| Paper | Title | Page |
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| MOPO001 | Interaction Point Feedback Design and Integrated Simulations to Stabilize the CLIC Final Focus* | 475 |
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| The Compact Linear Collider (CLIC) accelerator has strong precision requirements on offset position between the beams. The beam which is sensitive to ground motion needs to be stabilized to unprecedented requirements. Different Beam Based Feedback (BBF) algorithms such as Orbit Feedback (OFB) and Beam-Beam Offset Feedback (BBOF) have been designed. This paper focuses on the BBOF control which could be added to the CLIC baseline. It has been tested for different ground motion models in the presence of noises or disturbances and uses digital linear control with or without an adaptive loop. The simulations demonstrate that it is possible to achieve the required performances and quantify the maximum allowed noise level. This amount of admitted noises and disturbances is given in terms of an equivalent disturbance on the position of the magnet that controls the beam offset. Due to the limited sampling frequency of the process, the control loop is in a very small bandwidth. The study shows that these disturbances have to be lowered by other means in the higher frequency range. | ||
| MOPO002 | Fast Orbit Correction for the ESRF Storage Ring | 478 |
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| Today, at the ESRF, the correction of the orbit position is performed with two independent systems: one to deal with the slow movements and one to correct the motion in a range of up to 200Hz but with a limited number of fast BPMs and steerers. This later will be removed and one unique system will cover the frequency range from DC to 200Hz using all the 224 BPMs and the 96 steerers. Indeed, thanks to the procurement of the Liberas Brilliance and installation of new AC power supplies, it is now possible to access all the Beam positions at a frequency of 10 kHz and to drive a small current in the steerers in a 400Hz bandwidth. The first tests of correction of the beam position have been performed and will be presented. This new orbit correction system is also a powerful diagnostics system: the measurement and survey of the Ring's lattice parameters is possible thanks to the high measurement rate of very high resolution position data. Results of this will also be presented. | ||
| MOPO003 | A Broadband RF Stripline Kicker for Damping Transversal Multibunch Instabilities | 481 |
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| When operating an RF feedback system, being able to reliably act upon every single bunch is a necessity. By employing a broadband RF stripline kicker, any bunch displacement can be corrected for. In a 500 MHz accelerator, the decay time of the electromagnetic field inside the kicker has to be less than 2 ns in order to avoid the following bunch to be affected. By designing the kicker as an RF coax device matched to the line impedance of the power cables, perturbing reflected signals are avoided. Additionally, the kicking strength and thus the shunt impedance should be maximized over the full spectrum from DC to 250 MHz. The kicker design has been optimized to meet the above requirements by relying on CST Microwave Studio simulations. Their results and first measurements are presented. | ||
| MOPO004 | A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA | 484 |
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| At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented. | ||
| MOPO005 | A Transverse Feedback System using Multiple Pickups for Noise Minimization | 487 |
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| A new concept for using multiple pickups for estimating beam angle at the kicker is addressed. The estimated signal should be the driving feedback signal. The signals from the different pickups are delayed, such that they correspond to the same bunch. Consequently a weighted sum of the delayed signals is suggested as an estimator of the beam angle at the kicker. The weighting coefficients are calculated such that the estimator is unbiased, i.e. the output corresponds to the actual beam angle at the kicker for non-noisy pickup signals. Furthermore, the estimator must give the minimal noise power at the output among all linear unbiased estimators. Finally results for the heavy ions synchrotron SIS 18 at the GSI are shown. | ||
| MOPO006 | DAΦNE Bunch-by-bunch Feedback Upgrade as SuperB Design Test | 490 |
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| DAΦNE, the PHI-factory located in Frascati, has always shown dynamic behavior strongly dependent on the bunch-by-bunch feedback, since its first runs in 1997. Over the years, to keep up with the evolving machine requirements, transverse and longitudinal systems have received multiple upgrades and updates. During fall 2010, all the six DAΦNE feedback systems have been upgraded to support the next run for KLOE as well as to test bunch-by-bunch feedback architectures intended for the future Italian SuperB factory. Both e+/e- longitudinal feedback systems have been completely replaced with new hardware for increased reliability, better diagnostics and improved maintainability. In the effort to reduce residual dipole beam motion, determined by the front-end and quantization noise floor, vertical feedback systems now feature a 12-bit ADC, in place of the older 8-bit design. In the paper, we describe the hardware and software changes of this upgrade. Feedback performance analysis and beam dynamics data collected by the systems are presented. | ||
