IPAC2013 - List of Keywords (background)

Paper	Title	Other Keywords	Page
MOPFI005	XPS and UHV-AFM Analysis of the K2CsSb Photocathodes Growth	cathode, vacuum, electron, factory	291
	S.G. Schubert HZB, Berlin, Germany I. Ben-Zvi, M. Ruiz-Osés Stony Brook University, Stony Brook, USA X. Liang SBU, Stony Brook, New York, USA H.A. Padmore, T. Vecchione LBNL, Berkeley, California, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: This work is funded by the Department of Energy, under Contract No. KC0407-ALSJNT-I0013, DE-SC0005713, the Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany. Next generation light sources, based on Energy Recovery Linac and Free Electron Laser technology will rely on photoinjector based electron sources. Successful operation of such sources requires reliable photocathodes with long operational life, uniform and high quantum efficiency, low thermal emittance and low dark current. The goal of this project is to construct a cathode which meets these requirements. Advances in photocathode research must take a combined effort. The materials have to be analyzed by means of chemical composition, surface structure and these findings have to be correlated to the quantum efficiency and performance in the injector. The presented work focuses on the chemical composition and surface structure of K2CsSb photocathodes. The XPS and AFM measurements were performed at the Center of Functional Nanomaterials at BNL. K2CsSb photocathodes were grown under UHV conditions. The components were adsorbed one at a time and after each growth step the corresponding XPS spectra was taken. During growth the quantum efficiency was recorded. As last step the sample was moved into the AFM without exposure to air to determine the surface roughness.

MOPME010	Transverse Beam Profile Diagnostics using Point Spread Function Dominated Imaging with Dedicated De-focusing	radiation, electron, target, focusing	488
	G. Kube, S. Bajt DESY, Hamburg, Germany W. Lauth IKP, Mainz, Germany Yu.A. Popov, A. Potylitsyn, L.G. Sukhikh TPU, Tomsk, Russia
	Transverse beam profile diagnostics in electron accelerators is usually based on direct imaging of a beam spot via optical radiation (transition or synchrotron radiation). In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to achieve resolutions beyond the diffraction limit is to perform point spread function (PSF) dominated imaging, i.e. the recorded image is dominated by the resolution function of a point source (single electron), and with knowledge of the PSF the true image (beam spot) may be reconstructed. To overcome the limited dynamical range of PSF dominated imaging, a dedicated de-focusing of the optical system can be introduced. In order to verify the applicability of this method, a proof-of-principle experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) using optical transition radiation. Status and results of this experiment will be presented.

MOPME011	Investigation of the Applicability of Parametric X-ray Radiation for Transverse Beam Profile Diagnostics	radiation, photon, diagnostics, electron	491
	G. Kube, C. Behrens DESY, Hamburg, Germany A.S. Gogolev, Yu.A. Popov, A. Potylitsyn TPU, Tomsk, Russia W. Lauth IKP, Mainz, Germany S. Weisse DESY Zeuthen, Zeuthen, Germany
	Transverse beam profile diagnostics in electron linacs is widely based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern linac based light sources like LCLS or FLASH shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. A possibility to overcome this limitation is to measure at much shorter wavelengths, i.e. in the X-ray region, using parametric X-ray radiation (PXR) which additionally offers the advantage to be generated at crystal planes oriented under a certain angle to the crystal surface, thus allowing a spatial separation from a possible COTR background . A first test experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the applicability of PXR for beam diagnostics, and the status of this experiment will be presented. A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics 357 (2012) 012018

MOPME014	Electro-optical Bunch Length Measurements at the ANKA Storage Ring	laser, electron, wakefield, storage-ring	500
	N. Hiller, A. Borysenko, E. Hertle, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller, M.J. Nasse, A. Plech, M. Schuh, S.N. Smale KIT, Karlsruhe, Germany P. Peier, V. Schlott PSI, Villigen PSI, Switzerland B. Steffen DESY, Hamburg, Germany
	Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring.

MOPME068	Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC	radiation, simulation, electron, vacuum	634
	N. Fuster Martinez, A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain H.L. Andrews LANL, Los Alamos, New Mexico, USA F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson JAI, Oxford, United Kingdom J. Barros, N. Delerue, M. Grosjean LAL, Orsay, France V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA
	The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME075	Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4	laser, electron, linac, emittance	652
	T. Hofmann, E. Bravin, U. Raich, F. Roncarolo CERN, Geneva, Switzerland B. Cheymol ESS, Lund, Sweden
	Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191 The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

MOPWA053	Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System	laser, electron, alignment, photon	795
	L.J. Nevay, G.A. Blair, S.T. Boogert, V. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom A.S. Aryshev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan L. Corner, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579 We present the results from the laserwire system at the Accelerator Test Facility 2 (ATF2) during recent operation after relocation to the virtual image point of the ATF2 final focus. The characterisation of the 150 mJ, 77 ps long laser pulses at a scaled virtual interaction point is used to deconvolve the transverse laserwire profile demonstrating a 1.16 ± 0.06 um vertical electron beam profile. Horizontal laserwire scans were used in combination with the vertical scans to measure the electron beam size using a full overlap integral model due to the problems presented by a large aspect ratio electron beam.

MOPWA074	High Voltage Converter Modulator Optimization	high-voltage, controls, neutron, feedback	852
	A. Scheinker LANL, Los Alamos, New Mexico, USA M.J. Bland University of Nottingham, Nottingham, United Kingdom
	High voltage converter modulators (HVCM) are at the forefront of long pulse high voltage (100kV) technology for Klystron voltage sources. We present results of digitally implementing an extremum seeking (ES) algorithm with which we optimized the rise time of the output voltage of a HVCM at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieved a 50us rise time, which is reduction in half compared to the 100us currently achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The ES algorithm is successful despite the noisy measurements and cost calculations, confirming the theoretical predictions that the algorithm is not affected by noise unless it both matches exactly the frequency components of the controller's specific perturbing frequencies and is of comparable size.

