SSRF, Shanghai
SSRF is a 432 m-circumference synchrotron light source with a 150MeV linac, a 3.5GeV full energy booster, and a 3.5GeV storage ring. Principal diagnostics systems have been installed and nearly all have been commissioned during past two years. Data have been obtained on beam position, beam profile, current, and synchrotron radiation diagnostics beamline on the storage ring. Multi bunch transverse feedback system has been applied on the ring. Results for the 150MeV electron beams in the linac, up to 3.5GeV in the booster, and 3.5GeV in the ring will be presented.
GSI, Darmstadt
TEMF, TU Darmstadt, Darmstadt
This contribution focuses on extensive simulations based on Finite Element Methods (FEM) which were successfully used for the design of several Beam Position Monitor (BPM) types. These simulations allow not only to reduce the time required for BPM prototyping but open up new possibilities for the determination of characteristic BPM features like signal strength, position sensitivity etc. Since a precise visualization of the signal propagation along the BPM structure is possible, effects like resonances, field inhomogeneties or complex cross talks between adjacent electrodes can be controlled. Moreover, modern simulation programs enable to define a charge distribution that is moving also at non relativistic velocities, which has an impact on the electromagnetic field propagation. It is shown that for slow ion beams the frequency spectrum of the BPM signal depends on the beam position. A variety of simulation methods are discussed in the context of different BPM realizations applied in hadron accelerators.
DESY, Hamburg
The Positron Intensity Accumulator PIA at DESY is used to accumulate the intensity and damp down the emittance of the positrons produced in the Linac II before they are injected into DESY II. Up to 19 shots are collected and damped. During the damping process the (baseband) peak current is increased by about a factor 4. Therefore the signal from the circulating beam can be up to 80 times bigger than the injected beam and hence overload any first turn detectors. The injected beam however is bunched by the 3 GHz RF of the linac. By filtering the 3 GHz component of the antenna signal and subsequent demodulation it is possible to set up a BPM system detecting exclusively the injected beam.
DESY, Hamburg
The new synchrotron light source PETRA III is powered by a chain of pre-accelerators including Linac II, PIA, transfer lines, and DESY II. The whole chain is equipped with upgraded versions of diagnostic systems that were installed during the 2008 shutdown. This paper presents the upgrade of the beam position monitor (BPM) systems at PIA together with the transfer lines and DESY II. All systems rely on the ‘Delay Multiplex Single Path Technology’ (DMSPT). It is demonstrated that the self-triggered design of the BPM electronics is specifically suited to the different needs of such a heterogeneous pre-accelerator chain. Structures and dependencies of the BPM systems will be described in detail.
ORNL, Oak Ridge, Tennessee
The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The accelerator systems are equipped with variety of beam diagnostics. The beam diagnostics played important role during beam commissioning, they are used for accelerator tuning and monitoring beam status during production runs. The requirements to the various diagnostics systems are changing in the process of beam power ramp up. This talk will give an overview of the evolution of the major SNS beam diagnostics systems: commissioning, operation, power ramp up, and power upgrade.
IPN, Orsay
GANIL, Caen
IPHC, Strasbourg Cedex 2
The future SPIRAL2 facility will be composed of a multi-beam driver accelerator (5mA/40Mev deuterons, 5mA/33MeV protons, 1mA/14.5 MeV/u heavy ions) and a dedicated building for the production of radioactive ion beams (RIBs). RIBs will be accelerated by the existing cyclotron CIME for the post acceleration and sent to GANIL’s experimental areas. The injector, constituted by an ion source, a deuterons/protons source, a room temperature RFQ and the MEBT line, will produce and accelerate beams to an energy of 0,75MeV/u. An Intermediate Test Bench (B.T.I.) is being built to commission the SPIRAL2 Injector through the first re-buncher of the MEBT line in a first step and the last re-buncher in a second step. The B.T.I. is designed to perform a wide variety of measurements and functions and to go more deeply in the understanding of the behaviour of diagnostics under high average intensity beams operations. A superconducting LINAC with two types of cavity will allow reaching 20 MeV/u for deuterons beam. This paper describes injector diagnostic developments and gives information about the current progress.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The commissioning of the ALBA Linac (Autumn 2008) required a careful measurement of the beam parameters. This paper describes the diagnostics devices installed at the ALBA Linac and our experience with them.
INFN/LNF, Frascati (Roma)
The experimental setup implemented in the SPARC linac control system used to monitor the laser beam energy and to measure the beam charge by means of a Faraday Cup will be illustrated and discussed. The experimental setup makes use of National Instruments 2 GS/s 8-Bit digitizer board. This tool has been shown to be useful in order to monitor the laser beam energy stability and to evaluate the quantum efficiency of the cathode.
