LBNL, Berkeley, California
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
To uniformly heat targets to electron-volt temperatures for the study of warm dense matter, one strategy is to deposit most of the ion energy at the peak of energy loss (dE/dx) with a low (E < 5 MeV) kinetic energy beam and a thin target*. Lower mass ions have a peak dE/dx at a lower kinetic energy. To this end, a small lithium (Li+) alumino-silicate source has been fabricated, and its emission limit has been measured. These surface ionization sources are heated to {10}00-1150 C where they preferentially emit singly ionized alkali ions. Alumino-silicates sources of K+ and Cs+ have been used extensively in beam experiments, but there are additional challenges for the preparation of high-quality Li+ sources: There are tighter tolerances in preparing and sintering the alumino-silicate to the substrate to produce an emitter that gives uniform ion emission, sufficient current density and low beam emittance. We report on recent measurements of high ( up to 35 mA/cm2) current density from a Li+ source. Ion species identification of possible contaminants is being verified with a Wien (E x B) filter, and via time-of-flight.
*J.J. Barnard et al., Nuclear Instruments and Methods in Physics Research A 577 (2007) 275283.
INFN/LASA, Segrate (MI)
Funding: This work has partly been supported by the European Community, Contract Number RII3-CT-2004-506008.
Since ‘90s our laboratory is in charge of producing Cs2Te photocathodes employed as laser driven electron sources in the high brightness photoinjectors of the FLASH and PITZ facilities. The production recipe has been developed and standardized during years, fulfilling the requests for photocathode operation in the photoinjectors. Nevertheless, the growing process of the film is still not totally understood, mainly respect to the final material properties. In this paper, reflectivity and spectral response measurements, at different wavelengths, measured during the photocathode growth are presented and compared with the corresponding photocurrent behavior. The new information, together with results obtained with standard diagnostic tools, will help to improve the understanding of the growing process, of the compounds formation with different Cs/Te ratio and of the reproducibility of the Cs2Te film structure.
UMD, College Park, Maryland
Funding: Work sponsored by the Department of Defense Office of Naval Research and the Joint Technology Office
Recent theoretical and experimental results advancing the state of the art in OTR diagnostics are presented. In particular, new facilities are beginning to operate in regimes where coherent effects are being seen in OTR diagnostics. The state of the art in theory and beam diagnostic data are reviewed and implications for next-generation diagnostic opportunities are presented.
BNL, Upton, Long Island, New York
A new 3rd generation light source (NSLS-II project) is in the early stage of construction at Brookhaven National Laboratory. The NSLS-II facility will provide ultra high brightness and flux with exceptional beam stability. It presents several challenges in the diagnostics and instrumentation, related to the extremely small emittance. In this paper, we present an overview of all planned instrumentation systems, results from research & development activities; and then focus on other challenging aspects.
KEK, Ibaraki
ISSP/SRL, Chiba
TIPC, BeiJing
A new cavity diagnostic system has been introduced for vertical testing of nine-cell L-band superconducting cavities at KEK-STF. The present system is based on approximately 300 carbon resistors for temperature-mapping (T-mapping), and approximately 40 PIN photo diodes for detecting emission of X-rays. The system can accommodate up to total 600 sensors in needed in the future. While most of the sensors are attached to the cavity exterior in a pre-determined regular pattern, some sensors can be strategically placed at non-regular positions so as to watch the areas which are considered “suspicious” as per the surface inspection done prior to vertical testing. Data from the sensors can be collected every 100 msec. The data can be graphically displayed online and are stored for offline analysis. This paper describes the details of this system, together with results from its initial pilot operation which was done with a nine-cell cavity on loan from FNAL (AES#001). Effectiveness of the combined use of T-mapping and PIN photo diodes in operation of the pi-mode and other pass-band modes in conjunction with surface inspection is discussed.
BNL, Upton, Long Island, New York
The NSLS II is a state of the art 3 GeV synchrotron light source being developed at BNL. The injection system will consist of a 200 MeV linac and a 3GeVbooster synchrotron. The transport lines between the linac and booster (LtB) and the booster and storage ring (BtS) must satify a number of requirements. In addition to transporting the beam while mantaining the beam emittance, these lines must allow for commissioning, provide appropriate diagnostics, allow for the appropriate safety devices and and in the case of the BtS line, provide for a stable beam for top off injection. Appropriate diagnostics are also necessary in the linac and booster to complement the measurements in the transfer lines. In this paper we discuss the design of the transfer lines for the NSLSII along with the incorporated diagnostics and safety systems. Necessary diagnostics in the linac and booster are also discussed.
CLS, Saskatoon, Saskatchewan
Coherent Synchrotron Radiation (CSR) is produced when short bunch lengths are set up in the Canadian Light Source storage ring. To achieve short bunches large negative dispersion is introduced into the straight regions of the lattice such that the momentum compaction can be made to approach zero. In this way CSR has been observed using a few single bunches with currents up to 10 mA per bunch at the nominal operating energy of 2.9 GeV. Attempts produce CSR with low bunch currents in many bunches were unsuccessful at 2.9 GeV. At 1.5 GeV, however, it is possible to achieve CSR with a total of 5 mA stored in over 70 bunches. CSR production is enhanced by operating at a horizontal tune where the chromaticity can be kept near zero. Tracking simulations in longitudinal phase space indicate enhanced stability at tunes lower than the nominal tune. The optimum tune does not depend on the fractional tune but rather there is a tune "window" at the center of which stable longitudinal motion can be maximized.
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
ISM-CNR, Rome
The SPARX-FEL project consists in an X-ray-FEL facility which aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1.5 and 2.4 GeV. This facility will be built in the Tor Vergata University area in Rome. The paper describe the engineering aspects of the mechanical design of the accelerator, photo-injector, LINACs, bunch compressors, beam distribution, undulators and experimental stations. Morover the integration of accelerator with the civil infrastractures is discussed.
