| Paper | Title | Page |
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| TOAD001 | Techniques for Pump-Probe Synchronisation of Fsec Radiation Pulses | 59 |
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| The increasing interest on the production of ultra-short photon pulses in future generations of Free-Electron Lasers operating in the UV, VUV or X-ray regime demands new techniques to reliably measure and control the arrival time of the FEL-pulses at the experiment. For pump-probe experiments using external optical lasers the desired synchronisation is in the order of tens of femtoseconds, the typical duration of the FEL pulse. Since, the accelerators are large scale facilities of the length of several hundred meters or even kilometers, the problem of synchronisation has to be attacked twofold. First, the RF acceleration sections upstream of the magnetic bunch compressors need to be stabilised in amplitude and phase to high precision. Second, the remain electron beam timing jitter needs to be determined with femtosecond accuracy for off-line analysis. In this talk, several techniques using the electron or the FEL beam to monitor the arrival time are presented, and the proposed layout of the synchronisation system for the European XFEL towards the 10 fsec regime. | ||
| TOAD002 | Novel Tune Diagnostics for the Tevatron | 140 |
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| The Tevatron collides protons and antiprotons in the same beam pipe. This poses a challenge in the measurement of tunes for both species simultanously because of the possibility of signal contamination from the other species. On top of this, since both beams are in the same beam pipe, tunes of individual bunches are also important because tune shifts from the beam-beam effect affects each bunch differently. Three different tune diagnostics used in the Tevatron will be discussed in this paper: 1.7GHz Schottky pickups, 21.4 MHz Schottky pickups and 27 kHz baseband pickups. These pickups look at the tune spectrum at different frequency bands and provide useful physics information for each frequency regime. | ||
| TOAD003 | Development of the Beam Diagnostics System for the J-PARC Rapid-Cycling Synchrotron | 299 |
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| Development of the beam diagnostics system for the J-PARC (Japan Proton Accelerator Research Complex) Rapid-Cycling Synchrotron is described. The system consists of Beam Position Monitor (BPM), Beam Loss Monitor (BLM), Current monitors (DCCT, SCT, MCT, FCT, WCM), Tune meter system, 324MHz-BPM, Profile monitor, and Halo monitor. BPM electrode is electro-static type and its electronics is designed for both COD and turn-by-turn measurements. Five current monitors have different time constants in order to cover wide frequency range. The tune meter is consisted of RFKO and the beam pick-up electrode. For the continuous injected beam monitoring, 324MHz-BPM detects Linac frequency. Two types of profile monitor are multi-wire for low intensity tuning and the residual gas monitor for non-destructive measurement. | ||
| TOAD004 | The Possibility of Noninvasive Micron High Energy Electron Beam Size Measurement Using Diffraction Radiation | 404 |
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| During the last years a noninvasive method for beam size measurement based on the optical diffraction radiation (ODR) has been in progress (P. Karataev, et al., Physical Review Letters 93, 244802 (2004). However this technique encounters with hard sensitivity limitation for electron energies larger than several GeV. For example, for SLAC conditions the sensitivity of this method is 4 orders smaller than an appropriate one. We suggest to use a "dis-phased" slit target, where two semi-planes are turned with respect to each other at a small "dis-phased" angle. In order to ensure the interference between the diverged radiation beams we use a cylindrical lens. This method has much better sensitivity and resolution. A "dis-phased" angle 10 milliradians gives the optimal sensitivity to 5 microns transversal beam size. The theoretical model for calculating the ODR radiation from such targets (including focusing by cylindrical lens) is presented. It is shown that the sensitivity of this method does not depend on the Lorenz-factor directly. The target with the "dis-phased" angle 6.2 milliradians and the slit width 425 microns was manufactured for experimental test. Some preliminary experimental results are presented. | ||
| TOAD005 | Observation of Frequency Locked Coherent Transition Radiation | 452 |
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Funding: This work was supported by the Department of Energy, High Energy Physics, under contract DE-FG02-91ER40648. Measurements of frequency locked, coherent transition radiation (CTR) were performed at the 17 GHz high-gradient accelerator facility built by Haimson Research Corporation at MIT PSFC. CTR produced from a metallic foil placed in the beam path was extracted through a window, and measured with a variety of detectors, including: diode, Helium cooled Si Bolometer, and double heterodyne receiver system. The angular energy distribution measured by the diode and bolometer are in agreement and consistent with calculations for a 15 MeV 200 mA 110 ns beam of 1 ps bunches. Heterodyne receiver measurements were able to show frequency locking, namely inter-bunch coherence at integer multiples of the accelerator RF frequency of 17.14 GHz. At the locked frequencies the power levels are enhanced by the number of bunches in a single beam pulse. The CTR was measured as a comb of locked frequencies up to 240 GHz, with a bandwidth of 50 MHz. |