| MOPO007 | Resonant Strip-line Type Longitudinal Kicker | 493 |
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| The longitudinal feedback for the SPring-8 storage ring is under consideration as the device for suppression of the longitudinal instabilities driven by higher order modes of cavities, observed at test operation with 4 to 6 GeV low energy beam. As the beam energy and the ring circumference are rather high, and the length of the space for the longitudinal kickers is limited, high efficiency kicker per length is required in the our case. As a candidate of such kicker, we propose a resonant strip-line type longitudinal kicker with drive frequency of 13/4 of RF frequency. The shut impedance per length is higher than over-loaded cavities and the drive circuits can be simplified because of higher drive frequency. The design consideration, the result of the simulation and measurement of the prototype model, and the detail of the drive circuit will be reported in the presentation. | ||
| MOPO008 | Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ | 496 |
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| In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design. | ||
| MOPO010 | Orbit Feedback System for the MAX IV 3 GeV Storage Ring | 499 |
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| The paper describes the current orbit correction system design for the 3 GeV storage ring at the MAX IV laboratory, a light source facility under construction in Lund, Sweden. The orbit stability requirements for the 3 GeV storage ring are tight at roughly 200 nm vertical position stability in the insertion device (ID) straight sections. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and 380 dipole corrector magnets, 200 in the horizontal and 180 in the vertical plane. The feedback loop solution, one slow orbit feedback (SOFB) loop and one fast orbit feedback (FOFB) loop in fast acquisition mode at 10,000 samples/second, will be presented. The paper will also discuss the various boundary conditions specific to the MAX IV 3 GeV storage ring design, such as a Cu vacuum chamber, and the impact on the corrector design. | ||
| MOPO011 | The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC | 502 |
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| Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed. | ||
| MOPO012 | LHC Damper Beam Commissioning in 2010 | 505 |
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| The LHC transverse dampers were commissioned in 2010 with beam and their use at injection energy of 450 GeV, during the ramp and in collisions at 3.5 TeV for Physics have become part of the standard operations procedure. The system proved important to limit emittance blow-up at injection and maintain smaller than nominal emittances throughout the accelerating cycle. We describe the commissioning of the system step-by-step as done in 2010 and summarize its performance as achieved for proton as well as ion beams in 2010. Although its principle function is to keep transverse oscillations under control, the system has also been used as an exciter for abort gap cleaning and tune measurement. The dedicated beam position measurement system with its low noise properties provides additional possibilities for diagnostics. | ||
| MOPO013 | Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment | 508 |
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| The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed. | ||
| MOPO014 | SVD-based Filter Design for the Trajectory Feedback of CLIC | 511 |
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| The orbit feedback of the Compact Linear Collider (CLIC) is the basic counter-measure against ground motion effects below 1 Hz in the beam delivery system and the main linac of CLIC. In this paper we present significant improvements of the orbit feedback design, by using time-dependent and spatial filters. The design procedure is based on a singular value decomposition (SVD) of the orbit response matrix and on loop-shaping techniques. This modified design has essential advantages compared to previous ones. The required beam position monitor resolution in the beam delivery system could be relaxed by a factor of five. At the same time the suppression of ground motion effects is improved. As a consequence, the tight tolerances for the allowable luminosity loss due to ground motion effects in CLIC can be met. The presented methods can be easily adapted to other accelerators in order to relax sensor tolerances and to efficiently suppress ground motion effects. | ||
| MOPO015 | Operation Status of Bunch-by-bunch Feedback System in the TLS | 514 |
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| There are several FPGA based bunch-by-bunch feedback systems that were deployed in the Taiwan Light Source now. They play various roles to suppress beam instability. By using SPring-8 designed feedback processors is pioneer to apply in the storage ring of TLS successfully and help Dimtel system to be quick commission. The Dimtel feedback system provide a life spare unit and explore to control system integration especially to the EPICS toolkit system. Rich functionality includes of excitation of individual bunch or specifies bunches, averaged spectrum, tune measurement by the feedback dip in the averaged spectrum. Operation status of the system will be summary in this report. | ||
