calculate the non-equilibrium occupation function evolution in time for a copper photocathode, yielding a prediction of quantum efficiency and mean transverse energy as a function of input intensity.

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TUPML027

Barium Tin Oxide Ordered Photocathodes: First Measurements and Future Perspectives

electron, cathode, laser, emittance

1597

A. Galdi, E. B. Lochocki, H. Paik, C.T. Parzyck, D. G. Schlom, K.M. Shen
Cornell University, Ithaca, New York, USA
G. Adhikari, W.A. Schroeder
UIC, Chicago, Illinois, USA
I.V. Bazarov, L. Cultrera, W. H. Li, J.M. Maxson, C. M. Pierce
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Single crystalline photocathodes with small electron effective mass are supposed to enable ultra-low emittance beams, by taking advantage of the conservation of transverse (crystal) momentum. We present a preliminary study on photoemission from epitaxial films of La-doped BaSnO₃ with (100) orientation. We demonstrate here the possibility of generating and characterizing electron beams by exciting photoelectrons solely from the conduction band. We report quantum efficiency and mean transverse energy meaurements as a function of photon energy from the bare and Cs-activated La-doped BaSnO₃ surface.

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TUPML061

Study of Mean Transverse Energy of (N)UNCD with Tunable Laser Source

solenoid, cathode, electron, laser

1677

G. Chen
IIT, Chicago, Illinois, USA
G. Adhikari, W.A. Schroeder
UIC, Chicago, Illinois, USA
S.P. Antipov, C.-J. Jing, K. Kovi
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Baryshev
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: NSF grant No. NSF-1739150, DOE SBIR program grant No. DE-SC0013145, NSF grant No. PHYS-1535279, DOE Contract No. DE-AC02-06CH11357.
There is a strong motivation to develop and understand novel materials with the potential to be utilized as photocathodes, as these could have desirable photoemission properties for research and industrial applications. Nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) photocathodes have potential to become a material of choice for photocathode applications*. (N)UNCD has high quantum efficiency when processed in hydrogen plasma*, low surface roughness, and high electron conductivity through the bulk**. The mean transverse energy (MTE) was calculated for (N)UNCD thin films using the double-solenoid scan method. (N)UNCD thin film with thickness of 160nm was deposited on highly-doped silicon substrate. Studies of the MTE of a (N)UNCD sample were done using a tunable laser source with photon energies of 3.56 eV to 5.26 eV. These results are presented.
* K.J. Pérez Quintero et al., Appl. Phys. Lett. 105, 123103 (2014).
** S. Bhattacharyya et al., Appl. Phys. Lett. 79, 1441 (2001)

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WEXGBE2

Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings

emittance, wiggler, lattice, electron

1751

F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.

Slides WEXGBE2 [4.543 MB]

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WEYGBD3

The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source

factory, electron, neutron, positron

1780

M.W. Krasny
LPNHE, Paris, France
R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann
CERN, Geneva, Switzerland
P.S. Antsifarov
Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia
A. Apyan
ANSL, Yerevan, Armenia
E.G. Bessonov
LPI, Moscow, Russia
J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny
Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
D. Budker
Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer
LAL, Orsay, France
F. Castelli
Università degli Studi di Milano, Milano, Italy
C. Curatolo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
K. Kroeger
FSU Jena, Jena, Germany
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
V.P. Shevelko
LPI RAS, Moscow, Russia
T. Stöhlker
HIJ, Jena, Germany
G. Weber
IOQ, Jena, Germany
Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
M.S. Zolotorev
LBNL, Berkeley, California, USA

This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 10¹⁷ photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.

Slides WEYGBD3 [7.531 MB]

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WEPAF005

A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring

radiation, operation, shielding, detector

1815

J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.

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WEPAF006

Fast Photodetector Bunch Duration Monitor for the Advanced Photon Source Particle Accumulator Ring

detector, laser, synchrotron, linac

1819

J.C. Dooling, J.R. Calvey, K.C. Harkay, B.X. Yang, C. Yao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A fast photodetector is used to monitor the bunch duration in the Advanced Photon Source (APS) Particle Accumulator Ring (PAR). The Bunch Duration Monitor (BDM) diagnostic provides an accurate measure of the PAR bunch length. PAR BDM data show good agreement with streak camera measurements. The BDM is based on the metal-semiconductor-metal (MSM) photodetector Hamamatsu G4176-03 MSM with specified rise and fall times of 30 ps. The BDM has sufficient frequency response to resolve the PAR bunch near extraction where, under low-charge conditions, minimum rms pulse durations of 200-300 ps are observed. Beam from the PAR is injected into the Booster; for efficient capture, injected rms bunch duration from the PAR must be less than 600 ps. The MSM detector exhibits a ringing response to fast input signals. To overcome this, the BDM output is de-convolved with the impulse response function of the detector-amplifier circuit. Turn-by-turn bunch duration data is presented versus charge and time in the PAR cycle. Charge calibration is used to determine fit parameters for bunch duration measurements in peak-detection mode. Observations relevant to APS Upgrade high-charge studies are presented.

