| Paper | Title | Page |
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| CT01 | BPM Read-Out Electronics Based on the Broadband AM/PM Normalization Schema | 63 |
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| Recently developed circuit modules, used for the processing of position signals of electrostatic (“button”-type) pickups are presented. The concept is based on the broadband (“monopulse”) AM/PM normalisation technique. The short integration time (≈ 10 ns) makes this read-out electronics suitable for single-bunch position measurements nearby interaction areas and in linear accelerators. Details on circuit design and technology, as well as the practical realization are shown. The results discussed include beam position and orbit measurements made with a set of 40 units at the FEL-undulator sections of the TESLA Test Facility (TTF) linac. | ||
| CT02 | First Commissioning Results of the ELETTRA Transverse Multi-Bunch Feedback | 66 |
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| A wide-band bunch-by-bunch Transverse Multi-Bunch Feedback, developed in collaboration with the Swiss Light Source (SLS), has been installed at ELETTRA. After a description of the main hardware/software components, the first commissioning results and the present status of the system are given. | ||
| CT03 | Performance of the Digital BPM System for the Swiss Light Source | 69 |
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| The accelerator complex of the Swiss Light Source (SLS) is presently under commissioning at the Paul Scherrer Institute (PSI) in Villigen, Switzerland. The newly developed digital beam position monitor (DBPM) system has been successfully used to determine beam positions in the pre-injector LINAC, the transfer lines, the booster synchrotron and the storage ring. Instant and free selection of operation modes through the EPICS-based SLS control system allows to choose between single turn, turn-by-turn and closed orbit measurements. The operational experience and performance of the DBPM system is presented, based on measurements, taken during SLS commissioning. A monitoring system (POMS), which measures the horizontal and vertical mechanical positions of each BPM block in reference to the adjacent quadrupole magnets has been installed and first results, indicating transverse movements of the BPM blocks as a function of current in the storage ring will be presented. | ||
| CT04 | Fibre Optical Radiation Sensing System for TESLA | 73 |
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| High energy accelerators generate ionising radiation along the beam-line and at target places. This radiation is related to beam losses or dark currents. The in-situ measurement of this ionising dose that is distributed over long distances or large areas requires a new monitor system. This paper presents first results and the concept of such a monitor system at the Tesla Test Facility. | ||
| CT05 | Beam-Profile Instrumentation for a Beam-Halo Measurement: Overall Description, Operation, and Beam Data
Work supported by the US Department of Energy |
76 |
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| The halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory (LANL) has specific instruments that acquire horizontally and vertically projected particle-density beam distributions out to greater than 105:1 dynamic range. We measure the core of the distributions using traditional wire scanners, and the tails of the distribution using water-cooled graphite scraping devices. The wire scanner and halo scrapers are mounted on the same moving frame whose location is controlled with stepper motors. A sequence within the Experimental Physics and Industrial Control System (EPICS) software communicates with a National Instrument LabVIEW virtual instrument to control the movement and location of the scanner/scraper assembly. Secondary electrons from the wire scanner 33 μm carbon wire and protons impinging on the scraper are both detected with a lossy-integrator electronic circuit. Algorithms implemented within EPICS and in Research Systems Interactive Data Language (IDL) subroutines analyse and plot the acquired distributions. This paper describes the beam profile instrument, describes our experience with its operation, compares acquired profile data with simulations, and discusses various beam profile phenomenon specific to the halo experiment. | ||
| CT06 | The Measurement of Q' And Q'' in the CERN-SPS by Head-Tail Phase Shift Analysis | 79 |
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| A so-called "Head-Tail" chromaticity measurement system has recently been installed in the CERN-SPS, which allows the chromaticity (Q’) to be calculated from several hundred turns of data after transverse excitation. The measurement 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 turnby-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. In addition, by changing the orbit of the circulating beam this technique allows the variation of chromaticity with radial position (Q’’) to be measured with a much higher resolution than is currently possible using RF modulation. This paper describes this "Head-Tail" measurement technique and discusses some recent results obtained using prototype LHC beam (25 ns spacing) in the CERN-SPS. | ||
| CT07 | Excitation of Large Transverse Beam Oscillations without Emittance Blow-Up Using the "AC-Dipole" Principle | 82 |
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| The so-called "AC-Dipole" principle allows the excitation of transverse oscillations to large (several σ) excursions without emittance blow-up. The idea was originally proposed and tested at BNL for resonance crossing with polarized beams, using an orbit corrector dipole with an excitation frequency close to the betatron tune, hence "AC-Dipole". This method of beam excitation has several potential applications in the LHC, such as phase advance and β-measurements, dynamic aperture studies and the investigation of resonance strengths. The technique was recently tested in the CERN-SPS using the transverse damper as an "AC-Dipole" providing the fixed frequency excitation. results from this experiment are presented, along with an explanation of the underlying principle. | ||
| CT08 | Measuring Beta-Functions with K-Modulation | 85 |
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| The precise measurement of the local value of the beta-function at the place of a beam size monitor is necessary for the precise determination of the beam emittance. We developed a new method for the measurement of the beta-function by using of continuous square-wave modulation of the force of the quadrupole and by continuous tune tracking. Measurements were performed at LEP in order to evaluate the precision that can be achieved with this method in the LHC. The paper describes the method and discusses in details the results obtained at LEP for colliding and non-colliding beams. | ||
| CT09 | X-Ray Interference Methods of Electron Beam Diagnostics | 88 |
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| Electron beam diagnostics methods based interference and diffraction of synchrotron radiation (SR) in hard X-ray range will be discussed. Two simple optical schemes providing X-ray interference patterns highly sensitive to transverse size of the emitting electron beam, will be considered. For each scheme, the visibility of fringes in the pattern depends on transverse size of the electron beam. However, the pattern is also determined by the scheme geometry, shape and material of diffracting bodies. Therefore, for correct interpretation of the experimental results, high-accuracy computation of SR emission and propagation in the framework of physical optics should be used. Examples of practical measurements and processing of the results are presented. | ||
| CT10 | Beam Charge Asymmetry Monitors for Low Intensity Continuous Electron Beam
Work supported the Southeastern Universities Research Association (SURA) which operates the Thomas Jefferson National Accelerator Facility (JLAB) for the U.S. Department of Energy under contract DE-AC05-84ER40150 |
91 |
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| Experimental Hall B at Jefferson Lab (JLAB) typically operates with CW electron beam currents in the range of 1-10 nA. This low beam current coupled with a 30 Hz flip rate of the beam helicity required the development of new devices to measure and monitor the beam charge asymmetry. We have developed four independent devices with sufficient bandwidth for readout at 30 Hz rate: a synchrotron light monitor (SLM), two backward optical transition radiation monitors (OTR) and a Faraday Cup. We present the results from the successful operation of these devices during the fall 2000 physics program. The reliability and the bandwidth of the devices allowed the control of the current asymmetry at the source laser by means of a feedback loop. | ||
| CT11 | New Development of a Radiation-Hard Polycrystalline CDTE Detector for LHC Luminosity Monitoring | 94 |
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| Detectors presently considered for monitoring and control of the LHC luminosity will sample the hadronic/electromagnetic showers produced by neutrons and photons in copper absorbers designed to protect the superconducting magnets from quenching. At this location the detectors will have to withstand extreme radiation levels and their long term operation will have to be assured without requiring human intervention. For this application we have successfully tested thick poly-crystalline-CdTe detectors. The paper summarizes the results obtained on rise-times, sensitivity and resistance to neutron irradiation up to a dose of 1015/cm2. |