CNAO Foundation, Milan
INFN/LNF, Frascati (Roma)
The Centro Nazionale di Adroterapia Oncologica (National Center for Oncological Hadrontherapy, CNAO) is the Italian center for deep hadrontherapy. It will deliver treatments with active scanning both with proton and carbon ion beams. The accelerator complex is based on a 25 m diameter synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Four treatment lines, in three treatment rooms, are foreseen in a first stage. In one of the three rooms a vertical and a horizontal fixed beam lines are provided, while in the other two rooms the treatment will be administered with horizontal beams only. The injection chain is positioned inside the synchrotron ring itself, to save space and to better exploit the two non-dispersive regions in the synchrotron. The injection chain is made by a 8 keV/u Low Energy Beam Transfer line (LEBT), a RFQ accelerating the beam to 400 keV/u, a LINAC to reach the injection energy of 7 MeV/u and a Medium Energy Beam Transfer line (MEBT) to transport the beam to the synchrotron. This report describes the design and the performances of the CNAO complex, and reports about the status of the commissioning of the machine.
Fermilab, Batavia
A new experimental area, the Muon Test Area, has been constructed to develop, test, and verify muon ionization apparatus using the 400-MeV proton beam from the Fermilab Linac. Since muon-cooling apparatus is being developed for facilities that involve the capture, collection and cooling of ~1013 muons at a repetition rate of 15 Hz, conclusive tests require full Linac beam, or ~1013 protons/pulse at 15 Hz. A beamline has been designed which includes specialized insertions for linac beam diagnostics and beam measurements, greatly enhancing the functionality of the line in addition to providing beam for MTA experiments. Installation of the beamline is complete and first beam was achieved in November, 2008. The design, operational flexibility, and characteristics of the MTA beamline will be presented.
CERN, Geneva
Initial commissioning of the LHC beam dump system with beam took place in August and September 2008. The preparation, setting-up and the tests performed are described together with results of the extractions of beam into the dump lines. Analysis of the first detailed aperture measurements of extraction channels and kicker performance derived from dilution sweep shapes are presented. The performance of the other equipment subsystems is summarised, in particular that of the dedicated dump system beam instrumentation.
ELETTRA, Basovizza
Recent advances in high-stability electronic and electro-optic timing and synchronization systems are presented. These systems have been proposed for several new FEL facilities, and are in development at several labs. Several basic technical implementations are in development, some based on pulsed mode-locked laser technology, others using CW systems. There are numerous technical choices with regard to the stability, synchronizability, capability of multi-drop operation, availability of inherent diagnostic information, complexity of transmitters vs. receivers, use of commercial vs. custom-designed components, etc. This talk presents an overview of the basic timing and synchronization requirements in accelerator systems, and reviews the state of the art. Contrasts are made between the CW and pulsed optical distribution approaches. The technology in development to distribute a 38 GHz phase coherent LO at the ALMA radiotelescope is highlighted as a related technical system in development.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
EMMA, the Electron Model with Many Applications, was originally conceived as a model of a GeV-scale muon accelerator. The non-scaling (NS) properties of resonance crossing, small apertures, parabolic ToF and serpentine acceleration are novel, unproven accelerator physics and require "proof of principle". EMMA has metamorphosed from a simple "demonstration" objective to a sophisticated instrument for accelerator physics investigation with operational demands far in excess of the muon application that lead to technological challenges in magnet design, rf optimisation, injection and extraction, and beam diagnostics. Machine components procured in 2008 will be installed February-May 2009 leading to full system tests June-August and commissioning with electrons beginning September 2009.
GSI, Darmstadt
NSCL, East Lansing, Michigan
IAP, Frankfurt am Main
Funding: European Commission; contract number HPRI-CT-2001-50036 (HITRAP) German Ministry for Education and Research (BMBF; contract number 06 FY160I
Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u. First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.
IIT, Chicago, Illinois
Superconducting RF cavities are made of a thin metal shell (typically Niobium) with liquid Helium around it housed within another metal vessel. This geometry is effectively a Cerenkov radiator between two mirrors. Electrons stripped from the inner surface due to field emission can get accelerated by the electric field inside the cavity, punch through the cavity wall and still have enough energy to be faster than light in He. Detection of Cerenkov light generated by the electrons through an optical port integrated into the vessel can serve as a very sensitive diagnostic for field emission in cavity R&D and production as well as in operating superconducting linear accelerators. We report on simulation results for calculating the effective light yield in such a system to establish the feasibility of the technique.
LANL, Los Alamos, New Mexico
Funding: DTRA
A temperature mapping system with 4608 100-ohm Allen-Bradley resistors has been built and tested at LANL. With this temperature mapping system we were able to locate lossy regions in the 1.3 GHz 9-cell SRF cavity due to field emission and direct heating. The results of the temperature mapping have been correlated with the inside surface inspection of the cavity and will be shown together with Q-E curves. A brief description of the mapping system and improvements that have been made in the recent months will also be mentioned in the paper.
I-Tech, Solkan
In a feedback system the disturbances added in the receiver section are one of the major contributors to the amplitude and phase fluctuations of the fields in the RF cavities that are being controlled. It is therefore crucial to thoroughly evaluate the receiver section of the control system. Measurement results of parameters like amplitude noise, phase noise, coupling between RF channels, linearity and temperature dependent drifts of the receiver are presented. We also discuss what the influences of some of the measured parameters on phase and amplitude stability of the RF fields are. Finally, we summarize the results of the measurements and their impact on the future development of the Libera LLRF system.