MOPWA077	EPICS, MATLAB, GigE CCD Camera Based Beam Imaging System for the IAC-RadiaBeam THz Project	EPICS, controls, GUI, optics	858
	C.F. Eckman, A. Andrews, T. Downer, Y. Kim, C. O'Neill IAC, Pocatello, IDAHO, USA P. Buaphad, Y. Kim ISU, Pocatello, Idaho, USA Y. Kim JLAB, Newport News, Virginia, USA
	At the Idaho Accelerator Center (IAC) of Idaho State University, we have been operating an L-band RF linear accelerator running at low energies (5 - 44 MeV) for the IAC-RadiaBeam THz project. We have designed and implemented an image acquisition and analysis system that can be used for real time observation of the electron beam, tuning of THz radiation production, and measurement of the transverse beam emittance. The imaging system contains an Yttrium Aluminium Garnet (YAG) screen on an actuator, a Prosilica GC1290 GigE CCD camera with an adjustable lens, a screen illuminator, an optical alignment structure, and a lead tube for the camera shielding. The real time continuous beam images can be acquired by SampleViewer, while the single shot beam image can be acquired by the Experiential Physics and Industrial Control System (EPICS) and areaDetector. In this paper, we describe components of the imaging system, the real time beam image acquisition with SampleViewer, the single shot beam image acquisition with areaDetector, and a remote controllable beam image acquisition via MATLAB Channel Access (MCA), MATLAB, and EPICS.

MOPWO029	Remote Estimate of Collimator Jaw Damages with Sound Measurements during Beam Impacts	proton, radiation, simulation, extraction	951
	D. Deboy, O. Aberle, R.W. Aßmann, F. Carra, M. Cauchi, J. Lendaro, A. Masi, S. Redaelli CERN, Geneva, Switzerland
	Irregular hits of high-intensity LHC beams on collimators can lead to severe damage of the collimator jaws. The identification of damaged collimator jaws by observation of beam measurements is challenging: online loss measurements at the moment of the impacts can be tricky and degradation of the overall performance from single collimator damage can be difficult to measure. Visual inspections are excluded because collimator jaws are enclosed in vacuum tanks without windows. However, the sound generated during the beam impact can be used to give an estimate of the damage level. In 2012, high-intensity beam comparable to a full nominal LHC bunch at 7 TeV was shot on a tertiary type LHC collimator at the HiRadMat test facility at CERN. The paper presents results from sound recordings of this experiment.

MOPWO041	Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC	simulation, luminosity, proton, dipole	984
	A. Marsili, R. Bruce, F. Cerutti, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO050	Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods	collimation, injection, resonance, betatron	1008
	V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland V. Moens EPFL, Lausanne, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

TUPEA035	Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability	plasma, impedance, electron, space-charge	1220
	D. Huang, Q. Gu SINAP, Shanghai, People's Republic of China K.Y. Ng Fermilab, Batavia, USA
	Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747. In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor is widely used to explain the physics of the LSC-induced microbunching instability. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated. Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008) J. D. Jackson, Classical Electrodynamics (Wiley, 1999) * Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

TUPFI037	Collimation Down to 2 Sigma in Special Physics Runs in the LHC	proton, scattering, luminosity, emittance	1427
	H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland
	We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI057	Muon Accelerators for the Next Generation of High Energy Physics Experiments	collider, factory, proton, target	1475
	M.A. Palmer, S. Brice, A.D. Bross, D.S. Denisov, E. Eichten, R.J. Lipton, D.V. Neuffer Fermilab, Batavia, USA C.M. Ankenbrandt Muons. Inc., USA S.A. Bogacz JLAB, Newport News, Virginia, USA J.-P. Delahaye SLAC, Menlo Park, California, USA P. Huber Virginia Polytechnic Institute and State University, Blacksburg, USA D.M. Kaplan, P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA H.G. Kirk, R.B. Palmer BNL, Upton, Long Island, New York, USA R.D. Ryne LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy and the U.S. National Science Foundation Muon accelerator technology offers a unique and very promising avenue to a facility capable of producing high intensity muon beams for neutrino factory and multi-TeV lepton collider applications. The goal of the US Muon Accelerator Program is to provide an assessment, within the next 6 years, of the physics potential and technical feasibility of such a facility. This talk will describe the physics opportunities that are envisioned, along with the R&D efforts that are being undertaken to address key accelerator physics and technology questions.

TUPME007	Beam Lifetime in Low Emittance Rings	scattering, simulation, lattice, factory	1574
	M. Boscolo INFN/LNF, Frascati (Roma), Italy
	In this paper I will review the main effects in low emittance rings that determine the beam lifetime by causing beam losses along the ring. As an example, the case for a B-factory based on the crab-waist collision scheme has been studied. During the machine design all the effects that determine the beam lifetime and induce backgrounds in the detector have been analyzed in details. The crab-waist scheme provides an higher luminosity, but at the same time it induces higher beam losses at the final focus. For this reason single beam effects such as Touschek and beam-gas scattering have been studied in details, by means of a macroparticle tracking code developed for this purpose. Also Radiative Bhabha scattering, that is the dominant effect to lifetime and backgrounds has been studied with the same technique to check possible multiturn losses at IR. An efficient collimation system has been designed to intercept scattered particles that would be lost in the IR in both the horizontal and the vertical plane. Recently, the Touschek tracking simulation code has been implemented to study the lifetime behavior for extremely low-emittance rings. M. Boscolo and P. Raimondi, “Monte Carlo simulation for the Touschek effect with the crab-waist scheme”, Phys. Rev. ST-AB 15 104201 (2012)

TUPWO055	Phase Rotation Experiment at EMMA for testing Applicability of a Non-scaling FFAG for PRISM System	extraction, synchrotron, acceleration, electron	1991
	B.D. Muratori, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.T.P. D'Arcy UCL, London, United Kingdom J.K. Jones, B.D. Muratori Cockcroft Institute, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom H.L. Owen UMAN, Manchester, United Kingdom J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	EMMA is the world’s first non-scaling FFAG, based at Daresbury Laboratory. EMMA has a very large acceptance and has demonstrated acceleration in the serpentine channel. PRISM (Phase Rotated Intense Slow Muon source) is a next generation muon to electron conversion experiment aiming to obtain intense quasi-monochromatic low energy muon beams by performing RF phase rotation in an FFAG ring. Current baseline design for PRISM applies the scaling FFAG ring, but an alternative machine could be based on a ns-FFAG principle. As the transverse-longitudinal coupling is present in ns-FFAGs due to a natural chromaticity, its effect on the final energy spread and beam quality needs to be tested. In order to gauge the expected results, an experiment was designed to be performed on EMMA. We report here the details of this experiment and the results gathered from EMMA operation.

