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.
iThemba LABS, Somerset West
FZJ, Jülich
Non-destructive beam position monitors (BPMs) have been in use at iThemba LABS for several years in the neutron therapy and radioisotope production beamlines, as well as in the transfer lines between the K200 separated-sector cyclotron and the two K8 injector cyclotrons. The sensitivity of these BPMs is limited by noise and pickup from the RF systems to about 300 nA in the high energy beam lines. For proton therapy, using the scattering method, position measurement at beam currents as low as 20 nA have to be made. A new and more sensitive BPM as well as the electronic measuring equipment, using RF pickup cancellation and improved filtering, have been developed and installed in the proton therapy beamline. The BPM, the electronic equipment and the results of measurements at beam currents down to 10 nA for 200 MeV protons are described.
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.
GANIL, Caen
LPC, Caen
The SPIRAL2 project is based on a multi-beam driver facility in order to allow both ISOL and low-energy in-flight techniques to produce intense radioactive ion beams (RIB) in a new Facility. A superconducting linac capable of accelerating 5-mA deuterons up to 40 MeV is used to bombard both thick and thin targets. These primary beams will be used for the RIB production by several reaction mechanisms (fusion, fission, etc.) The production of high intensity RIB will be based on fission of uranium target induced by neutrons. These exotic particles will be produced, ionized, selected in a dedicated production building and transported to the existing CIME cyclotron for post acceleration. After this, they will be used in the present experimental area of GANIL. The construction phase of SPIRAL2 was officially started in 2005. The beam diagnostics for the production facility allow a pre-tuning with a stable beam followed by an extrapolation to the radioactive beam. Some diagnostic devices may also provide for equipment protections and for the safety systems. An overview is presented of the diagnostics which will allow tuning and control of the RIB in this new production facility.
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.
GSI, Darmstadt
LBNL, Berkeley, California
TU Darmstadt, Darmstadt
As conventional intercepting diagnostics will not withstand high intensity ion beams, Beam Induced Fluorescence (BIF) profile monitors constitute a pre-eminent alternative for online profile measurements. At present two BIF monitors are installed at the GSI UNILAC and several locations are planned for the FAIR high energy beam transport lines. For further optimizations accuracy issues like gas dynamics have to be investigated systematically. Especially the determination of focused beams in front of targets or beam intensities near the space charge limit rely on a careful selection of proper working gas transitions to keep profile distortions as low as possible. With an imaging spectrograph beam induced fluorescence spectra in the range of 300-800 nm were investigated. Wavelength-selective beam profiles were obtained for 5 MeV/u sulphur and tantalum beams in nitrogen, xenon, krypton, argon and helium gas at pressures below 10-3 mbar. In the calibrated BIF spectra the specific gas transitions were identified. The measurement results are compared with particle tracking simulations and discussed for typical applications at the present setup and the future FAIR facility.
SLAC, Menlo Park, California
CERN, Geneva
Synchrotron-light telescopes will monitor the profiles of the two LHC proton beams. At collision energy (7 TeV), each telescope will image visible light from a superconducting dipole used to increase beam separation for the RF-cavities. At injection (0.45 TeV), this source must be supplemented by a two-period superconducting undulator 80 cm from the dipole. We will present the mechanical and optical layouts of the telescope. The initial plan to use dipole edge radiation at high beam energy, for its increased visible emission, suffers from significant diffractive blurring. We will instead collect radiation from the first 2 to 3 m of the dipole’s interior. An optical "trombone" delay line will provide the large shift in focus. We will discuss calculations and measurements of blurring by diffraction and by this extended source, and present an alternative optical design using off-axis elliptical mirrors.
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.
MPI-K, Heidelberg
The University of Liverpool, Liverpool
Growing interest in the development of low energy projectile beams, in particular heavy ions and antiprotons, calls for new beam instrumentation to be developed to match the strict requirements on ultra-high vacuum and low beam perturbation. When it comes to transverse profile monitoring, a convenient solution for simultaneous determination of both transverse profiles is found in a neutral supersonic gas-jet target shaped into a thin curtain and the two-dimensional imaging of the gas ions created by impacting projectiles. The resolution and vacuum efficiency of this monitor is directly linked to the characteristics of the gas-jet curtain. In this contribution we describe the design of a nozzle-skimmer system to be used for the creation of the jet curtain in the first prototype of such a monitor. Using numerical fluid dynamics simulations, we present the effects resulting directly from changes in the geometry of the nozzle-skimmer system on the characteristics of the jet curtain.