Warsaw University of Technology, Institute of Electronic Systems, Warsaw
DESY, Hamburg
One of the most important requirements for the XFEL RF system is to assure a very precise RF field stability within the accelerating cavities. The required amplitude and phase stability equals respectively dA/A <3·10-5, dphi<0.01 deg @ 1.3GHz in the injector and dA/A<10-3, dphi <0.1 deg @1.3GHz in the main linac section of the XFEL facility. Fulfilling such requirements is a very challenging task for the 1.5 km long main linac system and about 3.4 km length of the entire facility. Thousands of electronic and RF devices must be precisely phase synchronized for effective controlling of the RF field parameters. We describe the the proposed architecture of the RF Master Oscillator and the Phase Reference Distribution System for the XFEL. Design choices were based on the experience gained during the commissioning of the FLASH phase reference distribution system and on many laboratory experiments with distribution system components. Proposed system parameter analysis shows that the given requirements for the distributed signal phase stability can be fulfilled easily for the main linac section. Fulfilling the injector requirements may require using optical distribution techniques.
SLAC, Menlo Park, California
BINP SB RAS, Novosibirsk
Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
For proper operation of the LCLS x-ray free-electron laser, measurement and control of the electron bunch longitudinal phase space is critical. The LCLS accelerator includes two bunch compressor chicanes to magnify the peak current. These magnetic chicanes can generate significant coherent synchrotron radiation (CSR), which can distort the phase space distribution. We propose a diagnostic scheme by exciting a weak skew quadrupole at an energy-chirped, high dispersion point in the first bunch compressor (BC1) to reconstruct longitudinal phase space on an OTR screen after BC1, allowing a detailed characterization of the CSR effects.
YerPhI, Yerevan
Diffusive Radiation is originated by the passage of charged particles through a randomly inhomogeneous medium. DR appears when the conditions for multiple scattering of pseudophotons are fulfilled in the medium. Such a situation can be realized when a charged particle slides over a rough surface. One of the important properties of DR is that the maximum of emission lies at large angles from particle velocity direction. Therefore it can be used for detection of beam touch to the accelerators vacuum chamber wall in case when generated photons will be observed on the opposite side of vacuum chamber. Such a diagnostics can be especially useful for observation of storage rings beam halo.
UCLA, Los Angeles, California
BNL, Upton, Long Island, New York
It is possible to obtain spectral and angular information of inverse Compton sources using only an x-ray imaging device and various foils with K-edges in the many keV energy range. Beam parameters are chosen such that on-axis photons are above the K-edge for a given material, where absorption is strong and there is relatively zero transmission. Photons observed off-axis are red-shifted and fall below the K-edge, therefore being transmitted and creating a “donut” pattern, or "lobes" in the ideal case for a circularly or linearly polarized laser, respectively. We present simulation and experimental results of the double differential spectrum (DDS) for angle and energy of Compton photons generated at the BNL ATF.
BNL, Upton, Long Island, New York
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
CERN, Geneva
PU, Princeton, New Jersey
Fermilab, Batavia
We report on the analysis of data collected from the optical diagnostics of the MERIT experiment which was run at CERN in the fall of 2007. The breakup of the free mercury jet resulting from the impact of intense proton beams from the CERN PS within a magnetic field environment is described.
SLAC, Menlo Park, California
EPFL, Lausanne
Funding: Work supported in part by the U.S. Department of Energy contract DE-AC02-76SF00515
The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z Phase II collimators. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. Design issues include: 1) Collimator jaw deflection due to heating and sagita must be small when operated in the steady state condition, 2) Collimator jaws must withstand transitory periods of high beam impaction with no permanent damage, 3) Jaws must recover from accident scenario where up to 7 full intensity beam pulses impact on the jaw surface and 4) The beam impedance contribution due to the collimators must be small to minimize coherent beam instabilities. The current design will be presented.
ANL, Argonne
Transition radiation is frequently used to determine the time profile of a bunched relativistic particle beam. Emphasis is usually given to diagnostics sensitive to wavelengths in the infrared-to-optical portion of the spectrum. In this study, CST Particle Studio simulations are used to make quantitative statements regarding the low-frequency (DC to microwave) behavior of coherent transition radiation from a mirror inclined at 45 degrees relative to the particle beam trajectory. A moving Gaussian bunch confined within a cylindrical beam pipe is modeled. Simulation results are presented.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The ALBA Linac is a turn-key system able to produce 4 nC electron beams at 100 MeV beams with a normalized emittance below 30 mm*mrad. Beam position stability below 0.1 mm is measured using new BPM electronics. Thorough analysis are carried out to measure the beam emittance, energy and energy spread. This paper discusses the measurement techniques, analysis method, and results obtained during the Linac commissioning.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: Work supported by the National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program
Wiggler magnets are one of the key components in the ILC Damping Ring. It is critical to the ILCDR GDE to understand electron cloud (EC) growth and patterns, and to develop EC suppression techniques in the wiggler beampipes. The CESR-c superconducting wigglers, closely matching the parameters of the ILCDR wigglers, serve as unique testing vehicles. As part of the CesrTA project, we replaced the copper beampipes of two SCWs with EC diagnostic beampipes, where one of the beampipes is uncoated and the second is coated with a thin TiN film. Each of the EC diagnostic beampipes is equipped with three retarding field analyzers (RFAs) at strategic longitudinal locations in the wiggler field. Each of the RFAs has 12-fold segmentation to measure the horizontal EC density distribution. To maintain sufficient vertical beam aperture and to fit within the SCW warm bore, a thin style of RFA (with a thickness of 2.5 mm) has been developed and deployed. These SCWs with RFA-equipped beampipe have been installed and successfully operated in the re-configured CesrTA vacuum system. This paper describes the design and the construction of the RFA-equipped SCW beampipes and operational experience.
CERN, Geneva
Diagnostic techniques based on the Schottky spectrum of the peak detected signal have been used at CERN for a long time to study the behaviour of bunched beams. In this paper it is shown how the measured spectrum is related to the particle distribution in synchrotron frequency. The experimental set-up used and its limitations are also presented together with examples of beam measurements in the SPS and LHC.