WEOAB103	Experimental Observations of a Multi-stream Instability in a Long Intense Beam	simulation, electron, space-charge, factory	2044
	B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth UMD, College Park, Maryland, USA
	Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office. We have observed evidence of a multi-stream instability in a long non-relativistic space-charge dominated beam evolving with an initial non-linear distribution and zero external longitudinal containment. This type of instability can be detrimental to intense accelerators that propagate rectangular distributions, such as in a ring with single or multi-bunch injection. The longitudinal forces in these intense bunches causes the beam to expand axially; in the case of the University of Maryland Electron Ring (UMER), the initial long bunch is injected to fill a fraction of the ring, coasting beyond the point where the head and tail overlap. Adjacent filaments at that point are separated in velocity space by 2cs and approach a separation of cs. The onset of the instability has been observed to depend on the injected beam current, bunch length, and other experimental factors. Comparisons with simple analytical calculations and PIC simulations have shown good agreement in the time to onset.
	Slides WEOAB103 [1.681 MB]

WEPEA074	Optimisation of the Beam Line for COMET Phase-I	dipole, electron, solenoid, target	2681
	A. Kurup, I. Puri, Y. Uchida, Y. Yap Imperial College of Science and Technology, Department of Physics, London, United Kingdom R. Appleby, S.C. Tygier UMAN, Manchester, United Kingdom R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing UCL, London, United Kingdom
	The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. It was recently proposed to build COMET is two phases with physics measurements being made in both phases. This requires re-optimising the beam line for a shorter curved solenoid. This will affect the pion and muon yield; the momentum distributions at the detector; and the collimator scheme required. This paper will present the beam line design for COMET Phase-I, which aims to maximise the yield for low momentum muons suppressing sources of backgrounds in the beam.

WEPEA075	Large Emittance Beam Measurements for COMET Phase-I	solenoid, electron, simulation, proton	2684
	A. Kurup, I. Puri, Y. Uchida, Y. Yap Imperial College of Science and Technology, Department of Physics, London, United Kingdom R. Appleby, S.C. Tygier UMAN, Manchester, United Kingdom R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing UCL, London, United Kingdom
	The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. Understanding the pion production yield and transport properties of the beam line is an important part of the experiment. The beam line is a continuous solenoid channel, so it is only possible to place a beam diagnostic device at the end of the beam line. Building COMET in two phases provides the opportunity to investigate the pion production yield and to measure the transport properties of the beam line in Phase-I. This paper will demonstrate how this will be done using the experimental set up for COMET Phase-I.

WEPFI049	CoStub: A 6 1/8” Coaxial Short Circuit using Stubs	cavity, simulation, synchrotron, high-voltage	2809
	B. Bravo, F. Mares, F. Pérez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a 3Gev synchrotron light source located in Barcelona and operating with users since May 2012. The ALBA storage ring uses six room temperature cavities; each one fed by two 80kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. The two possible operation modes of CaCo at high power have been tested. The symmetrical mode (two IOTs feed the CaCo symmetrically) works properly and without presenting any problem. But in the asymmetrical mode (one IOT feeds the CaCo and the other is keeping passive) a standing wave is created between the passive IOT and Caco, provoking a large voltage in the gap of the passive IOT that broke the ceramic. A new device, CoStub (coaxial stub), to short circuit the coaxial waveguide of the passive arm and protects the passive IOT has been built and successfully tested. This paper presents the design details and the low level and high power test of this device.

WEPFI058	Breakdown Localization Studies on the SwissFEL C-band Test Structures	linac, coupling, factory, impedance	2824
	J. Klavins, S. Dementjevs, F. Le Pimpec, L. Stingelin, M. Wohlmuther, R. Zennaro PSI, Villigen PSI, Switzerland N.C. Shipman CERN, Geneva, Switzerland
	The SwissFEL main linac will consist of 10⁴ C-band structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analyzed, in addition to acoustic measurements, the delay and phase of the rf power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuum-events at the same location. The experiments show that the linac test-structures fulfill the requirements in breakdown probability. Moreover developing a detection system based on acoustic emission sensors for breakdown localization for our C-band structure seems reasonable given the results obtained.

WEPFI074	RF Cavity Spark Localization Using Acoustic Measurement	cavity, diagnostics, LabView, collider	2863
	P. Snopok IIT, Chicago, Illinois, USA A.D. Bross Fermilab, Batavia, USA P.G. Lane, Y. Torun Illinois Institute of Technology, Chicago, Illinois, USA
	Current designs for muon cooling channels require high-gradient RF cavities to be placed in solenoidal magnetic fields in order to contain muons with large transverse emittances. It has been found that doing so reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields it would be helpful to have a diagnostic tool which can detect breakdown and localize the source of the breakdown inside the cavity. We report here on progress towards developing a diagnostic tool for detecting and localizing sparks in an RF cavity by using piezoelectric transducers.

WEPME024	Gaussian Spectrum Fiber Laser Pulses Generated in an All-normal-dispersion Cavity	laser, cavity, controls, status	2983
	Y. You, W.-H. Huang, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China H. Shimizu, J. Urakawa KEK, Ibaraki, Japan
	In this paper, we reported generating a broad bandwidth Gaussian shape spectrum fiber laser pulse directly in an all-normal dispersive cavity. Pulse-shaping is based on spectral filtering. The spectrum has a ~20 nm 20-dB spectrum bandwidth and it is different from the typical spectrum, of steep edge and two spikes. The Gaussian spectrum is preferred since it can be dechirped to transform-limited pulsed duration. The pulse duration corresponds to this kind of spectrum is ~315fs, and pulse energy is up to~9nJ, with a repetition rate of 18.9MHz.

WEPME032	Development Status of SINAP Timing System	PLC, linac, status, controls	2992
	M. Liu, D.K. Liu, C.X. Yin, L.Y. Zhao SINAP, Shanghai, People's Republic of China
	After successful implementation of SINAP timing solution at Pohang Light Source in 2011, the development of SINAP timing system version-II was finished by the end of 2012. The hardware of version-II is based on Virtex-6 FPGA chip, and bidirectional event frame transfer is realized in a 2.5Gbps fiber network. In event frame, data transfer functionality substitutes for distributed bus. The structure of timing system is also modified, where a new versatile EVO could be configured as EVG, FANOUT and EVR with optical outputs. Besides standard VME modules, we designed PLC-EVR as well, which is compatible with Yokogawa F3RP61 series. Based on brand new hardware architecture, the jitter performance of SINAP timing system version-II is improved remarkably.