UniDo/IBS, Dortmund
iThemba LABS, Somerset West
FZJ, Jülich
DELTA, Dortmund
Scintillation is one of the outcomes of beam interaction with residual gas. This process is utilized for non-destructive beam profile monitoring. Test bench measurements at various gas compositions and pressures as well as ones with the circulating proton beam at COSY-Juelich were performed. This was done using a single large photocathode PMT to estimate the photon yield. A multichannel photomultiplier was used along with a lens system to monitor the ion beam profile. Experimental results are presented and the challenges of the approach are discussed.
FZJ, Jülich
UniDo/IBS, Dortmund
GSI, Darmstadt
ITEP, Moscow
The advanced ionization beam profile monitor is being developed at GSI for the future FAIR facility in collaboration with ITEP and FZ-Jülich. In January 2009 the IPM prototype was installed in COSY-Jülich. After successful hardware test the beam tests followed. The prototype was operated without magnetic field, thus only residual gas ions were detected. An arrangement consisting of an MCP stack, a phosphor screen, and a CCD camera was used to detect ions. We report the first profile measurements of the proton beam up to 2.8 GeV at COSY.
IMP, Lanzhou
This paper gives the detectors used for slowly extracted heavy ions from CSR. The beam profiles are measured with viewing screens and anode-striped ion-chambers. The currents are determined with scintillators and ion-chambers. The signal processing system and the measurement results are also presented.
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.
GSI, Darmstadt
TUD, Darmstadt
Most timing systems used for particle accelerators send their time or reference signals via optical single mode fibres embedded in cables. An important question for the design of such systems is how fast the delay changes in the fibre optic cable take place, subject to the variation of the ambient air temperature. If this information is known, an appropriate method for delay compensation can be chosen, to enable a phase stabilised transmission of the timing signals. This is of interest particularly with regard to RF synchronisation applications. To characterise the velocity of the delay change, the delay behaviour after a sudden temperature change will be described. When trying to determine the step response, two problems occur. On the one hand, the material parameter of the coating, necessary for the calculation, is typically unknown. On the other hand, the measurement of the step response under realistic conditions is very laborious. Thus in this presentation it will be shown how the step response and, accordingly, the velocity of the delay change in a fibre optic cable can be calculated by means of theoretical considerations, utilizing the typical geometry of fibre optic cables.
MPI-K, Heidelberg
At the Max-Planck-Institute for Nuclear Physics in Heidelberg a cryogenic electrostatic storage ring (CSR) is under construction, which will be a unique facility for low velocity and in many cases also phase-space cooled ion beams. Among others the cooling and storage of molecular ions in their rotational ground state is planned. To meet this demand the ring must provide a very low level of blackbody radiation and a vacuum in the XHV range (10-15 mbar) which is achieved by cryogenic cooling of the ion beam vacuum enclosure to 2-10K. The beam current will be in the range of 1 nA -1 μA. The resulting low signal strengths together with the cold environment put strong demands on the amplifier electronics. We plan to make use of a resonant amplifying system. Using coils made from high purity copper, we expect quality factors of ~1000. The mechanical design has to provide stability of the alignment against thermal shrinking when switching from room temperature operation to cryogenic operation. A prototype pickup has been built in order to test resonant amplification and the mechanical design with a wire. The amplification principle will be tested in the MPI-K’s Test Storage Ring.
IMP, Lanzhou
HIRFL-CSR, a new heavy ion cooler-storage ring in China IMP, had been installed and started commission from 2005. We report here the BPM system on the main ring (CSRm) and the experimental ring (CSRe). The BPM structure, the signal processing system and on-line measurement experiments are presented. The measurement results such as turn-by-turn bunch observation, closed-orbit measurement, Schottky noise measurement are also presented in this paper.
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.
