| Paper | Title | Page |
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| PM01 | Use of Optical Transition Radiation Interferometry for Energy Spread And Divergence Measurements | 89 |
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OTR interferometry (OTRI) has been shown to be an excellent diagnostic
for measuring the rms divergence and emittance of relativistic electron
beams when the energy spread ∆γ/γ is less than the normalized rms
divergence σ = γΘrms. This is the case for most beams previously
diagnosed with OTRI. To extend this diagnostic capability to beams with
larger energy spreads, we have calculated the effects of all the
parameters effecting the visibility of OTR interferences, V; i.e. energy
spread, angular divergence, the ratio of foil separation to wavelength
ratio, d/λ and filter bandpass.
We have shown that:
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| PM03 | Studies of OTR Angular Distribution on CTF2 | 92 |
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| Today, Optical Transition radiation (OTR) is widely used in beam diagnostics. The most common application is the imaging of the transverse and longitudinal beam profiles. Other beam parameters like divergence and energy can also be deduced by observing the angular distribution of the OTR emission (“Donuts”). In order to investigate the possibilities and the limits offered by this technique we have performed a test on the 48 MeV, 1 nC electron beam of the CLIC Test Facility 2 (CTF2). Beam divergences between 2 and 6 mrad were measured with an accuracy of few percent. A good agreement was also found between the energy measurements obtained with a classical spectrometer and the OTR based technique. We conclude describing some possible future applications of OTR based diagnostics for CLIC. | ||
| PM04 | OTR from Non-Relativistic Electrons | 95 |
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| The CLIC Test Facility 3 (CTF3) injector will provide pulsed beams of high average current; 5 A over 1.56 μs at 140 keV. For transverse beam sizes of the order of 1mm, as foreseen, this implies serious damages to the commonly used scintillating screens. Optical Transition Radiation from thermal resistant radiators represents a possible alternative. At low energy the OTR emission is feeble and distributed over a large solid angle. In order to investigate the feasibility of such a diagnostic studies have been carried out on a test 80 keV photo injector. The experimental set-up is described and the results are compared to the calculations based on the OTR emission theory. Our conclusions for the design of the CTF3 injector profile monitor are also given. | ||
| PM05 | Optical Transmission Line For Streak Camera Measurements at Pitz | 98 |
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The photoinjector injector test facility at DESY Zeuthen (PITZ) [1]
produces electrons with a momentum of about 4 MeV/c. It is the aim to
measure the temporal characteristics of the electron bunch train and
single bunches with high accuracy of the order of 1 ps and less. Several
types of streak cameras will be used in combination with different
radiators which transform particle energy in light. The problem to be
solved is the light transport over a distance of about 27 m. Basic demands
to the optical system and design principles will be explained. The
optical and technical solutions will be presented. The strategy of
adjustment and commissioning of the optical system will be described. The
system contains switchable optics to use different radiators (OTR,
Cherenkov radiators). Diagnostic tools are foreseen at different
positions along the optical axis. The results of different measurements
in the lab and using the original system will be presented. The problems
on the minimalization of the time dipersion in the system will be
discussed.
[1] F.Stephan, et al., Photo injector test facility under construction at DESY Zeuthen, FEL 2000, Durham |
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| PM06 | An Improved PLL for Tune Measurements | 101 |
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| The key element determining the dynamic performance of such a PLL is the phase detector between the beam oscillation and the internal oscillation. Most circuits use a quadrature phase detector, for which the high frequency carrier at twice the excitation frequency is attenuated by a low-pass circuit. The remaining ripple of this component contributes to the bandwidth/noise performance of the PLL. In this paper we propose an alternative solution for the filter, notably an adaptive notch filter. We explain in detail design considerations and the resulting improvements in PLL bandwidth and/or noise figure. | ||
| PM07 | Real time management of the AD Schottky/BTF beam measurement system | 104 |
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| The AD Schottky and BTF system relies on rapid acquisition and analysis of beam quantisation noise during the AD cycle which is based on an embedded receiver and digital signal processing board hosted in a VME system. The software running in the VME sets up the embedded system and amplifiers, interfaces to the RF and control system, manages the execution speed and sequence constraints with respect to the various operating modes, schedules measurements during the AD cycle and performs post processing taking into account the beam conditions in an autonomous way. The operating modes of the instrument dynamically depend on a detailed configuration, the beam parameters during the AD cycle and optional user interaction. Various subsets of the processed data are available on line and in quasi real time for beam intensity, momentum spread and several spectrum types, which form an important part of AD operation today. | ||