DESY, Hamburg
The European XFEL is an X-ray free-electron-laser that is currently being built in Hamburg. It is organized as an international Project and will be a large scale user facility. Based on superconducting TESLA technology electron beams of high average power will be send to several undulator lines simultaneously to produce hard X-Rays with high average intensity and a peak brilliance by far superior to any 3rd generation light source. This paper will present the current status of the planning, the development and the prototyping process for this facility. It will cover as well as the BPM system, the other main diagnostic systems, like beam size measurements, charge, dark current and beam loss and protection systems.
GSI, Darmstadt
Technical University Darmstadt, Darmstadt
Optical properties of scintillating screens were studied for various materials and different ion beams at GSI. C2+, Ar10+, Ni9+ and U28+-ion beams were applied, in the energy range from 5.5 to 11.4 MeV/u with currents up to some mA, as delivered by the heavy ion LINAC at GSI. Scintillation screens are widely used and are an essential part of a pepper-pot emittance device for which the precise mapping of the beam profile is a critical issue. However, precise measurements of the beam profile yield ambivalent results, especially for high beam currents*,**. The investigations were not only focused on well-known scintillators but also ceramic materials with lower light yield were studied. Their properties (light yield, beam width and higher statistical moments) are compared with different Quartz-glass screens. The recorded beam width shows dependence on the scintillation material and a decrease of the light yield was observed for some materials. Additionally, the light yield and beam width depend significantly on the screen temperature, which is increased by the ion impact. The empirical results are discussed and concepts for further investigations on the materials are presented.
* E. Gütlich, P. Forck et al., GSI-Scientific Report 2007 p.105 and 2008 (to be published).
** E. Gütlich, P. Forck, et al., Proc. Beam Instrum. Workshop BIW, Lake Tahoe (2008).
GANIL, Caen
The SPIRAL2 project is based on a multi-beam driver in order to allow both ISOL and low-energy in-flight techniques to produce Radioactive Ion beams (RIB). A superconducting light/heavy-ion LINAC capable of accelerating 5 mA deuterons up to 40 MeV and 1 mA ions up to 14.5 MeV/u is used to bombard both thick and thin targets. These beams could be used for the production of intense RIB by several reaction mechanisms (fusion, fission, transfer, etc.). In order to visualize the SPIRAL2 beam dynamics, several beam profile monitors are under development. Multiwire beam profile monitors (SEM) will be used on the driver and RIB lines, a non interceptive beam profile monitor (RGM) should be mounted on the LINAC diagnostics box and before the experiment facility, and a low intensity beam profile monitor (EFM) on the RIB lines. Signal acquisition from these monitors will be accomplished through new associated electronics which digitize 94 channels in a parallel system. Each channel integrates the current of the associated wire or strip and performs a current-voltage conversion. The dedicated GANIL data display software has been adapted for these new monitors.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
One of the key diagnostics instruments during the ALBA Linac commissioning was the screen monitors, which allowed control of beam size and position. These screen monitors are equipped with a YAG and an OTR screen. This paper describes our screen monitor setup and the experience with both types of screens.
Soreq NRC, Yavne
ACCEL, Bergisch Gladbach
RI Research Instruments GmbH, Bergisch Gladbach
The first phase of the SARAF high current proton/deuteron accelerator facility is currently under commissioning. Along with traditional beam diagnostics instruments, a beam halo measuring station was implemented into the SARAF diagnostic plate. The beam halo is planned to be characterized using a mini Faraday cap, on-line and off-line measurements of radiation from LiF target crystals and by monitoring energy spectra of Rutherford scattered particles from a thin gold foil. The first experience with 3 mA, pulsed proton beam included measuring energy spectra of the protons at energies up to 2.2 MeV scattered at 45 degrees from a 0.3 mg/cm2 thick gold foil. The beam was accelerated by SARAF RFQ and by several cryogenic resonators in the SARAF Prototype Superconductive Module. The energy spectra of the scattered particles were taken for different RFQ voltages and for different voltages and phases of the PSM resonators. The results were compared with time of flight measurements utilizing two phase probes installed at the D-plate. Comparison of the experimental spectra with results of the TRACK Monte-Carlo simulations was also performed.
FZD, Dresden
At the ELBE Free Electron Laser (FEL) at Forschungszentrum Dresden Rossendorf (FZD) electron bunches having lengths between 1 to 4 ps are generated. It is required to compress these electron bunches to lengths below 1 ps which necessitates diagnosis of the electron bunch parameters. We use a Martin-Puplett interferometer (MPI) which is a modification of the Michelson interferometer, where the beams are linearly polarized at specific orientations. It measures the autocorrelation function of the coherent transition radiation (CTR) from a view screen which is an optical replication of the electron bunch. The interferometer setup consists of various optical components like polarizers, beam splitter, mirrors and Golay cell detectors. In our measurement a wire grid was used as a polarizer and also as a beam splitter. A thorough understanding of the response of the optical components, as a function of the CTR wavelength range of our interest, is required for correct analysis of the measured signal. We have therefore simulated the response of the entire interferometer setup including the diffraction losses and the window transmission and compared the results to experimental measurements.