INFN/LNF, Frascati (Roma)
USTC/NSRL, Hefei, Anhui
VIGO System S.A., Ozarow Maz.
Real time diagnostics is a fundamental tool for accelerator physics, particularly important to improve performances of existing synchrotron radiation sources, colliders and a key issue for 4th generation sources and FELs. We report the first measurements in the time and frequency domain performed at Hefei Light Source (HLS), the SR facility of the National Synchrotron Radiation Laboratory (NSRL), of the longitudinal bunch lengths. A fast uncooled HgCdTe photodiode optimized in the mid-IR range has been used to record at the IR port the length of the e- bunches. IR devices are compact and low cost detectors suitable for a bunch-by-bunch longitudinal diagnostics. The data are useful to investigate longitudinal oscillations and characterize the bunch length. The IR signal has been used to measure the synchrotron oscillation frequency, its harmonics in the multi-bunch mode and the bunch lengths in multi-bunch mode at different beam currents. For the first time, simultaneously, data have been collected at visible wavelengths using a fast photodiode at the diagnostics beamline of HLS. A comparison between IR data and diagnostics realized in the visible will be presented and discussed.
INFN/LNF, Frascati (Roma)
Università degli Studi di Firenze, Firenze
INOA, Firenze
VIGO System S.A., Ozarow Maz.
At the LNF (Laboratori Nazionali di Frascati) of the INFN a novel diagnostics experiment has been set-up to monitor the real time bunch behavior in the positron ring of the DAΦNE collider. The experiment has been installed on a bending magnet exit port of the e+ ring. The front-end consists of a UHV chamber where a gold-coated plane mirror deflects the radiation through a ZnSe window. After the window, a compact optical layout in air focuses the radiation on an IR detector. Compact mid-IR fast uncooled HgCdTe photodiodes are used to measure the bunch by bunch emission. A preliminary alignment of the mirrors and a first characterization of the radiation emitted have been performed. Longitudinal measurements of the bunch behavior, both in time and in frequency domain, obtained with fast IR detectors are presented. This novel diagnostics now available is ready to allow monitoring in real time of the bunch-by-bunch positron emission. It has been designed to improve the DAΦNE diagnostics with the main aim to identify and characterize positron bunch instabilities in the longitudinal plane. Developments for extending detection capability in the transverse planes are in progress.
LBNL, Berkeley, California
Y.Y. Labs, Inc., Fremont, California
Funding: Work supported by the U.S. Department of Energy under Contract No.
By coupling the emitted synchrotron light into an optical fiber, it is possible to transmit the signal at substantial distances from the light port, without the need to use expensive beamlines. This would be especially beneficial in all those cases when the synchrotron is situated in areas not easily access because of their location, or due to high radiation levels. Furthermore, the fiber output can be easily switched, or even shared, between different diagnostic instruments. We present the latest results on the coupling and dispersion measurements performed at the Advanced Light Source in Berkeley.
LANL, Los Alamos, New Mexico
Funding: US Department of Energy
Future improvements to the Los Alamos Neutron Scattering Center (LANSCE) include new Beam position and phase measuring systems that operate at 201.25 to 805 MHz. An effort is underway to build and test prototype electronics for these applications. We plan to use direct down conversion to 35 to 115 MHz followed by COTS FPGA hardware for in-phase and quadrature-phase (I/Q) signal processing. Self- calibration and system diagnostics circuits will be included. We are reporting on the status of these efforts.
LANL, Los Alamos, New Mexico
Funding: US DOE
The Compact Reconfigurable Input/Output (cRIO) hardware manufactured by National Instruments (NI) is evaluated as a wire scanner motion controller. This particular configuration utilizes a NI cRIO-9074 system combined with various C-series modules for wire scanner motion control I/O. Programs for this system have been written in LabVIEW and a majority of the motion-control functionality has been programmed into the cRIO's FPGA in order to provide the fastest motion control processing possible with cRIO. Additional topics of interest include, cRIO-based resolver-to-digital conversion and closed-loop, stepper-based motion control
NSRRC, Hsinchu
After commissioning of new BPM system in the TLS, it would support functionality of turn by turn data which can be applied in independent component analysis (ICA). This data analysis method is a special case of blind source separation to separate multivariable signal and additive noise and shown to be a useful diagnostic tool in acceleration application. In this paper, we use the ICA method to analyze experimental BPM turn by turn data of the TLS storage ring, measure betatron tunes, and identify abnormal BPM signals. Other possible applications have been also further studied continuously.
NSRRC, Hsinchu
Commissioning of new digital BPM system for TLS is done recently. The new BPM system could support functionalities of turn by turn data, post-mortem and 10Hz slow data acquisition. 10 kHz fast data translation through Liberas grouping mechanism also succeeded to acquire all bpm data and integrate into the orbit feedback system. Various tests are performed systematically to confirm its performance and reliability and will be discussed in this report. We also present the functionalities and infrastructure of the related diagnostic tools. It could record 10 sec orbit data simultaneously via hardware and software event trigger at 10 kHz. Turn by turn and post mortem are also supported through embedded EPICS IOC. More integrated software tools and environment will continue to be developed for future operation.
Northern Illinois University, DeKalb, Illinois
Euclid TechLabs, LLC, Solon, Ohio
ANL, Argonne
Funding: This work is supported by the U.S. Department of Energy under contract no. DE-FG02-06ER41435 with Northern Illinois University.
We present a diagnostics suite and analyze techniques for setting up the longitudinal beam dynamics in ILC e- injectors and e+ and e- bunch compressors. Techniques to measure the first order moments and recover the first order longitudinal transfer map of the injector's intricate bunching scheme are presented. Coherent transition radiation diagnostics needed to measure and monitor the bunch length downstream of the ~5 GeV bunch compressor are investigated using a vector diffraction model.