| MOPO016 | Commissioning Tune Feedback in the Taiwan Light Source | 517 |
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| The tune control is important parameter in the insertion devices operation. There are many difference type insertion devices are disturbed in the storage ring of TLS. The traditional feed-forward control to correct orbit change and tune shift that isn’t enough when difference type insertion devices are operated with various condition. The tune feedback is used to solve the tune change problem. The stable tune measurement is necessary in the stable storage ring. There are various excited bunch train methods to get stable tune that will be also discussed in this report. | ||
| MOPO017 | Latest Performance Results from the FONT5 Intra-train Position and Angle Feedback System at ATF2 | 520 |
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| A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. A total system latency as low as approximately 140 ns has been demonstrated. | ||
| MOPO018 | Active Beam Current Stabilization in the Cornell ERL Prototype Injector | 523 |
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| In order to operate the Cornell ERL prototype injector at beam currents beyond 10 mA, the beam current has to be highly stable. The reason is that fast beam current fluctuations generate transient effects in the DC gun voltage as well as in the fields of subsequent superconducting cavities, which can lead to excessive beam loss or to trips of subsystems. Therefore, a feedback scheme was developed which uses the signal of a beam current monitor as an input, and applies appropriate corrections to a Pockels cell installed within the laser path of the photo-injector laser. In this paper, high current results achieved with this feedback scheme are presented. | ||
| MOPO022 | Precision Beam Instrumentation and Feedback-Based Beam Control at RHIC | 526 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this report we present advances in beam instrumentation required for feedback-based beam control at the Relativistic Heavy Ion Collider (RHIC). Improved resolution has contributed to enabling now routine acceleration with multiple feedback loops. Better measurement and control of the beam’s properties have allowed acceleration at a new working point and have facilitated challenging experimental studies. |
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| MOPO023 | Laser-based Alignment System at the KEKB Injector Linac | 529 |
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| A laser-based alignment system is under development at the 500-m-long KEKB injector linac. The original system was designed and constructed more than thirty-years ago, and thus, we are revisiting our alignment system because the previous alignment system has become too obsolete. The new alignment system is again strongly required for the next generation SuperKEKB project. The new laser alignment system is similar to the previous one, which comprises a helium-neon laser and quadrant photodetectors installed in vacuum light pipes. A girder displacement of the accelerating structure can be precisely measured in the direction of the laser-ray trace, where the laser light must stably propagate up to 500-m downstream without any orbital and beam-size fluctuation. We tested the laser-ray propagation and the stability along a 100-m-long beam line under a vacuum condition of 0.1-1 Torr. In this paper, we will report the system description and test results in detail. | ||
| MOPO025 | Experimental Study on New Laser-based Alignment System utilizing a Sequential Three-point Method at the KEKB Injector Linac | 532 |
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| A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel lenses and a CCD camera is revisited in a preliminary design of the new alignment system. The new alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 200-m-long straight section at atmospheric pressure. In this report, the preliminary experimental results are reported along with the basic design of the new laser-based alignment system. | ||
| MOPO026 | Design, Manufacturing and Tests of Closed-loop Quadrupole Mover Prototypes for European XFEL | 535 |
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Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009 In this report the development of a quadrupole mover with submicron repeatability is reported, which will be used in the intersections of the Undulator Systems of the European XFEL (EXFEL). It is part of the Spanish in-kind contribution to this facility. The main specifications include submicron repeatability for a 70 kg quadrupole magnet within compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Compact linear actuators based on 5-phase stepping motors have been chosen. Vertical actuator works in a wedge configuration to take mechanical advantage. A closed-loop control system has been developed to achieve this repeatability. For the feedback, one LVDT sensor for each axis was used. Mechanical switches are used to limit movement. In addition, hard-stops are included for emergency. Prototyping stage is done and a serial production of more than 90 devices is expected, so intense work has been done to achieve a reliable industrial production and validation. In this report, results of mechanical measurements including reproducibility, tests of different operation strategies and critical situations will be reported. |