DESY, Hamburg
Uni HH, Hamburg
The need for timing and bunch-length monitors for free-electron lasers and other accelerators makes the electro-optic spectral decoding (EOSD) a promising diagnostic technique. Being non-destructive, it allows a single shot-measurement within the accelerator environment. In some cases, e.g. low charge or necessity to resolve time-structures below 20 fs, the bunch length is measured indirectly, using the spectrum of the coherent transition radiation (CTR). We present results of EOSD measurements on the CTR beam line at FLASH, using a chirped Ti:Sapphire oscillator pulse focused simultaneously with the THz radiation on a GaP crystal in vacuum. The CTR spectrum is in the range 200 GHz-100 THz and and the pulse energy in the focus is over 10 mJ. The measured narrow CTR temporal profiles in the order of 400 fs FWHM demonstrate, that the ultra short THz-pulses, emitted by the compressed electron bunches are transported through the 19 m long beam line without significant temporal broadening.
SLAC, Menlo Park, California
ANL, Argonne, Illinois
We present the performance of the cavity beam position monitor (BPM) system for the Linac Coherent Light Source (LCLS) undulator at SLAC. The construction and installation phase of 36 BPMs have been completed. Commissioning is underway. The X-band cavity BPM employs a TM010 monopole reference cavity and a TM110 dipole cavity designed to operate at nominal center frequency of 11.384 GHz. The signal processing electronics features a low-noise single-stage three-channel heterodyne receiver that has selectable gain and phase locking local oscillator. The approximately 40MHz intermediate frequency is digitized to 16 bits at a 119 MHz sampling rate then reduced to baseband digitally. Phase and charge are normalized with respect to the reference cavities. System requirements include sub-micron position resolution for a single-bunch beam charge of 200 pC. Early commissioning results indicate single-bunch resolutions better than 500 nm rms and stabilities better than 1 micron drift over 24 hours.
INFN/LNF, Frascati (Roma)
ELETTRA, Basovizza
The single pass functionality available in the recent release of the Libera Brilliance software, takes particular interest when compared with requirements of FEL machines, that need stable and precise control of the beam trajectory throughout Linacs and transfer lines in order to meet the stringent beam quality and transverse position constraints inside undulators. Results from tests performed on Libera with beam from ELETTRA, SPARC and DAΦNE, operating in Sincrotrone Trieste and LNF Frascati, are reported to characterize the resolution of single shot transverse beam position measurements.
IFIC, Valencia
A set of two Inductive Pick-Up (IPU) prototypes with its associated electronics for Beam Position Monitoring (BPM) in the Test Beam Line (TBL) of the 3rd Compact Linear Collider (CLIC) Test Facility (CTF3) at CERN were designed, constructed, and tested by the IFIC team. One prototype and two units of the series production are already installed in the TBL line. In the first part of the paper we describe the characterization tests of these two prototypes carried out at CERN, and the first beam tests performed to one of them. The second part of this paper is dedicated to the description of the issues addressed by the start of the series production and the characterization tests of the first series units performed with a custom-made low-frequency wire setup. This setup which emulates the beam position variation allows to carry out the series tests in an automatized manner and with higher accuracy.
GANIL, Caen
The SPIRAL2 project is composed of an accelerator and a radioactive beam section. Radioactive ions beams (RIBs) will be accelerated by the current cyclotron CIME and sent to GANIL experimental areas. The accelerator, with a RFQ and a superconducting Linac, will accelerate 5 mA deuterons up to 40MeV and 1 mA heavy ions up to 14.5 MeV/u. A new electronic device has been evaluated at GANIL to measure phase and amplitude of pick-up signals. The principle consists of directly digitizing pulses by under-sampling. Phase and amplitude of different harmonics are then calculated with a FPGA by an I/Q method. Tests and first results of a prototype are shown and presented as well as future evolutions.
GSI, Darmstadt
ITEP, Moscow
A device for accessing the longitudinal phase space at low energy sections (1.4 MeV/u) of the GSI heavy ion LINAC is presented. In the course of the FAIR project optimizations of the existing facility at GSI are required. Integral information for the optimization process is extracted by the knowledge of the six dimensional phase space. Opposed to the transversal parameters it is particular difficult to access the longitudinal degree of freedom at low energies. The presented interceptive measurement is based on the coincident detection of single particles by means of two detectors: The first detector provides measurement of secondary electrons emitted from a thin Al-foil by the impinging ion beam. Secondly, after a drift of 80 cm beam particles are registered directly by a fast diamond detector. This contribution describes the measurement setup in detail including the principle of particle number attenuation by Rutherford scattering in the Ta foil. The achievements concerning the required timing resolution are presented and the investigations are accompanied by recently recorded data.
