CERN, Geneva
At present more than 15000 particle accelerators exist worldwide, being built and optimised to handle a large variety of particle beams for basic research and applications in industry and medicine. Diagnostic tools have been developed and optimised according to the special requirements of these machines and to meet the demands of their users. Storage rings for ultra cooled heavy ion beams, third generation synchrotrons for the production of high brilliant radiation, super conducting protons machines working at the energy frontier and finally linear electron accelerators for FEL applications or high energy physics are just the most prominent representatives of the large variety of accelerators and each of them needs highly sophisticated tools to measure and optimise the corresponding beam parameters. Accordingly the issue addressed here is not to cover in full detail the different diagnostic devices but rather to concentrate on the aspects and needs as seen by the accelerator physicists and machine designers.
DESY, Hamburg
PETRA III is a new hard x-ray synchrotron radiation source which will be operated at 6 GeV with an extremely low horizontal emittance of 1 nmrad. This new facility is the result of a conversion of the existing storage ring PETRA II into a light source. The conversion comprises the complete rebuilding of one eighth of the 2304 m long storage ring, which will then house 14 undulator beam lines, the optical and experimental hutches, and the modernization and refurbishment of the remaining seven eighths. In addition two 100 m long damping wiggler sections have been installed which are required to achieve the small design emittance. Construction, installation and technical commissioning have been finished middle of March and then the commissioning with beam started. In this paper we present the results that have been achieved during commissioning with special emphasis on the role of diagnostic systems.
SOLEIL, Gif-sur-Yvette
Beam orbit stability is a crucial parameter for 3rd generation light sources in order to achieve their optimum performance. Sub-micron stability is now a common requirement for vertical beam position. To reach such performance, Global Orbit Feedback Systems are mandatory. This paper describes the different design approaches for Global Orbit Feedback Systems. A few machines can use a single set of strong correctors. Most machines have their strong corrector bandwidth limited by eddy currents in aluminium vacuum chamber, or power-supplies speed or digitization granularity. Then, a second set of fast correctors is required for high frequency correction. But Fast and Slow Orbit Feedback Systems cannot work together with a common frequency range, they fight each other. An earlier solution has been to separate fast and slow systems by a frequency deadband. This approach does not allow correcting efficiently the orbit shift due to the gap movements of the increasingly sophisticated insertion devices that are installed on new machines. The different solutions that have been recently implemented are reviewed.
Fermilab, Batavia
KEK, Ibaraki
To achieve a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring, the BPM read-out system is currently upgraded with new high resolution electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducable beam position readings. The concept and its technical realization, as well as preliminary beam study results are presented.
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.
Brunel University, Middlesex
Muon ionization cooling provides the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. A fist measurement of emittance is performed in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in liquid hydrogen and RF acceleration. A second spectrometer identical to the first one and a particle identification system provide a measurement of the outgoing emittance. By April 2009 it is expected that the beam and first set of detectors will have been commissioned, and a first measurement of input beam emittance may be reported. Along with the plan of measurements of emittance and cooling that will follow in the second half of 2009 and in 2010.
ISA, Aarhus
This paper presents an overview of the proposed beam diagnostic for Astrid2, which is the new 580 MeV 3rd generation synchrotron light source to be build in Aarhus, Denmark. Astrid2 will use the present Astrid1 as booster, allowing for full energy injection and thereby top-up-operation. The diagnostics will include viewers, beam current monitors, electronic beam position monitors, striplines, etc. The description will include both the storage ring and the transfer beam line.
CERN, Geneva
EPFL, Lausanne
LAL, Orsay
Within the framework of the second Joint Research Activity PHIN of the European CARE program, a new photo injector for CTF3 drive beam has been designed and installed by collaboration between LAL, CCLRC and CERN. The laser driven rf photo injectors are recent candidates for high-brightness, low-emittance electron sources. One of the main beam dynamics issues for a high brightness electron source is the optimization of beam envelope behavior in the presence of the space charge force in order to get low emittance. Beam based measurements have been made during the commissioning runs of the PHIN 2008 and 2009 including measurements of the emittance, using multi-slits technique. In this work the photo injector will be described and the first beam measurement results will be presented and compared with the PARMELA simulations.