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WEPAF012

Improvements of NSLS-II X-ray Diagnostic Beamlines

emittance, storage-ring, vacuum, radiation

1837

W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-SC0012704
There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.

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WEPAF034

A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC

electron, luminosity, gun, hadron

1891

H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
P. Forck, S. Udrea
GSI, Darmstadt, Germany
P. Smakulski
WRUT, Wroclaw, Poland

Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1.
The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given.

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WEPAF074

Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation

radiation, detector, electron, plasma

2005

T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni
CERN, Geneva, Switzerland
L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Bergamaschi, P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn
TPU, Tomsk, Russia
L. Bobb
DLS, Oxfordshire, United Kingdom
K. Lekomtsev
JAI, Egham, Surrey, United Kingdom

Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.

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WEPAK009

Applications of the Interferometric Beam Size Monitor at BESSY II

storage-ring, diagnostics, operation, electron

2103

M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz
HZB, Berlin, Germany

For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented.
* A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001

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WEPAL005

Beam Size Measurement and PSF Evaluate of KB Mirror Monitor at SSRF

SRF, storage-ring, optics, electron

2151

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

Funding: Work supported by National Nature Science Foundation of China(11605213)
A Kirkpatrick Baez mirror imaging system was designed and installed to measure the transverse beam size and emittance of SSRF storage ring. Two crossed cylindrical mirrors are used to image the dipole source point in the horizontal and vertical direction. Both mirrors could be moved in and out in order to interchangeable with an original X-ray pinhole system. Hard X-ray with peak energy of 20.5 keV was focused at the X-ray scintillator camera. Aberration and point spread function which would cause image blur were evaluated. System commissioning and optimization have been done. PSF measurement was acquired using beam based calibration scheme by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes.

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WEPAL027

Filling Pattern Measurements Using Dead-Time Corrected Single Photon Counting

synchrotron, storage-ring, radiation, data-analysis

2219

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

Time-correlated single photon counting (TCSPC) is a versatile tool for various accelerator diagnostics aspects. Amongst others it allows a precise determination of the filling pattern. At the visible light diagnostics port at the Karlsruhe Research Accelerator (KARA), the KIT storage ring, a Single-Photon Avalanche Diode (SPAD) in combination with a histogramming device (PicoHarp) is used. To compensate for possible dead-time effects, a correction scheme was developed and tested successfully. The compensation increases the dynamic range in which accurate measurements are possible and avoids distortion of the measured filling pattern. This contribution presents the experimental setup, as well as a series of benchmark measurements.

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WEPAL057

Methods to Detect Error Sources and Their Application at the TPS

kicker, storage-ring, cavity, injection

2305

C.H. Huang, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu
NSRRC, Hsinchu, Taiwan

For a low-emittance photon light source, beam stability is a very important property to attain a high-quality photon beam. While it is hard to avoid beam perturbations in a storage ring, it is more important to quickly find the source locations and to remove or eliminate the sources as soon as possible. In this report, we develop a method to identify the locations of multiple sources. For a source with a particular frequency, the relative phase between sources can also be obtained. This method has been a useful tool during TPS operation and its methodology and practical applications are described in this report.

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WEPAL062

Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS

synchrotron, lattice, operation, emittance

2316

C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements.
* L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15.
** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.

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WEPMF057

PETRA III Vacuum System - Experiences from the First Decade of Operation

vacuum, operation, radiation, experiment

2499

L. Lilje, R. Bospflug, N. Plambeck
DESY, Hamburg, Germany

In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.

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WEPML025

Advantages and Challenges of Nb3Sn Superconducting Undulators

undulator, site, experiment, operation

2734

A.V. Zlobin, E.Z. Barzi, D. Turrioni
Fermilab, Batavia, Illinois, USA
Y. Ivanyushenkov, I. Kesgin
ANL, Argonne, Illinois, USA

Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.