RadiaBeam, Marina del Rey
Spectrum Detector, Lake Oswego, Oregon
UGA, Athens, Georgia
UCLA, Los Angeles, California
Funding: Work supported by U.S. DOE Grant Number DE-FG02-07ER84814.
The generation of high peak current, high brightness beams routinely requires compression methods (e.g. four-bend chicane), which produce coherent radiation as a by-product. The sensing of this radiation, coupled with interferometric methods, yields crucial longitudinal bunch length and bunch profile information. This paper discusses the progress of the development of a real-time terahertz interferometer used for longitudinal beam profile diagnosis.
JAI, Egham, Surrey
Royal Holloway, University of London, Surrey
OXFORDphysics, Oxford, Oxon
KEK, Ibaraki
Funding: STFC LC-ABD Collaboration, Royal Society, Daiwa Foundation, Commission of European Communities under the 6th Framework Programme Structuring the European Research Area, contract number RIDS-011899
The KEK Accelerator Test Facility (ATF) extraction line laser-wire system has been upgraded, enabling the measurement of micron scale transverse size electron beams. The most recent measurements using the upgraded system are presented, including the major hardware upgrades to the laser transport, the laser beam diagnostics line, and the mechanical control systems.
SLAC, Menlo Park, California
Life Imaging Technology, Palo Alto, California
Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
An intensified, fast-gated CCD camera was recently installed on the visible diagnostic beam line in SPEAR3. The ~2nS electronic gate capability, ability to make multiple-exposure images and to acquire sequences of images provides good diagnostic potential. Furthermore, the addition of a rotating mirror just upstream of the photocathode provides the ability to optically ‘streak’ multiple images across the photocathode. In this paper, we report on several fast-gated camera studies including (1) resonant excitation of vertical bunch motion, (2) imaging of the injected beam with and without emittance-spoiling windows in the upstream transfer line, (3) injection kicker tuning to minimize perturbations to the stored beam and (4) images of short-bunch ‘bursting’ in the low momentum-compaction mode of operation.
SLAC, Menlo Park, California
ORNL, Oak Ridge, Tennessee
Funding: work supported by the Department of Energy under contract number DE-AC03-76SF00515 and DE-AC05
Fields induced by a beam and penetrated outside the beam pipe can be used for a beam diagnostic. Wires placed in longitudinal slots in the outside wall of the beam pipe can work as a beam pickup. This has a very small beam-coupling impedance and avoids complications of having a feed-through. The signal can be reasonably high at low frequencies. We calculate the beam-coupling impedance due to a long longitudinal slot in the resistive wall and the signal induced in a wire placed in such a slot and shielded by a thin screen from the beam. We present a field waveform at the outer side of a beam pipe, obtained as a result of calculations and measurements. Such kind of diagnostic can be used in storage rings, synchrotron light sources, and free electron lasers, like LINAC coherent light source.
SLAC, Menlo Park, California
Funding: Work supported by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) begins operation this year with 83 new stripline beam position monitor (BPM) processors. System requirements include several-micron position resolution for single-bunch beam charge of 200 pC. We describe the processing scheme, system specifications, commissioning experience, and performance measurements.
Saint-Petersburg State University, Saint-Petersburg
Funding: Physical Faculty of St.Petersburg State University (14.10.08); SBIR DOE (DE-FG02-08ER85031)
Radiation of a charge crossing the boundary between vacuum and left-handed medium is analyzed. The medium is characterized by permittivity and permeability with frequency dispersion of “plasmatic” type. Such properties can be realized in some modern metamaterials with a relatively simple structure. Both the case of unbounded medium and the case of circular waveguide are considered. Analytical expressions for field components are obtained and algorithm of their computation is developed. The main attention is given to the analysis of radiation in vacuum region. In particular, it is shown that two types of radiation can be generated in this region. One of them is an ordinary transition radiation having relatively large magnitude. Another type of radiation can be named the “Cherenkov-transition” radiation. Conditions of generating this type of radiation are obtained. This effect and some another properties of radiation can be used for diagnostics of beams. For example, the detector with two energy thresholds can be designed.
Saint-Petersburg State University, Saint-Petersburg
ANL, Argonne
Euclid TechLabs, LLC, Solon, Ohio
Funding: SBIR DOE (DE-FG02-08ER85031); Russian Foundation for Basic Research (06-02-16442-a); Physical Faculty of St.Petersburg State University (Russia) (14.10.08)
We consider microwave Cherenkov radiation in a waveguide containing an engineered medium, and show that the properties of the radiation can be used to determine the energy of charged particle beams. These properties can form the basis of a new technique for bunch diagnostics in accelerators. We propose to use a material characterized by a diagonal permittivity tensor with components depending on frequency as in the case of a plasma but with the constant terms not equal to unity. These properties can be realized in a metamaterial with a relatively simple structure. In contrast to previous work in the present paper a vacuum channel in the waveguide is taken into account. The particle energy can be determined by measurement of mode frequencies. It is shown that a strong dependence of mode frequencies on particle energy for some predetermined narrow range can be obtained by appropriate choice of the metamaterial parameters and radius of the channel. It is also possible to obtain energy measurements over a wider range at the cost of a weaker frequency dependence.
*A.V.Tyukhtin, S.P.Antipov, A.Kanareykin, P.Schoessow, PAC07, p.4156.