THPEA042	TREC: Traceability of Radioactive Equipment at CERN	radiation, HOM, controls, monitoring	3234
	M.P. Kepinski, L. Bruno, Ch. Delamare, S. Mallon Amerigo, P. Martel, S. Petit, T. Schmittler, M.J.S. Tavlet, D. Widegren CERN, Geneva, Switzerland
	Activated accelerator components are frequently removed from service due to changes in design, configuration or maintenance work. Safe and effective management of such components is a necessity. Moreover, local authorities require the tracking of this equipment: any piece of equipment or waste which has been in a potentially radioactive area must be controlled by a radio protection responsible before leaving the accelerator premises. CERN must also be able to prove that the required measurements have been done and are properly stored in a computerized system. TREC is the official system used at CERN to trace potentially radioactive equipment. It replaces paper work by electronic data, manual phone calls by automatic email notifications and helps to enforce CERN safety rules. Some of the major benefits are the reduction of the delays related to equipment movements (from installation to workshops or waste storage areas) as well as increased personal safety. The system is fully integrated with the CMMS* tools used at CERN to ensure the complete equipment lifecycle’s traceability. *CMMS: Computerized Maintenance Management System

THPFI014	Bellows with a New RF Shield Made of Metal Braid for High Intensity Proton Accelerators	impedance, vacuum, synchrotron, coupling	3321
	N. Ogiwara, J. Kamiya, M. Kinsho, Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan O. Koizumi Sun-Tech limited, Kobe, Japan
	In the 3 GeV-RCS (Rapid cycling Synchrotron) in J-PARC (Japan Accelerator Research Complex) project, large-scale hydro-formed bellows were developed to adjust the gap between the ceramic ducts and/or between the ceramic ducts and the transport ducts. They have been equipped with a newly developed RF shield, because the usual beryllium-copper spring finger contacts were found to be very hard (roughly 1000 N/mm) owing to the large size. This contact is made of Ti braid, which consists of wires with a diameter of 0.3 mm. This RF contact is a kind of basket (with two ports) made with the braids. Because of the spring effect, the contact can change shape easily. In addition, the contact can easily connect the different cross sections in a smooth fashion. Furthermore, this structure is almost free from the dust generation, which is one of the most troublesome problems for the usual spring finger contacts. This time, we have constructed reserve bellows with the RF shield made of SUS 316L wires to improve the reliability of user operation. The outline of the bellows will be presented, especially laying emphasis on the mechanical function of the RF shield.

THPFI017	Development of Harmonic Field Measurement System with Higher Resolution ADC	dipole, multipole, quadrupole, focusing	3330
	R. Kitahara, Y. Fuwa, Y. Iwashita, Y. Nasu Kyoto ICR, Uji, Kyoto, Japan
	Quadrupole magnets for ILC final focus should be enough strong with the limitation on the external radius, while the vibration of the magnetic center has to be highly avoided to keep the nm sized beam focusing stable at the interaction point a few m downstream from the lens. Gluckstern's 5-ring PMQ singlet seems a good candidate for the purpose, which is under investigation. The precise magnetic harmonic field measurement system is also under development for adjusting each magnet ring and evaluation of the assembled singlet. A rotating magnet system and a rotating coil system are prepared for the former and the latter purposes, respectively. Both systems have 24-bit ADC's for higher resolution. For the rotation coil, a flexible print circuit sheet, where a pair of one turn coils is printed on, is glued on a quartz rod. The two coils located on the quarts rod with the angle difference of 180 degree can separate the odd and even harmonics components by recording both the signals simultaneously to get their sum and difference. The two digitized signals are integrated digitally.

THPFI057	Development of Vacuum Chamber in Low Z Material	vacuum, radiation, impedance, coupling	3421
	C. Garion, P. Costa Pinto, M.A. Gallilee, J. Perez Espinos CERN, Geneva, Switzerland
	Highly transparent vacuum chambers are more and more required in high energy particle physics. In particular, vacuum chambers in the experiments should be as transparent as possible to minimize the background to the detectors while reducing also the material activation. Beryllium is, so far, the most performing material for this application, but it presents some drawbacks such as brittleness, manufacturing issues, toxic hazard, high cost and low availability. A development work to obtain alternative material to the beryllium with similar performance is being carried out at CERN. Three categories have been defined and considered: raw bulk material, material and structural composites. Main requirements are the vacuum compatibility: leak tightness, low outgassing rate, temperature resistance (in the range 200-230 °C), transparency, and mechanical stiffness and strength. Carbon is the element with the lowest atomic number after beryllium and that is appropriate for this application. Therefore carbon based materials have been considered in a variety of options. In this paper, several technologies are presented and discussed. Results of preliminary tests on samples are also shown.

THPFI058	Qualification of a Glassy Carbon Blade for a LHC Fast Vacuum Valve	vacuum, acceleration, accumulation, scattering	3424
	C. Garion, P. Coly CERN, Geneva, Switzerland
	To protect sensitive LHC machine systems against an unexpected gas inrush, a fast vacuum valve system is under development at CERN. The design of the shutter has to be compatible with dynamic loads occurring during the fast closure, namely in the 20 ms range. The material has to fulfil all main requirements such as transparency, high melting temperature, dust free and adequate leak tightness. A development of a blade in vitreous carbon material has been carried out at CERN. The blade has been successfully integrated in a commercial pendulum fast valve. In this paper, the vacuum and mechanical qualification tests are presented.

THPFI064	Crystal-assisted Collimation Experiment from the SPS to the LHC	collimation, simulation, extraction, alignment	3442
	W. Scandale, D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	UA9 was operated in the CERN-SPS for more than six years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 μrad, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency, showing a steady reduction of almost one order of magnitude of the loss rate at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency also in LHC. After a concise description of the results collected in the SPS we propose a scenario to integrate bent crystals in the LHC collimation system for machine experiment.

THPFI087	Measurements of Secondary Electron Yield of Metal Surfaces and Films with Exposure to a Realistic Accelerator Environment	electron, vacuum, photon, gun	3493
	W. Hartung, J.V. Conway, C.A. Dennett, S. Greenwald, J.-S. Kim, Y. Li, T.P. Moore, V. Omanovic CLASSE, Ithaca, New York, USA
	One of the central goals of the CESR Test Accelerator program is to understand electron cloud (EC) effects in lepton rings and how to mitigate them. To this end, measurements of the secondary electron yield (SEY) of technical surfaces are being done in CESR. The CESR in-situ system, in operation since 2010, allows for measurements of SEY as a function of incident electron energy and angle on samples that are exposed to a realistic accelerator environment, typically 5.3 GeV electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY and discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. Measurements so far have been done on bare metal surfaces (aluminum, copper, stainless steel) and EC-mitigatory coatings (titanium nitride, amorphous carbon, diamond-like carbon). A significant decrease in SEY with exposure to beam was observed for all cases other than the amorphous C samples; for the latter, the SEY remained near 1, independent of beam exposure. The SEY results are being used to improve predictive models for EC build-up and EC-induced beam effects.