| PM08 | Recent Advances in the Measurement of Chromaticity Via Head-Tail Phase Shift Analysis | 107 |
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| A so-called "Head-Tail" monitor has been operational in the CERN-SPS for a few years. The measurement of chromaticity using such a monitor relies on the periodic dephasing and rephasing that occurs between the head and tail of a single bunch for non-zero chromaticity. By measuring the turn-by-turn position data from two longitudinal positions in a bunch it is possible to extract the relative dephasing of the head and the tail, and so to determine the chromaticity. Until recently this technique had suffered from an unexplained “missing factor” when compared to conventional chromaticity measurements. This paper explains the source of this factor and also reports on the considerable experimental, simulation and analysis effort that has qualified the technique for use in the LHC. | ||
| PM09 | Diagnostics for Electron Cooled Beams | 110 |
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| Nearly all modern hadron storage/accumulator rings use an electron cooling device to increase the phase space density of the circulating beam before its transfer to another accelerator or to the experiments. For fast and efficient cooling, the properties of the electron and hadron beams need to be monitored before, during and after the cooling process in a non-destructive manner in order not to perturb the normal operation of the machine. In this paper we review the various techniques used to measure and optimise the different parameters that determine the quality of the cooling. | ||
| PM10 | Characterisation of Fast Faraday Cups at the ELETTRA Linac | 113 |
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| A major upgrade of the ELETTRA injector is currently on going: the 1 GeV LINAC will be replaced with a 100 MeV LINAC and a 2.5 GeV Booster Synchrotron. A new set of diagnostics is now under development for these two new machines. The new Fast Tune measurement system for the Booster represents a significant improvement as compared to the present Tune measurement system. With the Booster cycling at 3 Hz, horizontal and vertical tunes have to be measured during the energy ramp, whose duration is 160 ms. To completely characterise the dynamics of the Booster during the energy ramp, a set of 25 tune values has been required, corresponding to a 6.4 ms interval between successive measurements. The accuracy of this measurement is <10-3. Such frequency spans are achievable using a Real Time Spectrum Analyser (Tektronix 3026), which is a fast sampling instrument with built-in FFT algorithm and data presentation. In this paper, after describing the system specifications and architecture, we present the results of the preliminary tests, which have been carried out both in the laboratory and on the Storage Ring. | ||
| PM11 | Beam Studies Made With The SPS Ionization Profile Monitor | 116 |
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| During the last two years of SPS operation, investigations were pursued on the ability of the SPS ionization profile monitor prototype to fulfill different tasks. It is now established that the instrument can be used for injection matching tuning, by turn to turn recording of the beam size after the injection. Other applications concern beam size measurements on beams ranging from an individual bunch to a nominal SPS batch foreseen for injection into the LHC (288 bunches). By continuously tracking throughout the SPS acceleration cycle from 26 GeV to 450 GeV the evolution of parameters associated to the beam size, it is possible to explain certain beam behavior. Comparisons are also made at different beam currents and monitor gains with measurements made with the wire scanners. Data are presented and discussed, and the possible implementation of new features is suggested in order to further improve the consistency of the measurements. | ||
| PM12 | Cavity Mode Related Wire Breaking of the SPS Wire Scanners And Loss Measurements of Wire Materials | 119 |
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| During 2002 SPS running with the high intensity LHC type beam the breaking of several of the carbon wires in the wire scanners has been observed. This damage occurred with the scanners in their parking position. The observation of large changes in the wire resistivity and thermionic electron emission indicated clearly a strong RF beam induced heating and its bunch length dependence. A subsequent analysis in the laboratory, simulating the beam by a RF-powered wire, showed two main problems. The housing of the wire scanner acts as a cavity with a mode spectrum starting around 350 MHz and high impedance values around 700 MHz. The carbon wire used appears to be an excellent RF absorber and thus dissipates a significant part of the beam-induced power. The classical cavity mode technique is used to determine the complex permittivity and permeability of different samples. As a resonator, a rectangular TE01N type device is used. Different materials such as silicon carbide (SiC), carbon and quartz fibres as well as other samples were measured, since no data for these materials was available. In particular SiC properties are of interest, since SiC bulk material is often used as a microwave absorber. As a result, the carbon wire will be replaced by a SiC wire, which shows much less RF losses. Placing ferrite tiles on the inner wall of the wire scanner housing considerably reduces the impedance of the cavity modes. The reduction of the Q values of these modes is confirmed by laboratory measurements. | ||
