ANL, Argonne
YerPhI, Yerevan
A 5-wire vibrating wire monitor (VWM005) was developed and tested at the Advanced Photon Source (APS). The sensor was mounted on the outboard side of a bending-magnet synchrotron radiation terminating flange in sector 37 of the APS storage ring. The parallel wires were separated vertically by 0.5 mm; however, due to the possibility of rotation about a horizontal axis, the effective distance between the wires was reduced by 30%. To increase the response speed, the sensor was installed in air, resulting in a step response time of less than one second. Due to the extreme sensitivity of the detector, the very hard x-ray component of synchrotron radiation was successfully measured after its passage through the terminating flange.
NewPath Research L.L.C., Salt Lake City
NewPath, Salt Lake City, Utah
We have shown that a group of sinusoidally-wound non-ferrous coaxial toroids can be used to determine the transverse distribution of a time-dependent current that passes through their common aperture. A single current filament requires one uniformly-wound toroid, and two others having turn densities proportional to the sine and cosine of the azimuthal coordinate. Three simple algebraic equations give the magnitude and phase of the current and its position in terms of the voltages induced on the three toroids, and there is no ill-conditioning. Two current filaments require two additional toroids with turn densities proportional to the sine and cosine of two times the azimuthal coordinate, and the solution may be obtained by using steepest descent to minimize the residuals. Ill-conditioning makes it impractical to use more than two currents. We have tested our algorithms numerically by specifying the magnitudes and phases of the currents and their locations, calculating the voltages that would be induced on the toroids, adding Gaussian noise to these voltages, and then using the algorithms to calculate the currents and their locations from the simulated voltage measurements.
KEK, Ibaraki
SLAC, Menlo Park, California
Dimtel, San Jose
A bunch-by-bunch feedback system has been developed to suppress longitudinal coupled-bunch instabilities at the KEK-PF. A generalpurpose signal processor, called iGp, has been developed by a collaboration among KEK, SLAC and INFN-LNF. A longitudinal kicker based on the DAΦNE-type over-damped cavity was designed and installed in the ring. The whole feedback loop was closed at the end of June 2007. The longitudinal dipole-mode instabilities are successfully suppressed up to 430 mA. The performance and the details of the system will be presented in this paper.
SLAC, Menlo Park, California
A dual-axis, synchroscan streak camera was used to measure temporal bunch profiles in three storage rings at SLAC: the PEP-II low-energy and high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient shift in synchronous phase along the bunch train due to RF-cavity loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To avoid the noise of a dual-axis sweep, we accumulated a single-axis synchroscan image over multiple turns while applying a 50-ns gate to the microchannel plate. To improve the extinction ratio, we synchronized this 2-kHz gate with an upstream mirror pivoting at 1 kHz to deflect light from other bunches off the axis. At SPEAR3 we compared the bunch length as a function of current for several lattices: achromatic, low-emittance and low momentum compaction. In the first two cases, resistive and reactive impedance components were extracted from the longitudinal bunch profiles. In the low-alpha configurations, we observed natural bunch lengths approaching the camera resolution, requiring special care to remove instrumental effects, and saw evidence of instability and periodic bursting.
KIP, Heidelberg
CERN, Geneva
GSI, Darmstadt
Synchrotron radiation has proven to be a flexible and effective tool for measuring a wide range of beam parameters in storage rings, in particular information about the longitudinal beam profile. It is today an established and widely used diagnostic method providing online measurements and thus allowing for continuous optimization of the machine performance. At the CLIC Test Facility (CTF3), synchrotron radiation is routinely used at a number of diagnostic stations, in particular in the Delay Loop and the Combiner Ring. Measurements with both standard CCDs and a streak camera showed the wide range of possible applications of this method, including determination of inter-bunch spacing, charge per pulse and monitoring of the manipulation of the effective path length by an undulator. This contribution first addresses the critical points during the design phase of long optical lines with lengths of more than 30 meters as they had to be realized at CTF3. Second, a summary of the present installations is given and results from measurements are shown.
SLAC, Menlo Park, California
Bunched beam signals from button-style Beam-Position Monitor (BPM) electrodes can have spectral content up to 20-30 GHz and time-domain structure of narrow impulsive trains. Multi-bunch feedback systems require receivers to process such beam signals and generate ΔX, ΔY, and ΔZ beam motion signals. To realistically test these receivers, we have developed a 4-bunch programmable impulse generator, which mimics the signals from a multi-bunch beam. Based on step-recovering diode techniques, this simulator produces modulated 100-ps impulse signals. The programmable nature of the system allows us to mimic Betatron and Synchrotron signals from 4 independent bunches with adjustable beam spacing from 1 to 8 ns. Moreover, we can observe nonlinear effects and study the noise floor and the resolution of the receiver. This paper presents the design of the system and shows typical achieved results.