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| MOPO027 | Status of a Study of Stabilization and Fine Positioning of CLIC Quadrupoles to the Nanometre Level* | 538 |
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Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no.227579 Mechanical stability to the nanometre and below is required for the CLIC quadrupoles to frequencies as low as 1 Hz. An active stabilization and positioning system based on very stiff piezo electric actuators and inertial reference masses is under study for the Main Beam Quadrupoles (MBQ). The stiff support was selected for robustness against direct forces and for the option of incrementally repositioning the magnet with nanometre resolution. The technical feasibility was demonstrated by a representative test mass being stabilized and repositioned to the required level in the vertical and lateral direction. Technical issues were identified and the development programme of the support, sensors, and controller was continued to increase the performance, integrate the system in the overall controller, adapt to the accelerator environment, and reduce costs. The improvements are implemented in models, test benches, and design of the first stabilized prototype CLIC magnet. The characterization of vibration sources was extended to forces acting directly on the magnet, such as water-cooling induced vibrations. This paper shows the achievements, improvements, and an outlook on further R&D. |
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| MOPO028 | Modal Analysis and Measurement of Water Cooling Induced Vibrations on a CLIC Main Beam Quadrupole Prototype* | 541 |
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Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579. To reach the Compact Linear Collider (CLIC) design luminosity, the mechanical jitter of the CLIC main beam quadrupoles should be smaller than 1.5 nm integrated root mean square (r.m.s.) displacement above 1 Hz. A stiff stabilization and nano-positioning system is being developed but the design and effectiveness of such a system will greatly depend on the stiffness of the quadrupole magnet which should be as high as possible. Modal vibration measurements were therefore performed on a first assembled prototype magnet to evaluate the different mechanical modes and their frequencies. The results were then compared with a Finite Element (FE) model. The vibrations induced by water-cooling without stabilization were measured with different flow rates. This paper describes and analyzes the measurement results. |
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| MOPO029 | Validation of a Micrometric Remotely Controlled Pre-alignment System for the CLIC Linear Collider using a Test Setup (Mock-up) with 5 Degrees of Freedom | 544 |
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| The CLIC main beam quadrupoles need to be pre-aligned within 17μm rms with respect to a straight reference line along a sliding window of 200 m. A re-adjustment system based on eccentric cam movers, which will provide stiffness to the support assembly, is being studied. The cam movers were qualified on a 1 degree of freedom (DOF) test setup, where a repeatability of adjustment below 1 μm was measured along their whole range. This paper presents the 5 DOF mock-up, built for the validation of the eccentric cam movers, as well as the first results of tests carried out: resolution of displacement along the whole range, measurements of the support eigenfrequencies. | ||
| MOPO030 | Theoretical and Practical Feasibility Demonstration of a Micrometric Remotely Controlled Pre-alignment System for the CLIC Linear Collider | 547 |
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| The active pre-alignment of the Compact Linear Collider (CLIC) is one of the key points of the project: the components must be pre-aligned w.r.t. to a straight line within a few microns over a sliding window of 200 m, along the two linacs of 20 km each. The proposed solution consists of stretched wires of more than 200 m, overlapping over half of their length, which will be the reference of alignment. Wire Positioning Sensors (WPS), coupled to the supports to be pre-aligned, will perform precise and accurate measurements within a few microns, w.r.t. these wires. A micrometric fiducialisation of the components and a micrometric alignment of the components on common supports will make the strategy of pre-alignment complete. In this paper, the global strategy of active pre-alignment is detailed and illustrated by the latest results demonstrating the feasibility of the proposed solution. | ||
| MOPO031 | Alignment of theTPS Front-End Prototype | 550 |
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| The Taiwan Photon Source (TPS) is a 3-GeV third-generation source of synchrotron radiation with beam current 500 mA stored in the storage ring. A front end allows intense synchrotron light generated in the storage ring to pass through to a beamline. Most heat load of the synchrotron light is removed in the front ends to protect the beamline components. Alignment of front-end components becomes important to prevent damage from the large heat load. Because of the many front ends and the brief period of installation, the alignment work should be easy, quick and reliable. Using a shim method, the adjustable degrees of freedom are decreased from six to two. This adjustment work becomes easier and quicker. The alignment of a front-end prototype is described here. | ||