DESY Zeuthen, Zeuthen
LAL, Orsay
Research activities at the Photo Injector Test facility at DESY, Zeuthen site, (PITZ) aim to develop and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. To demonstrate the XFEL operation, an electron bunch train containing 3250 pulses of 1 nC charge at 10 Hz repetition rate is required. The spectrometers and related equipments for studying the longitudinal phase space for such long pulse trains do not yet exist at PITZ. Design and construction of a new high energy dispersive arm (HEDA2) is currently in progress. Besides the requirement to handle long electron bunch trains, the HEDA2 setup is designed to allow high resolution measurements of momentum distribution up to 40 MeV/c, a longitudinal phase space measurement with slice momentum spread down to 1 keV/c and transverse slice emittance measurements at off crest booster phases. The status of the physics design and technical considerations of this dispersive section will be presented in this contribution.
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.
CNAO Foundation, Milan
INFN/LNF, Frascati (Roma)
CERN, Geneva
The CNAO, the first Italian center for deep hadrontherapy, is presently in its final step of installation. It will deliver treatments with active scanning both with Proton and Carbon ion beams. Commissioning of the low energy injection lines has been successfully concluded in January 2009. CNAO beams are generated by two ECR sources which are both able to produce both particle species. The beam energy in the Low Energy Beam Transfer (LEBT) line is 8 keV/u. A compact and versatile tank containing a complete set of diagnostic tools has been intensively used for the line commissioning: in a length of 390mm it houses two wire scanners, for vertical and horizontal beam transverse profile, a Faraday Cup, for current measurement, and two vertical and horizontal plates for beam halo suppression , emittance measurements, beam collimation and particles selection. Using one tank devices, phase space distribution reconstruction can be quickly performed as well as synchronous profiles and intensity measurements. Commissioning results and measurements are presented.
NSRRC, Hsinchu
A new high brilliant 3 GeV storage-ring-based light source - Taiwan Photon Source (TPS) - is planned to be built at the National Synchrotron Radiation Research Center. Various diagnostics will be deployed to satisfy stringent requirements for commissioning, operation, and top-off injection of the TPS. Specifications and an overview of the planned beam instrumentation system for the TPS will be summarized in this report. Efforts in diagnostic devices and subsystems will also be addressed.
INFN/LNF, Frascati (Roma)
INFN-Roma II, Roma
Rome University La Sapienza, Roma
ENEA C.R. Frascati, Frascati (Roma)
One of the key diagnostics techniques for the full characterization of beam parameters for LINAC-based FELs foresees the use of RF deflectors. With these devices it is possible to completely characterize both the longitudinal and the transverse phase space. In the talk I will present the main design considerations for time resolved (sliced) beam parameter measurements using RF deflectors. Measurement setups for longitudinal pulse shape as well as phase space and transverse beam slice emittance characterizations are described. The main sources of errors are discussed and the design criteria of these devices are presented. In particular the SPARC RF deflector and the related diagnostic lines as well as recent measurement results from the SPARC facility are shown. RF deflectors in use or planned to be used in other FEL labs are then illustrated with an overview of these activities.
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).
ESRF, Grenoble
An additional electron beam emittance measurement at the ESRF storage ring is now installed that uses X-ray radiation from an undulator. The method consists in detecting the monochromatic spatial profile of the fifth harmonic of the undulator spectrum. The photon energy is roughly 30 keV, selected with a single bounce (3,1,1) Si monochromator. The X-rays are converted to visible light using a scintillating screen which is then imaged to a CCD camera. The emittance value is deduced from the image size, source distance, and the beta-function at the source point, taking into account the precisely known photon beam divergence. The direct use of undulator radiation is advantageous in terms of the precise knowledge of the source position and lattice parameters in the straight section. For this reason this device will find its main application as a horizontal emittance monitor with improved absolute precision compared to that of the pinhole cameras which are making use of bending magnet radiation. This paper will present the details of the method, the setup and the obtained results.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
The RAL front end FETS is currently under construction to demonstrate an H-ion beam with up to 18 kW at 3 MeV. Due to the beam power photo detachment techniques are the preferable choice for emittance instruments. Typically, measurements will be performed in just one transverse plane by using a magnet to separate ion beam from produced neutrals. Another general technique to work out a 2D emittance bases on several beam profiles applying an image reconstruction method called maximum entropy (MaxEnt). Combining both methods in one device has the significant advantage of reducing technical and physical problems which may occur by doubling magnet or laser beam path. Drawback of MaxEnt is the necessity of sufficient phase space advance to achieve reasonable results which can be either optimised by moving the particle detector or with additional focusing. The paper presents a conceptual design study discussing all possible constraints given by beam parameters and chopper/ MEBT. Simulations will help to estimate performance and errors.