**A.V.Tyukhtin, EPAC08, p.1302.
***A.V.Tyukhtin, Technical Physics Letters, v.34, p.884 (2008); v.35 (2009), in press.
USP/LAL, Sao Paulo
Funding: FAPESP, CNPq
In this work we describe a model to study the effect of charge saturation in phosphor screens in the determination of electron beam profiles. It is shown that the charge saturation introduces systematic errors in the beam diameter determination, since it tends to increase the observed beam diameter. The study is made supposing a Gaussian beam profile and a saturation model to the charge response of the phosphor material. The induced errors increase for higher currents and/or narrow beams. A possible correction algorithm that can be applied to some measurements is presented, together with a brief discussion about the consequences of these systematic errors in emittance measurements.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
MPI-K, Heidelberg
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
The novel electrostatic Ultra-low energy Storage Ring (USR), planned to be installed at the future Facility for Low-energy Antiproton and Ion Research (FLAIR), will slow down antiprotons and possibly highly charged ions down to 20 keV/q. This multipurpose machine puts challenging demands on the necessary beam instrumentation. Ultra-short bunches (1-2 ns) on the one hand and a quasi-DC beam structure on the other, together with a variable very low beam energies (20-300 keV/q), ultra-low currents (down to 1 nA or even less for a non-circulating beam) and few particles (< 2x107), require the development of new diagnostic devices as most of the standard techniques are not suitable. Several solutions, like resonant capacitive pick-ups, beam profile monitors, Faraday cups or cryogenic current comparators, are under consideration. This contribution presents the beam instrumentation foreseen for the USR.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
Funding: Supported by the EU under contract PITN-GA-2008-215080
Beam diagnostics is a rich field in which a great variety of physical effects are made use of and consequently provides a wide and solid base for the training of young researchers. Moreover, the principles that are used in any beam monitor or detector enter readily into industrial applications or the medical sector which guarantees that training of young researchers in this field is of relevance far beyond the pure field of particle accelerators. DITANET- "DIagnostic Techniques for particle Accelerators a European NETwork" - covers the development of advanced beam diagnostic methods for a wide range of existing or future accelerators, both for electrons and ions. DITANET is the largest ever coordinated EU education action for PhD students in the field of beam diagnostic techniques for future particle accelerators with a total budget of 4.2 M. This contribution gives an overview of the network’s activities and outlines selected research results from the consortium.
JLAB, Newport News, Virginia
Receivers designed for diagnostic applications range from those having moderate sensitivity to those possessing large dynamic range. Digital receivers have a dynamic range which are a function of the number of bits represented by the ADC and subsequent processing. If some of this range is sacrificed for extreme sensitivity, noise power can then be used to perform two-point load calibrations. Since load temperatures can be precisely determined, the receiver can be quickly and accurately characterized; minute changes in system gain can then be detected, and systematic errors corrected. In addition, using receiver pairs in a balanced approach to measuring X+, X-, Y+, Y-, eliminates systematic offset errors from non-identical system gains, and changes in system performance. This paper describes and demonstrates a balanced BPM-style diagnostic receiver, employing Dicke-switching to establish and maintain real-time system calibration. Benefits of such a receiver include wide bandwidth, solid absolute accuracy, improved position accuracy, and phase-sensitive measurements. System description, static and dynamic modeling, and measurement data are presented.
UCLA, Los Angeles, California
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
It has been suggested that an ultra-short, very low charge beam be used to drive short wavelength single-spike operation at the SPARC FEL. This paper explores the development and construction of a longitudinal diagnostic capable of completely characterizing the radiation based on the Frequency-Resolved Optical Gating (FROG) technique. In particular, this paper explores a new geometry based on a Transient-Grating (TG) nonlinear interaction and includes studies of start to end simulations for pulses at the SPARC facility using GENESIS and reconstructed using the FROG algorithm. The experimental design, construction and initial testing of the diagnostic are also discussed.
UCLA, Los Angeles, California
RadiaBeam, Marina del Rey
BNL, Upton, Long Island, New York
Funding: NSF grant # IIP-0724505
We describe our effort in the development of a low cost, wide-band detector/camera for generation of spatially resolved images of radiation beams in a multi-spectral range of wavelengths, from IR (infrared) to THz (terahertz). The detector (T-camera) utilizes a TLC (thermochromic liquid crystal) film as the sensitive element in a temperature controlled chamber and a CCD detector array and can be used as a powerful diagnostic for terahertz sources such as a synchrotron or an FEL
USTC/NSRL, Hefei, Anhui
A high brightness injector has been developing in HLS (Hefei Light Source), and the design of beam parameter measurement system is presented in this paper. The whole system will measure beam position, beam current, emittance of beam, bunch length, beam energy and energy spread. For the beam position, we have designed three types of BPMs: stripline BPM, with the resolution of 20 μm; cavity BPM, with the resolution of 10 μm, and resonant stripline BPM*. The beam position processor Libera will be used. The beam current will measured using the ICT and FCT. When going out of the gun, the energy of the beam is about 4MeV 5MeV, and the emittance of the beam is charge-dominated, so we use a set of slits with the width of 90 μm to split the beam to beamlets. The bunch length is measured using OTR and streak camera. Before entering the bending magnet, the beam will go pass a very narrow slit, with the width of 90 μm, and the resolution of energy spread will be improved.
*M.Dehler, “Resonant Strip line BPM for Ultra Low Current Measurements”, Proceedings of DIPAC 2005, Lyon, France, p.286-288
ELETTRA, Basovizza
DEEI, Trieste
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2.
Travelling wave and standing wave deflectors are well known RF devices that nowadays are used in particle accelerators as a beam diagnostic tool. They will also be implemented in FERMI@Elettra project, a soft X-ray fourth-generation light source under development at the ELETTRA laboratory, and used to completely characterize the beam phase space by means of measurements of bunch length and transverse slices emittance. In particular, one deflector will be placed at low energy (250MeV) and another at high energy (1.2GeV), just before the FEL process starts. In this note we collect our experience and simulation on this last device, making a comparison between the most relevant options we have considered to satisfy our RF and space constraints. Basic cell design is discussed for both the travelling and standing wave choice. In particular, two different modes, the 2/3π and the 5/6π, are analyzed for the travelling wave option while an 11 cells design in π mode is presented for the standing wave case. For both cases sensitivity analysis and other relevant RF parameters are given.