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WEPML057

First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB

vacuum, MMI, operation, positron

2826

K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
KEK, Ibaraki, Japan

To satisfy the requirements of high beam quality for positron injection into the SuperKEKB main ring, a new damping ring (DR) is constructed in an upgraded injector system. The DR is a racetrack-shaped storage ring with a circumference of 135.5 m, in which the 1.1 GeV positron beam is stored for 40 ms to damp the emittance. The maximum stored beam current is 70.8 mA. Required beam lifetime due to residual gas scattering is longer than 1000 s and the average pressure should be lower than 10^-5 Pa. Non-evaporable getter (NEG) pumps are mainly used, and the average effective pumping speed for CO is expected to be 0.013 m3s⁻¹m-1 immediately after NEG activation. The beam pipes are made of aluminum alloy, and have antechambers to deal with synchrotron radiation (critical energy 0.8-0.9 keV, total power 7.2 kW) in arc sections, which are effective in reducing the electron cloud and the impedance of the beam pipes. As additional countermeasures against the electron cloud effect, TiN coating and grooved surfacing are also adopted. The commissioning of the DR will commence at the beginning of 2018. The status of the vacuum system of the DR during the first commissioning will be reported.

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WEPML075

Test of Magnet Girder Prototypes for HEPS-TF

alignment, coupling, HOM, site

2863

H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu
IHEP, Beijing, People's Republic of China
H.Y. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China

Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.

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THYGBE4

Early Phase 2 Results of LumiBelle2 for the SuperKEKB Electron Ring

luminosity, background, simulation, electron

2934

S. Di Carlo, P. Bambade, D. Jehanno, V. Kubytskyi, C.G. Pang, Y. Peinaud, C. Rimbault
LAL, Orsay, France

We report on the early SuperKEKB Phase 2 operations of the fast luminosity monitor (LumiBelle2 project). Fast luminosity monitoring is required by the dithering feedback system, which is used to stabilize the beam in the presence of horizontal vibrations. In this report, we focus on the operations related to the electron side of LumiBelle2. Diamond sensors are located 30 meters downstream of the IP, just above, beside, and below the electron beam pipe. During early Phase 2, the sensors are used to measure the background, arising from beam-gas scattering. We present the hardware design, the detection algorithm, and the analysis of the background measurements taken up-to-date. The results are then compared with a detailed simulation of the background, in order to well understand the physical processes involved. The simulation is performed using SAD for generation and tracking purposes, while Geant4 is used to calculate the energy deposition in the diamond sensors.

Slides THYGBE4 [3.091 MB]

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THPAF026

Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA

electron, simulation, vacuum, site

3011

S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.

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THPAL058

Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber

vacuum, ECR, experiment, radiation

3778

C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang
NSRRC, Hsinchu, Taiwan

Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.

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THPMF005

Evaluating the Impact of Diamond-II Possible Lattices on Beamlines

lattice, radiation, synchrotron, emittance

4033

M. Apollonio, L. Alianelli, F. Bakkali Taheri, R. Bartolini, A.J. Dent
DLS, Oxfordshire, United Kingdom
R. Bartolini, J. Li
JAI, Oxford, United Kingdom

At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines.

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THPMF011

Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates

optics, laser, storage-ring, experiment

4057

S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
L. Assoufid, W.C. Grizolli, J. Qian, X. Shi
ANL, Argonne, Illinois, USA

Funding: DOE SBIR
The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations.

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THPMF056

Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source

laser, cavity, electron, gun

4192

I. Drebot, A. Bacci, F. Broggi, S. Cialdi, C. Curatolo, D. Giannotti, D. Giove, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Esposito, L. Faillace, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
V. Petrillo, F. Prelz, M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Placidi, G. Turchetti
Bologna University, Bologna, Italy
A. Sarno
INFN-Napoli, Napoli, Italy

We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam.

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THPMF057

Multi Colour X-Gamma Ray Inverse Compton Back-Scattering Source

laser, electron, radiation, cavity

4196

I. Drebot, S. Cialdi, D. Giannotti, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
R. Calandrino
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
G. Galzerano
Politecnico/Milano, Milano, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy

We present a simple and new scheme for producing multi colour Thomson/Compton radiation with the possibility of controlling separately their polarization, based on the interaction of one single electron beam with two and more laser pulses that can come from the same laser setup or from two different lasers system and that collide with the electrons at different angle inside one optical cavity. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy.