DESY, Hamburg
High-brightness electron bunches with low energy spread, small emittance and high peak currents are the basis for the operation of high-gain Free Electron Lasers (FELs). As only part of the longitudinally compressed bunches contributes to the lasing process, time-resolved measurements of the bunch parameters are essential for the optimisation and operation of the FEL. Transverse deflecting structures (TDS) have been proven to be powerful tools for time-resolved measurements. Operated in combination with a magnetic energy spectrometer, the measurement of the longitudinal phase space can be accomplished. Especially in case of ultra-short electron bunches with high peak currents for which a time resolution on the order of 10 fs would be desirable, both the TDS and magnetic energy spectrometer have intrinsic limitations on the attainable resolution. In this paper, we discuss the fundamental limitations on both the time and energy resolution, and how these quantities are connected.
DPNC, Genève
INFN-Napoli, Napoli
Muon ionization cooling provides the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum. The measurement of emittance is the subject of another contribution. This talk focuses on the particle identification devices, with three time-of-flight stations, Cherenkov detectors, a preshower device and a full absorption calorimeter. These devices ensure the purity of the muon sample separating off pions in the incoming beam upstream of the cooling cell and muon decay electrons downstream of the cooling cell. By April 2009 it is expected that the beam and first set of detectors will have been commissioned, and operation performance will be reported.
GSI, Darmstadt
A precise tune determination is crucial for stable operation of GSI SIS-18 synchrotron especially for intense beam conditions. In order to avoid nearby resonances in the tune diagram the fractional part of coherent betatron motion needs to be measured with a resolution of 10-3 also during ramping mode. This is achieved using a fast digital readout system for Beam Position Monitors (BPM). The broadband BPM signal is sampled with a rate of 125 MSa/s which corresponds to an average of about 50 Sa per bunch for SIS-18 machine parameters. The signal is integrated bunch-by-bunch which minimizes thermal and digitization noise and the beam position is calculated. The tune is then determined in baseband directly by Fourier-transformation of the positions of a certain bunch typically over 2048 turns. This algorithm does not require any additional input parameter. Since particle losses due to significant emittance blow-up have to be avoided, excitation power has to be kept as low as possible. This was achieved using a digital pseudo random noise (PRN) generator for beam excitation, which produces white noise on a carrier frequency with adjustable bandwidth.
HIT, Heidelberg
The ion cancer therapy facility HIT in Heidelberg is producing ions (H, He, C and O) from two ECR sources at an energy of 8 keV/u with different beam currents from about 80 μA up to 1.2 mA. Typical sizes for the beam in the LEBT range from are 5 40 mm. Matching the always slightly changing output from the ECR sources to the first accelerating structure, an RFQ, demands a periodical monitoring of the beam emittance. For that, a special pepper-pot measurement device is under design, whose most important parts are a damage-resistant pepper-pot mask and a vacuum-suitable scintillator material. The investigation of the material lifetime is done in the first step by computing the maximum intensity the target volume can stand without any radiation damage, shock and heating. A list of feasible materials will be discussed and results from SRIM calculations for them will be shown. A set-up for necessary material tests with beam will be presented.
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.
INFN/LNF, Frascati (Roma)
Università di Roma II Tor Vergata, Roma
INFN-Roma II, Roma
Rome University La Sapienza, Roma
ENEA C.R. Frascati, Frascati (Roma)
The characterization of the transverse phase space of electron beams with charge density and high energy is a fundamental requirement for particle accelerator facilities. The knowledge of characteristics of the accelerated electron beam is of great importance for the successful developement of the SPARC FEL. Here the high-energy emittance measurement with the quadrupole scan technique using two quadrupoles arranged as a doublet is discussed.
PSI, Villigen
A screen monitor containing OTR foils and scintillator crystals has been designed to measure the transverse profile of electron bunches in the PSI-XFEL. In conjunction with quadrupole magnets in FODO cells and a transverse deflecting structure, the screen monitors will be used to measure transverse and longitudinal phase space projections of the electron pulses in the 250 MeV Injector. Tomographic methods will be used to reconstruct the phase space distributions.
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.