FRYCA01	Neutrino Physics and Requirements to Accelerators	proton, target, factory, site	4010
	Y.F. Wang IHEP, Bejing, People's Republic of China
	This presentation reviews recent progress of neutrino experiments, both reactor- and accelerator-based, and discusses requirements for accelerators.
	Slides FRYCA01 [4.070 MB]

Paper

Title

Other Keywords

Page

MOPFI005

XPS and UHV-AFM Analysis of the K2CsSb Photocathodes Growth

cathode, vacuum, electron, factory

291

S.G. Schubert
HZB, Berlin, Germany
I. Ben-Zvi, M. Ruiz-Osés
Stony Brook University, Stony Brook, USA
X. Liang
SBU, Stony Brook, New York, USA
H.A. Padmore, T. Vecchione
LBNL, Berkeley, California, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: This work is funded by the Department of Energy, under Contract No. KC0407-ALSJNT-I0013, DE-SC0005713, the Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany.
Next generation light sources, based on Energy Recovery Linac and Free Electron Laser technology will rely on photoinjector based electron sources. Successful operation of such sources requires reliable photocathodes with long operational life, uniform and high quantum efficiency, low thermal emittance and low dark current. The goal of this project is to construct a cathode which meets these requirements. Advances in photocathode research must take a combined effort. The materials have to be analyzed by means of chemical composition, surface structure and these findings have to be correlated to the quantum efficiency and performance in the injector. The presented work focuses on the chemical composition and surface structure of K2CsSb photocathodes. The XPS and AFM measurements were performed at the Center of Functional Nanomaterials at BNL. K2CsSb photocathodes were grown under UHV conditions. The components were adsorbed one at a time and after each growth step the corresponding XPS spectra was taken. During growth the quantum efficiency was recorded. As last step the sample was moved into the AFM without exposure to air to determine the surface roughness.

MOPME010

Transverse Beam Profile Diagnostics using Point Spread Function Dominated Imaging with Dedicated De-focusing

radiation, electron, target, focusing

488

G. Kube, S. Bajt
DESY, Hamburg, Germany
W. Lauth
IKP, Mainz, Germany
Yu.A. Popov, A. Potylitsyn, L.G. Sukhikh
TPU, Tomsk, Russia

Transverse beam profile diagnostics in electron accelerators is usually based on direct imaging of a beam spot via optical radiation (transition or synchrotron radiation). In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to achieve resolutions beyond the diffraction limit is to perform point spread function (PSF) dominated imaging, i.e. the recorded image is dominated by the resolution function of a point source (single electron), and with knowledge of the PSF the true image (beam spot) may be reconstructed. To overcome the limited dynamical range of PSF dominated imaging, a dedicated de-focusing of the optical system can be introduced. In order to verify the applicability of this method, a proof-of-principle experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) using optical transition radiation. Status and results of this experiment will be presented.

MOPME011

Investigation of the Applicability of Parametric X-ray Radiation for Transverse Beam Profile Diagnostics

radiation, photon, diagnostics, electron

491

G. Kube, C. Behrens
DESY, Hamburg, Germany
A.S. Gogolev, Yu.A. Popov, A. Potylitsyn
TPU, Tomsk, Russia
W. Lauth
IKP, Mainz, Germany
S. Weisse
DESY Zeuthen, Zeuthen, Germany

Transverse beam profile diagnostics in electron linacs is widely based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern linac based light sources like LCLS or FLASH shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. A possibility to overcome this limitation is to measure at much shorter wavelengths, i.e. in the X-ray region, using parametric X-ray radiation (PXR) which additionally offers the advantage to be generated at crystal planes oriented under a certain angle to the crystal surface, thus allowing a spatial separation from a possible COTR background *. A first test experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the applicability of PXR for beam diagnostics, and the status of this experiment will be presented.
* A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics 357 (2012) 012018

MOPME014

Electro-optical Bunch Length Measurements at the ANKA Storage Ring

laser, electron, wakefield, storage-ring

500

N. Hiller, A. Borysenko, E. Hertle, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller, M.J. Nasse, A. Plech, M. Schuh, S.N. Smale
KIT, Karlsruhe, Germany
P. Peier, V. Schlott
PSI, Villigen PSI, Switzerland
B. Steffen
DESY, Hamburg, Germany

Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC
A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring.

MOPME068

Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC

radiation, simulation, electron, vacuum

634

N. Fuster Martinez, A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson
JAI, Oxford, United Kingdom
J. Barros, N. Delerue, M. Grosjean
LAL, Orsay, France
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA

The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME075

Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4

laser, electron, linac, emittance

652

T. Hofmann, E. Bravin, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland
B. Cheymol
ESS, Lund, Sweden

Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191
The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

MOPWA053

Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System

laser, electron, alignment, photon

795

L.J. Nevay, G.A. Blair, S.T. Boogert, V. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
A.S. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
L. Corner, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579
We present the results from the laserwire system at the Accelerator Test Facility 2 (ATF2) during recent operation after relocation to the virtual image point of the ATF2 final focus. The characterisation of the 150 mJ, 77 ps long laser pulses at a scaled virtual interaction point is used to deconvolve the transverse laserwire profile demonstrating a 1.16 ± 0.06 um vertical electron beam profile. Horizontal laserwire scans were used in combination with the vertical scans to measure the electron beam size using a full overlap integral model due to the problems presented by a large aspect ratio electron beam.

MOPWA074

High Voltage Converter Modulator Optimization

high-voltage, controls, neutron, feedback

852

A. Scheinker
LANL, Los Alamos, New Mexico, USA
M.J. Bland
University of Nottingham, Nottingham, United Kingdom

High voltage converter modulators (HVCM) are at the forefront of long pulse high voltage (100kV) technology for Klystron voltage sources. We present results of digitally implementing an extremum seeking (ES) algorithm with which we optimized the rise time of the output voltage of a HVCM at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieved a 50us rise time, which is reduction in half compared to the 100us currently achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The ES algorithm is successful despite the noisy measurements and cost calculations, confirming the theoretical predictions that the algorithm is not affected by noise unless it both matches exactly the frequency components of the controller's specific perturbing frequencies and is of comparable size.