| PM13 | The PS Booster Fast Wire Scanner | 122 |
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| The very tight emittance budget for LHC type beams makes precise emittance measurements in the injector complex a necessity. The PS machine uses 2 fast wire scanners per transverse plane for emittance measurement of the circulating beams. In order to ease comparison the same type of wire scanners have been newly installed in the upstream machine, the PS Booster, where each of the 4 rings is equipped with 2 wire scanners measuring the horizontal and vertical profiles. Those wire scanners use new and more modern control and readout electronics featuring dedicated intelligent motor movement controllers, which relieves the very stringent real time constraints due to the very high speed of 20 m/s. In order to be able to measure primary beams at the very low injection energy of the Booster (50 MeV) secondary emission currents from the wire can be measured as well as secondary particle flows at higher primary particle energies during and after acceleration. The solution adopted for the control of the devices is described as well as preliminary results obtained during measurements made in 2002. | ||
| PM14 | Upgrade Of The ESRF Fluorescent Screen Monitors | 125 |
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| The ESRF injector system contains 23 Fluorescent Screen monitors: 4 in the TL-1 transferline (200 MeV), 8 in the Booster, and 11 in the TL-2 transferline (6 GeV). They are based on Chromium doped Alumina screens that are pneumatically inserted at 45o angle in the beam path with an optical system, at 90o angle, collecting and focusing the emitted light onto a low-cost CCD camera with standard 75Ω video output. Serving mainly alignment purposes in the past 10 years, the present upgrade aims at a 200 μm fwhm resolution for beam-size and profile measurements. The particularity of the Alumina screen not in vacuum but in atmosphere will be explained. Details of the mechanics, the optic system and a cost-efficient way of light flux adjustment will be given. The analysis of the factors determining the ultimate spatial resolution will show that it is dominated by the screen characteristics. Results obtained with different screen material will be presented. | ||
| PM15 | First Experimental Results And Improvements On Profile Measurements With The Vibrating Wire Scanner | 128 |
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| The paper presents the first experimental results of transverse profile scans using a wire scanner based on a vibrating wire (vibrating wire scanner - VWS). The measurements were performed at the injector electron beam (6 nA) of the Yerevan synchrotron. The beam profile information is obtained by measuring the wire natural oscillations that depend on the wire temperature. This first experiments on weak electron beam proved this new method as a very sensitive tool, even suitable for tail measurements. Additional, improvements were tested to overcome some problems connected with signal conditioning and signal transfer in the presence of electromagnetic noise. As a result the noises were neatly separated and reduced. A mathematical method for rejection of distorted data was developed. Experiments with the scanner at the PETRA accelerator at DESY are planned for measurements of beam tails. | ||
| PM16 | Wire Scanner Beam Profile Measurement For ESRF | 131 |
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| Method of beam transverse profile measurement in accelerator by wire scanner is wide spread in accelerator field. The wire scanner is used in beam transfer lines of European Synchrotron Radiation Facility (ESRF) to provide data for beam profiles, which is being used in emittance measurements. The beam energy in the first transport line is 200 MeV and the peak current is 25 mA. The purpose of the scanner is to provide horizontal and vertical beam profiles. This work will discuss the operation of the wire scanner, and the first results of the scanner in ESRF. By changing the value of focus quad at (de focus quad = 18 A) we get the emittance value for the vertical plane. The value is 1.5·10-6 mrad. When we used this value to simulate our result we find that the simulation gives good fitting with real values of vertical plane. Also by changing the value of the focus quad at (focus quad = 10.46 A) we get the emittance value for the horizontal plane. The value is 2·10-7 mrad. And we find that the simulation gives good fitting with real values. | ||
| PM17 | Development of a Permanent Magnet Residual Gas Profile Monitor With Fast Readout | 134 |
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| Modern ion accelerators and storage rings require very fast beam profile measurements (turn-by-turn) with highest resolutions. We propose a new residual gas monitor, which will operate on secondary electrons whose trajectories are localized within ∅ 0.1 mm filaments along 0.1 T uniform magnetic field lines excited by a permanent magnet. The best way to adopt the resolution of 0.1 mm into the data acquisition system is the use of a CCD camera with upstream MCP-phosphor screen assembly. To realize a fast turn-by-turn beam profile measurement a photodiode readout by a 100-channel amplifier/digitizer is foreseen. | ||
| PM18 | Residual Gas Fluorescence for Profile Measurements at the GSI UNILAC | 137 |