CNAO Foundation, Milan
CERN, Geneva
The CNAO, the first Italian center for deep hadrontherapy, is presently in its final step of installation. Commissioning of the low energy injection lines has been successfully concluded in January 2009. The synchrotron injection chain consists of a 8 keV/u Low Energy Beam Transfer (LEBT) line, an RFQ to accelerate the beam up to 400 keV/u, a LINAC to reach the 7 Mev/u injection energy and a Medium Energy Beam Transfer line. At the end of the LEBT line, just upstream the RFQ, an electrostatic Chopper deviates the beam for about 100 micro-seconds every 2 seconds on the vacuum chamber, in order to shape the particles batch according to LINAC requirements and to minimize the beam lost at the RFQ entrance. The chamber section hit by the beam was electrically isolated from the adjacent vacuum chambers, allowing the reading of the LEBT beam current. The detector is based on the Faraday Cup working principle, but it results in a “not-interceptive” monitor that is able to measure, continuously, the source beam current ripples and stability without affecting the beam delivered to the synchrotron. The system is presently under commissioning with beam and preliminary results are presented.
INFN/LNF, Frascati (Roma)
The SPARC FEL facility is under commissioning at the Frascati National Laboratories of INFN. The synchronization system is working as expected and various devices are used to monitor its performances. In particular this paper is focused on a comparison between the results obtained using different methods and instruments to perform laser, RF and beam synchronization measurements. Both electro-optical and full electrical techniques are used to obtain information about the phase noise of the RF fields inside the accelerating structures, the phase noise of the IR laser oscillator, the time of arrival of the laser UV pulse on the cathode and the time of arrival of the accelerated electron bunch at a selected reference position along the linac.
PSI, Villigen
IAP Univ. Bern, Bern
Pulsed Yb fiber lasers emit at 1030 nm which provides a better phase matching in standard EO crystals (GaP, ZnTe) than Ti:Sa lasers (800nm). We present a mode locked ytterbium fiber laser which is phase locked to the RF. A subsequent fiber amplifier is used to boost the power and to broaden the spectrum due to nonlinear effects. The produced pulses have a spectral width of up to 100 nm and are therefore suitable for EO bunch length measurements, especially for spectral decoding. The laser delivers a chirped pulse of some ps, the fourier limited pulse duration of ~30 fs can be almost reached by an additional shaper setup with a spatial light modulator in the Fourier plane.
CERN, Geneva
Linac4 is the first step of the future LHC injectors chain. This LINAC will accelerate H- ions from 45 keV to 160 MeV. During the commissioning phase of LINAC4, emittance measurements will be required at 45 keV, 3 MeV and 12 MeV. For this purpose a slit&grid system is currently being developed. The material and geometry of the wires and of the slits need to be optimized in order to reduce the effects of the energy deposition and maximize the signals: carbon, titanium steel and tungsten have been considered and studied. This document describes the results of the studies carried out during the design of the emittance meter and the first results during the commissioning.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
NSCL, East Lansing, Michigan
IAP, Frankfurt am Main
STFC/RAL, Chilton, Didcot, Oxon
The pepperpot provides a unique and fast method of measuring emittance, providing four dimensional correlated beam measurements for both transverse planes. In order to make such a correlated measurement, the pepperpot must sample the beam at specific intervals. Such discontinuous data, and the unique characteristics of the pepperpot assembly, requires special attention be paid to both the data acquisition and the error analysis techniques. A first-principles derivation of the error contribution to the rms emittance is presented, leading to a general formula for emittance error calculation. Two distinct pepperpot systems, currently in use at GSI in Germany and RAL in the UK, are described. The data acquisition process for each system is detailed, covering the reconstruction of the beam profile and the transverse emittances. Error analysis for both systems is presented, using a number of methods to estimate the emittance and associated errors.
PSI, Villigen
In this paper, we describe four very different operating modes of the SwissFEL facility, the requirements of the challenging beam diagnostics and ultra-stable RF systems needed for two special operating modes with 10 pC, and the present status of developing beam diagnostics and RF systems for the PSI 250 MeV injector test facility, which is under construction.
ANL, Argonne, Illinois
This paper will give a general overview of active and passive stabilization systems, which are mainly required for future X-FEL and high energy linear colliders. Key physics requirements for beam stability for X-FELs and linear colliders will be introduced and resulting technical implications discussed. New and innovative approaches to the design and development of state-of-the-art linear accelerator components and stabilization systems will be reviewed, and recent results shown from selected prototypes and new machine installations.