MOPWA077

EPICS, MATLAB, GigE CCD Camera Based Beam Imaging System for the IAC-RadiaBeam THz Project

EPICS, controls, GUI, optics

858

C.F. Eckman, A. Andrews, T. Downer, Y. Kim, C. O'Neill
IAC, Pocatello, IDAHO, USA
P. Buaphad, Y. Kim
ISU, Pocatello, Idaho, USA
Y. Kim
JLAB, Newport News, Virginia, USA

At the Idaho Accelerator Center (IAC) of Idaho State University, we have been operating an L-band RF linear accelerator running at low energies (5 - 44 MeV) for the IAC-RadiaBeam THz project. We have designed and implemented an image acquisition and analysis system that can be used for real time observation of the electron beam, tuning of THz radiation production, and measurement of the transverse beam emittance. The imaging system contains an Yttrium Aluminium Garnet (YAG) screen on an actuator, a Prosilica GC1290 GigE CCD camera with an adjustable lens, a screen illuminator, an optical alignment structure, and a lead tube for the camera shielding. The real time continuous beam images can be acquired by SampleViewer, while the single shot beam image can be acquired by the Experiential Physics and Industrial Control System (EPICS) and areaDetector. In this paper, we describe components of the imaging system, the real time beam image acquisition with SampleViewer, the single shot beam image acquisition with areaDetector, and a remote controllable beam image acquisition via MATLAB Channel Access (MCA), MATLAB, and EPICS.

MOPWO029

Remote Estimate of Collimator Jaw Damages with Sound Measurements during Beam Impacts

proton, radiation, simulation, extraction

951

D. Deboy, O. Aberle, R.W. Aßmann, F. Carra, M. Cauchi, J. Lendaro, A. Masi, S. Redaelli
CERN, Geneva, Switzerland

Irregular hits of high-intensity LHC beams on collimators can lead to severe damage of the collimator jaws. The identification of damaged collimator jaws by observation of beam measurements is challenging: online loss measurements at the moment of the impacts can be tricky and degradation of the overall performance from single collimator damage can be difficult to measure. Visual inspections are excluded because collimator jaws are enclosed in vacuum tanks without windows. However, the sound generated during the beam impact can be used to give an estimate of the damage level. In 2012, high-intensity beam comparable to a full nominal LHC bunch at 7 TeV was shot on a tertiary type LHC collimator at the HiRadMat test facility at CERN. The paper presents results from sound recordings of this experiment.

MOPWO041

Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC

simulation, luminosity, proton, dipole

984

A. Marsili, R. Bruce, F. Cerutti, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO050

Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods

collimation, injection, resonance, betatron

1008

V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
V. Moens
EPFL, Lausanne, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

TUPEA035

Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability

plasma, impedance, electron, space-charge

1220

D. Huang, Q. Gu
SINAP, Shanghai, People's Republic of China
K.Y. Ng
Fermilab, Batavia, USA

Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747.
In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor** is widely used to explain the physics of the LSC-induced microbunching instability***. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated.
* Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008)
** J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
*** Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

TUPFI037

Collimation Down to 2 Sigma in Special Physics Runs in the LHC

proton, scattering, luminosity, emittance

1427

H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland

We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI057

Muon Accelerators for the Next Generation of High Energy Physics Experiments

collider, factory, proton, target

1475

M.A. Palmer, S. Brice, A.D. Bross, D.S. Denisov, E. Eichten, R.J. Lipton, D.V. Neuffer
Fermilab, Batavia, USA
C.M. Ankenbrandt
Muons. Inc., USA
S.A. Bogacz
JLAB, Newport News, Virginia, USA
J.-P. Delahaye
SLAC, Menlo Park, California, USA
P. Huber
Virginia Polytechnic Institute and State University, Blacksburg, USA
D.M. Kaplan, P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA
H.G. Kirk, R.B. Palmer
BNL, Upton, Long Island, New York, USA
R.D. Ryne
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy and the U.S. National Science Foundation
Muon accelerator technology offers a unique and very promising avenue to a facility capable of producing high intensity muon beams for neutrino factory and multi-TeV lepton collider applications. The goal of the US Muon Accelerator Program is to provide an assessment, within the next 6 years, of the physics potential and technical feasibility of such a facility. This talk will describe the physics opportunities that are envisioned, along with the R&D efforts that are being undertaken to address key accelerator physics and technology questions.

TUPME007

Beam Lifetime in Low Emittance Rings

scattering, simulation, lattice, factory

1574

M. Boscolo
INFN/LNF, Frascati (Roma), Italy

In this paper I will review the main effects in low emittance rings that determine the beam lifetime by causing beam losses along the ring. As an example, the case for a B-factory based on the crab-waist collision scheme has been studied. During the machine design all the effects that determine the beam lifetime and induce backgrounds in the detector have been analyzed in details. The crab-waist scheme provides an higher luminosity, but at the same time it induces higher beam losses at the final focus. For this reason single beam effects such as Touschek and beam-gas scattering have been studied in details, by means of a macroparticle tracking code developed for this purpose*. Also Radiative Bhabha scattering, that is the dominant effect to lifetime and backgrounds has been studied with the same technique to check possible multiturn losses at IR. An efficient collimation system has been designed to intercept scattered particles that would be lost in the IR in both the horizontal and the vertical plane. Recently, the Touschek tracking simulation code has been implemented to study the lifetime behavior for extremely low-emittance rings.
* M. Boscolo and P. Raimondi, “Monte Carlo simulation for the Touschek effect with the crab-waist scheme”, Phys. Rev. ST-AB 15 104201 (2012)

TUPWO055

Phase Rotation Experiment at EMMA for testing Applicability of a Non-scaling FFAG for PRISM System

extraction, synchrotron, acceleration, electron

1991

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.T.P. D'Arcy
UCL, London, United Kingdom
J.K. Jones, B.D. Muratori
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
H.L. Owen
UMAN, Manchester, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA is the world’s first non-scaling FFAG, based at Daresbury Laboratory. EMMA has a very large acceptance and has demonstrated acceleration in the serpentine channel. PRISM (Phase Rotated Intense Slow Muon source) is a next generation muon to electron conversion experiment aiming to obtain intense quasi-monochromatic low energy muon beams by performing RF phase rotation in an FFAG ring. Current baseline design for PRISM applies the scaling FFAG ring, but an alternative machine could be based on a ns-FFAG principle. As the transverse-longitudinal coupling is present in ns-FFAGs due to a natural chromaticity, its effect on the final energy spread and beam quality needs to be tested. In order to gauge the expected results, an experiment was designed to be performed on EMMA. We report here the details of this experiment and the results gathered from EMMA operation.