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THPMF067

Design and Tests of Switchable Period Length Superconducting Undulator Coils

undulator, insertion-device, insertion, synchrotron

4226

T. Holubek, S. Casalbuoni, S. Gerstl, N. Glamann, A.W. Grau, C.A.J. Meuter, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany

Several photon beamlines in different synchrotron make use of undulators with switchable period length, which offer a larger tunability of the emitted photons energy. Superconducting technology allows switching the period length by changing the sign of the current in separately powered subset of windings. We present here the design and tests performed in liquid helium of switchable period length superconducting undulator coils performing period doubling from 17 mm to 34 mm.

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THPMF076

New Simulation Programs for Partially Stripped Ions - Laser Light Collisions

laser, electron, factory, FEL

4249

C. Curatolo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M.W. Krasny
LPNHE, Paris, France
W. Placzek
Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland

We present for the first time two new indipendent Monte Carlo codes for simulating the collisions of Partially Stripped Ions with Laser light. Such collisions if realised at LHC could drive a high intensity gamma source and are the back-bone of the recent Gamma Factory proposal. The implementation aspects will be discussed and the simulation results will be compared.

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THPMF081

Intrinsic Emittance of Single Crystal Cathodes

electron, cathode, acceleration, emittance

4263

S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA
G. Adhikari, W.A. Schroeder
UIC, Chicago, Illinois, USA

The transverse momentum of electrons is conserved during photoemission from atomically ordered surfaces of single crystal materials. Photocathodes used in all photoinjectors today have disordered surfaces and do not exploit this phenomenon. Recently, using this conservation of transverse momentum, significant reduction in intrinsic emittance was demonstrated from the (111) surface of silver*. Here, we present measurements of transverse momentum distributions of electrons photoemitted from the ordered surfaces of Ag and Cu single crystals at several photon energies. These measurements will help in understanding the photoemission process and show how band-structure and the conservation of transverse momentum can be used to obtain further reduction in intrinsic emittance from photocathodes.
*Karkare et al., Phys. Rev. Lett. 118, 164802 (2017)

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THPMK004

Pulse-Picking by Resonant Excitation (PPRE) for Timing Users at the MAX IV 3 GeV Storage Ring

emittance, simulation, storage-ring, cavity

4300

T. Olsson, Å. Andersson, D.K. Olsson
MAX IV Laboratory, Lund University, Lund, Sweden

At synchrotron light storage rings there is demand for serving both high-brilliance and timing users simultaneously. At many rings this is commonly achieved by operating fill patterns with gaps of sufficient length, but this is not favorable for rings that operate with passive harmonic cavities to damp instabilities and increase Touschek lifetime by lengthening the bunches. For such rings, gaps in the fill pattern could severely reduce the achievable bunch lengths. For the MAX IV 3 GeV storage ring, sufficient bunch lengthening is also essential for conserving the ultralow emittance and reducing heat load on vacuum components at high current. It is therefore of interest to study methods to serve timing users while operating without gap in the fill pattern. Once such method is PPRE, where the transverse emittance of one bunch in the bunch train is increased by an incoherent betatron excitation. This paper presents simulations for the MAX IV 3 GeV storage ring and discusses the machine requirements as well as the achievable performance for timing users.

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THPMK007

Surface Acoustic Wave Enhancement of Photocathodes

simulation, electron, cathode, laser

4304

R.P. Johnson
Muons, Inc, Illinois, USA
A. Afanasev, B. Dong, M. E. Zaghloul
GWU, Washington, USA

Funding: Work supported by DOE HEP STTR Grant DE-SC0017831
Numerical simulations and fabrication techniques are being used to investigate the use of surface acoustic waves to suppress electron-hole recombination on the surface of GaAs photocathodes in order to increase the quantum efficiency for polarized and unpolarized electron beam generation.

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THPMK013

A Wiggler Magnet Design for the TPS

emittance, wiggler, electron, undulator

4317

J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.