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| The high beam currents, delivered at the LINAC at GSI (UNILAC) can destroy intercepting diagnostics within one macro-pulse. As an alternative for a non-destructive profile measurement the methode for residual-gas-fluorescence is investigated. The fluorescence light is emitted by the N2 molecules of the residual gas at the blue wavelength range and can be monitored with a modern CCD-camera. The images are transferred via digital bus (IEEE 1394 'FireWire') and the profiles are generated by analysis of the images with a modern software tool (National Instruments 'LabView'). Due to the short beam pulses (about 0.2 ms) the light intensities emitted by the residual gas are low and require a high amplification (gain >106) which is realized with an image intensifier with double MCP (multi channel plate), connected with a fiber taper to the CCD-chip. The design parameters of the optics and electronics are discussed as well as the advantages of the digital data transmission. Measurements with heavy ion beams of several 100 μA and a comparison to other profile measurement methods show a good signal-to-noise ratio and prove a good applicability. | ||
| PM19 | Ionisation Beam Profile Monitor at the Cooler Synchrotron COSY-Jülich | 140 |
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| For beam profile measurements, a residual-gas ionisation beam profile monitor using a position sensitive micro channel plate (MCP) detector was developed and installed at the cooler synchrotron and storage ring COSY at Forschungszentrum Julich. A parallel ion drift field is maintained in the gap between two electrodes. Residual gas ions are drifted onto an MCP assembly that provides a charge gain of about 107. For online calibration the detector can be illuminated with an α-source. The secondary charge produced from each ion is collected by a wedge and strip anode. After some processing the charge signal is digitized and read out by means of a PC running Cobold PC software. Since COSY operates with beam intensities up to 1011 protons and a vacuum of 10-9 mbar, there is a high risk of detector damage. The lifetime of the channel plates and the event rate are crucial issues for the profile measurement of intense proton beams. The aging of the channel plates (i.e. inhomogeneous decrease of the gain) were investigated using scanning electron microscope and energy dispersive x-ray microanalysis. Different implemented detector protection mechanisms are discussed. Measurements with electron cooled beams are reported. | ||
| PM21 | Recent Developments Of The EXCYT Radioactive Beam Diagnostics | 143 |
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| The EXCYT radioactive beam facility at LNS, based on the ISOL (Isotope Separator On Line) technique, will start producing its first radioactive beams during 2004. We are setting up a suitable high sensitivity diagnostics, in order to guarantee a real time monitoring of the beam parameters (transversal profiles, ion composition and current), offering also the capability to perform the beam imaging at very low beam energy (50 keV). For this purpose, a simple technique based on the use of a thin CsI(Tl) scintillating plate that does not require any amplification system inside the beam pipe, has been employed. Tests performed with stable beams have shown a current sensitivity well below 105 pps, a value that can be improved by adopting a more suitable lens and an intensified and cooled CCD camera. | ||
| PM23 | Networked Attached Devices at SNS | 146 |
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| The Spallation Neutron Source (SNS) diagnostic instruments at Oak Ridge National Laboratory are based on the Network Attached Device (NAD) concept. Each pickup or sensor has its own resources such as timing, data acquisition and processing. NADs are individually connected to the network, thus reducing the brittleness inherent in tightly coupled systems. This architecture allows an individual device to fail or to be serviced or removed without disrupting other devices. This paper describes our implementation of the nearly 400 NADs to be deployed. The hardware consists of rack-mounted PCs with standard motherboards and PCI data-acquisition boards. The software environment is based on LabVIEW and EPICS. LabVIEW supports the agile development demanded by modern diagnostic systems. EPICS is the control system standard for the entire SNS facility. To achieve high performance, LabVIEW and EPICS communicate through shared memory. SNS diagnostics are developed by a multi-laboratory partnership including ORNL, BNL, LANL, and LBNL. The NAD concept proved successful during the commissioning of the SNS front-end both at LBNL and ORNL. | ||
| PM24 | Parasitic Bunch Measurement in e+/e- Storage Rings | 149 |
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| The lepton storage rings DORIS and PETRA at DESY are used as sources for synchrotron radiation experiments. In normal operation the distance between the bunches should be 96 ns in PETRA and 192 ns in DORIS. The adjacent buckets must not have any stored particles or, in reality, as few as possible. This is particularly important for time triggered photon measuring experiments. The principle of the 'parasitic bunch' measurement down to a fraction of 10-6 of the main bunch within 20 seconds are described. Additionally, the sources of the 'parasitic bunches' and the actions to minimize them are discussed. | ||
| PM25 | Diagnostics of the PROSCAN beam lines | 152 |