WEOAB103

Experimental Observations of a Multi-stream Instability in a Long Intense Beam

simulation, electron, space-charge, factory

2044

B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
We have observed evidence of a multi-stream instability in a long non-relativistic space-charge dominated beam evolving with an initial non-linear distribution and zero external longitudinal containment. This type of instability can be detrimental to intense accelerators that propagate rectangular distributions, such as in a ring with single or multi-bunch injection. The longitudinal forces in these intense bunches causes the beam to expand axially; in the case of the University of Maryland Electron Ring (UMER), the initial long bunch is injected to fill a fraction of the ring, coasting beyond the point where the head and tail overlap. Adjacent filaments at that point are separated in velocity space by 2cs and approach a separation of cs. The onset of the instability has been observed to depend on the injected beam current, bunch length, and other experimental factors. Comparisons with simple analytical calculations and PIC simulations have shown good agreement in the time to onset.

Slides WEOAB103 [1.681 MB]

WEPEA074

Optimisation of the Beam Line for COMET Phase-I

dipole, electron, solenoid, target

2681

A. Kurup, I. Puri, Y. Uchida, Y. Yap
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing
UCL, London, United Kingdom

The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. It was recently proposed to build COMET is two phases with physics measurements being made in both phases. This requires re-optimising the beam line for a shorter curved solenoid. This will affect the pion and muon yield; the momentum distributions at the detector; and the collimator scheme required. This paper will present the beam line design for COMET Phase-I, which aims to maximise the yield for low momentum muons suppressing sources of backgrounds in the beam.

WEPEA075

Large Emittance Beam Measurements for COMET Phase-I

solenoid, electron, simulation, proton

2684

A. Kurup, I. Puri, Y. Uchida, Y. Yap
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing
UCL, London, United Kingdom

The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. Understanding the pion production yield and transport properties of the beam line is an important part of the experiment. The beam line is a continuous solenoid channel, so it is only possible to place a beam diagnostic device at the end of the beam line. Building COMET in two phases provides the opportunity to investigate the pion production yield and to measure the transport properties of the beam line in Phase-I. This paper will demonstrate how this will be done using the experimental set up for COMET Phase-I.

WEPFI049

CoStub: A 6 1/8” Coaxial Short Circuit using Stubs

cavity, simulation, synchrotron, high-voltage

2809

B. Bravo, F. Mares, F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3Gev synchrotron light source located in Barcelona and operating with users since May 2012. The ALBA storage ring uses six room temperature cavities; each one fed by two 80kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. The two possible operation modes of CaCo at high power have been tested. The symmetrical mode (two IOTs feed the CaCo symmetrically) works properly and without presenting any problem. But in the asymmetrical mode (one IOT feeds the CaCo and the other is keeping passive) a standing wave is created between the passive IOT and Caco, provoking a large voltage in the gap of the passive IOT that broke the ceramic. A new device, CoStub (coaxial stub), to short circuit the coaxial waveguide of the passive arm and protects the passive IOT has been built and successfully tested. This paper presents the design details and the low level and high power test of this device.

WEPFI058

Breakdown Localization Studies on the SwissFEL C-band Test Structures

linac, coupling, factory, impedance

2824

J. Klavins, S. Dementjevs, F. Le Pimpec, L. Stingelin, M. Wohlmuther, R. Zennaro
PSI, Villigen PSI, Switzerland
N.C. Shipman
CERN, Geneva, Switzerland

The SwissFEL main linac will consist of 10⁴ C-band structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analyzed, in addition to acoustic measurements, the delay and phase of the rf power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuum-events at the same location. The experiments show that the linac test-structures fulfill the requirements in breakdown probability. Moreover developing a detection system based on acoustic emission sensors for breakdown localization for our C-band structure seems reasonable given the results obtained.

WEPFI074

RF Cavity Spark Localization Using Acoustic Measurement

cavity, diagnostics, LabView, collider

2863

P. Snopok
IIT, Chicago, Illinois, USA
A.D. Bross
Fermilab, Batavia, USA
P.G. Lane, Y. Torun
Illinois Institute of Technology, Chicago, Illinois, USA

Current designs for muon cooling channels require high-gradient RF cavities to be placed in solenoidal magnetic fields in order to contain muons with large transverse emittances. It has been found that doing so reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields it would be helpful to have a diagnostic tool which can detect breakdown and localize the source of the breakdown inside the cavity. We report here on progress towards developing a diagnostic tool for detecting and localizing sparks in an RF cavity by using piezoelectric transducers.

WEPME024

Gaussian Spectrum Fiber Laser Pulses Generated in an All-normal-dispersion Cavity

laser, cavity, controls, status

2983

Y. You, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
H. Shimizu, J. Urakawa
KEK, Ibaraki, Japan

In this paper, we reported generating a broad bandwidth Gaussian shape spectrum fiber laser pulse directly in an all-normal dispersive cavity. Pulse-shaping is based on spectral filtering. The spectrum has a ~20 nm 20-dB spectrum bandwidth and it is different from the typical spectrum, of steep edge and two spikes. The Gaussian spectrum is preferred since it can be dechirped to transform-limited pulsed duration. The pulse duration corresponds to this kind of spectrum is ~315fs, and pulse energy is up to~9nJ, with a repetition rate of 18.9MHz.

WEPME032

Development Status of SINAP Timing System

PLC, linac, status, controls

2992

M. Liu, D.K. Liu, C.X. Yin, L.Y. Zhao
SINAP, Shanghai, People's Republic of China

After successful implementation of SINAP timing solution at Pohang Light Source in 2011, the development of SINAP timing system version-II was finished by the end of 2012. The hardware of version-II is based on Virtex-6 FPGA chip, and bidirectional event frame transfer is realized in a 2.5Gbps fiber network. In event frame, data transfer functionality substitutes for distributed bus. The structure of timing system is also modified, where a new versatile EVO could be configured as EVG, FANOUT and EVR with optical outputs. Besides standard VME modules, we designed PLC-EVR as well, which is compatible with Yokogawa F3RP61 series. Based on brand new hardware architecture, the jitter performance of SINAP timing system version-II is improved remarkably.