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THPMK019

Generation of Tunable Femtosecond X-Rays from High-Period-Number Resonant Transition Radiation Emitters

radiation, electron, linac, bunching

4339

P. Wang, K.C. Leou
NTHU, Hsinchu, Taiwan
M.C. Chou, J.-Y. Hwang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan
C.T. Lee
ITRC, Hsinchu, Taiwan

Funding: Work supported by the Ministry of Science and Technology, ROC (Taiwan).
Femtosecond resonant transition radiation (RTR) in x-ray region can be generated from alternatively stacked multilayer structures when they are driven by relativistic ultrashort electron beams. These structures can be fabricated by coating layer pairs of high and low density materials. By increasing the number of these layer pairs, narrow-band x-ray can be generated. In this report, we present our efforts on the development of a 12 keV femtosecond narrow-band x-ray source by driving high-period-number RTR emitters with the NSRRC photoinjector linac system. Radiation wavelength is tunable by varying the incident angle of the beam. A few tens MeV, ultrashort beam has been available from the photoinjector system via velocity bunching in the rf linac. A 100-period (200 layers) Mo/Si multi-layer emitters with thin substrate have been fabricated. For a 100 pC drive beam, the expected photon yield from such emitter is about 4x104.

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THPMK020

Beam-Based Alignment Procedures for Small Gap in-Vacuum Undulators at the Taiwan Photon Source

alignment, undulator, MMI, electron

4342

Y.-C. Liu, J.C. Huang, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We have developed a beam-based alignment procedure for small gap IVUs (In-vacuum undulators) at TPS, which allow us to measure the field center and mechanical canter of IVUs with 0.1 mm accuracy. The measurement method and results are presented in this paper.

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THPMK042

Two and Multiple Bunches at LCLS

laser, undulator, diagnostics, FEL

4378

F.-J. Decker, K.L.F. Bane, R.N. Coffee, W.S. Colocho, S. Gilevich, S.H. Glenzer, A.A. Lutman, A. Miahnahri, D.F. Ratner, J.C. Sheppard, S. Vetter
SLAC, Menlo Park, California, USA

The LCLS X-Ray FEL at SLAC typically delivers one bunch at the time. Different schemes of two pulses have been developed: Two bucket, Twin bunch, split undulator, and fresh slice. Here we discuss a four bunch or even eight bunch setup, where the separation between the individual bunches is two RF buckets: 0.7 ns.

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THPMK045

Generation of High Power, High Intensity, Ultra Short X-Ray FEL Pulses

electron, laser, free-electron-laser, emittance

4384

M.W. Guetg, Y. Ding, Z. Huang, A.A. Lutman
SLAC, Menlo Park, California, USA

X-ray Free Electron Lasers combine high pulse power, short pulse length, narrow bandwidth and a high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key XFEL applications including single molecule imaging and novel nonlinear X-ray methods. We will present experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit, while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw, and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.

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THPMK053

Simulation for LCLS-II Hard X-ray Self Seeding Scheme

undulator, FEL, simulation, electron

4406

C. Yang, Y. Feng, J. Krzywinski, T.O. Raubenheimer, C.-Y. Tsai, J. Wu, M. Yoon, G. Zhou
SLAC, Menlo Park, California, USA
H.X. Deng
SINAP, Shanghai, People's Republic of China
D.H. He
USTC/NSRL, Hefei, Anhui, People's Republic of China
Y. Hong, B. Yang
University of Texas at Arlington, Arlington, USA
X.F. Wang
CIAE, Beijing, People's Republic of China
M. Yoon
POSTECH, Pohang, Kyungbuk, Republic of Korea
G. Zhou
IHEP, Beijing, People's Republic of China

Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Oﬃce of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Typical SASE FELs have poor temporal coherence because of starting from shot noise. Self-seeding scheme is an approach to improve the longitudinal coherence. The single crystal monochromator self-seeding has been in successful operation in LCLS. For the high repetition rate LCLS-II machine, for damage consideration, it was initially proposed to have a two-stage self-seeding scheme, yet we have found the two-stage self-seeding scheme has no advantage over one-stage self-seeding scheme. In this paper, we investigate the optimal self-seeding conﬁguration of LCLS-II for different photon energies, and present a comparison between one-stage and two-stage self-seeding scheme of LCLS-II.

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THPMK073

Multi FEL Lines with Compact Undulator Layout

undulator, FEL, electron, laser

4470

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

Today the high repetition rate X-ray Free Electron Lasers based on superconducting radiofrequency technologies have come to their age. Such kind of facilities are able to serve many FEL photon beamlines simultaneously with each of which have large flexibilities in selecting wavelength, intensity, polarization, coherence and other properties through independent tuning of the undulator magnets. In reality the space needed to accommodate many undulator lines could be a limiting factor of user capacity, especially for the high rep rate XFELs that tend to utilize the underground tunnel to host long superconducting accelerator machines. In this paper we present a concept of compact undulator layout for more FEL lines in the precious tunnel spaces or similar environment. Shanghai Coherent Light Facility(SCLF) is a high repe-tition rate X-ray Free Electron Lasers installed in under-ground tunnels with an overall length of more than 3 km. The concept described in this paper could be applied to the SCLF or similar FEL facilities. The design and R&D progress will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK073