| MOPO032 | The Survey Status at NSRRC during the TPS Civil Construction | 553 |
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| In this paper, the survey status at NSRRC site duirng the TPS (Taiwan Photon Source) civil construction is described. The TLS (Taiwan Light Source) ring is still under operation in the meantime. In order to maintain the TLS for normal operation and also monitoring the building construction, an expanded survey setups including permanent leveling and GPS monuments were installed both on the site and TPS building. Combined with the orignal TLS survey sockets and sensor monitoring system (hydrostatic leveling system and precision inclination sensors) installed both in the TLS storage ring and beamlines, an extensive survey tasks were performed. The ground deformation situation of the TLS and deviation of the TPS building construction are presented. | ||
| MOPO033 | Design and Development of a Laser Positioning System for TPS Magnets Alignment Inspection during the Installation on a Girder | 556 |
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| A novel optical inspection architecture is designed and developed for positioning the TPS (Taiwan Photon Source) quadrupole and sextupole magnets on the girder within 30 um. This positioning system is a laser-based scheme consists of two laser position sensing devices (PSD) and two granite blocks as the standard reference of magnets. The laser position sensing device (PSD) is mounted on an adjustable circular steel module and the module is installed in a granite block. With the PSD position being adjusted and corrected, the PSD module center can be identical to the ideal pole position of magnets on the girder within 10um. The Laser ray is also adjusted and aligned according to the ideal reference line of magnets. Finally the granite blocks are replaced with the quadrupole and sextupole magnets at installation, the assembling error of magnets can be detected from the PSD module. This paper describes the detail of the system development and testing results. | ||
| MOPO034 | From Survey Alignment toward Auto-alignment for the Installation of the TPS Storage Ring Girder System | 559 |
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| The TPS (Taiwan Photon Source) project is now under civil construction. The whole building is constructed half underground and 12m deep compared to the TLS due to the stability consideration, so the survey and alignment works are quite confined and difficult. For positioning the magnets precisely and quickly, a high accuracy auto-tuning girders system combined with survey network procedures were established to accomplish the installation tasks. The position data from the survey network will define a basis for the motorized girder system to auto-tune and improve the accuracy. A mockup of one twenty-fourth section (one cell) had been installed at NSRRC for interface examination and further testing. In this paper, the procedures from the traditional survey network to auto-aliment system design and algorithm are described. Meanwhile, a preliminary testing result is also included. | ||
| MOPO035 | Stability of the Floor Slab at Diamond Light Source | 562 |
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| A Hydrostatic Leveling System (HLS) has been installed at Diamond Light Source. 8 sensors have been positioned along a 60 metre portion of the floor of the Storage Ring and the Experimental Hall, stretching out along a typical beamline route from Insertion Device to sample. Results since June 2008 are presented comparing actual performance with the original specification as well as identifying movements associated with environmental factors. | ||
| MOPO037 | Concept of Femtosecond Timing and Synchronization Scheme at ELBE | 565 |
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| The Radiation Source ELBE at Helmholtz-Zentrum Dresden-Rossendorf is undergoing an extension to offer capacity for various applications. The extension includes the setup of a THz-beamline with a dedicated laboratory and a beamline for electron-beam - high-power laser interaction. The current synchronization scheme offers stability on the picoseconds level. For pump-probe experiments using optical lasers, the desired synchronization between the pump and the probe pulse should be on the femtosecond scale. In the future there will be an optical synchronization system with a pulsed fiber laser as an optical reference. The laser pulses will be distributed over stabilized fiber links to the remote stations. It is planned to install EOM-based beam arrival time monitors (BAMs) in order to monitor the bunch jitter and to establish a beam-based feedback to reduce the jitter. Besides that, the timing system has to be revised to generate triggers for experiments with low repetition rate, two electron guns (thermionic DC, superconducting RF) and several lasers. The Poster will show the possible layout of the future Timing and Synchronization System at ELBE. | ||
| MOPO039 | B-train Performances at CNAO | 568 |