THPEA042

TREC: Traceability of Radioactive Equipment at CERN

radiation, HOM, controls, monitoring

3234

M.P. Kepinski, L. Bruno, Ch. Delamare, S. Mallon Amerigo, P. Martel, S. Petit, T. Schmittler, M.J.S. Tavlet, D. Widegren
CERN, Geneva, Switzerland

Activated accelerator components are frequently removed from service due to changes in design, configuration or maintenance work. Safe and effective management of such components is a necessity. Moreover, local authorities require the tracking of this equipment: any piece of equipment or waste which has been in a potentially radioactive area must be controlled by a radio protection responsible before leaving the accelerator premises. CERN must also be able to prove that the required measurements have been done and are properly stored in a computerized system. TREC is the official system used at CERN to trace potentially radioactive equipment. It replaces paper work by electronic data, manual phone calls by automatic email notifications and helps to enforce CERN safety rules. Some of the major benefits are the reduction of the delays related to equipment movements (from installation to workshops or waste storage areas) as well as increased personal safety. The system is fully integrated with the CMMS* tools used at CERN to ensure the complete equipment lifecycle’s traceability.
*CMMS: Computerized Maintenance Management System

THPFI014

Bellows with a New RF Shield Made of Metal Braid for High Intensity Proton Accelerators

impedance, vacuum, synchrotron, coupling

3321

N. Ogiwara, J. Kamiya, M. Kinsho, Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
O. Koizumi
Sun-Tech limited, Kobe, Japan

In the 3 GeV-RCS (Rapid cycling Synchrotron) in J-PARC (Japan Accelerator Research Complex) project, large-scale hydro-formed bellows were developed to adjust the gap between the ceramic ducts and/or between the ceramic ducts and the transport ducts. They have been equipped with a newly developed RF shield, because the usual beryllium-copper spring finger contacts were found to be very hard (roughly 1000 N/mm) owing to the large size. This contact is made of Ti braid, which consists of wires with a diameter of 0.3 mm. This RF contact is a kind of basket (with two ports) made with the braids. Because of the spring effect, the contact can change shape easily. In addition, the contact can easily connect the different cross sections in a smooth fashion. Furthermore, this structure is almost free from the dust generation, which is one of the most troublesome problems for the usual spring finger contacts. This time, we have constructed reserve bellows with the RF shield made of SUS 316L wires to improve the reliability of user operation. The outline of the bellows will be presented, especially laying emphasis on the mechanical function of the RF shield.

THPFI017

Development of Harmonic Field Measurement System with Higher Resolution ADC

dipole, multipole, quadrupole, focusing

3330

R. Kitahara, Y. Fuwa, Y. Iwashita, Y. Nasu
Kyoto ICR, Uji, Kyoto, Japan

Quadrupole magnets for ILC final focus should be enough strong with the limitation on the external radius, while the vibration of the magnetic center has to be highly avoided to keep the nm sized beam focusing stable at the interaction point a few m downstream from the lens. Gluckstern's 5-ring PMQ singlet seems a good candidate for the purpose, which is under investigation. The precise magnetic harmonic field measurement system is also under development for adjusting each magnet ring and evaluation of the assembled singlet. A rotating magnet system and a rotating coil system are prepared for the former and the latter purposes, respectively. Both systems have 24-bit ADC's for higher resolution. For the rotation coil, a flexible print circuit sheet, where a pair of one turn coils is printed on, is glued on a quartz rod. The two coils located on the quarts rod with the angle difference of 180 degree can separate the odd and even harmonics components by recording both the signals simultaneously to get their sum and difference. The two digitized signals are integrated digitally.

THPFI057

Development of Vacuum Chamber in Low Z Material

vacuum, radiation, impedance, coupling

3421

C. Garion, P. Costa Pinto, M.A. Gallilee, J. Perez Espinos
CERN, Geneva, Switzerland

Highly transparent vacuum chambers are more and more required in high energy particle physics. In particular, vacuum chambers in the experiments should be as transparent as possible to minimize the background to the detectors while reducing also the material activation. Beryllium is, so far, the most performing material for this application, but it presents some drawbacks such as brittleness, manufacturing issues, toxic hazard, high cost and low availability. A development work to obtain alternative material to the beryllium with similar performance is being carried out at CERN. Three categories have been defined and considered: raw bulk material, material and structural composites. Main requirements are the vacuum compatibility: leak tightness, low outgassing rate, temperature resistance (in the range 200-230 °C), transparency, and mechanical stiffness and strength. Carbon is the element with the lowest atomic number after beryllium and that is appropriate for this application. Therefore carbon based materials have been considered in a variety of options. In this paper, several technologies are presented and discussed. Results of preliminary tests on samples are also shown.

THPFI058

Qualification of a Glassy Carbon Blade for a LHC Fast Vacuum Valve

vacuum, acceleration, accumulation, scattering

3424

C. Garion, P. Coly
CERN, Geneva, Switzerland

To protect sensitive LHC machine systems against an unexpected gas inrush, a fast vacuum valve system is under development at CERN. The design of the shutter has to be compatible with dynamic loads occurring during the fast closure, namely in the 20 ms range. The material has to fulfil all main requirements such as transparency, high melting temperature, dust free and adequate leak tightness. A development of a blade in vitreous carbon material has been carried out at CERN. The blade has been successfully integrated in a commercial pendulum fast valve. In this paper, the vacuum and mechanical qualification tests are presented.

THPFI064

Crystal-assisted Collimation Experiment from the SPS to the LHC

collimation, simulation, extraction, alignment

3442

W. Scandale, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

UA9 was operated in the CERN-SPS for more than six years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 μrad, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency, showing a steady reduction of almost one order of magnitude of the loss rate at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency also in LHC. After a concise description of the results collected in the SPS we propose a scenario to integrate bent crystals in the LHC collimation system for machine experiment.

THPFI087

Measurements of Secondary Electron Yield of Metal Surfaces and Films with Exposure to a Realistic Accelerator Environment

electron, vacuum, photon, gun

3493

W. Hartung, J.V. Conway, C.A. Dennett, S. Greenwald, J.-S. Kim, Y. Li, T.P. Moore, V. Omanovic
CLASSE, Ithaca, New York, USA

One of the central goals of the CESR Test Accelerator program is to understand electron cloud (EC) effects in lepton rings and how to mitigate them. To this end, measurements of the secondary electron yield (SEY) of technical surfaces are being done in CESR. The CESR in-situ system, in operation since 2010, allows for measurements of SEY as a function of incident electron energy and angle on samples that are exposed to a realistic accelerator environment, typically 5.3 GeV electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY and discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. Measurements so far have been done on bare metal surfaces (aluminum, copper, stainless steel) and EC-mitigatory coatings (titanium nitride, amorphous carbon, diamond-like carbon). A significant decrease in SEY with exposure to beam was observed for all cases other than the amorphous C samples; for the latter, the SEY remained near 1, independent of beam exposure. The SEY results are being used to improve predictive models for EC build-up and EC-induced beam effects.

FRYCA01

Neutrino Physics and Requirements to Accelerators

proton, target, factory, site

4010

Y.F. Wang
IHEP, Bejing, People's Republic of China

This presentation reviews recent progress of neutrino experiments, both reactor- and accelerator-based, and discusses requirements for accelerators.

Slides FRYCA01 [4.070 MB]