Melbourne
ASCo, Clayton, Victoria
Recently a transverse bunch-by-bunch feedback system was commissioned to combat the resistive-wall instability in the storage ring. The system successfully controls the vertical beam motion so 200 mA can be stored with all in-vacuum undulators at minimum gap and a slightly positive chromaticity setting. The FPGA that comes with the feedback system also provides powerful possibilities for diagnostic measurements. Results will be presented for a) growth/damp measurements to quantitatively characterise the resistive-wall instability, b) bunch-by-bunch diagnostics such as tune chromaticity and c) initial bunch-cleaning attempts in conjunction with a APD bunch purity measurement system.
INFN/LNF, Frascati (Roma)
The SuperB project consists of an asymmetric (4x7 GeV), very high luminosity, B-Factory to be built at Roma-II University campus in Italy, with the ambitious luminosity goal of 1036 cm-2 s-1. To achieve the very challenging performances, robust and powerful bunch-by-bunch feedback systems are necessary to cope with fast coupled bunch instabilities in rings with high beam currents and very low emittances. The SuperB bunch by bunch feedback should consider the rich legacy of previous systems, the longitudinal (DSP-based) feedback built in 1993-97 and the recent “iGp” feedback system designed in 2002-06. Both were designed by large collaborations between Research Institute (SLAC, DAΦNE@LNF/INFN, ALS@LBNL, KEK). The core of the new system will be the digital processing module, based on powerful FPGA components, to be used in longitudinal and transverse planes. Off-line analysis programs, as well real-time diagnostic tools, will be included. The feedback impact on very low emittance beams have to be carefully considered. A MATLAB simulator based on a beam/feedback model is also foreseen for performance checks and fast downloads of firmware/gateware code and parameters.
DESY, Hamburg
Uni HH, Hamburg
Next generation FEL light sources like the European XFEL require timing stability between different subsystems of 10-20 fs. In optical synchronization systems, the timing information is distributed across the facilities via sub-ps laser pulses travelling on length stabilized optical fibers. Different methods are available for RF extraction from the pulse train. In this paper, we characterize the long-term phase stability of a 1.3 GHz signal gained from the direct conversion of a higher harmonic of the pulse repetition frequency, and from a voltage controlled oscillator locked with a PLL that uses a Sagnac-Loop as balanced optical-microwave phase detector.
Uni HH, Hamburg
PSI, Villigen
DESY, Hamburg
CLASSE, Ithaca, New York
ITER, St Paul lez Durance
The free-electron laser FLASH and the planned European XFEL generate X-ray light pulses on the femtosecond time-scale. The feasibility of time-resolved pump-probe experiments, special diagnostic measurements and future operation modes by means of laser seeding crucially depend on the long-term stability of the synchronization of various laser systems across the facility. For this purpose an optical synchronization system is being installed and tested at FLASH. In this paper, we report on the development and the performance of a background-free optical cross-correlation scheme to synchronize two individual mode-locked lasers of different center wavelengths and repetition rates with an accuracy of better than 10 fs. The scheme can be tested by linking a Ti:sapphire oscillator, used for electro-optical diagnostics at FLASH, to both a locally installed erbium-doped fiber laser and the end-point of an actively length-stabilized fiber link distributing the pulses from a master laser oscillator. After the commissioning of this fiber link, the diagnostics laser can be synchronized to the electron beam and first accelerator based measurements on the performance of the system will be carried out.
JLAB, Newport News, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab’s CEBAF accelerator operation requires various frequency signals to be distributed along the site. Three signals: 10 MHz, 70 MHz and 499 MHz are synthesized in the Machine Control Center (MCC) while 1427 MHz and 429 MHz are derived from 499 MHz and 70 MHz signals in four separate locations. We are replacing our obsolete 10 MHz, 70 MHz and 499 MHz sources with new sources that will incorporate a GPS receiver to discipline a 10 MHz reference. In addition the MO (Master Oscillator) system will be redundant (duplicate MO) and a third signal source will be used as a system diagnostic. Moreover the 12 GeV Energy Upgrade for CEBAF accelerator will be adding 80 new RF systems. To support them the distribution of 1427 MHz and 70 MHz signals has to be extended and be able to deliver enough LO (Local Oscillator) and IF (Intermediate Frequency) power to 320 old and 80 new 80 RF systems. This paper discusses the new MO and the drive line extension.
Rutgers University, The State University of New Jersey, Piscataway, New Jersey
Fermilab, Batavia
BNL, Upton, Long Island, New York
A transverse to longitudinal emittance exchange experiment is installed at the Fermilab A0 Photoinjector. We report on the completed measurement of emittance exchange transport matrix as well as the ongoing program to directly measure the emittance exchange. Both the transverse and longitudinal input beam parameters are being explored in order to achieve direct emittance exchange with minimal dilution effects
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
Results of designing of the extended ALICE injector with the aim to include a special dedicated diagnostic line are presented. The purpose of the diagnostic line is to characterise the low energy beam, before it enters the booster, as much as possible. A key component of the ALICE is the high brightness injector. The ALICE injector consists of a DC photocathode gun generating ~ 80 pC electron bunches at 350 keV. These bunches are then matched into a booster cavity which accelerates them to an energy of 8.35 MeV. In order to do this, three solenoids and a single-cell buncher cavity are used, together with the off-crest of the first booster cavity where the beam is still far from being relativistic. The performance of the injector has been studied using the particle tracking code ASTRA.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a 50 Hz proton synchrotron, which accelerates ~3·1013 ppp from 70 to 800 MeV, corresponding to beam powers of 0.2 MW. Beam loss imposes limits on operational intensity, and a main contributing mechanism is the action of half integer resonance under high space charge. The same loss mechanism is also a potential problem in ISIS upgrade scenarios involving either higher energy injection into the existing ring, or the addition of a new 3 GeV, high intensity RCS. Progress on particle in cell simulation studies investigating the effects of the driven coherent envelope motion, the associated parametric halo, along with implications of momentum spread, dispersion and longitudinal motion, is reported. Where possible, comparisons are made with relevant theoretical models. Closely related benchmarking work, experimental studies and plans are also summarised.