J. Xu, J.D. Fox, D. Van Winkle
Stanford Linear Accelerator Center
Stanford, CA 94309, U.S.A.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
ALBA synchrotron light source is a 3rd generation light source being constructed by the CELLS consortium near Barcelona, Spain. Orbit correction system will be based on the Libera Brilliance electronics and its goal will be the stabilization of the beam at the submicron level. Important parameters to reach such corrections have been measured and are reported in this document, like electronics resolution, beam current dependence, latency (among others). Comparison of the two different Libera products offered by the company (Libera Electron and Libera Brilliance) is also reported in order to analyze the benefits of choosing Libera Brilliance.
Fermilab, Batavia
SLAC, Menlo Park, California
KEK, Ibaraki
A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring is currently in progress, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, also implementing a novel automatic gain error correction schema. The technical concept and realization, as well as preliminary results of the beam studies are presented.
GSI, Darmstadt
HIT, Heidelberg
The Heidelberg Ion Therapy Center (HIT) for tumor treatment is presently being commissioned using the beam diagnostic devices designed and produced by the GSI beam diagnostic department. To fulfil the requirements for hadron therapy a high-resolution analysis of the particle distribution within the slowly extracted beam is necessary. We present spill-structure measurements for carbon ion beams at energies from 88 MeV up to 430 MeV, also with respect to the spill-pause and abort functionality of the rf-knock-out extraction method. The spill-structure, as measured by internal intercepting ionization chambers (IC) is compared to data recorded with external beam loss monitors (BLM). The high-resolution data acquisition system with sampling rates up to 10 kSa/s and the connected detectors are described and the achievements during the commissioning phase are discussed.
BNL, Upton, Long Island, New York
NSLS-II Storage Ring will provide ultrabright radiation sources with extra small sizes of the circulating electron beam. The beam dimensions will be monitored with a pinhole camera. In this paper we discuss possible design and ultimate achievable resolution of the system. The modeling is based on the SRW code as well as numerical calculations using MATLAB.
Diamond, Oxfordshire
Top up is becoming more and more a standard mode of operation for synchrotron light sources. Although it brings a very stable source in terms of position and intensity, the regular injections potentially perturb the beam. In order to investigate the perturbation of the beam from imperfections of the injection kickers (i.e. non-closure of the bump), we use an X-ray pinhole camera equipped with a fast CMOS-sensor giving a rate of up to 3200 frames per second to monitor the image of the beam. The analysis of the observed beam size as well as position allows quantifying the perturbation from the kickers that can be seen on beamlines. In addition we compare the observed motion to bunch-by-bunch position data recorded in both vertical and horizontal planes, which reveals to be very complementary.
Fermilab, Batavia
Several complementary transverse emittance monitors have been developed and used at the Fermilab accelerator complex. These include Ionization Profile Monitors (IPM's), Flying Wires, Schottky detectors and a Synchrotron Light Monitor. Mechanical scrapers have also been used for calibration purposes. This paper describes the various measurement devices by examining their basic features, calibration requirements, systematic uncertainties, and applications to collider operation. A comparison of results from different kinds of measurements is also presented.
ANL, Argonne
The Advanced Photon Source (APS) injection booster is a 7-GeV electron synchrotron with a ramping time of 220 ms and a repetition rate of 2 Hz. A real-time tune measurement system is needed in order to monitor and possibly correct tune drift during the 220-ms energy ramp. Such a drift may occur during user beam operations, especially during top-up operations, and results in shot-to-shot charge fluctuations. We designed and developed a new FPGA-based system that pings the beam at variable intervals and measures booster tune. A prototype system has been built and tested, and it has achieved the specified time resolution of 2 ms and a tune resolution of better than 0.002. This report describes the design and main parameters, test results from our preliminary commissioning, and application of such a system in ramping correction.
INFN/LNF, Frascati (Roma)
Università degli Studi di Firenze, Firenze
INOA, Firenze
VIGO System S.A., Ozarow Maz.
Low cost bunch-by-bunch longitudinal diagnostics is a key issue of modern accelerators. To face up this challenging demand mid-IR compact uncooled PC HgCdTe detectors have been characterized at DAΦNE. These devices were used to monitor the emission of e- bunches. The first experiment allowed to record 2.7 ns long bunches in the e- ring with a FWHM of a single pulse of about 600 ps. To improve diagnostics at DAΦNE an exit port on a bending magnet of the e+ ring has been set-up to monitor the positron bunch structure. The front-end of this port includes an HV chamber hosting a gold-coated plane mirror that collects and deflects the radiation through a ZnSe window. After the window a simple optical layout in air will focus the radiation on IR detectors. The instrumentation will allow comparison in the ns time domain between the two rings and to identify and characterize bunch instabilities. To improve the established performances new faster IR photovoltaic detectors with sub-ns response times are under characterization. In this work we will present the actual status of the 3+L experiment and new measurements obtained with photovoltaic detectors on the e- ring.