NERS-UM, Ann Arbor, Michigan
Michigan Ion Beam Laboratory (MIBL) is equipped with a 1.7 MV tandem particle accelerator and a 400 KV ion implanter. Ion beams can be produced from a variety of ion sources and delivered to different beamlines. Precise beam profiling and current measurements are critical aspects of everyday activity in the laboratory and influence the success of each experiment. The paper will present the beam simulation software employed and the benefits and the shortcomings of the devices used at MIBL to precisely know all the parameters of the ion beams
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.
iThemba LABS, Somerset West
INFN/LNL, Legnaro, Padova
Equipment for non-destructive, two-dimensional beam profile measurement has been developed for the 15 MV tandem accelerator at INFN, Legnaro and the K200 variable-energy, separated-sector cyclotron at iThemba Labs. Ions, produced by the interaction of the beam with residual gas, are accelerated in an electrostatic field towards microchannel plates (MCP) for signal amplification. With the first of the two prototypes that were built, ions are collected in an electric field between two parallel plates and after passing through an aperture in one of the plates, move through the electric field between two curved plates and bend through an angle of ninety degrees before reaching the MCP. The spread in ion energies provides the second position. In the second prototype two one-dimensional systems, rotated through ninety degrees with respect to each other, were installed close together. The measured beam profiles for both systems were compared with those of measurements with a nearby profile grid. Measurements were made on various beams and intensities between 10 and 10{00} nA. The beam position display with the MCP was calibrated to within 0.75 mm with the profile grid.
DESY, Hamburg
IKP, Mainz
For the European XFEL with a maximum beam energy of 20 GeV and an average beam power of up to 300 kW it is planned to install beam profile monitors in the dump sections in order to control beam position and size. Usually OTR monitors are used for electron profile measurements. For intense beams however, thermal load in the screen material may result in resolution degradation and even screen damage. To overcome this problem the beam can be swept over the screen, but the strong OTR light emission directivity will reduce the optical system's collection efficiency. Therefore it is planned to use luminescent screens because of their robustness and isotropic light emission. While only little information is available about scintillator properties for applications with high energetic electrons, a test experiment has been performed at the 855 MeV beam of the Mainz Microtron MAMI in order to study light yield and robustness of different screen materials like Aluminum and Zirconium oxide under electron bombardment. The results will be compared to independent measurements from studies with heavy ion beams.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
The RAL Front End Test Stand is under construction with the aim of demonstrating production of a high-quality, chopped 60 mA H- beam at 3 MeV and 50 pps. In addition to the accelerator development, novel laser-based diagnostics will be implemented. This paper reports on a device that will be able to measure multiple profiles of the beam density distribution in such a way that the full 2D density distribution can be reconstructed. The device is currently being commissioned. The status of the device is presented together with results of the commissioning and plans for future development.
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.
MPI-K, Heidelberg
The cryogenic storage ring CSR is a 35 m circumference electrostatic ring, for molecular- and atomic physics experiments at MPI-K Heidelberg. It will operate at pressures down to 10-13 mbar and temperatures <10 K. The beam intensities will be in the range of 1 nA to 1 uA, particle energies are between 20 - 300 keV. An intensity measurement for coasting beams below 1 uA requires magnetic field detection devices, which are much more sensitive than existing DC beam transformers. The highest sensitivity is currently achieved with DC SQUID based cryogenic current comparators (CCCs). At GSI, a prototype of such a CCC was successfully tested in the mid 90’s, reaching a resolution of ~250 pA/Hz1/2. Recently a resolution of 40 pA/Hz1/2 could be achieved under laboratory conditions at Jena University, however, the CCC sensitivity in an accelerator environment depends strongly on efficient shielding and mechanical decoupling. We describe our work on adaptation and improvement of the CCC beam transformer for the CSR. Furthermore a concept for an ionisation profile monitor is discussed, which in addition to low beam intensities, has to cope with extremely low gas densities at 10-13 mbar.
GSI, Darmstadt
The FAIR (Facility for Antiprotons and Ions Research) accelerator complex is currently designed and projected at GSI. The unique features of the central machine SIS100, like e.g. the acceleration of high intensity beams of 2.5·1013 protons and 5·1011 Uranium ions, the operation close to the space charge limit leading to a large tune spread and the extreme UHV conditions of the cryogenic system for fast ramped superconducting magnets, make challenging demands on the beam diagnostic components. This contribution describes the general concept of beam diagnostics for FAIR and reports on the present status of prototype studies. Exemplarily the achievements for a novel type of dc transformer, beam position monitors and the ionization profile monitor are discussed and first measurements with prototype setups are presented.