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THPMK077

The Preliminary Experiment Studies for Soft X-Ray Self-Seeding System Design of SCLF Facility

FEL, experiment, simulation, electron

4481

K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

The preliminary experiment studies for soft x-ray self-seeding system design of SCLF facility have been pre-sented in this paper. Some practical problems and pre-engineering design have been studied for the experimental prepare of soft x-ray self-seeding for the future SCLF facility. The monochromator system designs in this paper include optical structure, optical parameters and mechanical design. The designed optical system has an optical resolution of 1/10000 at the photon energy of 700-1300eV based on the optical simulation. To make the system satisfy the experimental requirements, mechanical install requirements and install precisions are also analysed. Considering the actual varies errors, the errors analyses such as the surface errors of the optical mirror and the machining errors of the VLS grating are also carried out. In conclusion, preliminary experimental studies including system design and varies engineering requirements are introduced to make sure that the presented design is reliable for final soft x-ray self-seeding experiment of SCLF facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK077

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THPMK146

Enhancement of Laser-Compton X-ray by Crab Crossing

laser, electron, luminosity, scattering

4645

Y. Koshiba, R. Morita, S. Ota, M. Washio
Waseda University, Tokyo, Japan
T. Higashiguchi
Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: This work is supported by JSPS Research Fellowships for Young Scientists (17J04371).
We are going to apply crab crossing of electrons and laser photons for the enhancement of laser-Compton X-ray flux. Crab crossing will enable quasi-head-on collision and increase the luminosity. Therefore, it could be combined with an optical enhancement cavity without the interference of beams and cavity mirrors, leading to the generation of intense X-ray pulses. Calculation show more than fourfold luminosity will be achievable in our system, and could be larger depending on beam parameters. Although crab crossing in laser-Compton scattering has been already proposed*, it has not been demonstrated yet anywhere. This will be the proof-of-principle study of the crab crossing laser-Compton scattering. In this conference, we will report our laser system based on thin-disk technology, and results of crab crossing laser-Compton scattering.
*Variola Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK146

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THPMK148

Design Study on Linac-bsed Laser-cmpton Scattering X-Ray Source

cavity, laser, electron, linac

4651

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M.K. Fukuda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
Y. Koshiba
RISE, Tokyo, Japan
M. Washio
Waseda University, Tokyo, Japan

We have been developing a laser-Compton scattering X-ray source using multi-bunch linac and optical enhancement cavity. This combination have a possibility to realize a high brightness compact X-ray source. A key issue of the system is around interaction point. Compatibility of electron focusing, optical cavity and X-ray path is difficult in the current setup. Thus we propose to use rf transverse deflecting cavity for crab crossing of laser and electron. In this conference, design study of the whole laser-Compton X-ray source consist of electron linac and optical enhancement cavity will be reported. The system configuration, resulting flux and brightness, and its applications will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK148

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THPML034

Baseline Lattice for the Upgrade of SOLEIL

emittance, lattice, injection, storage-ring

4726

A. Loulergue, P. Alexandre, P. Brunelle, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka, K.T. Tavakoli, M.-A. Tordeux, A. Vivoli
SOLEIL, Gif-sur-Yvette, France
L. Hoummi
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Previous MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML034

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THPML070

Point Spread Function Study of Quasi-Monochromatic X-Ray Pinhole Camera at SSRF

simulation, SRF, experiment, synchrotron

4803

B. Gao, H.J. Chen
SINAP, Shanghai, People's Republic of China
J. Chen, Y.B. Leng
SSRF, Shanghai, People's Republic of China

Since 2009 an X-ray pinhole camera that has been used to present the transverse beam size and emittance on diagnostic beam line of the storage ring at SSRF. The real beam size is a function of the image size of the CCD camera and point spread function (PSF) of the system. The performance of the measurement of the transverse electron beam size is given by the width of the PSF of X-ray pinhole camera. The contributions to the PSF width are the PSF of pinhole itself due to diffraction, and the PSF of the screen and camera. An X-ray monochromatic system has been established to measure the PSF accurately, and decrease the variation in the beam size between the theoretical values and the measured ones at SSRF. In this article, both calculated and measured PSF of quasi-monochromatic X-ray pinhole camera will be presented in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML070

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