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| The commissioning of CNAO, the Italian Centre of Oncological Hadrontherapy, with proton beams is completed. The real-time measurement of the synchrotron dipole field with the so-called B-train, together with its electronic systems and related software and firmware are here described. An additional magnet, powered in series with the synchrotron dipoles, is equipped with a special coil that measures the field integral variation along the beam nominal path. The voltage induced in the coil is digitized with a fast ADC and numerically integrated by an FPGA. The field integral is then distributed to the users every time that the equivalent field changes by 0.1 G. The measured B field ranges from 0 to 1.6 T with maximum ramps of 3 T/s. The B-train system will be used to provide feedback in field to the dipole power supply. It will handle the limited bandwidth of the active filter, the B-field lag in the magnets and will avoid current jumps. | ||
| MOPO040 | RF Reference Distribution for the Taiwan Photon Source | 571 |
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| Taiwan Photon Source (TPS) is a low-emittance 3-GeV synchrotron light source with circumference of 518.4 m which is being under construction at National Synchrotron Radiation Research Center (NSRRC) campus. Low noise 500 MHz master oscillator and novel fiber based CW RF reference distribution system will be employed to take advantages of advanced technology in this field and deliver better performance. The preliminary test of the prototype system is summarized in this report. | ||
| MOPO041 | Preliminary Testing of TPS Timing System | 574 |
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| The timing system of Taiwan Photon Source (TPS) provides synchronization for electron gun, modulators of linac, pulse magnet power supplies, booster power supply ramp, bucket addressing of storage ring, diagnostic equipments, beamline gating signal for top-up injection. The timing system utilizes a central event generator to generate events and distribute them over optic fiber network, and decodes them at the event receivers. The system supports uplink functionality which will be used for the fast interlock system to distribute signals like beam dump and post-mortem trigger. The timing system has now been in operation for Linac of TPS. This paper presents prototype for the timing system of TPS. | ||
| MOPO042 | Photonic Crystal Fibre Laser for Electron Beam Emittance Measurement* | 577 |
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| We discuss the recent progress in the development of a high repetition rate, high energy fibre laser for intratrain laser-wire scans of transverse electron beam sizes. A commercial fibre laser (1uJ, 6.49MHz) is amplified in rod type photonic crystal fibre using a burst mode format, which has the advantage of allowing us to exploit very high transient gain while reducing the heat load deposited in the amplifier. The amplified pulses are over 180uJ spaced at 154ns, suitable for intratrain scanning at the ATF2. The spatial beam quality is excellent (M2 = 1.07), indicating that it will be possible to focus the laser to a spot size of ~ λ, enabling us to reach high intensities. The amplified pulse duration is 200ps, which can be compressed to less than the electron bunch length to increase the laser-wire signal to noise ratio. The performance of the laser system is analysed with respect to the demands of the laser-wire experiment. | ||
| MOPO043 | Applications of Lasers to Accelerator Physics at SSRL | 580 |
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| Recent advances in accelerator physics and SR research have generated the need for high-power lasers in the SPEAR3 accelerator complex. On the injector side, two lasers are being used to test different photocathode materials and to provide photo-assisted emission from the standard dispenser cathode RF gun. For the storage ring, both a TiSa oscillator and a fiber laser locked to the RF master oscillator have been used to characterize short-pulse electron bunches in cross-correlation experiments. These lasers are also used in SR experiments for pump-probe characterization of materials. In this paper we review the laser-based systems, preliminary results and outlook for the future. | ||
| MOPO044 | Bunch Length Measurements in Low-Alpha Mode at SPEAR3 with First Time-Resolved Pump/Probe Experiments* | 583 |
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Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515, Office of Basic Energy Sciences and SLAC Laboratory Directed Research Development funds (LDRD) The SPEAR3 synchrotron light source can be operated in low-alpha mode to generate x-ray pulse durations of order 1ps, well below streak camera resolution limits yet accessible by laser/sr cross-correlation measurements. Initial CC tests performed with a 50fs TiSa laser, frequency doubling BBO, photodiode and lock-in amplifier resolved bunch lengths down to about 6ps rms with 85uA single-bunch current. By reconfiguring the experimental setup to utilize a fiber laser, sum frequency generation and single photon counter it is now possible to measure profiles in the 1ps rms range with only 5uA single-bunch current. In this paper we report on the most recent measurements, simulations, modeling efforts and prospects for further improvement. |
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