RadiaBeam, Marina del Rey
UCLA, Los Angeles, California
The accelerator community has many codes that model beams and emitted radiation. Many of these codes are specialized and often, as in start-to-end simulations, multiple codes are employed in subsequent fashion. One of the most important goals of simulations is to accurately model beam parameters and compare results to those obtained from real laboratory diagnostics. This paper describes the development of a user-friendly code that models the coherent radiation of high brightness beams, with a heavy emphasis on simulation of observables via laboratory diagnostics.
LANL, Los Alamos, New Mexico
TechSource, Santa Fe, New Mexico
Funding: Work supported, in part, by DOE SBIR Grant No. DE-FG02-04ER84105 and CRADA No. LA05C10535 between TechSource, Inc. and the Los Alamos National Laboratory.
Recent beam studies have focused on understanding the main sources and locations of electron clouds (EC) which drive the observed e-p instability at the Los Alamos Proton Storage Ring (PSR). Strong EC signals are observed in drift spaces and quadrupole magnets at PSR which together cover ~65% of the ring circumference. New results making use of two longitudinal barriers to isolate the drift space electron diagnostic provide definitive evidence that most of the drift space EC signal is “seeded” by electrons ejected longitudinally by ExB drifts from adjacent quadrupole magnets. This result can explain why weak solenoids and TiN coatings in several drifts spaces had no effect on the e-p instability threshold. Modeling of EC generation in 3D quadrupoles using a modified version of the POSINST code shows that a sizeable fraction of the electrons generated in the quadrupoles are ejected longitudinally into the adjacent drifts. The experimental findings and simulation results will be presented.
GSI, Darmstadt
Cosylab, Ljubljana
One of the main challenges of the planned Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is to handle its complex parallel and multiplexed beam operation. In addition, the size of the FAIR project demands for tailor-made but yet extendible solutions with respect to all technical subsystems, especially for the control system. In order to operate and maintain the large amount of front-end equipment standardized solutions are an absolute must. Moreover, to give guidelines and interface specifications to the international collaborators and external partners for so-called "in-kind contributions" facility-wide standards have to be defined. For that purpose, GSI decided to use the Front-end Software Architecture (FESA) at the lowest level of the control system. FESA was developed by CERN and is already operational at LHC and its injectors. This report presents a framework overview and summarizes the status of the FESA test installation at GSI. Additionally, first experiences with the SIS18 BPM system controlled via FESA are presented.
NSRRC, Hsinchu
To improve the reliability of a contemporary synchrotron as light source, a diagnostic system is crucial. A satisfactory diagnostic system must enable a clear presentation of the reason for a system fault, and provide sufficient information to the data analyzer for system recovery and improvement. To identify a fault and to monitor the operation of a RF system, many diagnostic utilities have been adopted. The architecture for the diagnostics of the TLS RF system is here reported.
CERN, Geneva
Construction work for the new CERN linear accelerator, Linac4, started in October 2008. Linac4 will replace the existing Linac2 and provide an H- beam at 160 MeV (as opposed to the present 50 MeV proton beam) for injection into the CERN PS Booster (PSB). The charge-exchange H- injection combined with the higher beam energy will allow for an increase in beam brightness required for reaching the ultimate LHC luminosity. Commissioning of Linac4 and of the transfer line to the PSB is planned for the last quarter of 2012. Appropriate beam instrumentation is foreseen to provide transverse and longitudinal beam characterization at the exit of Linac4 and in two dedicated measurement lines located before injection into the PSB. A detailed description of the diagnostics set, especially of spectrometer and emittance meter, and the upgrade of the measurement lines for Linac4 commissioning and operation is presented.
Cockcroft Institute, Warrington, Cheshire
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG currently under construction at Daresbury Laboratory. The energy recovery linac prototype ALICE will operate as its injector, at a reduced the energy of 10 to 20 MeV, compared to its nominal energy of 35 MeV. An injection line has been designed which consists of a dogleg to extract the beam from ALICE, a matching section, a tomography section and some additional dipoles and quadrupoles to transport and match the beam to the entrance of EMMA. This injection line serves both as a diagnostic to measure the properties of the beam being injected into EMMA and also a useful diagnostic tool for ALICE operation. This paper details the simulations undertaken of the electron beam passing through the matching and tomography sections of the EMMA injection line, including the effect of space charge. This will be an issue in the energy range at which this diagnostic is being operated when combined with high bunch charge. A number of different scenarios have been modelled and an attempt made to compensate for the effects of space charge in the matching and tomography sections.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG to be hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. It also represents a possible active element for an ADSR (Accelerator Driven Sub-critical Reactor). This paper will summarize the design of the extraction / diagnostic transfer line of the NS-FFAG. In order to operate EMMA, the energy recovery linac ALICE shall be used as injector and the energy will range from 10 to 20 MeV. Because this would be the first non-scaling FFAG, it is important that as many of the bunch properties are studied as feasible, both at injection and at extraction. To do this, a complete diagnostic line was designed consisting of a tomography module together with several other diagnostic devices including the possibility of using a transverse deflecting cavity. Details of the diagnostics are also presented.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
BNL, Upton, Long Island, New York
Fermilab, Batavia
TRIUMF, Vancouver
EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG to be hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. It also represents a possible active element for an ADSR (Accelerator Driven Sub-critical Reactor). This paper summarises the commissioning plans for this machine together with the major steps and experiments involved along the way. A description of how the 10 to 20 MeV beam is achieved within ALICE is also given, as well as extraction from the EMMA ring to the diagnostics line and then dump.