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| PROSCAN, an extended medical facility using proton beams for the treatment of deep seated tumours and eye melanoma, is now in preparation at PSI. A 250 MeV proton beam of 0.1 to 500 nA will be extracted from the COMET cyclotron. After degradation to 70 to 230 MeV it can be delivered (at a maximum current of 1 to 5 nA) into one of four areas: Two gantries, an eye treatment room and an irradiation area for various experiments. Fast changes of beam energy are foreseen for the spot-scanning treatment of deep-seated tumours in the gantries. Several diagnostics will be used to control the beam parameters in different modes of operation. An overview is given on the devices foreseen for the measurement of beam profile, position, current and losses in the beam lines. | ||
| PM26 | A System For Beam Diagnostics in the External Beam Transportation Lines of the DC-72 Cyclotron | 155 |
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| The isochronous four-sector Cyclotron DC-72 will serve as the basic facility of the Cyclotron Center of the Slovak Republic in Bratislava. It will be used for accelerating ion beams of H- to Xe up to energy of 72-2.7 MeV/nucleon. In the present work a system for external beam diagnostics is presented, which is intended for on-line acquisition of data on the main parameters of accelerated beams (current, position, profile, emittance and energy of the ion beams) to allow effective tuning of the accelerator operation regime as well as ion beam transport along the transport lines through the ion optical systems to physical targets and set-ups. | ||
| PM27 | Multifunction Test-Bench For Heavy Ion Sources | 158 |
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| The new test-bench for heavy ion sources has been created in ITEP. It is planned to equip test-bench with a set of measurement devices to cover wide range of beam widths, divergences, durations, currents etc. It will provide measurements of different heavy ion beams parameters, particularly, emittance and charge state distribution. The last parameter may be measured both by the time-of-flight method and with the magnet analyzer. Two emittance measurement devices will be installed. It will be possible to use both slit/grid and CCD based "pepperpot" methods, which will give advantages of combination of classical emittance measurements with performance of the CCD based devices. The detailed description of test-bench and its equipment is presented. The first results at MEVVA ion source and beam investigations are discussed. | ||
| PM28 | Application of Beam Diagnostics for Intense Heavy Ion Beams at the GSI UNILAC | 161 |
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| With the new High Current Injector (HSI) of the GSI UNILAC the beam pulse intensity had been increased by approximately two orders of magnitudes. The HSI was mounted and commissioned in 1999; since this time the UNILAC serves as an injector for the synchrotron SIS, especially for high uranium intensities. Considering the high beam power of up to 1250 kW and the short stopping range for the UNILAC beam energies (≤12 MeV/u), accelerator components could be destroyed, even during a single beam pulse. All diagnostic elements had to be replaced preferably by non-destructive devices. The beam current is mainly measured by beam transformers instead of Faraday cups, beam positions are measured with segmented capacitive pick-ups and secondary beam monitors instead of profile harps. The 24 installed pick-ups are also used to measure intensities, widths and phase of the bunches, as well beam energies by evaluating pick-ups at different positions. The residual gas ionization monitors allow on-line measurements of beam profiles. The knowledge of the real phase space distribution at certain position along the linac is necessary for optimizing the machine tuning, for the improvement of the matching to the synchrotron and for a better understanding of beam dynamic issues under space charge conditions. The paper will report the application of different beam diagnostic devices for the measurement of transverse beam emittances at different UNILAC beam energies and for different beam intensities. Additionally, measurements of the bunch structure after the HSI and a the design of a new device for the measurement of the longitudinal emittance at the end of the UNILAC will be included. | ||
| PM29 | A Modular VME Data Acquisition System for Counter Applications at the GSI Synchrotron | 164 |
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| Particle counters perform the control of beam loss and slowly extracted currents at the heavy ion synchrotron (SIS) at GSI. A new VME/Lynx - PC/Linux based data acquisition system has been developed to combine the operating purposes beam loss measurement, spill analysis, spill structure measurement and matrix switching functionality in one single assembly. In this paper a detailed PC-side software description is presented. To achieve best system stability, the software has been divided into time critical networking and data deploying threads and low or normal priority interface tasks. Some new abilities in the fields of data computation and presentation are reported. A hardware description is presented, in detail a programmable GSI-EVENT controller, which is based on an ordinary 8 bit RISC microprocessor and which has been integrated into the system, to synchronize the data acquisition with the sophisticated “virtual accelerator” timing at GSI. First experiences gained while the commissioning of the system are discussed. |