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| TOPC001 | Visualizing Electron Beam Dynamics and Instabilities with Synchrotron Radiation at the APS | 74 |
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38. The Advanced Photon Source (APS) is a third generation hard x-ray source serving a large user community. In order to characterize the high-brilliance beams, the APS diagnostics beamlines have been developed into a full photon diagnostics suite. We will describe the design and capabilities of the APS visible light imaging line, the bend magnet x-ray pinhole camera, and a unique diagnostics undulator beamline. Their primary functions are to support the APS user operations by providing information on beam sizes (20 - 100 micrometers), divergence (3 – 25 microradians), and bunch length (20 – 50 ps). Through the use of examples, we will show how these complementary imaging tools are used to visualize the electron dynamics and investigate beam instabilities. Special emphasis will be put on the use of undulator radiation, which is uniquely suitable for time-resolved imaging of electron beam with high spatial resolution, and for measurements of longitudinal beam properties such as beam energy spread and momentum compaction. |
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| TOPC002 | Residual-Gas-Ionization Beam Profile Monitors in RHIC | 230 |
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Funding: Work performed under Contract #DE-AC02-98CH10886 under the auspices of the U.S. Department of Energy. Four ionization profile monitors (IPMs) are in RHIC to measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. During the last two years both the collection accuracy and signal/noise ratio have been improved. An electron source is mounted across the beam pipe from the collector to monitor microchannel plate (MCP) aging and the signal electrons are gated to reduce MCP aging and to allow charge replenishment between single-turn measurements. Software changes permit simultaneous measurements of any number of individual bunches in the ring. This has been used to measure emittance growth rates on six bunches of varying intensities in a single store. Also the software supports FFT analysis of turn-by-turn profiles of a single bunch at injection to detect dipole and quadrupole oscillations. |
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| TOPC003 | Beam Measurements and Upgrade at BL 7.2, the Second Diagnostics Beamline of the Advanced Light Source | 281 |
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Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. Beamline BL 7.2 of the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory is a beam diagnostics system that uses the synchrotron radiation (SR) emitted by a dipole magnet. It consists of two branches, in the first one the x-ray portion of the SR is used in a pinhole camera system for measuring the transverse profile of the beam. The second branch is equipped with a x-ray BPM system and with a multipurpose port where the visible and the infrared part of the SR can be used for various applications such as bunch length measurements and IR coherent synchrotron radiation experiments. The pinhole system has been commissioned at the end of 2003 and since then is in successful operation. The installation of the second branch has been completed recently and the results of its commissioning are presented in this paper together with examples of beam measurements performed at BL 7.2. |
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| TOPC004 | Tevatron Beam Position Monitor Upgrade | 410 |
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Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. The Tevatron Beam Position Monitor (BPM) readout electronics and software have been upgraded to improve measurement precision, functionality and reliability. The original system, designed and built in the early 1980s, became inadequate for current and future operations of the Tevatron. The upgraded system consists of 960 channels of new electronics to process analog signals from 240 BPMs, new front-end software, new online and controls software, and modified applications to take advantage of the improved measurements and support the new functionality. The new system reads signals from both ends of the existing directional stripline pickups to provide simultaneous proton and antiproton position measurements. Measurements using the new system are presented that demonstrate its improved resolution and overall performance. |
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| TOPC005 | Transverse Emittance Blow-Up Due to the Operation of Wire Scanners, Analytical Predictions and Measurements | 437 |
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| Wire Scanner monitors are used in the CERN accelerators to measure the transverse beam size. In the SPS and the LHC they will serve as calibration devices for other emittance monitors. The PSB, PS and SPS are equipped with scanners which move through the beam a 30 um wire, with a speed that can vary between 0.4 to 20 m/s. During each scan, the beam suffers an emittance blow up, due to multiple Coulomb scattering of the beam protons on the lattice nuclei of the wire material. The effect depends on the particles' energy, the betatron function at the monitor location and on the wire characteristics (material, diameter and speed). In this paper we will present a comparison of the analytically predicted emittance increase caused by the instruments and a number of experimental measurements. For the small LHC beams the relative emittance blow-up can exceed a few 10e-2. |